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Purpose: Gamma-aminobutyric acid (GABA) is a four-carbon and nonprotein amino acid, made by various microorganisms, especially lactic acid bacteria (LAB) and probiotics. GABA has various physiological roles, for instance, insomnia, depression, hypotensive activity as well as diuretic effects. The production of GABA-based foods is a favorable result from GABA's biological and functional properties. The purpose of this study is to investigate different methods of improving GABA production in probiotics and LAB to select the superlative method and bacterial strain. Design/methodology/approach: In this review paper, all articles from five electronic databases containing Google Scholar, Web of Science, PubMed, Scopus and Science Direct were considered from 2000 to January 11, 2023, with keywords "Optimization" OR "Enhance" OR "Increase" AND "Gamma-aminobutyric acid" OR "GABA" AND "Probiotics" OR "Lactic acid bacteria" and selected according to the purpose of the study. Findings: It seems that among all the investigated methods, an effective fermentation procedure with optimal conditions including fermentation medium, 5 L; glutamic acid, 295 g/L; incubation temperature, 32°C; inoculum, 10% (v/v); and agitation, 100 rpm, after 48 h of fermentation led to producing 205,800 mg/L of GABA from the effective bacterial strain Lactobacillus brevis NCL912. Originality/value: With a simple but optimized fermentation, L. brevis NCL912 can be used for the efficient GABA production in the pharmacy and food factories. [ABSTRACT FROM AUTHOR]

Hyperuricemia is a prevalent disease worldwide that is characterized by elevated urate levels in the blood owing to purine metabolic disorders, which can result in gout and comorbidities. To facilitate the treatment of hyperuricemia through the uricolysis, we engineered a probiotic Escherichia coli Nissle 1917 (EcN) named EcN C6 by inserting an FtsP‐uricase cassette into an "insulated site" located between the uspG and ahpF genes. Expression of FtsP‐uricase in this insulated region did not influence the probiotic properties or global gene transcription of EcN but strongly increased the enzymatic activity for urate degeneration, suggesting that the genome‐based insulated system is an ideal strategy for EcN modification. Oral administration of EcN C6 successfully alleviated hyperuricemia, related symptoms and gut microbiota in a purine‐rich food‐induced hyperuricemia rat model and a uox‐knockout mouse model. Together, our study provides an insulated site for heterologous gene expression in EcN strain and a recombinant EcN C6 strain as a safe and effective therapeutic candidate for hyperuricemia treatment. [ABSTRACT FROM AUTHOR]

Yogurt is a fermented milk product characterised by a peculiar nutritional composition with live and viable cultures of bacteria. Few studies have analysed the benefits of yogurt consumption on health outcomes during paediatric age. Recent epidemiological studies evaluating the nutritional impact of yogurt have demonstrated its significant contribution to nutrients intakes among children. Thus, consuming yogurt is a strategy to achieve recommended nutrient intake and healthier dietary choices, with potential impact on obesity and cardiometabolic outcome in children. Yogurt's effects on paediatric infectious diseases, gastrointestinal diseases and atopic-related disorders are ascribed to the specific probiotic strain administered. Interestingly, the benefits of yogurt consumption are most likely due to effects mediated through the gut microbiota and the enhancement of innate and adaptive immune responses. Therefore, supplementing standard yogurt cultures with probiotic strains could be useful to promote health at different paediatric ages, although more evidence is needed regarding the strain-related effects and their interplay within the paediatric immune system. [ABSTRACT FROM AUTHOR]

