Novel insight into the formation and improvement mechanism of physical property in fermented tilapia sausage by cooperative fermentation of newly isolated lactic acid bacteria based on microbial contribution.

Single starter can hardly elevate the gel property of fermented freshwater fish sausage. In this work, in order to improve the physical properties of tilapia sausage, two newly isolated strains of lactic acid bacteria (LAB), Latilactobacillus sakei and Pediococcus acidilactici were used for cooperative fermentation of tilapia sausage, followed by the revelation of their formation mechanisms during cooperative fermentation and their improvement mechanisms after comparison with natural fermentation. Both strains, especially L. sakei possessed good growth, acidification ability, and salt tolerance. The gel strength, hardness, springiness, chewiness, whiteness, acidification, and total plate count significantly elevated during cooperative fermentation with starters. Pediococcus, Acinetobacter, and Macrococcus were abundant before fermentation, while Latilactobacillus quickly occupied the dominant position after fermentation for 18-45 h with the relative abundance over 51.5 %. The influence of each genus on the physical properties was calculated through the time-dimension and group-dimension correlation networks. The results suggested that the increase of Latilactobacillus due to the good growth and metabolism of L. sakei contributed the most to the formation and improvement of gel strength, texture properties, color, acidification, and food safety of tilapia sausage after cooperative fermentation. This study provides a novel analysis method to quantitatively evaluate the microbial contribution on the changes of various properties. The cooperative fermentation of LAB can be used for tilapia sausage fermentation to improve its physical properties.

Improvement mechanism of volatile flavor in fermented tilapia surimi by cooperative fermentation of Pediococcus acidilactici and Latilactobacillus sakei: Quantization of microbial contribution through influence of genus.

Single starter can hardly improve the volatile flavor of fermented fish surimi. In this study, the changes of volatile compounds (VCs) and microbial composition during cooperative fermentation of Latilactobacillus sakei and Pediococcus acidilactici were studied by headspace solid-phase microextraction gas chromatography-mass spectrometry and 16S rRNA gene high-throughput sequencing. During cooperative fermentation, most VCs and the abundance of Latilactobacillus and Lactococcus significantly increased, while Pediococcus, Acinetobacter, and Macrococcus obviously decreased. After evaluation of correlation and abundance of each genus, Latilactobacillus and Lactococcus possessed the highest influence on the formation of volatile flavor during cooperative fermentation. Compared with the natural fermentation, cooperative fermentation with starters significantly enhanced most of pleasant core VCs (odor activity value≥1), but inhibited the production of trimethylamine and methanethiol, mainly resulting from the absolutely highest influence of Latilactobacillus. Cooperative fermentation of starters is an effective method to improve the volatile flavor in the fermented tilapia surimi.

Investigating human-derived lactic acid bacteria for alcohol resistance.

BACKGROUND: Excessive alcohol consumption has been consistently linked to serious adverse health effects, particularly affecting the liver. One natural defense against the detrimental impacts of alcohol is provided by alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), which detoxify harmful alcohol metabolites. Recent studies have shown that certain probiotic strains, notably Lactobacillus spp., possess alcohol resistance and can produce these critical enzymes. Incorporating these probiotics into alcoholic beverages represents a pioneering approach that can potentially mitigate the negative health effects of alcohol while meeting evolving consumer preferences for functional and health-centric products. RESULTS: Five lactic acid bacteria (LAB) isolates were identified: Lactobacillus paracasei Alc1, Lacticaseibacillus rhamnosus AA, Pediococcus acidilactici Alc3, Lactobacillus paracasei Alc4, and Pediococcus acidilactici Alc5. Assessment of their alcohol tolerance, safety, adhesion ability, and immunomodulatory effects identified L. rhamnosus AA as the most promising alcohol-tolerant probiotic strain. This strain also showed high production of ADH and ALDH. Whole genome sequencing analysis revealed that the L. rhamnosus AA genome contained both the adh (encoding for ADH) and the adhE (encoding for ALDH) genes. CONCLUSIONS: L. rhamnosus AA, a novel probiotic candidate, showed notable alcohol resistance and the capability to produce enzymes essential for alcohol metabolism. This strain is a highly promising candidate for integration into commercial alcoholic beverages upon completion of comprehensive safety and functionality evaluations.

