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Giant freshwater prawn (Macrobrachium rosenbergii (MR)) is a significant aquafarm species commercially cultured in Taiwan. Intensive farming practices have led to the outbreak of Lactococcus garvieae (LG), which causes Lactococcosis in MR. Recently, LG has re‐emerged and the number of mortalities in prawn farms has increased in Taiwan. However, there is no preventative strategy described and a lack of knowledge on virulence factors and pathogenesis from LG in MR. The most virulent strain of L. garvieae from M. rosenbergii was screened in vivo among seven isolates selected for infectivity testing injecting 0.1 mL of 108 CFU/mL bacterial concentration. Among the seven isolates screened, L. garvieae 109‐6 resulted in 100% mortality within 3 days post‐infection. Furthermore, 109‐6 L. garvieae LD50 dosage from in MR was found to be 106 CFU/mL. Subsequently, the most virulent strain 109‐6 was sequenced using MinIon Nanopore sequencing. Results indicated that the LG genome yielded a protein‐coding of 3857 with 59 tRNA and 16 rRNA and no plasmid. Interestingly, the distribution of subsystems in the annotated genome revealed genes related to virulence, defence, and disease among LG 50 genes. Altogether, the virulent strain and its genome data revealed distinctive features of LG, which hinted toward its pathogenicity and could facilitate for better preventive strategies. [ABSTRACT FROM AUTHOR]

Viili is ropey and sticky traditional fermented milk that originated in Scandinavia. In this study, raw hazelnut milk (HM) with a nutritionally rich composition was used in developing new plant-based fermented products by using Viili starter cultures in order to produce health-promoting and functional plant-based dairy-like products. For this purpose, physicochemical, microbiological, and sensory properties were determined by producing Viili yogurt from both raw cow milk (VY) and fermented HM. Microbial analysis results showed that the defined formulation yielded high probiotic survivals (6.68–7.14 log CFU/g of TMAB, 6.90–7.85 log CFU/g of yeast-mold, 5.80–7.91 log CFU/g of LAB, and 5.14–7.60 log CFU/g of Lactococcus spp.) during the storage period. Sensory analysis showed that the properties of FHM such as color and appearance, structure, consistency, flavor, and odor were less appreciated than VY, whereas some other properties were found to be sufficient for consumption. [ABSTRACT FROM AUTHOR]

Background: Gut microbiota and its by‐products are increasingly recognized as having a decisive role in cardiovascular diseases. The aim is to study the relationship between gut microbiota and early vascular ageing (EVA). Methods: A cross‐sectional study was developed in Salamanca (Spain) in which 180 subjects aged 45–74 years were recruited. EVA was defined by the presence of at least one of the following: carotid‐femoral pulse wave velocity (cf‐PWV), cardio‐ankle vascular index (CAVI) or brachial‐ankle pulse wave velocity (ba‐PWV) above the 90th percentile of the reference population. All other cases were considered normal vascular ageing (NVA). Measurements: cf‐PWV was measured by SphygmoCor® System; CAVI and ba‐PWV were determined by Vasera 2000® device. Gut microbiome composition in faecal samples was determined by 16S rRNA Illumina sequencing. Results: Mean age was 64.4 ± 6.9 in EVA group and 60.4 ± 7.6 years in NVA (p <.01). Women in EVA group were 41% and 53% in NVA. There were no differences in the overall composition of gut microbiota between the two groups when evaluating Firmicutes/Bacteriodetes ratio, alfa diversity (Shannon Index) and beta diversity (Bray‐Curtis). Bilophila, Faecalibacterium sp.UBA1819 and Phocea, are increased in EVA group. While Cedecea, Lactococcus, Pseudomonas, Succiniclasticum and Dielma exist in lower abundance. In logistic regression analysis, Bilophila (OR: 1.71, 95% CI: 1.12–2.6, p =.013) remained significant. Conclusions: In the studied Spanish population, early vascular ageing is positively associated with gut microbiota abundance of the genus Bilophila. No relationship was found between phyla abundance and measures of diversity. [ABSTRACT FROM AUTHOR]

Depression is one of the most common psychiatric conditions worldwide, with an annual escalation in prevalence. The serotonin (5‐Hydroxytryptamine [5‐HT]) metabolism through the gut–brain axis has been revealed to be related to the development of depression. Our previous study demonstrated that Lactococcus lactis WHH2078 alleviated depression in mice by shaping the gut microbiome composition and 5‐HT metabolism. However, little research has explored the synergistic effects of probiotics and natural mental health‐improving products. In this study, three natural products (saffron, l‐theanine, and phosphatidylserine), either individually or in combination, were orally administrated for 4 weeks in chronic restraint stress (CRS)‐induced mice, and their depressive behaviors, hippocampal 5‐HT, and serum corticosterone were assessed. Saffron demonstrated improvement of the depressive‐like behaviors via multiple behavioral tests and reversed the declined concentration of 5‐HT and increased concentration of corticosterone. Following an initial screening, saffron was chosen to be combined with WHH2078, referred to as WHHMOOD™. Furthermore, the effects of WHHMOOD were evaluated in mice with depressive‐like behaviors. WHHMOOD reduced immobility time in the forced swimming test and tail suspension test, increased the time spent in the central area in open field test, and reduced the serum corticosterone level. Besides, WHHMOOD improved the CRS‐induced gut microbial dysbiosis by reversing gut microbial diversity and the abundances of Ligilactobacillus, Candidatus Arthromitus, and Erysipelatoclostridium. Compared to WHH2078, WHHMOOD treatment significantly increased the travel distance and hippocampal 5‐HT level in mice. In conclusion, WHHMOOD exhibited prophylactic effects on depressive‐like in CRS mice, which may act as a promising agent for improving the symptoms of depression. [ABSTRACT FROM AUTHOR]

Lactococcosis is a common bacterial fish disease caused by Lactococcus garvieae, L. petauri and L. formosensis. Although there are different PCR‐based techniques to identify the etiological agent, none of these can differentiate these two bacteria without sequencing PCR‐amplified fragments. In the present study, we developed a multiplex PCR assay for simultaneous detection and differentiation of L. garvieae and L. petauri. The specificity of the primers was validated against the bacterial DNA of the targeted and non‐targeted bacteria. The sizes of the PCR amplicons were obtained as 204 bp for the DUF1430 domain‐containing protein gene of L. garvieae, 465 bp for the Lichenan permease IIC component gene of L. petauri, and 302 bp for the teichoic acid biosynthesis protein F gene of both L. garvieae and L. petauri. The PCR amplicons were clearly separated by agarose gel electrophoresis. The multiplex PCR assay did not produce any amplification products with the DNA of the non‐targeted bacteria. The multiplex PCR detection limits for L. garvieae and L. petauri were 5 and 4 CFU in pure culture and 50 and 40 CFU/g in spiked tissue samples, respectively. It takes less than 2 h from plate‐cultured bacteria and 3 h from tissue samples to get results. In conclusion, the developed multiplex PCR assay is a rapid, specific, accurate, and cost‐effective method for the detection and differentiation of L. garvieae and L. petauri and is suitable to be used for routine laboratory diagnosis of L. garvieae and L. petauri. [ABSTRACT FROM AUTHOR]

Being generally regarded as safe, Kluyveromyces lactis has been widely taken for food, feed, and pharmaceutical applications, owing to its ability to achieve high levels of protein secretion and hence being suitable for industrial production of heterologous proteins. Production platform strains can be created through genetic engineering; while prototrophic cells without chromosomally accumulated antibiotics resistance genes have been generally preferred, arising the need for dominant counterselection. We report here the establishment of a convenient counterselection system based on a Frs2 variant, Frs2v, which is a mutant of the alpha-subunit of phenylalanyl-tRNA synthase capable of preferentially incorporating a toxic analog of phenylalanine, r-chloro-phenylalanine (4-CP), into proteins to bring about cell growth inhibition. We demonstrated that expression of Frs2v from an episomal plasmid in K. lactis could make the host cells sensitive to 2 mM 4-CP, and a Frs2v-expressing plasmid could be efficiently removed from the cells immediately after a single round of cell culturing in a 4-CP-contianing YPD medium. This Frs2v-based counterselection helped us attain scarless gene replacement in K. lactis without any prior engineering of the host cells. More importantly, counterselection with this system was proven to be functionally efficient also in Saccharomyces cerevisiae and Komagataella phaffii, suggestive of a broader application scope of the system in various yeast hosts. Collectively, this work has developed a strategy to enable rapid, convenient, and high-efficiency construction of prototrophic strains of K. lactis and possibly many other yeast species, and provided an important reference for establishing similar methods in other industrially important eukaryotic microbes. [ABSTRACT FROM AUTHOR]