Disruption of quorum sensing (QS) system, which is a central regulator for pathogenesis of Pseudomonas aeruginosa, is referring to as quorum quenching (QQ). This study was undertaken to evaluate and enhance the anti-quorum sensing (AQS) potential of probiotic strain Lactobacillus rhamnosus GG. The cell-free supernatant (CFS) of this probiotic strain showed anti-quorum sensing activity against Pseudomonas aeruginosa, which was determined using well-diffusion agar-plate assay. Anti-quorum sensing potential of L. rhamnosus GG was enhanced by optimization of various cultural conditions using classical and statistical optimization approaches. Six variables were optimized using one-variable-at-a-time (OVAT) method. Four significant variables, viz., temperature, pH, incubation time, metal ion, and its concentration, were chosen for further optimization by response surface methodology (RSM) using central composite design (CCD). Analysis of variance (ANOVA) demonstrated that the regression model is highly significant, as indicated by F test with a low probability value (p < 0.0002) and high value of coefficient of determination (0.8738) and also had significant influence on the generation of anti-quorum sensing effector molecules. Maximum production of anti-quorum sensing activity, in terms of zones of inhibition, was achieved under the following optimized conditions such as 37 °C temperature, pH 6.5, incubation time 24 h, and 2.5 mM concentration of zinc sulfate (ZnSO4). The quadratic model predicted 1.3-fold increase anti-quorum sensing activity production over un-optimized cultural conditions. The present research is the first report representing the enhancement of anti-quorum sensing potential of L. rhamnosus GG. [ABSTRACT FROM AUTHOR]

Disruption of quorum sensing (QS) system, which is a central regulator for pathogenesis of Pseudomonas aeruginosa, is referring to as quorum quenching (QQ). This study was undertaken to evaluate and enhance the anti-quorum sensing (AQS) potential of probiotic strain Lactobacillus rhamnosus GG. The cell-free supernatant (CFS) of this probiotic strain showed anti-quorum sensing activity against Pseudomonas aeruginosa, which was determined using well-diffusion agar-plate assay. Anti-quorum sensing potential of L. rhamnosus GG was enhanced by optimization of various cultural conditions using classical and statistical optimization approaches. Six variables were optimized using one-variable-at-a-time (OVAT) method. Four significant variables, viz., temperature, pH, incubation time, metal ion, and its concentration, were chosen for further optimization by response surface methodology (RSM) using central composite design (CCD). Analysis of variance (ANOVA) demonstrated that the regression model is highly significant, as indicated by F test with a low probability value (p < 0.0002) and high value of coefficient of determination (0.8738) and also had significant influence on the generation of anti-quorum sensing effector molecules. Maximum production of anti-quorum sensing activity, in terms of zones of inhibition, was achieved under the following optimized conditions such as 37 °C temperature, pH 6.5, incubation time 24 h, and 2.5 mM concentration of zinc sulfate (ZnSO4). The quadratic model predicted 1.3-fold increase anti-quorum sensing activity production over un-optimized cultural conditions. The present research is the first report representing the enhancement of anti-quorum sensing potential of L. rhamnosus GG. [ABSTRACT FROM AUTHOR]

Probiotics are live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. The aim of this study was to identify genotypically lactobacilli strains isolated from newborn stools and selecting strain based on probiotic properties (gastrointestinal tolerance, antibiotic susceptibility, inhibition of pathogen biofilm formation, absence of alfa or gamma-blood hemolysis, and lysozyme sensibility) and technological properties of surviving either in ice cream bar or ice-lolly. Reduction of 1.2log cfu ml-1 of the Lactobacillus paracasei strain was observed after exposure through in vitro gastrointestinal conditions. It inhibited biofilms of Escherichia coli, Salmonella Typhimurium and Candida albicans by mechanisms of competition, exclusion and displacement, and was resistant up to 3000μg ml-1 of egg white lysozyme. It presented neither alfa nor gamma-hemolysis or was antibiotic resistant to usual antibiotics for human use. Microbial survivability in ice cream bar or ice-lolly was assessed up to 21 days of storage at -18°C. Viability was maintained in ice cream bar, but there was a reduction of almost 2.0logs in ice-lolly. [ABSTRACT FROM AUTHOR]

Yogurt products fermented with probiotic bacteria are a consumer trend and a challenge for functional food development. So far, limited research has focused on the behavior of the various probiotic strains used in milk fermentation. In the present study, we characterized folic acid production and the sensory and textural characteristics of yogurt products fermented with probiotic bacteria. Yogurt fermented with Lactobacillus plantarum had improved nutrient content and sensory and textural characteristics, but the presence of L. plantarum significantly impaired the growth and survival of Lactobacillus delbrueckii ssp. bulgaricus during refrigerated storage. Overall, L. plantarum was a good candidate for probiotic yogurt fermentation; further studies are needed to understand the major metabolite path of lactic acid bacteria in complex fermentation. [ABSTRACT FROM AUTHOR]