Pediococcus acidilactici reduces tau pathology and ameliorates behavioral deficits in models of neurodegenerative disorders.

BACKGROUND: Alzheimer's disease (AD), affecting many elders worldwide, is characterized by A-beta and tau-related cognitive decline. Accumulating evidence suggests that brain iron accumulation is an important characteristic of AD. However, the function and mechanism of the iron-mediated gut-brain axis on AD is still unclear. METHODS: A Caenorhabditis elegans model with tau-overexpression and a high-Fe diet mouse model of cognitive impairment was used for probiotic function evaluation. With the use of qPCR, and immunoblotting, the probiotic regulated differential expression of AD markers and iron related transporting genes was determined. Colorimetric kits, IHC staining, and immunofluorescence have been performed to explore the probiotic mechanism on the development of gut-brain links and brain iron accumulation. RESULTS: In the present study, a high-Fe diet mouse model was used for evaluation in which cognitive impairment, higher A-beta, tau and phosphorylated (p)-tau expression, and dysfunctional phosphate distribution were observed. Considering the close crosstalk between intestine and brain, probiotics were then employed to delay the process of cognitive impairment in the HFe mouse model. Pediococcus acidilactici (PA), but not Bacillus subtilis (BN) administration in HFe-fed mice reduced brain iron accumulation, enhanced global alkaline phosphatase (AP) activity, accelerated dephosphorylation, lowered phosphate levels and increased brain urate production. In addition, because PA regulated cognitive behavior in HFe fed mice, we used the transgenic Caenorhabditis elegans with over-expressed human p-tau for model, and then PA fed worms became more active and longer lived than E.coli fed worms, as well as p-tau was down-regulated. These results suggest that brain iron accumulation influences AD risk proteins and various metabolites. Furthermore, PA was shown to reverse tau-induced pathogenesis via iron transporters and AP-urate interaction. CONCLUSIONS: PA administration studies demonstrate that PA is an important mediator of tau protein reduction, p-tau expression and neurodegenerative behavior both in Caenorhabditis elegans and iron-overload mice. Finally, our results provide candidates for AP modulation strategies as preventive tools for promoting brain health. Video Abstract.

Orange juice containing Pediococcus acidilactici CE51 modulates the intestinal microbiota and reduces induced inflammation in a murine model of colitis.

The management of inflammatory bowel diseases has been widely investigated, especially ulcerative colitis. Thus, studies with the application of new probiotic products are needed in the prevention/treatment of these clinical conditions. The objective of this work was to evaluate the effects of probiotic orange juice containing Pediococcus acidilactici CE51 in a murine model of colitis. 45 male Swiss lineage mice were used, divided into five groups (n = 9): control, colitis, colitis + probiotic (probiotic orange juice containing CE51), colitis + placebo (orange juice) and colitis + sulfasalazine (10 mg/kg/Weight). The induction of colitis was performed with dextran sodium sulfate (3%). The treatment time was 5 and 15 days after induction. Histopathological analysis, serum measurements of TNF-α and C-reactive protein and metagenomic analysis of feces were performed after euthanasia. Probiotic treatment reduced inflammation in the small intestine, large intestine and spleen. The probiotic did not alter the serum dosages of TNF-α and C-reactive protein. Their use maintained the quantitative ratio of the phylum Firmicutes/Bacteroidetes and increased Lactobacillus helveticus with 15 days of treatment (p < 0.05). The probiotic orange juice containing P. acidilactici CE51 positively modulated the gut microbiota composition and attenuated the inflammation induced in colitis.

Glucose-lowering effects of a synbiotic combination containing Pediococcus acidilactici in C. elegans and mice.