Lactococcus garvieae has recently been identified and listed as one of the causative agents of hyperacute hemorrhagic sepsis in fish. In intensive recirculating aquaculture systems where there are high fish densities and minimal water changes, not only will it be conducive to the growth of bacteria, but Cryptocaryon irritans as a marine protozoan fish parasite is also prone to appear. This study reports the disease status of Trachinotus ovatus in an aquaculture area in Yangjiang City, Guangdong Province. Through the diagnosis of clinical symptoms of the diseased fish, identification of specific primers, 16s rRNA sequences phylogenetic tree analysis, physiological and biochemical identification, and observation of histopathological sections, the result of the experiment is that the mass death of T. ovatus is caused by a mixture of L. garvieae and C. irritants infections. Subsequently, regression infection experiments were performed to verify Koch's law. It was confirmed that the pathogen had strong virulence to T. ovatus. This is the first time that the co-infection of L. garvieae and C. irritans to T. ovatus was found in South China. The research results of this experiment have certain enlightenment significance for the epidemic trend of fish diseases in relevant sea areas. [ABSTRACT FROM AUTHOR]

Background: Given the increasing interest in the role of gut microbiota in glioblastoma multiforme (GBM), our objective was to examine the potential causal relationship between gut microbiota and GBM, as well as the mediating effects of specific metabolites. Methods: A bidirectional two-sample Mendelian randomization (MR) analysis was conducted to investigate the associations between 196 microbial taxa and GBM. A two-step MR technique was used to identify significant mediators in this relationship. Subsequently, a mediation analysis was performed to explore and quantify the mediating effects of specific metabolites on the causal relationship between gut microbiota and GBM. Results: Five taxa showed significant associations with GBM. Among them, family Victivallaceae [odds ratio (OR): 1.95; 95% confidence interval (CI): 1.21, 3.13; p = 0.005] and genus Lactococcus (OR: 1.81; 95% CI: 1.04, 3.15; p = 0.036) were positively correlated with the risk of GBM, while phylum Cyanobacteria had a protective effect against GBM (OR: 0.45; 95% CI: 0.22, 0.89; p = 0.021). The mediation analysis revealed that the connections among family Victivallaceae, genus Lactococcus, phylum Cyanobacteria and GBM were mediated by Methyl-4-hydroxybenzoate sulfate, phosphoethanolamine and dehydroepiandrosterone sulfate. Each of these accounted for 7.27, 7.98, and 8.65%, respectively. Conclusion: Our study provides evidence supporting a potential causal association between certain gut microbiota taxa and GBM. The study highlights the central role of gut microbiota in GBM pathogenesis and their interactions with vital serum metabolites. This paves the way for potential novel therapeutic interventions in GBM management. [ABSTRACT FROM AUTHOR]

Lactococcus lactis is a lactic acid bacterium of major importance for food fermentation and biotechnological applications. The ability to manipulate its genome quickly and easily through competence for DNA transformation would accelerate its general use as a platform for a variety of applications. Natural transformation in this species requires the activation of the master regulator ComX. However, the growth conditions that lead to spontaneous transformation, as well as the regulators that control ComX production, are unknown. Here, we identified the carbon source, nitrogen supply, and pH as key factors controlling competence development in this species. Notably, we showed that these conditions are sensed by three global regulators (i.e., CcpA, CodY, and CovR), which repress comX transcription directly. Furthermore, our systematic inactivation of known signaling systems suggests that classical pheromone-sensing regulators are not involved. Finally, we revealed that the ComX-degrading MecA-ClpCP machinery plays a predominant role based on the identification of a single amino-acid substitution in the adaptor protein MecA of a highly transformable strain. Contrasting with closely-related streptococci, the master competence regulator in L. lactis is regulated both proximally by general sensors and distantly by the Clp degradation machinery. This study not only highlights the diversity of regulatory networks for competence control in Gram-positive bacteria, but it also paves the way for the use of natural transformation as a tool to manipulate this biotechnologically important bacterium. Author summary: Lactic acid bacteria play important roles in our daily lives as microbiota members or fermentation starters. Understanding the natural horizontal gene transfer mechanisms that shape their genomes will allow us to better control and understand their evolution over time. This study identified the physiological conditions that activate competence for DNA transformation in Lactococcus lactis, one of the most important lactic acid bacteria. We also unveiled the guardians of the master competence regulator, ComX. In this species, global carbon and nitrogen regulators, as well as a general stress system, directly repressed its production instead of its activation by classical cell-to-cell communication systems as reported in streptococci. Furthermore, it was discovered that ComX degradation, orchestrated by the Clp machinery, plays a dominant role in the strict control of competence activation. This alternative regulation model could inspire future work aiming to uncover competence regulation networks in other Gram-positive bacteria with important medical or biotechnological implications. [ABSTRACT FROM AUTHOR]

In recent years, the use of natural preservatives in food products has gained significant attention due to their potential health benefits and effectiveness. A standardized microbiological analysis was conducted on Slovak farm-produced lump goat cheese samples to determine the antibacterial activity of dry herbs and essential oils added to vacuum-packed goat cheese. We employed five dried herbs and five essential oils derived from the same plants. The microbiological quality of 145 fresh and vacuum-packed goat cheese samples was assessed. The number of coliform bacteria, total viable count, lactic acid bacteria, and microscopic filamentous fungi were examined in raw cheese samples stored for 12 days at 4 °C. All cheese samples were vacuum-packed (control samples were packed without vacuum). This study evaluated the potential benefits of using essential oils and dried herbs from thyme (Thymus serpyllum L.), black pepper (Piper nigrum L.), clove (Eugenia caryophyllus Thunb.), mint (Mentha × piperita L.), and basil (Ocimum basilicum L.) as preservatives. The essential oils were obtained from Hanus Ltd., Nitra, Slovakia, and were applied at a concentration of 2%. The dried herbs were obtained from Popradský čaj (Poprad, Slovakia) and Mäspoma Ltd. (Zvolen, Slovakia). The results showed that all microorganism groups were significantly reduced in cheese samples following the application of essential oils throughout the entire storage period. During the preservation of cheese samples in polyethylene bags used for vacuum packing food, Lactococcus garvieae, L. lactis, Enterobacter cloacae, and Serratia liquefaciens were the most frequently isolated microbiota. Essential oils and dried herbs demonstrated antimicrobial potential during the storage of vacuum-packed goat cheese. [ABSTRACT FROM AUTHOR]

The present work reports the development and validation of a chromosomal expression system in Streptococcus pneumoniae which permits gene expression under the control of Lactococcus lactis lantibiotic nisin. The system is based on the integrative and conjugative element (ICE) Tn5253 of S. pneumoniae capable of site-specific chromosomal integration and conjugal transfer to a variety of bacterial species. We constructed an insertion vector that integrates in Tn5251, an ICE contained in Tn5253, which carries the tetracycline resistance tet(M) gene. The vector contains the nisRK regulatory system operon, the L. lactis nisin inducible promoter PnisA upstream of a multiple cloning site for target DNA insertion, and is flanked by two DNA regions of Tn5251 which drive homologous recombination in ICE Tn5253. For system evaluation, the emm6.1::ha1 fusion gene was cloned and integrated into the chromosome of the Tn5253-carrying pneumococcal strain FR24 by transformation. This gene encodes a fusion protein containing the signal peptide, the 122 N-terminal and the 140 C-terminal aa of the Streptococcus pyogenes M6 surface protein joined to the HA1 subunit of the influenza virus A hemagglutinin. Quantitative RT-PCR analysis carried out on total RNA purified from nisin treated and untreated cultures showed an increase in emm6.1::ha1 transcript copy number with growing nisin concentration. The expression of M6-HA1 protein was detected by Western blot and quantified by Dot blot, while Flow cytometry analysis confirmed the presence on the pneumococcal surface. Recombinant ICE Tn5253::[nisRK]-[emm6.1::ha1] containing the nisin-inducible expression system was successfully transferred by conjugation in different streptococcal species including Streptococcus gordonii, S. pyogenes, Streptococcus agalactiae and Enterococcus faecalis. As for S. pneumoniae, the emm6.1::ha1 transcript copy number and the amount of M6-HA1 protein produced correlated with the nisin concentration used for induction in all investigated bacterial hosts. We demonstrated that this host-vector expression system is stably integrated as a single copy within the bacterial chromosome, is transferable to both transformable and non transformable bacterial species, and allows fine tuning of protein expression modulated by nisin concentration. These characteristics make our system suitable for a wide range of applications including complementation assays, physiological studies, host-pathogen interaction studies. [ABSTRACT FROM AUTHOR]

Abstract Background Emerging evidence emphasized the role of oral microbiome in oral lichen planus (OLP). To date, no dominant pathogenic bacteria have been identified consistently. It is noteworthy that a decreased abundance of Streptococcus, a member of lactic acid bacteria (LAB) in OLP patients has been commonly reported, indicating its possible effect on OLP. This study aims to investigate the composition of LAB genera in OLP patients by high-throughput sequencing, and to explore the possible relationship between them. Methods We collected saliva samples from patients with OLP (n = 21) and healthy controls (n = 22) and performed 16 S rRNA gene high-throughput sequencing. In addition, the abundance of LAB genera was comprehensively analyzed and compared between OLP and HC group. To verify the expression of Lactococcus lactis, real time PCR was conducted in buccal mucosa swab from another 14 patients with OLP and 10 HC. Furthermore, the correlation was conducted between clinical severity of OLP and LAB. Results OLP and HC groups showed similar community richness and diversity. The members of LAB, Lactococcus and Lactococcus lactis significantly decreased in saliva of OLP cases and negatively associated with OLP severity. In addition, Lactococcus and Lactococcus lactis showed negative relationship with Fusobacterium and Aggregatibacter, which were considered as potential pathogens of OLP. Similarly, compared with healthy controls, the amount of Lactococcus lactis in mucosa lesion of OLP patients was significantly decreased. Conclusions A lower amount of Lactococcus at genus level, Lactococcus lactis at species level was observed in OLP cases and associated with disease severity. Further studies to verify the relationship between LAB and OLP, as well as to explore the precise mechanism is needed.

