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Within the context of the circular economy, the transformation of agri-food waste or by-products into valuable products is essential to promoting a transition towards more sustainable and efficient utilisation of resources. Whey is a very abundant by-product of dairy manufacturing. Apart from partial reutilisation in animal feed or some food supplements, the sustainable management and disposal of whey still represent significant environmental challenges. In this work, whey is considered a valuable resource for producing high-value products, specifically 2,3-butanediol (2,3-BDO), which was produced through fermentation using the bacterial strain Lactococcus lactis 43103. The described process yielded a >90% purity of 2,3-BDO, which was evaluated as a potential chain extender in the synthesis of bio-based waterborne polyurethane dispersions (PUDs). The incorporation of whey-derived 2,3-BDO led to the development of PUDs with up to 90% bio-based content without detrimental effects on the process or liquid-phase properties. The combination of 100% bio-based polyether polyols with partially renewable L-lysine ethyl ester diisocyanate and whey-derived 2,3-BDO as a chain extender generated totally stable, low-particle-size water dispersions of amorphous polymers characterised by similar structure and molecular weight compared to those of alternative petroleum-based PUDs. These results open up the possibility of incorporating fermentation-derived 2,3-BDO as a totally renewable component in bio-based PUDs as potential sustainable resinous systems for further formulation of water-based coatings or adhesives. [ABSTRACT FROM AUTHOR]

DNA molecules are a promising data storage medium for the future; however, effective de novo synthesis of DNA using an enzyme that catalyzes the polymerization of natural nucleoside triphosphates in a user-defined manner, without the need for multiple injections of polymerase, remains a challenge. In the present study, we demonstrated that the bacteriophage abortive infection system reverse transcriptase AbiK from Lactococcus lactis facilitates such an approach. We employed surface plasmon resonance to monitor the polymerization of the DNA strand with a user-defined sequence of multiple segments through a sequential buffer exchange process. Using this method, we synthesized synthetic DNA with segments of random length and a sequence consisting of only three of the four natural nucleotides. The information is encoded using the absence of one nucleotide in each segment. We demonstrated that synthetic DNA can be stored on the chip, and when the DNA is released from the chip, the second strand can be synthesized and read by sequencing. Our setup facilitates a writing speed of one nucleotide in less than 1 s and holds enormous potential for synthesizing DNA for data storage. [ABSTRACT FROM AUTHOR]

Introduction: Animal influenza viruses pose a danger to the general public. Eurasian avian-like H1N1 (EA H1N1) viruses have recently infected humans in several different countries and are often found in pigs in China, indicating that they have the potential to cause a pandemic. Therefore, there is an urgent need to develop a potent vaccine against EA H1N1. Methods: In this study, we report the effective intramuscular (i.m.) and/or intranasal (i.n.) vaccination of mice with a subunit influenza vaccine utilizing safe adjuvant gram-positive enhancer matrix (GEM) particles derived from the food-grade bacterium Lactococcus lactis. The hemagglutinin (HA)-protein anchor (PA) subunit vaccine can be simply mixed with GEM particles to produce vaccines. Results: After two booster injections, the i.m.+i.n. administered GEM subunit vaccine achieved hemagglutination inhibition titers in the serum that were equivalent to those observed using the conventional i.m. method. The mucosal and Th1-biased immune responses generated by the i.m. administered subunit vaccine alone were inferior to those induced by the i.n. and i.m.+i.n. administered subunit vaccines. Vaccinated mice were challenged with live viruses (G4 EA H1N1 and A/PR/8/34) to determine whether the adjuvant combination protected against the virus after vaccination with the influenza subunit vaccine. Compared to mice inoculated with HA alone, mice immunized with i.m.+i.n. or i.n. HA-PA-GEM displayed undetectable viral titers in the lungs, at 5 d after challenge. Discussion: Overall, this study not only offers other potential platforms for the generation of swine influenza vaccines, but also a theoretical foundation for vaccine vector platforms that can be utilized for future research on other infections. [ABSTRACT FROM AUTHOR]

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Lactococcus lactis is a potential bacterial cell factory to develop delivery systems for vaccines and therapeutic proteins. Much progress has been made in applications using engineered L. lactis against, e.g., inflammatory bowel disease and cervical cancer, but the improvement of secretion and cell anchoring efficacy is still desirable. A double-labeling method based on biarsenical hairpin binding and nickel–polyhistidine affinity was used for visualization of protein trafficking and the quantification of targeted proteins on the cell surface and in the cytoplasm. To investigate the importance of mature domain targeting signals (MTSs), we generated truncated constructs encoding 126, 66, and 26 amino acid residues from the N-terminus of the basic membrane protein A (BmpA) and fused those with the gene for the human papillomavirus serotype 16 (HPV16) E7 oncoprotein. Overexpression of fusion proteins was observed to come at the cost of cell proliferation. L. lactis cells produced and displayed the shortest fusion protein only with difficulty, suggesting that the entire absence of a homologous sequence containing MTSs significantly impedes the export and surface anchoring of fusion proteins. With 40 amino acids following the signal peptide and containing one MTS, effective translocation was possible. Mutations of MTSs towards increased hydrophobicity resulted in increased secreted and surface-displayed fusion protein, suggesting the potential to design rationally improved constructs. [ABSTRACT FROM AUTHOR]

Synbiotics may be useful to mitigate intestinal diseases such as ulcerative colitis. Here we show that combining 13′-carboxychromanol (δT3-13′), a metabolite of vitamin E δ-tocotrienol (δT3) via omega-oxidation, and Lactococcus lactis subsp. cremori (L. cremoris), but neither agent alone, significantly attenuated dextran sulfate sodium (DSS)-induced fecal bleeding and diarrhea, histologic colitis and interleukin 1β in mice. The combination of δT3-13'+ L. cremoris also synergistically prevented DSS-caused compositional changes in gut microbiota and enriched beneficial bacteria including Lactococcus and Butyricicoccus. Interestingly, the anti-colitis effect correlated with the concentrations of δT3-13′-hydrogenated metabolite that contains 2 double bonds on the side chain (δT2-13′), instead of δT3-13′ itself. Moreover, in contrast to δT3-13′, combining δT3 and L. cremoris showed modest anti-colitis effects and did not prevent colitis-associated dysbiosis. In addition, ex vivo anaerobic incubation studies revealed that gut microbes selected by δT3-13′ in the animal study could metabolize this compound to δT2-13′ via hydrogenation, which appeared to be enhanced by L. cremoris. Overall, our study demonstrates that combining δT3-13′ and L. cremoris can synergically prevent dysbiosis, and may be a novel synbiotic against colitis potentially via promoting δT3-13′ metabolizers, which in turn contributes to superior beneficial effects of the combination. [Display omitted] • Combining lactic acid bacteria and vitamin E metabolite δT3-13′ is a novel synbiotic. • This combination synergistically mitigated experimental colitis in mice. • This combination prevented colitis-caused dysbiosis and promoted beneficial bacteria. • Gut microbes can metabolize δT3-13′ via hydrogenation. • δT3-13′ promoted its metabolizers, which were enhanced by lactic acid bacteria. [ABSTRACT FROM AUTHOR]