Introduction. Lactobacillus gasseri is a lactic bacteria in the digestive tract, which has important probiotic features for control of pathogens, while S. aureus is a pathogenic strain important in the food industry due to health problems resulting in various countries. Objective. We sought to assess the probiotic L. gasseri features on S. aureus in vitro conditions. Materials and methods. susceptibility of both strains to various antibiotics was evaluated; The inhibition effect of L. gasseri and on S.aureus supernatant; growth of lactic strain at different pHs, temperatures, bile salts and bile bovine; fermentation kinetics was also established therein and counting viable microorganism in plaque, pH, sugar intake, protein intake and percentage of lactic acid was determined;, peptides, lactic acid and amino acids in the supernatant was determined for HPLCDAD y HPLC-PDA. Results. Both strains resistance to the antibiotics penicillin, dicloxacillin, cephalexin and cifoxitin. Lactic strain and the supernatant inhibited the growth of S. aureus. Growth was adequate for the different variables with values between 1.5 x 108 to 3.0 x 1014 CFU/150 μl. The exponential phase at 9 hours with values of 33.33 Ln CFU/150 μl was observed. Finally he identified by HPLC-DAD VAL-VAL-TIR peptide, 11.70 g/l of lactic acid and amino acid tyrosine. Conclusion. The results show that Lactobacillus gasseri have probiotic characteristics on S. aureus in vitro conditions. [ABSTRACT FROM AUTHOR]

Simple Summary: Considerable attention has been given to the species Limosilactobacillus reuteri regarding its probiotic potential. Here, the genome-scale metabolic model (GSMM) of L. reuteri KUB-AC5, namely iTN656 was developed and exploited to evaluate the metabolic capability of L. reuteri KUB-AC5 under various carbon sources. The simulated growth behaviors of iTN656 under single and double omission analysis promisingly identified 14 essential single nutrients and 2 essential double nutrients (pairwise glutamine-glutamate and asparagine-aspartate) for L. reuteri KUB-AC5 growth. Moreover, the integrated transcriptomic analysis using iTN656 allowed to probe the potential metabolic routes for enhancing growth of L. reuteri KUB-AC5 involved in sucrose uptake, nucleotide biosynthesis, urea cycle, and glutamine transporter. Overall, iTN656 provides a powerful systems biology platform for gaining insights into cell metabolism of lactic acid bacteria and guiding the rational development of synthetic media design for scale-up of probiotic production in industrial scale. Limosilactobacillus reuteri KUB-AC5 displays the hallmark features of probiotic properties for food and feed industries. Optimization of cultivation condition for the industrial production is important to reach cell concentration and cost reduction. Considering the strain-specific growth physiology, metabolic capability, and essential nutrients of L. reuteri KUB-AC5, the genome-scale metabolic model (GSMM) of L. reuteri KUB-AC5 was developed. Hereby, the GSMM of iTN656 was successfully constructed which contained 656 genes, 831 metabolites, and 953 metabolic reactions. The iTN656 model could show a metabolic capability under various carbon sources and guide potentially 14 essential single nutrients (e.g., vitamin B complex and amino acids) and 2 essential double nutrients (pairwise glutamine-glutamate and asparagine-aspartate) for L. reuteri KUB-AC5 growth through single and double omission analysis. Promisingly, the iTN656 model was further integrated with transcriptome data suggesting that putative metabolic routes as preferable paths e.g., sucrose uptake, nucleotide biosynthesis, urea cycle, and glutamine transporter for L. reuteri KUB-AC5 growth. The developed GSMM offers a powerful tool for multi-level omics analysis, enabling probiotic strain optimization for biomass overproduction on an industrial scale. [ABSTRACT FROM AUTHOR]