AIMS/HYPOTHESIS: Modulation of gut microbiota has emerged as a promising strategy to treat or prevent the development of different metabolic diseases, including type 2 diabetes and obesity. Previous data from our group suggest that the strain Pediococcus acidilactici CECT9879 (pA1c) could be an effective probiotic for regulating glucose metabolism. Hence, the objectives of this study were to verify the effectiveness of pA1c on glycaemic regulation in diet-induced obese mice and to evaluate whether the combination of pA1c with other normoglycaemic ingredients, such as chromium picolinate (PC) and oat ß-glucans (BGC), could increase the efficacy of this probiotic on the regulation of glucose and lipid metabolism. METHODS: Caenorhabditis elegans was used as a screening model to describe the potential synbiotic activities, together with the underlying mechanisms of action. In addition, 4-week-old male C57BL/6J mice were fed with a high-fat/high-sucrose diet (HFS) for 6 weeks to induce hyperglycaemia and obesity. Mice were then divided into eight groups (n=12 mice/group) according to dietary supplementation: control-diet group; HFS group; pA1c group (1010 colony-forming units/day); PC; BGC; pA1c+PC+BGC; pA1c+PC; and pA1c+BGC. Supplementations were maintained for 10 weeks. Fasting blood glucose was determined and an IPGTT was performed prior to euthanasia. Fat depots, liver and other organs were weighed, and serum biochemical variables were analysed. Gene expression analyses were conducted by real-time quantitative PCR. Sequencing of the V3-V4 region of the 16S rRNA gene from faecal samples of each group was performed, and differential abundance for family, genera and species was analysed by ALDEx2R package. RESULTS: Supplementation with the synbiotic (pA1c+PC+BGC) counteracted the effect of the high glucose by modulating the insulin-IGF-1 signalling pathway in C. elegans, through the reversal of the glucose nuclear localisation of daf-16. In diet-induced obese mice, all groups supplemented with the probiotic significantly ameliorated glucose tolerance after an IPGTT, demonstrating the glycaemia-regulating effect of pA1c. Further, mice supplemented with pA1c+PC+BGC exhibited lower fasting blood glucose, a reduced proportion of visceral adiposity and a higher proportion of muscle tissue, together with an improvement in the brown adipose tissue in comparison with the HFS group. Besides, the effect of the HFS diet on steatosis and liver damage was normalised by the synbiotic. Gene expression analyses demonstrated that the synbiotic activity was mediated not only by modulation of the insulin-IGF-1 signalling pathway, through the overexpression of GLUT-1 and GLUT-4 mediators, but also by a decreased expression of proinflammatory cytokines such as monocyte chemotactic protein-1. 16S metagenomics demonstrated that the synbiotic combinations allowed an increase in the concentration of P. acidilactici, together with improvements in the intestinal microbiota such as a reduction in Prevotella and an increase in Akkermansia muciniphila. CONCLUSIONS/INTERPRETATION: Our data suggest that the combination of pA1c with PC and BGC could be a potential synbiotic for blood glucose regulation and may help to fight insulin resistance, diabetes and obesity.

Selective Antagonism of Lactiplantibacillus plantarum and Pediococcus acidilactici against Vibrio and Aeromonas in the Bacterial Community of Artemia nauplii.