Bread is an indispensable staple food that has been consumed by humans since they settled. Thousands of breads and other products are made around the world with sourdough adventure that started approximately 6000 years ago. Tu rkiye, which has hosted numerous ancient civilizations (Hatti, Hittites, etc.) and has significant archaeological sites (Çatalho yu k, Go beklitepe, Karahantepe, etc.), possesses a wide variety of sourdoughs. In this study, the general characteristics of Turkish sourdough breads, their cultural values, and the health and technological effects of sourdough are explained in the light of the information obtained through the document examination method. The stoves or ovens where sourdough breads are baked, fuels, and kitchen utensils used in bread preparation are clarified. In Tu rkiye, up to 21 types of traditional sourdough-making methods have been find. It's determined that sourdough types are made such as yoghurt water (zembek), ayran (waterry yoghurt), flower, chickpea, potato, onion, ash, grape, dew, tarhana, colostrum, pinecone and date sourdough. The most common microorganisms in Turkish sourdough include Lactobacillus plantarum, L. paraplantarum, L. brevis, L. pentosus, L. curvatus, Lactococcus lactis ssp. lactis, Saccharomyces cerevisiae, Kazachstania servazzii, and K. humilis. Sourdough breads display mediumhigh to high volumes such as Trabzon Vakfıkebir bread) while others are low-volume breads (such as yufka-phyllo dough, bazlama, pita-pide breads. The majority of these breads are produced using traditional methods and are baked in different wood-fired stoves and stone ovens burnt with kind of woods such as alder, oak, pine, fir, hornbeam, olive, willow, poplar, cherry, apple, plum, peach tree woods, plant and animal wastes. Turkish sourdough breads also have a positive effect on health, and sourdoughs have a technological improvement effect on bread. Turkish sourdough breads have many sociological and gastronomic features. [ABSTRACT FROM AUTHOR]

Raw goat and ewe's milk samples were used for the isolation of seven lactic acid bacteria new strains. After testing hemolytic activity and resistance to antibiotics, specific functional properties were evaluated; Lactococcus lactis subsp. lactis FBM_1321 and Lacticaseibacillus paracasei FBM_1327 strains resulted in the highest cholesterol assimilation percentages ranging from 28.78 to 30.56%. In addition, strong adhesion capacity to differentiated Caco-2 cells (1.77–21.04%) was mapped, and the lactobacilli strains exhibited strong antagonistic activity against foodborne pathogens compared to lactococci. The strains were able to grow at low pH and high NaCl concentrations, conditions that prevail in food systems (cell counts ranged from 1.77 to 8.48 log CFU/mL after exposure to pH 3 and from 5.66 to 9.52 log CFU/mL after exposure to NaCl concentrations up to 8%). As a next step, freeze-dried immobilized Lc. paracasei FBM_1327 cells on oat flakes were used for the preparation of functional yoghurt and ayran products. Cell loads of the functional strain remained high and stable in both products (7.69 log CFU/g in yoghurt and 8.56 log CFU/g in ayran after 30 days of storage at 4 °C) throughout their shelf life. No significant changes in the volatile profile were noticed, and the new products were accepted by the panel during the sensory evaluation. [ABSTRACT FROM AUTHOR]

Encapsulation in alginate hydrogel microspheres is an effective method for protecting and improving the survival of lactic acid bacteria in different environments. This research aims to expand the knowledge about the structure/property relationship of calcium alginate microspheres loaded with a mixture of autochthonous probiotic bacteria (Lactococcus lactis and Lactiplantibacillus plantarum). A novel hydrogel formulation (FORMLAB) was prepared by ionic gelation and the molecular interactions between the FORMLAB constituents, surface morphology, structure, swelling degree, and release profile were characterized. The simultaneous encapsulation of two bacterial cultures in the same compartment does not diminish their viability. The binding of calcium ions to bacterial cells creates favorable conditions for the propagation of the encapsulated bacteria. The molecular interactions between the FORMLAB constituents are complex, involving mainly hydrogen bonds and electrostatic interactions. With a very high degree of swelling followed by low crosslinking, the surface of the microspheres covered with bacterial cells and diffusion through the hydrogel matrix allow for the delivery of probiotics at the right time. The findings suggest that bacterial cells are efficiently delivered from calcium alginate microspheres, offering promising applications in the development of functional foods, especially in cheese production. [ABSTRACT FROM AUTHOR]

Canastra cheese, an artisanal cheese produced in Serra da Canastra—Brazil, has great cultural importance. Furthermore, this cheese has nutritional and sensory attributes that make it of great economic importance. Its microbiota is composed of different bacteria and yeasts. Some yeasts already isolated by our research group have been characterized as potential probiotics. Probiotic microorganisms have garnered scientific interest, as improvements in the physical, chemical and sensory characteristics of food products have been reported when these microorganisms are used. In this context, the objective of this work was to evaluate Kluyveromyces lactis and Torulaspora delbrueckii, which were previously isolated from Canastra cheese, as autochthonous starter cultures. Canastra cheese was produced under three different conditions: (1) cheese with "Pingo" (natural starter), (2) cheese with "Pingo" + yeast mixed culture, and (3) cheese with only mixed yeast culture. The results showed that the mixed yeast inoculum significantly influenced the lactic acid bacteria population. Yeast populations remained at around 106 CFU/g after 45 days of maturation. Furthermore, cheeses containing the yeast mixed with inoculum had an initial lactose content reduced by 92.80% compared to cheese produced with "Pingo" (87.70%). The antioxidant activity, evaluated using the ABTS method, showed that cheeses containing the mixed yeast culture had higher percentages of antioxidant activity at 45 days of maturation. The texture profile of the cheeses changed over time. In general, the cheese containing the yeast mixed culture and "Pingo" and the cheese containing "Pingo" had the lowest hardness at 30 days of maturation (5245 and 5404 N, respectively). Among the volatile compounds, 3-methylbutyl octanoate, phenethyl butyrate, phenethyl propionate, isobutyl butanoate and pentyl propionate were found only in cheeses produced with yeast mixed culture. The obtained results demonstrated that the use of autochthones probiotic cultures could improve the cheese characteristics without negatively impacting the traditional physicochemical attributes of Canasta cheese. [ABSTRACT FROM AUTHOR]

Selecting new probiotics involves evaluating their functional, technological and safety properties to ensure both health benefits and product stability. The study focused on evaluating the probiotic potential of ten lactic acid bacteria (LAB) strains isolated from Minas artisanal cheese through safety and functional tests. The strains were resistant to kanamycin and vancomycin but susceptible to clindamycin and did not exhibit hemolytic activity. Autoaggregation values ranged from 0.97 to 85.23% at 4 °C. Lactococcus lactis GV103 showed the highest hydrophobicity result (45.60%). In interactions with pathogens, the ten strains demonstrated the capacity for multiplication. GV17, GV103 and GV15 survived the gastrointestinal tract (GIT) simulation conditions. Milk fermentation, evaluation of technological properties and GIT resistance in a dairy matrix were performed with the strains Lacticaseibacillus paracasei GV17 and Lactococcus lactis GV103, which showed the best performance in probiotic screening tests. In lactic fermentation tests, GV103 exhibited a growth rate of 2.37 log CFU/h and fit the Baranyi model, with a correlation coefficient of 0.898. After 28 days of storage, the syneresis and water holding capacity of were 57.04% and 23.43%, respectively for GV17, and 51.80% and 27.85% for GV103. Furthermore, these strains maintained populations above 8.00 log CFU/mL. Under conditions simulating the GIT in a dairy matrix, both strains showed counts above 9 log CFU/mL after 360 min. Technologically stable and potentially probiotic strains, like GV17 and GV103, offer promising opportunities for developing health-enhancing functional foods. [ABSTRACT FROM AUTHOR]