Lactobacillus rhamnosus strain GG ( ATCC 53103) is one of the most widely studied and commercialized probiotic strains, and thus strain-specific identification for the strain is highly valuable. In this study, two published PCR-based identification methods for strain GG, a transposase gene-targeting system and a phage-related gene-targeting system, were evaluated. The former produced amplicons from eight of the 41 strains tested and the phage-related system from five of the tested strains, including the strain GG. Fingerprinting analysis indicated that the strains LMG 18025, LMG 18030, and LMG 18038, which had an amplicon by the former system but none by the latter, were genetically distinguishable from L. rhamnosus GG at strain level. Strains LMG 23320, LMG 23325, LMG 23534, and LMG 25859 showed profiles very similar to that of the strain GG, suggesting that these strains might be identical to GG or derivative strains of it. The results here indicated that the phage-related gene-targeting system is a good tool for accurate identification of L. rhamnosus GG. This system would be able to detect both the original L. rhamnosus GG and its derivative strains. [ABSTRACT FROM AUTHOR]

Probiotic bacteria are live microorganisms which confer to health benefits of the host. They help to maintain the integrity of the intestinal barrier function by modulating the mucosal and systemic immune response of the host. These bacteria have proven their beneficial effect in several conditions of ulcerative colitis. More recently probiotics/synbiotics have been included in the treatment of critically ill patients. However to date it remains uncertain whether probiotics/synbiotics are beneficial or even dangerous to the clinical outcome of this patient group. This article reviews the current evidence of the use of bacteria in critically ill patients in intensive care settings. [ABSTRACT FROM AUTHOR]

To develop a quick and accurate PCR-based method to evaluate viable Bifidobacterium breve strain Yakult (BbrY) in human faeces. The number of BbrY in faeces was detected by using strain-specific quantitative real-time PCR (qPCR) derived from a randomly amplified polymorphic DNA analysis. And using propidium monoazide (PMA) treatment, which combined a DNA-intercalating dye for covalently linking DNA in dead cells and photoactivation, only viable BbrY in the faeces highly and significantly correlated with the number of viable BbrY added to faecal samples within the range of 10-10 cells per g of faeces was enumerated. After 11 healthy subjects ingested 10·7 log CFU of BbrY daily for 10 days, 6·9 (±1·5) log CFU g [mean (±SD)] of BbrY was detected in faeces by using strain-specific transgalactosylated oligosaccharide-carbenicillin (T-CBPC) selective agar medium. Viable BbrY detected by qPCR with PMA treatment was 7·5 (±1·0) log cells per g and the total number (viable and dead) of BbrY detected by qPCR without PMA treatment was 8·1 (±0·8) log cells per g. Strain-specific qPCR with PMA treatment evaluated viable BbrY in faeces quickly and accurately. Combination of strain-specific qPCR and PMA treatment is useful for evaluating viable probiotics and its availability in humans. [ABSTRACT FROM AUTHOR]

Abstract: The behavior of Bifidobacterium animalis subsp. lactis Bb 12 under batch cultivation, after continuous culturing for up to 12d, was monitored in skim milk-based media. Previous continuous culture for longer than 6d affected the physiology of said microorganism. The minimum inhibitory concentrations of lactic and acetic acids increased from 18 to 26g/l, whereas the molar ratio of acetic to lactic acid increased from 0.8 to 1.55, when the previous continuous culture increased its duration from 1 to 12d. The specific lactose consumption rate decreased from 0.94 to 0.77glactose/gcelldrymass/h within the batch culture timeframe; this was concomitant with greater amounts of acetic and formic acids, and lower amounts of lactic acid produced. The β-galactosidase activity increased as continuous culturing time increased, and reached 446units/ml by 12d; however, the rate of enzyme synthesis decreased concomitantly. Succinic acid was produced during the exponential growth and stationary phases of the batch culture, but the former at exponential growth phase was higher as the continuous culturing time was longer. For comparison purposes, batch cultivation of samples taken from continuous cultures by 1 and 12d was done using a semi-synthetic medium with glucose as carbon source; a pattern similar to that observed when using skim milk-based media was observed. [Copyright &y& Elsevier]