Empiric probiotics are commonly consumed by healthy individuals as a means of disease prevention, pathogen control, etc. However, controversy has existed for a long time regarding the safety and benefits of probiotics. Here, two candidate probiotics, Lactiplantibacillus plantarum and Pediococcus acidilactici, which are antagonistic to Vibrio and Aeromonas species in vitro, were tested on Artemia under in vivo conditions. In the bacterial community of Artemia nauplii, L. plantarum reduced the abundance of the genera Vibrio and Aeromonas and P. acidilactici significantly increased the abundance of Vibrio species in a positive dosage-dependent manner, while higher and lower dosages of P. acidilactici increased and decreased the abundance of the genus Aeromonas, respectively. Based on the liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analyses of the metabolite of L. plantarum and P. acidilactici, pyruvic acid was used in an in vitro test to explain such selective antagonism; the results showed that pyruvic acid was conducive or suppressive to V. parahaemolyticus and beneficial to A. hydrophila. Collectively, the results of this study demonstrate the selective antagonism of probiotics on the bacterial community composition of aquatic organisms and the associated pathogens. IMPORTANCE Over the last decade, the common preventive method for controlling potential pathogens in aquaculture has been the use of probiotics. However, the mechanisms of probiotics are complicated and mostly undefined. At present, less attention has been paid to the potential risks of probiotic use in aquaculture. Here, we investigated the effects of two candidate probiotics, L. plantarum and P. acidilactici, on the bacterial community of Artemia nauplii and the in vitro interactions between these two candidate probiotics and two pathogens, Vibrio and Aeromonas species. The results demonstrated the selective antagonism of probiotics on the bacterial community composition of an aquatic organism and its associated pathogens. This research contributes to providing a basis and reference for the long-term rational use of probiotics and to reducing the inappropriate use of probiotics in aquaculture.

Biological Selenite Reduction, Characterization and Bioactivities of Selenium Nanoparticles Biosynthesised by Pediococcus acidilactici DSM20284.

Selenium (Se) is in great demand as a health supplement due to its superior reactivity and excellent bioavailability, despite selenium nanoparticles (SeNPs) having signs of minor toxicity. At present, the efficiency of preparing SeNPs using lactic acid bacteria is unsatisfactory. Therefore, a probiotic bacterial strain that is highly efficient at converting selenite to elemental selenium is needed. In our work, four selenite-reducing bacteria were isolated from soil samples. Strain LAB-Se2, identified as Pediococcus acidilactici DSM20284, had a reduction rate of up to 98% at ambient temperature. This strain could reduce 100 mg L-1 of selenite to elemental Se within 48 h at pH 4.5-6.0, a temperature of 30-40 °C, and a salinity of 1.0-6.5%. The produced SeNPs were purified, freeze-dried, and subsequently systematically characterised using FTIR, DSL, SEM-EDS, and TEM techniques. SEM-EDS analysis proved the presence of selenium as the foremost constituent of SeNPs. The strain was able to form spherical SeNPs, as determined by TEM. In addition, DLS analysis confirmed that SeNPs were negatively charged (-26.9 mV) with an average particle size of 239.6 nm. FTIR analysis of the SeNPs indicated proteins and polysaccharides as capping agents on the SeNPs. The SeNPs synthesised by P. acidilactici showed remarkable antibacterial activity against E. coli, B. subtilis, S. aureus, and K. pneumoniae with inhibition zones of 17.5 mm, 13.4 mm, 27.9 mm, and 16.2 mm, respectively; they also showed varied MIC values in the range of 15-120 µg mL-1. The DPPH, ABTS, and hydroxyl, and superoxide scavenging activities of the SeNPs were 70.3%, 72.8%, 95.2%, and 85.7%, respectively. The SeNPs synthesised by the probiotic Lactococcus lactis have the potential for safe use in biomedical and nutritional applications.

Screening and Constructing a Library of Promoter-5'-UTR Complexes with Gradient Strength in Pediococcus acidilactici.

The GRAS (generally recognized as safe) strain Pediococcus acidilactici is well known for its antibacterial and probiotic functions. Furthermore, as P. acidilactici has excellent high temperature and salt resistance, it is an ideal host for the production of food enzymes, food additives, and pharmaceuticals. In this regard, it is desirable and feasible to enhance the production of these products through the metabolic engineering of P. acidilactici. However, the rare gene expression elements greatly obstruct the development of engineering P. acidilactici. In this study, we screened and constructed a library of promoter-5'-UTR (PUTR) complexes in P. acidilactici DY15 for regulating gene expression at the transcription and translation levels. In the post-log phase, the mRNA and protein expression level ranges of the 90 screened native PUTRs were 0.059-2010% and 0.77-245%, respectively, of the P32 promoter. Besides, several PUTRs exhibited great expression stability under high temperature, salt, and ethanol stress. We analyzed the structure of PUTRs and obtained the conserved regions of the promoter and 5'-UTR. Based on the identified core regions of PUTRs, we constructed a panel of combinatorial PUTRs with higher and stable protein expression levels. The strongest combinatorial PUTR was 853% of the P32 promoter in the protein expression level. Finally, the obtained PUTRs were applied to optimize the expression level of aminotransferase and improve the phenyllactic acid (PLA) production in P. acidilactici DY15. The achieved yield was 950.6 mg/L, which was 79.2% higher than the wild-type strain. These results indicated that the obtained PUTRs with gradient strength had great potential for precisely regulating gene expression to achieve various goals in P. acidilactici.