Objective: To explore whether acupuncture combined with clomiphene can reduce the luteinizing hormone-to follicle-stimulating hormone ratio and impact the gut microbiota in patients with obese polycystic ovary syndrome. Methods: This open-label, randomized, parallel-group controlled trial included 86 women aged 20–40 years with obese polycystic ovary syndrome and 19 healthy controls. Participants were randomly assigned to either an acupuncture combined with clomiphene group or a clomiphene-only group, with a healthy control group for comparison. The treatment lasted three menstrual cycles, with acupuncture administered three times weekly and clomiphene given daily from day five of menstruation for five consecutive days per cycle. The primary outcome was the change in the luteinizing hormone-to-follicle-stimulating hormone (LH/FSH) ratio. Secondary outcomes included levels of other sex hormones, glucose and lipid metabolism parameters, self-rating anxiety and depression scale scores, and gut microbiota composition. Results: Intention-to-treat analysis showed that the adjusted mean luteinizing hormone-to follicle-stimulating hormone ratio decrease was -0.8 (95% CI: -1.14 to -0.46) in the acupuncture combined with clomiphene group and -0.22 (95% CI: -0.47 to 0.01) in the clomiphene group. The adjusted between-group difference was 0.53 (95% CI: 0.24 to 0.82, p < 0.001). The levels of Agathobacter faecis increased, and those of Erysipelatoclostridium spiroforme , Streptococcus lutetiensis , and Lactococcus lactis decreased after acupuncture combined with clomiphene treatment (p < 0.05). Conclusion: Acupuncture combined with clomiphene may be safe and effective, reduce the luteinizing hormone-to follicle-stimulating hormone ratio, and improve insulin resistance in obese polycystic ovary syndrome, and these outcomes may be related to the gut microbiota. [ABSTRACT FROM AUTHOR]

To understand the action mechanism of probiotics against postmenopausal symptoms, we examined the effects of Lactococcus lactis P32 (PL) and Bifidobacterium bifidum P45 (PB), which suppressed interleukin (IL)-6 and receptor activator of nuclear factor-κB (RANK) ligand (RNAKL) expression in Gardnerella vaginalis (Gv)-stimulated macrophages, on vaginitis, osteoporosis, and depression/cognitive impairment (DC) in mice with vaginally infected Gv, ovariectomy (Ov), or Ov/Gv (oG). Oral administration of PL or PB decreased Gv-induced DC-like behavior and tumor necrosis factor (TNF)-α, IL-6, RANK, and/or RANKL expression in the vagina, bone, hypothalamus, hippocampus, and colon, while Gv-suppressed bone osteoprotegerin and brain serotonin and brain-derived neurotrophic factor (BDNF) levels increased. They partially shifted vaginal and gut dysbiosis in Gv-infected mice to the gut microbiota composition in normal control mice. In mice with oG, oral administration of PL or PB decreased oG-induced DC-like behavior and TNF-α, IL-6, RANK, and/or RANKL expression in the vagina, bone, brain, and colon, while oG-suppressed bone osteoprotegerin and brain serotonin and BDNF levels increased. They also alleviated oG-induced vaginal and gut dysbiosis: they decreased Proteobacteria population. PL and PB (4:1) mix (PM) suppressed DC-like behavior in mice with Gv, Ov, or oG. PM also suppressed TNF-α, IL-6, RANK, and/or RANKL expression in the vagina, bone, colon, and brain. PM alleviated Gv-induced vaginal and gut dysbiosis: it decreased Proteobacteria population. These findings suggest that PL and PB, singly or together, can alleviate postmenopausal symptoms including vaginitis, colitis, osteoporosis, and DC by suppressing RANK/RANKL-mediated NF-κB activation and alleviating vaginal/gut microbiota dysbiosis. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a highly contagious, acute, febrile disease caused by the African swine fever virus (ASFV), with morbidity and mortality rates approaching 100% in domestic and wild swine, resulting in massive economic losses to the pig industry worldwide. This study aimed to express the p30, p54, and p72 proteins encoded by ASFV in vitro using the Lactobacillus lactis (L. lactis) expression system. Here, six new functional recombinant L. lactis were constructed, and the expression of the p30 protein, p54 protein, p72 protein, p30-LTB (heat-labile enterotoxin B, LTB) fusion protein, p54-LTB fusion protein, and the p72-LTB fusion protein was successfully detected by Western blot analysis. Following oral immunization of rabbits with recombinant L. lactis , serum IgG, intestinal mucosal sIgA, cytokines (IL-4 and INF-γ), and splenocyte viability were higher than in the control group via ELISA. Notably, without the LTB adjuvant group, humoral and Th1 cellular immunity were promoted, whereas, with the LTB adjuvant group, local mucosal immunity, humoral immunity, and Th2 cellular immunity were promoted, providing new insights into the design and development of an ASFV subunit vaccine. [ABSTRACT FROM AUTHOR]

Helicobacter pylori (HP) causes gastritis and peptic ulcer. Therefore, we examined whether probiotics Lactococcus lactis P135 and Bifidobacterium longum P142, which inhibited HP growth by 37.9% and 35.3%, respectively, and HP-induced IL-8 expression in KATO III cells by 68.6% and 63.1%, respectively, compared to those of normal controls, could mitigate HP-induced gastritis and psychiatric disorder in mice. Oral administration of P135 and/or P142 alleviated HP- or aspirin-induced gastritis, colitis, neuroinflammation, and depression/cognitive impairment-like behavior. They also suppressed HP infection, neutrophil infiltration, and NF-κB activation in the stomach and TNF-α expression and NF-κB activation in the colon and hippocampus. of P135 and/or P142 alleviated HP- or aspirin-induced gut dysbiosis: they decreased Lachnospiracease, Helicobacteriaceae, and Akkermansiaceae populations and increased Bacteroidaceae and Muribaculaceae populations. These findings suggest that HP growth/inflammation-inhibitory P135 and/or P142 may alleviate gut inflammation (gastritis and colitis) and neuroinflammation through the suppression of neutrophil infiltration, NF-κB activation, and HP growth, thereby leading to the attenuation of systemic inflammation and psychiatric disorder. [ABSTRACT FROM AUTHOR]