This study aimed to explore whether Lactococcus G423 could improve growth performance and lipid metabolism of broilers by the modulation of gut microbiota and metabolites. A total of 640 1-day-old AA broilers were randomly divided into 4 groups [Control (CON), Lac_L, Lac_H, and ABX]. Average daily gain (ADG), average daily feed intake (ADFI), feed conversion ratio (FCR), breast muscle, thigh muscle, and abdominal fat pad were removed and weighed at 42 days of age. Serum was obtained by centrifuging blood sample from jugular vein (10 mL) for determining high-density lipoprotein (HDL), total cholesterol (TC), low-density lipoprotein (LDL), and triglyceride (TG) using ELISA. The ileal contents were harvested and immediately frozen in liquid nitrogen for 16S rRNA and LC-MS analyses. Then, the results of 16S rRNA analysis were confirmed by quantitative polymerase chain reaction (qPCR). Compared with the CON group, FCR significantly decreased in the Lac_H group (p < 0.05) in 1-21 days; ADG significantly increased and FCR significantly decreased in the Lac_H group (p < 0.05) in 22-42 days. 42 days weight body and ADG significantly increased in the Lac_H group (p < 0.05) in 42 days. Abdominal fat percentage was significantly decreased by Lactococcus G423 (p < 0.05), the high dose of Lactococcus G423 significantly decreased the serum of TG, TC, and LDL level (p < 0.05), and the low dose of Lactococcus G423 significantly decreased the serum of TG and TC level (p < 0.05). A significant difference in microbial diversity was found among the four groups. Compared with the CON group, the abundance rates of Firmicutes and Lactobacillus in the Lac_H group were significantly increased (p < 0.05). The global and overview maps and membrane transport in the Lac_L, Lac_H, and ABX groups significantly changed versus those in the CON group (p < 0.05). The results of LC-MS demonstrated that Lactococcus could significantly improve the levels of some metabolites (6-hydroxy-5-methoxyindole glucuronide, 9,10-DiHOME, N-Acetyl-l-phenylalanine, and kynurenine), and these metabolites were involved in four metabolic pathways. Among them, the pathways of linoleic acid metabolism, phenylalanine metabolism, and pentose and glucuronate interconversions significantly changed (p < 0.05). Lactococcus G423 could ameliorate growth performance and lipid metabolism of broilers by the modulation of gut microbiota and metabolites. [ABSTRACT FROM AUTHOR]

Background: Emerging evidence emphasized the role of oral microbiome in oral lichen planus (OLP). To date, no dominant pathogenic bacteria have been identified consistently. It is noteworthy that a decreased abundance of Streptococcus, a member of lactic acid bacteria (LAB) in OLP patients has been commonly reported, indicating its possible effect on OLP. This study aims to investigate the composition of LAB genera in OLP patients by high-throughput sequencing, and to explore the possible relationship between them. Methods: We collected saliva samples from patients with OLP (n = 21) and healthy controls (n = 22) and performed 16 S rRNA gene high-throughput sequencing. In addition, the abundance of LAB genera was comprehensively analyzed and compared between OLP and HC group. To verify the expression of Lactococcus lactis, real time PCR was conducted in buccal mucosa swab from another 14 patients with OLP and 10 HC. Furthermore, the correlation was conducted between clinical severity of OLP and LAB. Results: OLP and HC groups showed similar community richness and diversity. The members of LAB, Lactococcus and Lactococcus lactis significantly decreased in saliva of OLP cases and negatively associated with OLP severity. In addition, Lactococcus and Lactococcus lactis showed negative relationship with Fusobacterium and Aggregatibacter, which were considered as potential pathogens of OLP. Similarly, compared with healthy controls, the amount of Lactococcus lactis in mucosa lesion of OLP patients was significantly decreased. Conclusions: A lower amount of Lactococcus at genus level, Lactococcus lactis at species level was observed in OLP cases and associated with disease severity. Further studies to verify the relationship between LAB and OLP, as well as to explore the precise mechanism is needed. [ABSTRACT FROM AUTHOR]

Aquaculturists use polyploid fish to maximize production albeit with some unintended consequences including compromised behaviors and physiological function. Given benefits of probiotic therapies (e.g., improved immune response, growth, and metabolism), we explored probiotic supplementation (mixture of Bifidobacterium, Lactobacillus, and Lactococcus), to overcome drawbacks. We first examined fish gut bacterial community composition using 16S metabarcoding (via principal coordinate analyses and PERMANOVA) and determined probiotics significantly impacted gut bacteria composition (p = 0.001). Secondly, we examined how a genomic disruptor (triploidy) and diet supplements (probiotics) impact gene transcription and behavioral profiles of hatchery‐reared Chinook salmon (Oncorhynchus tshawytscha). Juveniles from four treatment groups (diploid‐regular feed, diploid‐probiotic feed, triploid‐regular feed, and triploid‐probiotic feed; n = 360) underwent behavioral assays to test activity, exploration, neophobia, predator evasion, aggression/sociality, behavioral sensitivity, and flexibility. In these fish, transcriptional profiles for genes associated with neural functions (neurogenesis/synaptic plasticity) and biomarkers for stress response and development (growth/appetite) were (i) examined across treatments and (ii) used to describe behavioral phenotypes via principal component analyses and general linear mixed models. Triploids exhibited a more active behavioral profile (p = 0.002), and those on a regular diet had greater Neuropeptide Y transcription (p = 0.02). A growth gene (early growth response protein 1, p = 0.02) and long‐term neural development genes (neurogenic differentiation factor, p = 0.003 and synaptysomal‐associated protein 25‐a, p = 0.005) impacted activity and reactionary profiles, respectively. Overall, our probiotic treatment did not compensate for triploidy. Our research highlights novel applications of behavioral transcriptomics for identifying candidate genes and dynamic, mechanistic associations with complex behavioral repertoires. [ABSTRACT FROM AUTHOR]

Nisin is used as a natural food preservative because of its broad-spectrum antimicrobial activity against Gram-positive bacteria. However, free nisin is susceptible to various factors that reduce its antimicrobial activity. Milk protein, a protein derived from milk, has self-assembly properties and is a good carrier of bioactive substances. In this study, lactoferrin–nisin nanoparticles (L-N), bovine serum albumin–nisin nanoparticles (B-N), and casein–nisin nanoparticles (C-N) were successfully prepared by a self-assembly technique, and then their properties were investigated. The studies revealed that lactoferrin (LF) and nisin formed L-N mainly through hydrophobic interactions and hydrogen bonding, and L-N had the best performance. The small particle size (29.83 ± 2.42 nm), dense reticular structure, and good thermal stability, storage stability, and emulsification of L-N laid a certain foundation for its application in food. Further bacteriostatic studies showed that L-N enhanced the bacteriostatic activity of nisin, with prominent inhibitory properties against Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus, which mainly disrupted the cell membrane of the bacteria. The above results broaden our understanding of milk protein–nisin nanoparticles, while the excellent antibacterial activity of L-N makes it promising for application as a novel food preservative, which will help to improve the bioavailability of nisin in food systems. [ABSTRACT FROM AUTHOR]

Aquaculture plays an important role in meeting human demand for animal protein. Disease is a critical factor that restricts the green and healthy development of aquaculture. Intensive aquaculture practices can increase the susceptibility of aquatic animals to pathogens due to environmental stress. Antibiotics are commonly used for disease prevention and control, but their frequent use in aquaculture can increase the risk of antibiotic‐resistant bacteria and resistance gene transmission, posing a threat to the health of aquatic animals and humans. Recent studies have shown that bacteriocins have inhibitory effects on different species of bacteria, fungi and viruses, and can even affect natural resistance structures such as bacterial biofilms, presenting promising prospects as antimicrobial agents. Bacteriocins have potential applications in various fields such as agriculture, food and medicine, but limited research has been conducted on their impact on aquaculture disease prevention and control, and the underlying mechanisms remain to be explored. Therefore, this review aims to summarise the classification, sources, preparation methods, antibacterial activity against multidrug‐resistant bacteria and application of bacteriocins as antimicrobial agents in aquaculture disease prevention and control. In addition, limitations of bacteriocin application in aquaculture and future research directions are also discussed. [ABSTRACT FROM AUTHOR]