Abstract: Lactobacillus casei strain Shirota (LcS) has been used in the production of fermented milk products for many years and is one of the most intensively studied probiotics. To evaluate the ability of LcS to proliferate in human intestines after it has been ingested, we developed a PCR-based method to identify and quantify LcS using an LcS-specific primer set (pLcS) derived from a randomly amplified polymorphic DNA (RAPD) analysis. We confirmed the high specificity of the pLcS primer set in 167 bacterial strains (57 strains of L. casei and 110 other strains of bacteria commonly isolated from human feces). The method''s ability to identify LcS matched that of an ELISA using a monoclonal antibody and a RAPD analysis in a representative sample of colonies cultured from human feces. The detection limit of quantitative PCR (qPCR) using pLcS was 104.6 per gram of feces. The number of LcS in feces detected with qPCR was highly and significantly correlated with the number of LcS added to fecal samples within the range of 104.6 to 109.6 per gram feces (r 2 =0.999, P <0.001). After 14 healthy subjects ingested 1011.0 CFU of LcS daily for 7 days, 109.1±0.5 LcS g−1 (mean±S.D.) was detected in the fecal samples of all subjects by qPCR, and 108.0±0.9 CFU g−1 was detected by culture; these values were significantly different (P <0.001, paired t-test). After the subjects stopped ingesting LcS, fecal LcS counts obtained with both methods decreased daily. The values produced by the 2 methods might have differed because of an overestimation in the PCR analysis due to the presence of dead LcS cells or an underestimation in the culture system due to the use of selective culture media; however, dead LcS cells can also be beneficial as immunomodulators. We confirmed that qPCR with an LcS-specific primer set was a rapid and accurate method for determining the total amount of LcS in feces including dead or less active cells which could not be detected by culture method. [Copyright &y& Elsevier]

The present study aimed to test the effects of probiotic treatment on gut microbiota and the contribution to the well-being of European sea bass (Dicentrarchus labrax, L.). A bacterial strain of Lactobacillus delbrueckii subsp. delbrueckii (AS13B), isolated from adult European sea bass gut, was administered during sea bass development using Brachionus plicatilis and/or Artemia salina as carriers. The effective strain colonization and modulation of the gut microbiota, the mortality and the cortisol levels of sea bass were monitored during early developmental stages. The L. delbrueckii subsp. delbrueckii strain showed good capability to colonize the gut of sea bass larvae, therefore modifying the gut microbiota, and exerting positive effects on the survival of the treated sea bass. L. delbrueckii subsp. delbrueckii as a probiotic dietary supplement represents an advantageous and ecological strategy for improving the health of fish in aquaculture and increasing fish production. [ABSTRACT FROM AUTHOR]

Being a human isolate and bacteriocin producer with wide antimicrobial spectrum, Lactobacillus acidophilus LF221 fulfills preliminary conditions as a potential probiotic strain. To investigate the LF221 strain with respect to its persistence in complex ecosystems, viable LF221 cells were orally administered to laboratory animals (mice and piglets) and added to cheese milk. During the 10-day feeding of mice with LF221 viable cells, 0.9% of lactobacilli isolated from faeces were identical with LF221 strain. Within the piglets'' feeding trial, 920 lactobacilli colonies randomly selected from faecal samples were screened for the presence of LF221-like colonies. During the six times of sampling of piglets'' faeces, LF221 colonies were always detected. Even the final sampling 10 days after the last LF221 cell suspension was dosed into piglets revealed the presence of LF221 strain at a concentration of about 3×108 cells/g of faeces. LF221 intake did not significantly influence the total count of lactobacilli in faecal samples and it had no negative health effects on animals. Analyses of cheese demonstrated that the LF221 strain maintained a high viability during ripening and that it could be detected for at least 6 weeks at a level of about 6.8×106 cells/g of cheese. According to these results, semihard cheese represents a suitable medium for introducing a potential probiotic LF221 into a diet. [Copyright &y& Elsevier]

Lactobacillus reuteri ZLR003 was isolated from the caecum mucosa of healthy weaned pigs with displaying probiotic properties in our laboratory. Here, we present the complete genome sequence of L. reuteri ZLR003, which consists of a circular 2,234,097 bp chromosome (G+C content of 38.66%). Such information will provide insights into the molecular mechanism of its probiotic activity and facilitate its application in animal production. [ABSTRACT FROM AUTHOR]