In fermented plant foods, phenolic compounds are metabolized by 2-ene reductases, which reduce double bonds adjacent to an aromatic rings in phytochemicals, including hydroxycinnamic acids, isoflavones, and flavones. Only few 2-ene reductases of lactic acid bacteria were characterized, including the hydrocinnamic reductases HcrB and Par1, and the daidzein reductase of Lactococcus lactis. This study aimed to characterize HcrF, a homologue of HcrB, in Limosilactobacillus fermentum. HcrF was purified after cloning in Escherichia coli and purification by affinity chromatography. HcrF was optimally active at 30°C–40°C and pH 7.0 and required both flavin mononucleotide and nicotinamide adenine dinucleotide as co-factors. Ferulic, caffeic, p-coumaric, and sinapic acids but not trans- cinnamic acids were reduced to dihydro derivatives. The maximum reaction velocity V max of HcrF was highest for ferulic acid. On a phylogenetic tree of 2-ene reductases, HcrF clustered most closely with the hydroxycinnamic acid reductase HcrB of Lactiplantibacillus plantarum. The hydroxycinnamic acid reductase Par1 of Furfurilactobacillus milii and flavone or isoflavone reductases were only distantly related to HcrF. In summary, current knowledge does not allow to predict the substrate specificity of 2-ene reductases on the basis of the protein sequence; this study adds HcrF to the short list of enzymes with known substrate specificity. [ABSTRACT FROM AUTHOR]

Objective: Recent work examined the influence of topically applied just‐add‐water creams containing Lactobacillus plantarum probiotic cultures on to reconstructed human epidermis (RHE). The ability to blend various quiescent probiotic powders in topical systems allows for the examination of these powders on RHEs employing various individual quiescent probiotics using human gene microarrays. Methods: Four topical Just‐Add‐Water powders (STRATABIOSYS™ Technologies) were prepared containing the following: (1) Lactobacillus plantarum Lp90 [200 M CFU/g]; (2) Saccharomyces cerevisiae [200 M CFU/g]; (3) Streptococcus thermophilus [200 M CFU/g]; and (4) Lactococcus Lactis LLa61 [200 M CFU/g]. A powder without probiotics was used as a placebo control. The creams were prepared by taking 3% of each powder and dissolving it into sterile water. A 15 μL sample of each cream was applied to a RHE tissue that presented approximately 90 K CFU/g of each microorganism on the tissue. The RHE was treated for 24 h with the creams whereupon the residual cream was rinsed off, and the tissues were analysed using Agilent human gene microarrays containing 19 217 individual genes from which a smaller subset of 244 genes pertinent to skin were culled. Results: The following probiotic specific gene responses were found: (1) Lactobacillus plantarum upregulated 4.9% of the skin‐relevant gene set; (2) Saccharomyces cerevisiae upregulated 7.8% of the skin relevant gene set; Streptococcus thermophilus upregulated 6.1% of the skin relevant gene set; Lactococcus lactis upregulated 7.0% of the skin relevant gene set. Conclusion: A method to examine topical probiotics on RHE has been described that involves converting the powders to preservative‐free creams. [ABSTRACT FROM AUTHOR]

The symptoms of foodborne illness caused by Bacillus cereus often go unreported, complicating the effectiveness of conventional chemical and physical methods used to inhibit its growth in food production. This challenge, combined with the increasing use of lactic acid bacteria (LAB) in the food industry and consumer preference for minimally processed products, prompted this study. The antibacterial activity of diffusible substances produced by Lactococcus lactis ATCC 11454 against Bacillus cereus NC11143 and Escherichia coli K-12 MG1655 was investigated using a non-contact co-culture model utilising deMann Rogosa and Sharpe broth, with glucose as a carbon source. This study employed plate counting and flow cytometry to assess the impact of these substances on bacterial growth and to analyse their composition and antimicrobial efficacy. The co-culture of Lactococcus lactis ATCC 11454 resulted in the production of a stable antimicrobial peptide, which was heat resistant and acid tolerant. Purification was achieved via ammonium sulphate precipitation and preparative HPLC, yielding a peptide with a molecular mass of 3.3 kDa, with daughter ion fractions similar to nisin A. Antimicrobial activity studies demonstrated that the diffusible substances effectively inhibited B. cereus growth over a period of eight days and exhibited bactericidal activity, killing 99% of the B. cereus cells. Additionally, these substances also inhibited Escherichia coli K-12 MG1655 grown under similar conditions. Comparative analysis revealed that in the co-culture assay, L. lactis produced a 50% higher yield of the antimicrobial peptides compared to pure cultures. Similarly, the specific growth rate of L. lactis was four times higher. With respect to protein purification and concentration, ammonium sulphate precipitation coupled with solid phase extraction was most effective in the purification and concentration of the diffusible substances. The findings provide a basis for utilising bacteriocin-producing strains as a preservation method, offering an alternative to traditional chemical and physical control approaches especially for the food industry. [ABSTRACT FROM AUTHOR]

Background: In ovo stimulation introduces bioactive compounds, such as prebiotics, probiotics, or synbiotics into incubating eggs to enhance gut health and immune system development in chickens. This study aimed to determine the genetic and environmental effects modulating responses to in ovo stimulation in commercial broilers and Green-legged Partridge-like (GP) native chickens. Methods: Eggs were stimulated on day 12 of incubation with prebiotics (GOS—galactooligosaccharides), probiotics (Lactococcus lactis subsp. cremoris), or synbiotics (GOS + L. lactis), with controls being mock-injected. Hatched chicks were reared in group pens and challenged with lipopolysaccharide (LPS) on day 42 post-hatching. Cecal tonsils (CT) and spleens were harvested 2 h post-challenge. RT-qPCR was used to analyze the relative gene expression of cytokine genes: IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12p40, and IL-17. Results: The results show that genotype influenced the expression of all immune-related genes, with broiler chickens exhibiting stronger innate inflammatory responses than native chickens. LPS induced both mucosal (CT) and systemic (spleen) immune responses in broilers but only systemic (spleen) responses in native chickens. Conclusions: In ovo stimulation had less of an impact on cytokine gene expression than LPS challenge. Broilers expressed higher inflammatory immune responses than GP native chickens. [ABSTRACT FROM AUTHOR]

Background/Objectives: Antimicrobial-resistant (AMR) pathogens represent a serious threat to public health, particularly in food production systems where antibiotic use remains widespread. As a result, alternative antimicrobial treatments to antibiotics are essential for effectively managing bacterial infections. This study aimed to identify and characterize novel antimicrobial peptides produced by bacteria, known as bacteriocins, as well as to recognize safe bacteriocin-producing strains, sourced from poultry slaughterhouse effluents. Methods: A total of 864 bacterial isolates were collected across eight stages of a poultry slaughter line and screened for antimicrobial activity against Gram-positive and Gram-negative indicator strains. Whole-genome sequencing (WGS) was performed on 12 selected strains, including Enterococcus faecium (6 isolates), Lactococcus lactis (1 isolate), Lactococcus garvieae (1 isolate) and Escherichia coli (4 isolates). The presence of bacteriocin gene clusters (BGC), antibiotic resistance genes (ARG), and virulence factors (VF) was analyzed. The antimicrobial activity of a novel bacteriocin was further evaluated using in vitro cell-free protein synthesis (IV-CFPS). Results: WGS revealed multiple BGCs, including a novel class IId bacteriocin, lactococcin P1A (LcnP1A), in L. lactis SWD9. LcnP1A showed antimicrobial activity against various indicator strains, including Listeria monocytogenes. While most bacteriocin-encoding strains harbored ARGs and VFs, E. faecium SWG6 was notable for its absence of ARGs and minimal VFs, highlighting its potential as a probiotic. Conclusions: These findings underscore the importance of discovering novel bacteriocins and safer bacteriocin producing strains to address antimicrobial resistance in the food chain. Further research would validate the efficacy of both the novel lactococcin P1A bacteriocin and the E. faecium SWG6 isolate for application in processed food and animal production systems. [ABSTRACT FROM AUTHOR]