There is a growing demand from consumers on functional food and beverages. Potential probiotics such as L. lactis could be incorporated into food and beverages as a value-added ingredient. However, sufficient viable cell counts are required to be present in the food or beverages products to confer health benefits to hosts. Therefore, this study aimed to encapsulate food-grade recombinant L. lactis NZ3900 in 1:1, 2:1, and 3:1 ratio of sodium alginate-resistant starch matrix using co-extrusion technique and evaluate its storage stability in coconut water. All the microbeads were spherical with size ranged from 528.33 to 560.67 μm. The microbeads with 2:1 ratio sodium alginate-resistant starch had the highest microencapsulation efficiency (91.1%) and highest survivability (78.4%) after 6 h of simulated sequential digestion. After 4 weeks of storage, L. lactis microbeads had higher survivability in coconut water with 11.4 log10 CFU/g and lesser reduction in total soluble solids than free cells. There was no significant difference (p > 0.05) between the coconut water with free cells and microbeads in terms of pH, titratable acidity, and viscosity after 4 weeks of storage. At the end of the storage, the coconut water with microbeads had pH 3.9, 0.32% malic acid, 5.4 °Brix, 1.4 cP of viscosity, and total colour changes of < 1.26. This study shows that co-extrusion technique with sodium alginate-resistant starch matrix are suitable for the formation of L. lactis microbeads. Moreover, the stability of the L. lactis microbeads in coconut water showed its potential to be marketed as a functional isotonic beverage. [ABSTRACT FROM AUTHOR]

Nisin is a bacteriocin produced by Lactococcus lactis and it is generally recognised as safe by the U.S. Food and Drug Administration. The study aimed to determine the presence of nisin-resistant Staphylococcus , Enterococcus, and Listeria spp. in 157 raw milk and 125 cheese samples. As a result of the isolation procedure, a total of 282 bacterial strains were isolated. 83/282 strains showed resistance to 300 ppm nisin concentration and they were identified by 16S rRNA sequencing. The two most common species were Enterococcus faecalis and Staphylococcus aureus. In both raw milk and cheese samples, nisin-resistant Listeria could not be detected. Generally, enterococci (59/65) showed higher biofilm formation ability than staphylococci (13/18). 38% (25/65) of enterococci and 88% (16/18) of staphylococci were determined to have protease activity in at least one of Skim Milk Agar, Casein Agar, or Milk Agar. In addition, the most common antibiotic resistance in nisin-resistant enterococci was against chloramphenicol. This study revealed that nisin-resistant staphylococci and enterococci are present in raw milk and cheese. In addition, the presence of some virulence factors such as biofilm production, protease activity, and antibiotic resistance in resistant isolates needs to be drawn attention to. Consumption of nisin-resistant microorganisms with virulence factors through food is a food safety risk. [ABSTRACT FROM AUTHOR]

Aims: This study investigates the activity of the broad-spectrum bacteriocin nisin against a large panel of Gram-negative bacterial isolates, including relevant plant, animal, and human pathogens. The aim is to generate supportive evidence towards the use/inclusion of bacteriocin-based therapeutics and open avenues for their continued development. Methods and Results: Nisin inhibitory activity was screened against a panel of 575 strains of Gram-negative bacteria, encompassing 17 genera. Nisin inhibition was observed in 309 out of 575 strains, challenging the prevailing belief that nisin lacks effectiveness against Gram-negative bacteria. The genera Acinetobacter, Helicobacter, Erwinia, and Xanthomonas exhibited particularly high nisin sensitivity. Conclusions: The findings of this study highlight the promising potential of nisin as a therapeutic agent for several key Gram-negative plant, animal, and human pathogens. These results challenge the prevailing notion that nisin is less effective or ineffective against Gram-negative pathogens when compared to Gram-positive pathogens and support future pursuits of nisin as a complementary therapy to existing antibiotics. Significance and Impact of Study: This research supports further exploration of nisin as a promising therapeutic agent for numerous human, animal, and plant health applications, offering a complementary tool for infection control in the face of multidrug-resistant bacteria. [ABSTRACT FROM AUTHOR]

A Lactococcus (L.) lactis strain producing antimicrobial and anti-inflammatory biomolecules (mainly 1,4-Diaza-2,5-dioxobicyclo[4.3.0]nonanes and pyrazine-derivatives) was tested for its capacity to cure clinical endometritis in buffaloes compared to conventional antibiotic-based treatment. Clinical endometritis-diagnosed buffaloes (n = 16/group) were infused intrauterine with four doses of 109 CFU-free (FLC group) or nanoencapsulated L. lactis (NLC group) and compared to those that received three doses of saline + a single dose of 500 mg cephapirin benzathin (AB group) or four doses of saline (control, C group) every other day. Endometrium samples were analyzed for cytological (polymorphonuclear cells, PMN), bacteriological, and proinflammatory mRNA expression. Uterine wash and blood samples were collected to determine proinflammatory cytokine concentrations and metabolites in the blood samples. The reproductive performance of buffaloes was assessed. Compared to the C group, the AB and NLC groups had the lowest percentage of PMN, followed by those in the FLC group (p < 0.05). All treated buffaloes had significantly lower numbers of pathogens than the control buffaloes. Compared to control, all treatments significantly down-regulated endometrial proinflammatory encoding mRNA expression. The concentrations of IL1B, TNFAIP7, and leukocyte esterase activity in the uterine washings were significantly decreased in the AB and NLC groups compared to the C and FLC groups. All treatments significantly decreased concentrations of serum proinflammatory cytokines compared to control. Both the AB and NLC groups had significantly lower concentrations of serum NEFA than the C and FLC groups. The percentage of control buffaloes having an echogenic uterus and PVD score > 2 was significantly higher than those in the treated buffaloes with higher numbers of corpora lutea, higher conception rates, and shorter days open than control buffaloes (p < 0.05). In conclusion, L. lactis-producing antimicrobial and anti-inflammatory metabolites reduce uterine inflammatory responses and improve fertility in buffaloes. [ABSTRACT FROM AUTHOR]

Objective: Acute mortality with clinical symptoms of streptococcal‐like infections was observed in red tilapia Oreochromis sp. cultured in floating cages in Prachin Buri Province, Thailand, during May 2023. Herein, we identified an emerging pathogen, Lactococcus garvieae, as the etiological agent. Methods: After bacterial isolation from the brain and kidney of diseased fish, identification was performed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and the VITEK 2 system. Sequencing of the 16S ribosomal RNA (rRNA) gene and phylogenetic analysis were applied to confirm bacterial species. Antimicrobial susceptibility testing was conducted. Histopathological findings in the brain, kidney, spleen, liver, and heart were evaluated. Result: From 20 fish samples, L. garvieae (n = 18 isolates) and Streptococcus agalactiae (n = 2 isolates) were identified. A phylogenetic tree of the 16S rRNA gene revealed that Thai isolates of either L. garvieae or S. agalactiae clustered with reference piscine isolates from intercontinental locations. Our isolates showed resistance against quinolones while being susceptible to other antimicrobials. Histopathological changes demonstrated severe septicemic conditions, with more invasive lesions—especially in the heart and liver—being apparent in L. garvieae‐infected fish compared to S. agalactiae‐infected fish. Conclusion: This study represents the first reported outbreak of L. garvieae with a concurrent S. agalactiae infection in farmed red tilapia in Thailand. Impact statementAn emerging pathogen, Lactococcus garvieae, was isolated from red tilapia in Thailand during May 2023. Concurrent infection by Streptococcus agalactiae was also diagnosed. Although the clinical findings and antimicrobial resistance patterns of these bacterial isolates were comparable, the observed histopathological lesions caused by L. garvieae were more severe. [ABSTRACT FROM AUTHOR]

Microbial nitrogen sources are promising, and soy protein as a plant-based nitrogen source has absolute advantages in creating microbial culture medium in terms of renewability, eco-friendliness, and greater safety. Soy protein is rich in variety due to different extraction technologies and significantly different in the cell growth and metabolism of microorganisms as nitrogen source. Therefore, different soy proteins (soy meal powder, SMP; soy peptone, SP; soy protein concentrate, SPC; soy protein isolate, SPI; and soy protein hydrolysate, SPH) were used as nitrogen sources to culture Bacillus subtilis, Streptococcus lactis, and Streptomyces clavuligerus to evaluate the suitable soy nitrogen sources of the above strains. The results showed that B. subtilis had the highest bacteria density in SMP medium; S. lactis had the highest bacteria density in SPI medium; and S. clavuligerus had the highest PMV in SPI medium. Nattokinase activity was the highest in SP medium; the bacteriostatic effect of nisin was the best in SPI medium; and the clavulanic acid concentration was the highest in SMP medium. Based on analyzing the correlation between the nutritional composition and growth metabolism of the strains, the results indicated that the protein content and amino acid composition were the key factors influencing the cell growth and metabolism of the strains. These findings present a new, high-value application opportunity for soybean protein. [ABSTRACT FROM AUTHOR]

The integration of aqueous clove extract (ACE) and spray-dried probiotics into an edible film presents numerous health advantages, such as enhanced probiotic stability and antibacterial efficacy against harmful bacteria like Klebsiella pneumoniae and Pseudomonas aeruginosa. This study aimed to formulate a probiotic edible film with antibacterial properties by incorporating milk powder containing ACE and probiotic strains, namely Streptococcus thermophilus ATCC 19258, Lactobacillus bulgaricus ATCC 11842, and Lactococcus lactis MG1363. The milk powders, containing 7.5% (w/v) ACE with various probiotic strains, were combined with 2% (w/v) pectin biopolymer and 60% (w/w) glycerol plasticizer to produce the probiotic edible film with ACE. Antibacterial effects were investigated using disc diffusion, while probiotic film viability was assessed through the pour plate method. The study revealed higher viability in the probiotic strains L. lactis and S. thermophilus within the edible film, compared to L. bulgaricus. The specific strains exhibited increased antibacterial activity against K. pneumoniae and P. aeruginosa, underscoring the critical role of probiotic strain selection in determining functional properties. Notably, the edible film containing L. lactis and S. thermophilus demonstrated substantial antibacterial activity against both pathogens. However, further research is imperative to optimize industrial-scale production methods, assess efficacy in diverse food items, evaluate sensory properties, gauge barrier attributes, and investigate the impact of storage conditions on stability and performance. [ABSTRACT FROM AUTHOR]

Piscine lactococcosis is a significant threat to cultured and wild fish populations worldwide. The disease typically presents as a per-acute to acute hemorrhagic septicemia causing high morbidity and mortality, recalcitrant to antimicrobial treatment or management interventions. Historically, the disease was attributed to the gram-positive pathogen Lactococcus garvieae. However, recent work has revealed three distinct lactococcosis-causing bacteria (LCB)--L. garvieae, L. petauri, and L. formosensis--which are phenotypically and genetically similar, leading to widespread misidentification. An update on our understanding of lactococcosis and improved methods for identification are urgently needed. To this end, we used representative isolates from each of the three LCB species to compare currently available and recently developed molecular and phenotypic typing assays, including whole-genome sequencing (WGS), end-point and quantitative PCR (qPCR) assays, matrix-assisted laser desorption/ionization timeofflight mass spectrometry (MALDI-TOF MS), API 20 Strep and Biolog systems, fatty acid methyl ester analysis (FAME), and Sensititre antimicrobial profiling. Apart from WGS, sequencing of the gyrB gene was the only method capable of consistent and accurate identification to the species and strain level. A qPCR assay based on a putative glycosyltransferase gene was also able to distinguish L. petauri from L. garvieae/formosensis. Biochemical tests and MALDI-TOF MS showed some speciesspecific patterns in sugar and fatty acid metabolism or protein profiles but should be complemented by additional analyses. The LCB demonstrated overlap in host and geographic range, but there were relevant differences in host specificity, regional prevalence, and antimicrobial susceptibility impacting disease treatment and prevention. [ABSTRACT FROM AUTHOR]

Lactococcus garvieae is the causative agent of lactococcosis in fish and an emerging zoonotic pathogen with high levels of antimicrobial resistance. We report a case of L. garvieae– associated septicemia in a central bearded dragon (Pogona vitticeps) confirmed via whole-blood PCR and direct sequencing. Following a 30-d course of ceftazidime (20 mg/kg IM q72h), the animal's clinical condition had not resolved; leukopenia persisted, with heterophil toxic change. Coelomic ultrasound findings were consistent with preovulatory follicular stasis, folliculitis, and coelomitis. Following surgical ovariectomy and an additional 30-d course of ceftazidime, the animal's behavior and appetite returned to normal, the animal tested negative via whole-blood PCR assay, and the CBC was unremarkable. To our knowledge, L. garvieae with L. garvieae– associated clinical disease has not been reported previously in a bearded dragon. We conclude that L. garvieae should be considered as a possible etiologic agent in cases of septicemia in bearded dragons, with the potential for zoonotic transmission warranting further investigation. [ABSTRACT FROM AUTHOR]

Finding strategies for decolonizing gut carriers of multidrug-resistant Escherichia coli (MDR-Ec) is a public-health priority. In this context, novel approaches should be validated in preclinical in vivo gut colonization models before being translated to humans. However, the use of mice presents limitations. Here, we used for the first time Zophobas morio larvae to design a new model of intestinal colonization (28-days duration, T28). Three hyperepidemic MDREc producing extended-spectrum β-lactamases (ESBLs) or carbapenemases were administered via contaminated food to larvae for the first 7 days (T7): Ec-4901.28 (ST131, CTX-M-15), Ec-042 (ST410, OXA-181) and Ec-050 (ST167, NDM-5). Growth curve analyses showed that larvae became rapidly colonized with all strains (T7, ~106-7 CFU/mL), but bacterial load remained high after the removal of contaminated food only in Ec-4901.28 and Ec-042 (T28, ~103-4 CFU/mL). Moreover, larvae receiving a force-feeding treatment with INTESTI bacteriophage cocktail (on T7 and T10 via gauge needle) were decolonized by Ec-4901.28 (INTESTI-susceptible); however, Ec-042 and Ec-050 (INTESTIresistant) did not. Initial microbiota (before administering contaminated food) was very rich of bacterial genera (e.g., Lactococcus, Enterococcus, Spiroplasma), but patterns were heterogeneous (Shannon diversity index: range 1.1-2.7) and diverse to each other (Bray-Curtis dissimilarity index ≥30%). However, when larvae were challenged with the MDR-Ec with or without administering bacteriophages the microbiota showed a non-significant reduction of the diversity during the 28-day experiments. In conclusion, the Z. morio larvae model promises to be a feasible and high-throughput approach to study novel gut decolonization strategies for MDR-Ec reducing the number of subsequent confirmatory mammalian experiments. [ABSTRACT FROM AUTHOR]

Lactococcus lactis is widely applied by the dairy industry for the fermentation of milk into products such as cheese. Adaptation of L. lactis to the dairy environment often depends on functions encoded by mobile genetic elements (MGEs) such as plasmids. Other L. lactis MGEs that contribute to industrially relevant traits like antimicrobial production and carbohydrate utilization capacities belong to the integrative conjugative elements (ICE). Here we investigate the prevalence of ICEs in L. lactis using an automated search engine that detects colocalized, ICE-associated core-functions (involved in conjugation or mobilization) in lactococcal genomes. This approach enabled the detection of 36 candidate-ICEs in 69 L. lactis genomes. By phylogenetic analysis of conserved protein functions encoded in all lactococcal ICEs, these 36 ICEs could be classified in three main ICE-families that encompass 7 distinguishable ICE-integrases and are characterized by apparent modular-exchangeability and plasticity. Finally, we demonstrate that phylogenetic analysis of the conjugation-associated VirB4 ATPase function differentiates ICE- and plasmid-derived conjugation systems, indicating that conjugal transfer of lactococcal ICEs and plasmids involves genetically distinct machineries. Our genomic analysis and sequence-based classification of lactococcal ICEs creates a comprehensive overview of the conserved functional repertoires encoded by this family of MGEs in L. lactis, which can facilitate the future exploitation of the functional traits they encode by ICE mobilization to appropriate starter culture strains. [ABSTRACT FROM AUTHOR]

Nisin is an effective biopreservative, however its wide application in food is restricted due to its low productivity. Therefore, the present work aimed to increase its yield by disrupting lactate dehydrogenase (ldh) and re-directing the carbon flow towards nisin production. The ldh-deficient Lactococcus lactis ATCC 11454 (ldhΔ) strain was created by inserting ampicillin (amp) within the ldh to disrupt its function. Under controlled fermentation conditions (30°C, pH 6, 1.0% glucose), the ldhΔ strain exhibited negligible decrease in pH (2.5%) over 48 h, in contrast to the wild-type (WT) strain, which experienced a 23.6% decrease in pH (pH 4.2). Overall, the ldhΔ strain showed a significant (p < 0.05) increase in growth and nisin activity by 24.9% and 62% compared to the WT strain, respectively. This strategy could serve as a practical approach to further enhance the production of bacteriocin or other compounds by modulating their metabolic pathways. [ABSTRACT FROM AUTHOR]