Chitosan, a positively charged polymer obtained by treating chitin with hot alkali to remove acetyl groups, has extensive biological applications due to its non-toxicity, biocompatibility, and natural biodegradability. In this study, chitosan nanoparticles were prepared and encapsulated with bacteriocin isolated from Lactococcus lactis subsp. lactis, resulting in chitosan-bacteriocin conjugate nanoparticles produced using the ionic gelation method. The antibacterial activity of this formulation was evaluated as a potential food preservative against Bacillus cereus, Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus. The effectiveness of the conjugate nanoparticles was compared to that of crude chitosan, chitosan nanoparticles, and free bacteriocin. The agar diffusion method was employed to assess the in vitro dissolution of the substance and to investigate the effects of temperature and pH on its stability. The results indicated that the release of chitosan nanoparticles conjugated with bacteriocin in vitro was controlled at around 60% within 24 hours, demonstrating a cumulative and sustained effect. This release control was significantly higher compared to the free bacteriocin, which achieved a 90% release. Among the formulations tested, chitosan nanoparticles conjugated with bacteriocin (CSNps-B) demonstrated the most potent antibacterial activity. CSNps-B achieved inhibition zones ranging from 30.32 to 32.45 mm against Gram-positive bacteria and from 30.22 to 36.26 mm against Gram-negative bacteria. The superior performance of CSNps-B was statistically significant, with a p-value of less than 0.05 compared to the other formulations. In contrast, chitosan alone showed inhibition zones of 6.7 to 8.45 mm, chitosan nanoparticles (CSNps) exhibited zones of 10.12 to 12.6 mm, and free bacteriocin (free-B) ranged from 13.38 to 15.67 mm. The enhanced antibacterial effectiveness of CSNps-B underscores its potential as a superior antimicrobial agent compared to the other formulations evaluated. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Lactococcus lactis , widely used in the food fermentation industry, has developed various ways to regulate acid adaptation in the process of evolution. Investigation into how peptidoglycan (PG) senses and responds to acid stress is an expanding field. Here, we addressed the regulation of murT-gatD genes, which are responsible for the amidation of PG d -Glu. We found that lactic acid stress reduced murT-gatD expression, and overexpressing these genes notably decreased acid tolerance of L. lactis NZ9000, possibly due to a reduction in the negative charge of PG, thereby facilitating the influx of extracellular protons into the cell. Subsequently, by using a combination of DNA pulldown assay and electrophoretic mobility shift assay, we identified a novel MarR family regulator, RmaH, as an activator of murT-gatD transcription. Further MEME motif prediction, electrophoretic mobility shift assay verification, and fluorescent protein reporter assay showed that RmaH directly bound to the DNA motif 5′-KGVAWWTTTTGCT-3′ located in the upstream region of murT - gatD. Beyond the mechanistic investigation of RmaH activation of murT-gatD , this study provides new insight into how PG modification is regulated and responds to lactic acid stress. [ABSTRACT FROM AUTHOR]

Whole-genome sequencing was carried out, and the main characteristics of the genomes of three new strains of L. lactis AM1, MA1, and dlA, isolated from fermented milk and cereal grain products of South Africa and Russia, were established. The dual approach of in vitro and in silico analysis used in this work allowed us to assess more fully the bacteriocinogenic potential and antibiotic resistance of L. lactis strains. It was shown that L. lactis AM1 and dlA had an antagonistic effect against the test cultures of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538. The growth retardation of E. coli and S. aureus after 48 hours of cocultivation was 65–75 and 30–50%, respectively. The L. lactis MA1 strain did not exhibit a significant antagonistic effect; the growth inhibition of E. coli and S. aureus was 13 and 26%, respectively. According to the results of in silico analysis using the BAGELv4.0 service, gene clusters of class IId lactococcin-like bacteriocins were found in the genomes of all three strains. In the genomes of the dlA and AM1 strains, the sactipeptide cluster, a class I bacteriocin, is additionally annotated. In silico analysis of the L. lactis genomes showed the absence of transmissible antibiotic resistance genes, and all three strains showed a phenotype susceptible to the main classes of clinically relevant antibiotics (ampicillin, streptomycin, kanamycin, gentamicin, erythromycin, clindamycin, vancomycin, tetracycline, and chloramphenicol). Taken together, the results provide valuable information about the intraspecific diversity of L. lactis and indicate the promise of using new strains as starter cultures and biopreservatives. [ABSTRACT FROM AUTHOR]

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A high degree of hydrolysis can reduce the allergenicity of milk, while lactic acid bacteria (LAB) fermentation can further enhance the antioxidant ability of enzymatic milk. LAB with a strong antioxidant ability was screened, and the effects of LAB on the bitterness, taste and flavor of enzymatic skim milk (ESM) with a high degree of hydrolysis were investigated in this paper, in addition to the response surface methodology optimized the conditions of the LAB fermentation of ESM. The results indicate that the skim milk hydrolyzed by Protamex has a higher degree of hydrolysis and lower bitterness. The scavenging rate of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical, the inhibition rate of hydroxyl radical (·OH) and the superoxide dismutase (SOD) activity of Lactiplantibacillus plantarum 16 and Lactococcus lactis subsp. lactis m16 are significantly higher than those of other strains (p < 0.05), while the improvement effect of L. plantarum 16 on the bitterness and flavor of ESM is better than that of L. lactis subsp. lactis m16. The fermented ESM has a strong antioxidant ability and low bitterness when the inoculum quantity of L. plantarum 16 is 5%, fermentation at 37 °C for 18 h and the pH of the ESM is 6.5, for which the DPPH free radical scavenging rate is 61.32%, the ·OH inhibition rate is 83.35%, the SOD activity rate is 14.58 and the sensory evaluation is 4.25. The contents of amino acids related to bitterness and antioxidants were reduced and increased, respectively. The ESM fermented by L. plantarum 16 has a good flavor, antioxidant ability and low bitterness. [ABSTRACT FROM AUTHOR]

Novel antibiotic substitutes are increasingly in demand in the animal husbandry industry. An oral recombinant Lactococcus lactis (L. lactis) expressing human LL-37 (oral LL-37) was developed and its safety and antiviral effectiveness in vivo was tested. In addition to impairing liposome integrity, LL-37 polypeptide from recombinant L. lactis could prevent the host cell infection by a variety of viruses, including recombinant SARS, SARS-CoV-2, Ebola virus, and vesicular stomatitis virus G. Subchronic toxicity studies performed on Sprague–Dawley rats showed that no cumulative toxicity was found during short-term intervention. Oral LL-37 treatment after the onset of fever could reduce mortality in piglets infected with porcine reproductive and respiratory syndrome virus. Moreover, body weight gain of piglets receiving treatment was progressively restored, and nucleic acid positive rebound was not undetected after discontinuation. Oral LL-37 consistently increased the lifespan of chickens infected with Newcastle viruses. These findings suggested a potential use of recombinantly modified microorganisms in veterinary medicine. [ABSTRACT FROM AUTHOR]