Probiotics are beneficial for intestinal diseases. Research shows that probiotics can regulate intestinal microbiota and alleviate inflammation. Little research has been done on the effects of probiotics on colitis in mice. The purpose of this study was to investigate the inhibitory effect of the strains isolated and screened from the feces of healthy piglets on the enteritis of rocitrobacter. The compound ratio of isolated Lactobacillus L9 and Enterococcus faecalis L16 was determined, and the optimal compound ratio was selected according to acid production tests and bacteriostatic tests in vitro. The results showed that when the ratio of Lactobacillus L9 to Enterococcus faecalis L16 was 4:1, the pH value was the lowest, and the antibacterial diameter was the largest. Then, in animal experiments, flow cytometry was used to detect the number of T lymphocytes in the spleen and mesenteric lymph nodes of mice immunized with complex lactic acid bacteria. The results showed that the number of T lymphocytes in the spleen and mesenteric lymph nodes of mice immunized with complex lactic acid bacteria significantly increased, which could improve the cellular immunity of mice. The microbiota in mouse feces were sequenced and analyzed, and the results showed that compound lactic acid bacteria could increase the diversity of mouse microbiota. It stabilized the intestinal microbiota structure of mice and resisted the damage of pathogenic bacteria. The combination of lactic acid bacteria was determined to inhibit the intestinal colitis induced by Citrobacter, improve the cellular immune response of the body, and promote the growth of animals. [ABSTRACT FROM AUTHOR]

Aging often accompanies cognitive and mood disturbances. Emerging evidence indicates that specific probiotics mitigate cognitive and mood dysfunctions. Strains within Lactococcus, a subgroup of probiotics, including Lactococcus lactis and Lactococcus cremoris are shown beneficial effects on brain functions via the gut microbiota-brain axis (GBA). Our previous study identified two Lactococcus strains (L. lactis WHH2078 and L. cremoris WHH2080) with the ability to promote the secretion of gut 5-hydroxytryptophan (5-HTP), the precursor of the GBA mediator 5-hydroxytryptamine (5-HT). In this study, the modulatory effects of WHH2078 and WHH2080 on cognitive and mood alternations were investigated in aged mice. Oral administration of WHH2078 and WHH2080 (1 × 109 CFU/mL/day) in aged mice (12-month-old) for 12 weeks significantly improved cognitive and depressive-and anxiety-like behaviors. The neuronal loss, the 5-HT metabolism dysfunction, and the neuroinflammation in the hippocampus of aged mice were restored by WHH2078 and WHH2080. the disturbances in the serum tryptophan metabolism in aged mice were unveiled by metabolomics, notably with decreased levels of 5-HT and 5-HTP, and increased levels of kynurenine, 3-hydroxykynurenine, and indolelactic acid, which were reversed by WHH2078 and WHH2080. Regarding the gut microbial community, WHH2078 and WHH2080 restored the increased abundance of Firmicutes, Desulfobacterota, and Deferribacterota and the decreased abundance of Bacteroidota and Actinobacteriota in aged mice. The beneficial effects of the two strains were linked to the modulation of 5-HT metabolism and gut microbiota. Our findings point to the potential role of Lactococcus strains with 5-HTP-promoting abilities as therapeutic approaches for age-related cognitive and mood disorders.

Background: Colorectal cancer (CRC) is one of the most commonly diagnosed cancers, posing a serious public health challenge that necessitates the development of new therapeutics, therapies, and prevention methods. Among the various therapeutic approaches, interventions involving lactic acid bacteria (LAB) as probiotics and postbiotics have emerged as promising candidates for treating and preventing CRC. While human-isolated LAB strains are considered highly favorable, those sourced from environmental reservoirs such as dairy and fermented foods are also being recognized as potential sources for future therapeutics. Results: In this study, we present a novel and therapeutically promising strain, Lactococcus lactis ssp. lactis Lc4, isolated from dairy sources. Lc4 demonstrated the ability to release the cytostatic agent - arginine deiminase (ADI) - into the post-cultivation supernatant when cultured under conditions mimicking the human gut environment. Released arginine deiminase was able to significantly reduce the growth of HT-29 and HCT116 cells due to the depletion of arginine, which led to decreased levels of c-Myc, reduced phosphorylation of p70-S6 kinase, and cell cycle arrest. The ADI release and cytostatic properties were strain-dependent, as was evident from comparison to other L. lactis ssp. lactis strains. Conclusion: For the first time, we unveil the anti-proliferative properties of the L. lactis cell-free supernatant (CFS), which are independent of bacteriocins or other small molecules. We demonstrate that ADI, derived from a dairy-Generally Recognized As Safe (GRAS) strain of L. lactis, exhibits anti-proliferative activity on cell lines with different levels of argininosuccinate synthetase 1 (ASS1) expression. A unique feature of the Lc4 strain is also its capability to release ADI into the extracellular space. Taken together, we showcase L. lactis ADI and the Lc4 strain as promising, potential therapeutic agents with broad applicability. [ABSTRACT FROM AUTHOR]

In order to clarify the microflora structure in Cheddar cheese processing, MiSeq high-throughput sequencing technology was used to analyze the community structure of Cheddar cheese at three stages of processing (postpasteurization, curdling, and ripening 0, 30, 60 and 90 d) in this study. The results showed that the community structure varies widely of cheddar cheese during processing. The highest microbial community diversity and abundance were found after pasteurization (Chao1 index and Shannon index mean values were 6.09 and 1415.78, respectively). The dominant microflora in the pasteurization stage at the genus level was Stenotrophomonas (21.04%). The community structure was relatively similar in the curd and ripening stages, Lactococcus were the dominant flora in both stages, with abundance averaging more than 85%. During the ripening period, the relative abundance of Lactococcus increased first and then decreased. The community structure in the pasteurized cheeses was different compared to the other groups, and there was less change in the community structure of the groups during the ripening period. This study provides a basis for clarifying the community structure of Cheddar cheese, and has a certain reference value for the expansion of Cheddar cheese microbiome information. [ABSTRACT FROM AUTHOR]

Members of the genus Cryptococcus are the causative agents of cryptococcal meningitis, a disease mainly associated with HIV-induced immunosuppression. Patients with cryptococcal meningitis are at a serious risk of death. Most patients suffering from cryptococcosis belong to neglected populations. With reduced support for research, new therapies are unlikely to emerge. In this essay, we used the Policy Cures/G-finder platform as a reference database for funding research on cryptococcal disease. Funding for cryptococcal research started being tracked by G-finder in 2013 and has continued to appear in the annual reports ever since. In total, 15 institutions were reported as major funders for research on cryptococcal disease over the years. The US National Institutes of Health (NIH) was the main funder, followed by the UK's Wellcome Trust. The annual analysis suggested slow yearly growth in funding from 2013 to 2021. The development of new tools to prevent and fight cryptococcal disease is urgent but requires improved funding. [ABSTRACT FROM AUTHOR]

Consumer demand for plant cheeses is increasing, but challenges of improving both flavor and quality remain. This study investigated the microbiological and physicochemical impact of seed germination and fermentation with Bacillus velezensis and Bacillus amyloliquefaciens on the ripening of plant cheese analogs. Chlorine treatment or addition of Lactiplantibacillus plantarum and Lactococcus lactis controlled microbial growth during seed germination. Lp. plantarum and Lc. lactis also served as starter cultures for the acidification of soy and lupine milk and were subsequently present in the unripened plant cheese as dominant microbes. A cidification also inhibited the growth and metabolic activity of bacilli but Bacillus spores remained viable throughout ripening. During plant cheese ripening, Lc. lactis was inactivated before Lp. plantarum and the presence of bacilli during seed germination delayed Lc. lactis inactivation. Metagenomic sequencing of full-length 16S rRNA gene amplicons confirmed that the relative abundance of the inoculated strains in each ripened cheese sample exceeded 99%. Oligosaccharides including raffinose, stachyose, and verbascose were rapidly depleted in the initial stage of ripening. Both germination and the presence of bacilli during seed germination had impact on polysaccharide hydrolysis during ripening. Bacilli but not seed germination enhanced proteolysis of plant cheese during ripening. In conclusion, the use of germination with lactic acid bacteria in combination with Bacillus spp. exhibited the potential to improve the quality of ripened plant cheeses with a positive effect on the reduction of hygienic risks. IMPORTANCE The development of novel plant-based fermented food products for which no traditional templates exist requires the development of starter cultures. Although the principles of microbial flavor formation in plant-based analogs partially overlap with dairy fermentations, the composition of the raw materials and thus likely the selective pressure on the activity of starter cultures differs. Experiments that are described in this study explored the use of seed germination, the use of lactic acid bacteria, and the use of bacilli to reduce hygienic risks, to acidify plant milk, and to generate taste-active compounds through proteolysis and fermentative conversion of carbohydrates. The characterization of fermentation microbiota by culture-dependent and culture-independent methods also confirmed that the starter cultures used were able to control microbial communities throughout 90 d of ripening. Taken together, the results provide novel tools for the development of plant-based analogs of fermented dairy products. [ABSTRACT FROM AUTHOR]