The industrial amino acid production workhorse, Corynebacterium glutamicum naturally produces low levels of 2,3,5,6-tetramethylpyrazine (TMP), a valuable flavor, fragrance, and commodity chemical. Here, we demonstrate TMP production (∼0.8 g L-1) in C. glutamicum type strain ATCC13032 via overexpression of acetolactate synthase and/or α-acetolactate decarboxylase from Lactococcus lactis in CGXII minimal medium supplemented with 40 g L-1 glucose. This engineered strain also demonstrated growth and TMP production when the minimal medium was supplemented with up to 40% (v v-1) hydrolysates derived from ionic liquid-pretreated sorghum biomass. A key objective was to take the fully engineered strain developed in this study and interrogate medium parameters that influence the production of TMP, a critical post-strain engineering optimization. Design of experiments in a high-throughput plate format identified glucose, urea, and their ratio as significant components affecting TMP production. These two components were further optimized using response surface methodology. In the optimized CGXII medium, the engineered strain could produce up to 3.56 g L-1 TMP (4-fold enhancement in titers and 2-fold enhancement in yield, mol mol-1) from 80 g L-1 glucose and 11.9 g L-1 urea in shake flask batch cultivation.One-sentence summaryCorynebacterium glutamicum was metabolically engineered to produce 2,3,5,6-tetramethylpyrazine followed by a design of experiments approach to optimize medium components for high-titer production.

This study aimed to determine the efficacy of lactic acid bacteria probiotics containing Lactobacillus acidophilus and Lactococcus lactis on nutrient consumption and egg weight of Japanese quail. A total of 120 females Japanese quails comprised four treatments and six replications. T0, T1, T2, and T3 treatment groups were administered L. acidophilus and L. lactis with concentrations of 0, 1, 2, and 3 mL/liter of drinking water. Consumption data were collected weekly, and egg weight data were collected daily during treatment. The data obtained were then analyzed statistically using analysis of variance (ANOVA) and continued with the Duncan multiple range test (p < 0.05). The results of this study showed that probiotics in drinking water reported significant differences (p < 0.05) compared between treatments (T1, T2, and T3) to reduce nutrient intake of organic matter, crude protein, crude fat, crude fiber and increase egg weight of quail. It can be concluded that the combination of L. acidophilus and L. lactis can reduce nutrient consumption but can increase the egg weight of Japanese quail.

ABSTRACT: Lactococcus lactis, widely used in the manufacture of dairy products, encounters various environmental stresses both in natural habitats and during industrial processes. It has evolved intricate machinery of stress sensing and defense to survive harsh stress conditions. Here, we identified a novel TetR/AcrR family transcription regulator, designated AcrR1, to be a repressor for acid and antibiotic tolerance that was derepressed in the presence of vancomycin or under acid stress. The survival rates of acrR1 deletion strain ΔAcrR1 under acid and vancomycin stresses were about 28.7-fold (pH 3.0, HCl), 8.57-fold (pH 4.0, lactic acid) and 2.73-fold (300 ng/mL vancomycin) greater than that of original strain F44. We also demonstrated that ΔAcrR1 was better able to maintain intracellular pH homeostasis and had a lower affinity to vancomycin. No evident effects of AcrR1 deletion on the growth and morphology of strain F44 were observed. Subsequently, we characterized that the transcription level of genes associated with amino acids biosynthesis, carbohydrate transport and metabolism, multidrug resistance, and DNA repair proteins significantly upregulated in ΔAcrR1 using transcriptome analysis and quantitative reverse transcription-PCR assays. Additionally, AcrR1 could repress the transcription of the nisin post-translational modification gene, nisC, leading to a 16.3% increase in nisin yield after AcrR1 deletion. Our results not only refined the knowledge of the regulatory mechanism of TetR/AcrR family regulator in L. lactis, but presented a potential strategy to enhance industrial production of nisin.

Abstract Background Herpes simplex virus type 1 (HSV-1) is a major cause of viral encephalitis, genital mucosal infections, and neonatal infections. Lactococcus lactis (L. lactis) has been proven to be an effective vehicle for delivering protein antigens and stimulating both mucosal and systemic immune responses. In this study, we constructed a recombinant L. lactis system expressing the protective antigen glycoprotein D (gD) of HSV-1. Results To improve the stability and persistence of antigen stimulation of the local mucosa, we inserted the immunologic adjuvant interleukin (IL)-2 and the Fc fragment of IgG into the expression system, and a recombinant L. lactis named NZ3900-gD-IL-2-Fc was constructed. By utilizing this recombinant L. lactis strain to elicit an immune response and evaluate the protective effect in mice, the recombinant L. lactis vaccine induced a significant increase in specific neutralizing antibodies, IgG, IgA, interferon-γ, and IL-4 levels in the serum of mice. Furthermore, in comparison to the mice in the control group, the vaccine also enhanced the proliferation levels of lymphocytes in response to gD. Moreover, recombinant L. lactis expressing gD significantly boosted nonspecific immune reactions in mice through the activation of immune-related genes. Furthermore, following the HSV-1 challenge of the murine lung mucosa, mice inoculated with the experimental vaccine exhibited less lung damage than control mice. Conclusion Our study presents a novel method for constructing a recombinant vaccine using the food-grade, non-pathogenic, and non-commercial bacterium L. lactis. The findings indicate that this recombinant vaccine shows promise in preventing HSV-1 infection in mice.

Biotechnology continues to drive innovation in the production of pharmaceuticals, biofuels, and other valuable compounds, leveraging the power of microbial systems for enhanced yield and sustainability. Genome-scale metabolic (GSM) modeling has become an essential approach in this field, which enables a guide for targeting genetic modifications and the optimization of metabolic pathways for various industrial applications. While single-species GSM models have traditionally been employed to optimize strains like Escherichia coli and Lactococcus lactis, the integration of these models into community-based approaches is gaining momentum. Herein, we present a pipeline for community metabolic modeling with a user-friendly GUI, applying it to analyze interactions between Methylococcus capsulatus, a biotechnologically important methanotroph, and Escherichia coli W3110 under oxygen- and nitrogen-limited conditions. We constructed models with unmodified and homoserine-producing E. coli strains using the pipeline implemented in the original BioUML platform. The E. coli strain primarily utilized acetate from M. capsulatus under oxygen limitation. However, homoserine produced by E. coli significantly reduced acetate secretion and the community growth rate. This homoserine was taken up by M. capsulatus, converted to threonine, and further exchanged as amino acids. In nitrogen-limited modeling conditions, nitrate and ammonium exchanges supported the nitrogen needs, while carbon metabolism shifted to fumarate and malate, enhancing E. coli TCA cycle activity in both cases, with and without modifications. The presence of homoserine altered cross-feeding dynamics, boosting amino acid exchanges and increasing pyruvate availability for M. capsulatus. These findings suggest that homoserine production by E. coli optimizes resource use and has potential for enhancing microbial consortia productivity. [ABSTRACT FROM AUTHOR]

Enhancing the secretion of recombinant proteins, particularly non-enzymatic proteins that predominate in food and pharmaceutic protein products, remains a significant challenge due to limitations in high-throughput screening methods. This study addresses this bottleneck by establishing a yeast surface display system in the food-grade microorganism Kluyveromyces lactis, enabling efficient display of model target proteins on the yeast cell surface. To assess its potential as a universal high-throughput screening tool for enhanced non-enzymatic protein secretion, we evaluated the consistency between protein display levels and secretion efficiency under the influence of various genetic factors. Our results revealed a strong correlation between these two properties. Furthermore, screening in a random mutagenesis library successfully identified a mutant with improved secretion. These findings demonstrate the potential of the K. lactis surface display system as a powerful and universal tool for high-throughput screening of strains with superior non-enzymatic protein secretion capacity. We believe this study could pave the way for efficient large-scale production of heterologous food and therapeutic proteins in industries. Key points: • A YSD (yeast surface display) system was established in Kluyveromyces lactis • This system enables high-throughput screening of non-enzymatic protein secretion • This technology assists industrial production of food and therapeutic proteins [ABSTRACT FROM AUTHOR]

Enterococcus faecalis incorporates and elongates exogeneous short‐ and medium‐chain fatty acids to chains sufficiently long to enter membrane phospholipid synthesis. The acids are activated by the E. faecalis fatty acid kinase (FakAB) system and converted to acyl‐ACP species that can enter the fatty acid synthesis cycle to become elongated. Following elongation the acyl chains are incorporated into phospholipid by the PlsY and PlsC acyltranferases. This process has little effect on de novo fatty acid synthesis in the case of short‐chain acids, but a greater effect with medium‐chain acids. Incorporation of exogenous short‐chain fatty acids in E. faecalis was greatly increased by overexpression of either AcpA, the acyl carrier protein of fatty acid synthesis, or the phosphate acyl transferase PlsX. The PlsX of Lactococcus lactis was markedly superior to the E. faecalis PlsX in incorporation of short‐chain but not long‐chain acids. These manipulations also allowed unsaturated fatty acids of lengths too short for direct transfer to the phospholipid synthesis pathway to be elongated and support growth of E. faecalis unsaturated fatty acid auxotrophic strains. Short‐ and medium‐chain fatty acids can be abundant in the human gastrointestinal tract and their elongation by E. faecalis would conserve energy and carbon by relieving the requirement for total de novo synthesis of phospholipid acyl chains. [ABSTRACT FROM AUTHOR]

Interleukin (IL) 36 is a member of the IL-1-like proinflammatory cytokine family that has a protective role in mucosal immunity. We hypothesized that mucosal delivery of IL-36γ to the intestine would be a very effective way to prevent intestinal diseases. Here, we genetically engineered a lactic acid bacterium, Lactococcus lactis, to produce recombinant mouse IL-36γ (rmIL-36γ). Western blotting and enzyme-linked immunosorbent assay results showed that the engineered strain (NZ-IL36γ) produced and hypersecreted the designed rmIL-36γ in the presence of nisin, which induces the expression of the recombinant gene. We administered NZ-IL36γ to mice via oral gavage, and collected the ruminal contents and rectal tissues. Colony PCR using primers specific for NZ-IL36γ, and enzyme-linked immunosorbent assay to measure the rmIL-36γ concentrations of the ruminal contents showed that NZ-IL36γ colonized the mouse intestines and secreted rmIL-36γ. A microbiota analysis revealed increased abundances of bacteria of the genera Acetatifactor, Eubacterium, Monoglobus, and Roseburia in the mouse intestines. Real-time quantitative PCR of the whole colon showed increased Muc2 expression. An in vitro assay using murine colorectal epithelial cells and human colonic cells showed that purified rmIL-36γ promoted Muc2 gene expression. Taken together, these data suggest that NZ-IL36γ may be an effective and attractive tool for delivering rmIL-36γ to improve the intestinal environment. [ABSTRACT FROM AUTHOR]

Vitamin K (VitK) is a vital nutrient that is newly recognized to support bone and cardiovascular health. As a nutraceutical, VitK is produced via plant extraction and bacterial fermentation. This study examined the potential anti-inflammatory and osteogenic benefits of VitK, i.e., VitK1 (phylloquinone; PK) and VitK2 (menaquinone; MKs), derived from Sargassum fulvellum fermented by Lactococcus lactis and Leuconostoc mesenteroides (SfLlLm) using lipopolysaccharide (LPS)-induced Raw264.7, MC3T3-E1 cells, and ovariectomized (OVX) mice. MK4, MK7, and MK9, as well as PK, were effectively acquired from SfLlLm and analyzed. SfLlLm_VitK reduced levels of proinflammatory cytokine in LPS-induced Raw264.7 cells and induced an osteogenesis regulating factor in MC3T3-E1 cells. In OVX mice, SfLlLm feeding reduced plasma levels of alkaline phosphatase, phosphate, and the pro-collagen type I alpha 2 gene (pro-Col1a2) while elevating cancellous bone volume and trabecular numbers. Accordingly, SfLlLm, comprising MKs, may be a candidate for preventing and treating immune and bone diseases. [ABSTRACT FROM AUTHOR]

Bacteriocins are ribosomally synthesized peptides with the innate ability to kill or inhibit growth of other bacteria. In recent years, bacteriocins have received increased interest, as their antimicrobial activity enhances food safety and shelf life by combatting pathogens such as Listeria monocytogenes. They also have application potential as an active pharmaceutical compound to combat multidrug‐resistant pathogens. As new bacteriocins continue to be discovered, accelerated workflows for screening, identification, and process development have been developed. However, antimicrobial activity measurement is often still limited with regards to quantification and throughput. Here, we present the use of a non‐linear calibration model to infer nisin concentrations in cultivation supernatants of Lactococcus lactis ssp. lactis B1629 using readouts of pHluorin2 fluorescence‐based antimicrobial activity assays. [ABSTRACT FROM AUTHOR]

Inflammation plays a crucial role in atherosclerosis and nonalcoholic fatty liver disease (NAFLD). We previously engineered a recombinant Lactococcus lactis strain expressing the Ling-Zhi immunomodulatory protein (L. lactis-LZ8). This study investigated the anti-atherosclerotic effects of L. lactis-LZ8 in rabbits fed a high-fat diet (HFD). Changes in body weight, serum lipid profiles, and liver function were monitored. The aorta and liver tissues were analyzed for gross pathology and histopathology. Eight-week administration of L. lactis-LZ8 with HFD ameliorated atherosclerosis by downregulating protein and gene expression associated with lipid metabolism and inflammation in the aortas. The rabbits receiving L. lactis-LZ8 exhibited a significant dose-dependent reduction in hepatic fat accumulation. RNA sequencing of the livers revealed that inflammatory genes in the L. lactis-LZ8 groups were downregulated compared to the HFD group. Disease ontology enrichment analysis indicated that these genes were involved in atherosclerosis. Gene set enrichment analysis plots revealed significant enrichment in the gene sets related to cholesterol homeostasis. CIBERSORT immune cell fraction analysis indicated significant infiltration by regulatory T cells, CD8+ T cells, activated dendritic cells, and natural killer cells in the L. lactis-LZ8 group. Our studies underscore LZ8's role in precision nutrition, providing a potential solution to the current challenges in modifying atherosclerosis and NAFLD. [ABSTRACT FROM AUTHOR]