Investigating the diversity of a given species could give clues for the development of autochthonous starter cultures. However, few studies have focused on the intraspecies diversity of Lactobacillus delbrueckii strains, a technologically important lactic acid bacterium for the dairy industry. For this reason, Lactobacillus delbrueckii strains from the Saint-Nectaire Protected Designation of Origin (PDO) area were isolated and characterized. Genetic diversity was determined based on core genome phylogenetic reconstruction and pangenome analysis, while phenotypic assessments encompassed proteolysis and volatile compound production potential. A total of 15 L. delbrueckii ssp. lactis unique new strains were obtained. The genetic analysis and further proteolytic activities measurement revealed low variability among these Saint-Nectaire strains, while substantial genetic variability was observed within the L. delbrueckii ssp. lactis subspecies as a whole. The volatile compound profiles slightly differed among strains, and some strains produced volatile compounds that could be of particular interest for cheese flavor development. While the genetic diversity among Saint-Nectaire strains was relatively modest compared to overall subspecies diversity, their distinct characteristics and pronounced differentiation from publicly available genomes position them as promising candidates for developing autochthonous starter cultures for cheese production. [ABSTRACT FROM AUTHOR]

To assess the possible impact of climatic variation on microbial community composition in organic winemaking, we employed a metabarcoding approach to scrutinize the microbiome in a commercial, organic, Pinot noir wine production system that utilizes autochthonous fermentation. We assessed microbial composition across two vintages (2018 and 2021) using biological replicates co-located at the same winery. Microbial dynamics were monitored over four important fermentation time points and correlated with contemporaneous climate data. Bacterial (RANOSIM = 0.4743, p = 0.0001) and fungal (RANOSIM = 0.4738, p = 0.0001) compositions were different in both vintages. For bacteria, Lactococcus dominated the diversity associated with the 2018 vintage, while Tatumella dominated the 2021 vintage. For fungal populations, while Saccharomyces were abundant in both vintages, key differences included Starmerella, copious in the 2018 vintage; and Metschnikowia, substantive in the 2021 vintage. Ordination plots correlated the climatic variables with microbial population differences, indicating temperature as a particularly important influence; humidity values also differed significantly between these vintages. Our data illustrates how climatic conditions may influence microbial diversity during winemaking, and further highlights the effect climate change could have on wine production. [ABSTRACT FROM AUTHOR]

Bioactive peptides (BPs) are molecules of paramount importance with great potential for the development of functional foods, nutraceuticals or therapeutics for the prevention or treatment of various diseases. A functional BP-rich dairy product was produced by lyophilisation of bovine milk fermented by the autochthonous strains Lactococcus lactis subsp. lactis ZGBP5-51, Enterococcus faecium ZGBP5-52 and Enterococcus faecalis ZGBP5-53 isolated from the same artisanal fresh cheese. The efficiency of the proteolytic system of the implemented strains in the production of BPs was confirmed by a combined high-throughput mass spectrometry (MS)-based peptidome profiling and an in silico approach. First, peptides released by microbial fermentation were identified via a non-targeted peptide analysis (NTA) comprising reversed-phase nano-liquid chromatography (RP nano-LC) coupled with matrix-assisted laser desorption/ionisation-time-of-flight/time-of-flight (MALDI-TOF/TOF) MS, and then quantified by targeted peptide analysis (TA) involving RP ultrahigh-performance LC (RP-UHPLC) coupled with triple-quadrupole MS (QQQ-MS). A combined database and literature search revealed that 10 of the 25 peptides identified in this work have bioactive properties described in the literature. Finally, by combining the output of MS-based peptidome profiling with in silico bioactivity prediction tools, three peptides (75QFLPYPYYAKPA86, 40VAPFPEVFGK49, 117ARHPHPHLSF126), whose bioactive properties have not been previously reported in the literature, were identified as potential BP candidates. [ABSTRACT FROM AUTHOR]

Magnetotactic bacteria are microorganisms that produce intracellular magnetic nanoparticles organized in chains, conferring a magnetic moment to the bacterial body that allows it to swim following the geomagnetic field lines. Magnetotactic bacteria usually display two swimming polarities in environmental samples: the South-seeking (SS) polarity and the North-seeking (NS) polarity, characterized by the bacteria swimming antiparallel or parallel to the magnetic field lines, respectively. It has been observed that in the presence of inhomogeneous magnetic fields, NS magnetotactic bacteria can change their swimming polarity to SS or vice versa. The present study analyzes populations of NS cocci obtained from SS cocci isolated in the presence of a magnet. The aim was to study differences in the swimming characteristics and magnetic moment among both populations of cocci. For that, trajectories were recorded and the velocity and angle among the velocity and the applied magnetic field were calculated. In addition, micrographs from both SS and NS cocci were obtained and their magnetosomes were measured to analyze their length, width, aspect ratio and magnetic moment, to finally obtain the magnetic moment for each coccus. The results showed the following properties of NS relative to SS cocci: higher velocities, narrow bacterial magnetic moment distribution, higher dispersion in the distribution of angles among the velocity and the applied magnetic field and lower magnetic field sensibility. Those differences cannot be explained by the simple change in magnetic polarity of the magnetosome chain and can be related to the existence of an active magnetoreceptive process in magnetotactic bacteria. [ABSTRACT FROM AUTHOR]

Nowadays, the bacteriocin industries have seen significant growth, supplanting chemical preservatives in its ability to improve the shelf-life and safety of food. The increasing customer desire to use natural preservatives has fueled advancing bacteriocin research. The objective of this study was to identify lactic acid bacteria (LAB) that produce bacteriocin-like inhibitory substance (BLIS) and have strong anti-listerial activity. We have identified and analyzed a LAB obtained from chhurpi samples, a popular milk-derived product in the Himalayan regions of India and Nepal. The strain was studied and identified based on its morphological, biochemical, and physiological characteristics. Furthermore, the molecular 16s-rDNA analysis suggests that the strain was Lactococcus sp. RGUAM1 (98.2% similar to Lactococcus lactis subsp. hordniae NBRC 100931T). The isolated strain can produce a potent BLIS, which has shown efficacy against three gram-positive bacteria responsible for food spoilage, such as Listeria monocytogenes (MTCC 657), Staphylococcus aureus subsp. aureus (MTCC 87), Lactobacillus plantarum (MTCC 1407), Lactobacillus paraplantarum (MTCC 12904). The scanning electron microscope (SEM) image illustrates that the crude cell-free supernatant (CFS) disrupts the cell envelope, leading to the release of cellular contents and the clustering of cells. In addition, this BLIS can easily withstand a wide range of pH (2–12), temperature (up to 100 °C for 15 min), bile salt (0.3% W/V), salinity (4% W/V), and enzyme activity of 1600 AU/ml against Listeria monocytogenes. Our research offers a robust framework and valuable insights into bio-preservation and its potential applications in diverse food products. [ABSTRACT FROM AUTHOR]

BACKGROUND: Predictive microbiology is a tool that allows us to evaluate the behavior of the concentration of biomass and estimated cells under extrinsic conditions, providing scientific and industrial benefits. In the present study, the growth of L. lactis and L. casei combined with inulin and fructose was modeled using the Gompertz sigmoidal growth functions and plotted using data obtained from batch culture in relation to biomass and cell concentration expressed as estimates in ln N (OD600nm and cells mL−1) as a function of time. RESULTS: The results of the kinetic modeling indicated that (T1) A1B1 = L. lactis + fructose and (T4) A2B2 = L. casei + inulin presented the best function coefficients and best fits in most cases compared to the rest. The specific growth rate of the maximum acceleration was from 0.364 to 0.473 h−1 and 0.100 to 0.129 h−1, the concentration of bacterial cells (A) was from 0.556 to 0.713 and 0.425 to 0.548 respectively and the time where (μ) occurred with a greater magnitude (L) fluctuated between 0.854 and 0.802 and when this time in (L) is very fast, it presents values of ≤0.072 to ≤0.092. Its coefficient of determination and/or multiple regression (R2) obtained in the two adjustments was 0.97. CONCLUSION: It was possible to predict the influence of the carbon source on the behavior of maximum growth rates, higher consumption due to nutrient affinity and shorter growth time. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Mastitis is an important problem affecting animal health, welfare, and economy. Bacterial agents play a dominant role in the disease. The role of enterococcal and lactococcal species among environmental bacterial agents in mastitis has been underestimated due to inadequate identification. The aim of this study was to isolate and identify Enterococcus spp. and Lactococcus spp. from mastitic bovine milk and to evaluate the agents phenotypically in terms of antimicrobial resistance. A total of 108 milk samples from cattle with suspected mastitis were analyzed for enterococci and lactococci by standard microbiological techniques and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). By standard microbiological methods, 38 (35%) Enterococcus spp. and 13 (12%) Lactococcus spp. were isolated and identified from 51 milk samples. In species-level identification with MALDI-TOF MS, six different enterococci and three different lactococci were identified within acceptable score ranges. In antibiogram tests performed with the standard Kirby-Bauer method using 10 antimicrobials, 26% of the Enterococcus spp. and 46% of the Lactococcus spp. were resistant to at least 50% of the antimicrobials tested. In Enterococcus spp., the highest resistance rates were observed for enrofloxacin (79%) and ampicillin + cloxacillin (71%), while the best sensitivity (100%) was obtained for penicillin and ampicillin. In Lactococcus spp., the highest resistance rate was observed for enrofloxacin (85%) and amoxicillin + clavulanic acid (70%) and the best sensitivity (100%) was obtained for penicillin, ampicillin, and gentamicin. As a result, it was concluded that the diversity and high rate of antimicrobial resistance of enterococcal and lactococcal species in mastitis isolates poses a serious potential threat to animal and public health. [ABSTRACT FROM AUTHOR]