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Despite efforts to prevent atypical ensiling conditions, such as delayed ensiling or sealing, these issues frequently occur in practice. This study aimed to investigate the effects of delayed ensiling (forage held for 24 h) and sealing, along with inoculation using a blend of Lentilactobacillus buchneri and Lactococcus lactis, on the characteristics of the resulting silages. Whole-plant maize (Zea mays L.) was treated with or without a commercial inoculant and ensiled (36% dry matter) for 60 days in 3.0 L glass containers. The forage was either ensiled immediately or subjected to a 24 h delay before ensiling. During the delay, the forage was either covered or left uncovered. Each treatment was replicated five times. All data were analyzed using the MIXED procedure of SAS statistical software (version 9.4; SAS Institute Inc., Cary, NC, USA). Delaying the ensiling process by 24 h worsens fermentation parameters, significantly increases dry matter (DM) losses (p < 0.01), and significantly reduces aerobic stability and the hygienic quality of the silage (p < 0.01), as evidenced by higher concentrations of undesirable fermentation products and elevated yeast and mold counts. The inoculation has a significant impact on both forage before ensiling and the characteristics of the resulting silage. Maize forage treated with inoculant showed a lower temperature increase by 8.2–8.1 °C (p < 0.01) when delayed for 24 h before ensiling. In silages, it also resulted in a reduced pH (p < 0.01); increased concentrations of lactic acid; acetic acid; and 1,2-propanediol (p < 0.01); and decreased levels of negative fermentation indicators such as ammonia-N, alcohols, and butyric acid (p < 0.01) During both the fermentation and aerobic exposure periods, inoculated silages exhibited up to 36% and 2.6 times lower (p < 0.01) dry matter loss, while suppressing the growth of yeasts and molds by up to 2.6 and 3.1 times (p < 0.01), respectively, compared to non-inoculated silages. The results of this study support the recommendation to minimize the duration of aerobic exposure of fresh forage during silo filling and to use LAB-based inoculants. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Endoglucanase (EG) and cellobiohydrolase (CBH) which produced by microorganisms, have been widely used in industrial applications. Methods: In order to construct recombinant bacteria that produce high activity EG and CBH, in this study, eg (endoglucanase) and cbh (cellobiohydrolase) were cloned from the rumen microbial genome of yak and subsequently expressed independently and co-expressed within Lactococcus lactis NZ9000 (L. lactis NZ9000). Results: The recombinant strains L. lactis NZ9000/pMG36e-usp45-cbh (L. lactis-cbh), L. lactis NZ9000/pMG36e-usp45-eg (L. lactis-eg), and L. lactis NZ9000/pMG36e-usp45-eg-usp45-cbh (L. lactis-eg-cbh) were successfully constructed and demonstrated the ability to secrete EG, CBH, and EG-CBH. The sodium carboxymethyl cellulose activity of the recombinant enzyme EG was the highest, and the regenerated amorphous cellulose (RAC) was the specific substrate of the recombinant enzyme CBH, and EG-CBH. The optimum reaction temperature of the recombinant enzyme CBH was 60℃, while the recombinant enzymes EG and EG-CBH were tolerant to higher temperatures (80℃). The optimum reaction pH of EG, CBH, and EG-CBH was 6.0. Mn2+, Fe2+, Cu2+, and Co2+ could promote the activity of CBH. Similarly, Fe2+, Ba2+, and higher concentrations of Ca2+, Cu2+, and Co2+ could promote the activity of EGCBH. The addition of engineered strains to whole-plant corn silage improved the nutritional quality of the feed, with the lowest pH, acid detergent fiber (ADF), and neutral detergent fiber (NDF) contents observed in silage from the L. lactiseg group (p < 0.05), and the lowest ammonia nitrogen (NH3-N), and highest lactic acid (LA) and crude protein (CP) contents in silage from the L. lactis-eg + L. lactis-cbh group (p < 0.05), while the silage quality in the L. lactis-cbh group was not satisfactory. Discussion: Consequently, the recombinant strains L. lactis-cbh, L. lactis-eg, and L. lactis-eg-cbh were successfully constructed, which could successfully expressed EG, CBH, and EG-CBH. L. lactis-eg promoted silage fermentation by degrading cellulose to produce sugar, enabling the secretory expression of EG, CBH, and EG-CBH for potential industrial applications in cellulose degradation. [ABSTRACT FROM AUTHOR]

Aim To investigate the effect of pyruvate and glucose on leucine transamination and 3-methylbutanal production by Lactococcus lactis , including the comparison with cells possessing glutamate dehydrogenase (GDH) activity. Methods and results Lactococcus lactis cells were incubated in chemically defined medium (CDM) with the pH controlled at 5.2 to mimic cheese conditions. Pyruvate supplementation stimulated the production of the key flavour compound 3-methylbutanal by 3–4 times after 72 h of incubation. Concurrently, alanine production increased, demonstrating the involvement of pyruvate in transamination reactions. Glucose-metabolizing cells excreted α-ketoisocaproic acid and produced even 3 times more 3-methylbutanal after 24 h than pyruvate-supplemented cells. Conjugal transfer technique was used to transfer the plasmid pGdh442 carrying the gdh gene encoding for GDH to L. lactis. Introducing GDH did not stimulate the excretion of α-ketoisocaproic acid and the production of 3-methylbutanal. Conclusions These results demonstrate that Lactococcus uses pyruvate to transaminate leucine into α-ketoisocaproic acid which supports 3-methylbutanal production. Surprisingly, GDH activity did not stimulate leucine transamination and 3-methylbutanal production. [ABSTRACT FROM AUTHOR]

Spontaneous fermentation of Brassica vegetables is an ancient method that improves the foods' sensory properties, safety, and shelf life. However, in recent years, there has been a growing interest in studying controlled fermentation with lactic acid bacteria selected based on their technological properties. This study reported the inhibitory activity of a Lactococcus lactis ssp. lactis of marine origin and the evolution of a two-step controlled fermentation using the cited strain and two selected Lactiplantibacillus strains. Lc. lactis ssp. lactis was studied by phenotypic and genotypic methods. The inhibitory activity was assayed against common contaminants and pathogens. The strain behaviour in Chinese cabbage and white cabbage fermentation was studied by monitoring the cell count and inhibitory activity against Listeria innocua ATCC 33090. The two-step controlled fermentation of Chinese and white cabbage was conducted using, in the first step, the Lactococcus strain and, in the second step, the two Lactiplantibacillus strains. The evolution of the processes was monitored by cell counts and pH measurements. PCR amplification confirmed the presence of nisin Z gen in the Lc. lactis ssp. lactis strain. The bacteriocin exerted inhibitory activity against Gram-positive related species but not against Gram-negative ones. The results obtained in the controlled fermentation suggested that the combination of the selected strains is compatible and may improve the fermented matrices' safety. [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]