In this study, we investigated the dietary effects of dandelion root extract (DRE) on growth performance, body composition, serum biochemical parameters, intestinal and liver histology, and fish resistance against Lactococcus garvieae infection in the rainbow trout. In total, 540 rainbow trout fry (22.05±1.740 g and 13.03±0.470 cm) were used. Six experimental groups (control, 2.5 mL/kg (DRE-1), 5 mL/kg (DRE-2), 10 mL/kg (DRE-3), 20 mL/kg (DRE-4), and 40 mL/kg (DRE-5) dandelion root extract) with three replicates were formed. In each tank, 30 fish were placed and fed for 90 days, and the volume of water was adjusted to 80 L with a flow-through system. The results showed that the final fish weight, weight gain, specific growth rate, protein efficiency ratio, and protein deposition rate were significantly higher in the DRE-4 group, while the feed conversion ratio and fat deposition ratio were significantly lower compared to that in the control group (P<0.05). The viscerosomatic index and the hepatosomatic index decreased in the experimental groups depending on the concentration of the extract used, while the condition factor was higher than that in the control (P<0.05). The DRE significantly decreased glucose, cholesterol, triglyceride, low-density lipoprotein, alanine aminotransferase, and aspartate aminotransferase levels in blood serum in the fish from the experimental groups, but it significantly increased high-density lipoprotein, alkaline phosphatase, and total protein levels (P<0.05). Similarly, the DRE positively affected intestinal histology by increasing the stratum compactum, submucosa, lamina propria, villi length, villi width, absorption area, tunica muscularis thickness, mucosal folds, and goblet cell count. In the liver, depending on the high-fat diet (crude lipid = 20%), vacuolization areas, hepatocellular degeneration areas, apoptotic hepatocyte nucleus, and necrotic areas recorded in the control group decreased or even disappeared completely in the extract groups. The results of the challenge test showed that adding 2.5 mL/kg of the DRE to the feed positively affected the disease resistance against Lactococcus garvieae infection. The results of the quadratic polynomial regression showed that an average level of 23.91±1.048 mL/kg of DRE would be suitable for optimum fish growth. [ABSTRACT FROM AUTHOR]

This study was aimed to produce a biosurfactant from Lactococcus sp. and study its synergistic effects with some standard antibiotics. Lactococcus sp. HN21 isolate was selected for its highly biosurfactant production and antibacterial activity. It was identified by 16s r RNA as Lactococcus lactis HN21. Optimum conditions for production were studied and it was: Modified M17 media (M17 media with some modifications in its composition) at ph 6.5, for 96 hrs incubation time. The E24% at these conditions was 77%. FTIR and GC-MS results identified the produced biosurfactant as glycolipopeptide with a major fatty acid octadecenoic acid. P. aeruginosa was successfully inhibited by the glycolipopeptide alone, with overall inhibition ranging from (15 to 19 mm). The combined use of antibiotics and glycolipopeptide, however, resulted in an increase in the total inhibition zones to (17 to 28 mm), while glycolipopeptide alone was effective against S. aureus and showed total inhibition zones ranging from (15 to 22) mm. glycolipopeptide in combination with antibiotics, the total inhibition zones were increased (26 to 40) mm. The results observed a great pharmaceutical application in increasing the bactericidal effect. [ABSTRACT FROM AUTHOR]

In Gram-positive bacteria, cell wall polysaccharides (CWPS) play critical roles in bacterial cell wall homeostasis and bacterial interactions with their immediate surroundings. In lactococci, CWPS consist of two components: a conserved rhamnan embedded in the peptidoglycan layer and a surface-exposed polysaccharide pellicle (PSP), which are linked together to form a large rhamnose-rich CWPS (Rha-CWPS). PSP, whose structure varies from strain to strain, is a receptor for many bacteriophages infecting lactococci. Here, we examined the first two steps of PSP biosynthesis, using in vitro enzymatic tests with lipid acceptor substrates combined with LC-MS analysis, AlfaFold2 modeling of protein 3D-structure, complementation experiments, and phage assays. We show that the PSP repeat unit is assembled on an undecaprenylmonophosphate (C55P) lipid intermediate. Synthesis is initiated by the WpsA/WpsB complex with GlcNAc-P-C55 synthase activity and the PSP precursor GlcNAc-P-C55 is then elongated by specific glycosyltransferases that vary among lactococcal strains, resulting in PSPs with diverse structures. Also, we engineered the PSP biosynthesis pathway in lactococci to obtain a chimeric PSP structure, confirming the predicted glycosyltransferase specificities. This enabled us to highlight the importance of a single sugar residue of the PSP repeat unit in phage recognition. In conclusion, our results support a novel pathway for PSP biosynthesis on a lipid-monophosphate intermediate as an extracellular modification of rhamnan, unveiling an assembly machinery for complex Rha-CWPS with structural diversity in lactococci. [ABSTRACT FROM AUTHOR]

In this study, we cloned and characterized three bacterial laccases from strains of the species Pediococcus parvulus, Lacticaseibacillus paracasei, and Lactococcus lactis isolated from wine and cheese and evaluated their biogenic amine degradation abilities in the presence/absence of artificial 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) or natural (epicatechin) mediator compounds. Although some recombinant bacterial laccases have been characterized and found to be biological tools for degrading biogenic amines with or without the use of mediators, no prior research has investigated the role of natural mediators, like phenolic substrates found in wine and certain vegetable foods, in the degradation of biogenic amines. The three recombinant bacterial laccases exhibited sigmoidal kinetics and had similar molecular mass but varied in k0.5, kcat, and specific activity toward ABTS. They are acidophilic and have an optimal temperature of 28 °C. However, they exhibit low thermal stability at temperatures higher than 37 °C. The three laccases were capable of degrading dopamine without the use of mediators, while the other amines were not degraded. The presence of ABTS enhanced the degradation of dopamine and tyramine, but the addition of epicatechin did not improve their degradation. This study presents a comparison of the laccases' biogenic amine-degrading efficiency using different mediators. This is the first time such a comparison has been made. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the minimum inhibitory concentrations of antimicrobials included in a commercial broth microdilution panel among Gram-positive pathogens that caused non-severe clinical mastitis on three Michigan dairy farms. Duplicate quarter milk samples were collected from eligible quarters of cows enrolled in a randomized clinical trial, cultured in a university laboratory, and identified using MALDI-TOF. Etiologies were grouped by genus as Enterococcus species (n = 11), Lactococcus species (n = 44), non-aureus Staphylococcus species (n = 39), or Streptococcus species (n = 25). Minimum inhibitory concentrations (MICs) were determined using the mastitis panel of a commercially available broth microdilution test. In vitro susceptibility was determined using approved guidelines and included breakpoints for mastitis pathogens, or when not available, breakpoints from other species. Most isolates were inhibited at or below breakpoints that demonstrated in vitro susceptibility. The proportions of susceptible isolates varied among pathogens for pirlimycin, penicillin, and tetracycline. The greatest proportion of resistance was observed for pirlimycin, tetracycline, and sulfadimethoxine. Survival analysis was performed to evaluate differences in MICs among pathogen groups. MIC values varied among pathogens for ceftiofur, cephalothin, erythromycin, penicillin, pirlimycin, and tetracycline. However, nearly all isolates were susceptible to ceftiofur and cephalothin, indicating that pathogen differences in MIC are not likely clinically relevant, as these are the two most commonly administered mastitis treatments in the United States. While differences in vitro susceptibility were observed for some antimicrobials, susceptibility was high to cephalosporin-based IMM treatments that are most commonly used and did not vary among pathogens. [ABSTRACT FROM AUTHOR]

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In aquaculture, Lactococcus garvieae is a common fish pathogen that can cause significant economic losses in several fresh and saltwater species. Despite the extensive range of hosts, L. garvieae infection in sea bass (Dicentrarchus labrax) has rarely been reported. During the summer of 2023, an outbreak occurred in an inland farm in the Gulf of Follonica (Tuscany, Italy). Fish of various sizes were affected, showing apathy, inappetence, erratic swimming and eye lesions, while the mortality was low (2–3% per month). Anatomopathological examinations suggested a septicaemic infection characterised by melanosis, diffuse redness (skin and fins), paleness (gills and internal organs), haemorrhages and splenomegaly. Seventy swabs from the viscera of 14 subjects were collected and colonies similar to Streptococcus spp. grew from all the samples. Lactococcus garvieae was identified via the biochemical tests, API20STREP, MALDI-TOF, 16S rDNA and whole genome sequencing. Genetical characterisation revealed remarkable differences between this isolate and the strains previously isolated in Italian fish farms. Feed treatments with flumequine and erythromycin were ineffective. Considering the limited effects of antimicrobials, preventive measures, such as vaccination and biosecurity, should be implemented. [ABSTRACT FROM AUTHOR]