Isolation, identification and safety evaluation of OTA-detoxification strain Pediococcus acidilactici NJB421 and its effects on OTA-induced toxicity in mice.

Ochratoxin A (OTA) is a potent mycotoxin found in foods and feeds, posing a health risk to animals and humans. Biological detoxification of OTA is considered a promising method, and some bacteria and fungi which can degrade OTA are isolated. However, research on safety and alleviating toxic effects are scarce. This study aims to isolate OTA-detoxification probiotics from natural samples and evaluate their safety and protective effects in mice. Here, a new OTA-detoxification strain named Pediococcus acidilactici NJB421 (P. acidilactici NJB421) was isolated from cow manure, which exhibited a removal rate of OTA at 48.53% for 48 h. P. acidilactici NJB421 exhibited high temperature resistance, acid tolerance, 0.3% bile salt and 1.4% trypsin resistance. The safety evaluation showed that P. acidilactici NJB421 at 2 × 108 CFU/per mouse had no abnormalities in body weight, organ indices, ALT, AST and ALP activities, BUN, CRE and TP contents. And P. acidilactici NJB421 alleviated the decreases in body weight, organ indices and small intestinal length, and alleviated intestinal injury, liver injury and kidney injury. These results suggest P. acidilactici NJB421 is safe and has protection against OTA poisoning, which provides a new OTA-detoxification strain for livestock and food industries.

Lignocellulose conversion of ensiled Caragana korshinskii Kom. facilitated by Pediococcus acidilactici and cellulases.

To explore the biofuel production potential of Caragana korshinskii Kom., Pediococcus acidilactici and an exogenous fibrolytic enzyme were employed to investigate the fermentation profile, structural carbohydrates degradation, enzymatic saccharification and the dynamics of bacterial community of C. korshinskii silage. After 60 d of ensiling, all additives increased the fermentation quality. The highest lactic and acetic acids and lowest non-protein nitrogen (NPN) and ammonia nitrogen (NH3 -N) were observed in P. acidilactici and Acremonium cellulase (PA + AC) treated silage. Additionally, all additives significantly increased the ferulic acid content and fibre degradability with the highest values obtained from PA + AC silage. The bacterial community in all silages was dominated by P. acidilactici throughout the entire fermentation process. The bacterial community was also modified by the silage additives exhibiting a relatively simple network of bacterial interaction characterized by a lower bacterial diversity in P. acidilactici (PA) treated silage. The highest 6-phospho-beta-glucosidase abundance was observed in PA-treated silage at the mid-later stage of ensiling. PA treatment exhibited lower structural carbohydrates degradation but performed better in lignocellulose conversion during enzymatic saccharification. These results indicated that pretreating C. korshinskii improved its silage quality and potential use as a lignocellulosic feedstock for the production of bio-product and biofuel.

Enrichment and Distribution of Selenium in Pediococcus acidilactici MRS-7: Impact on Its Biochemical Composition, Microstructure, and Gastrointestinal Survival.

Lactic acid bacteria can convert selenium (Se) from inorganic to organic and elemental forms, but the distribution and existence form of organic Se in the bacteria are not clear after Se enrichment, and the effects of selenization on the growth and nutritional value of strains also need to be studied. In this study, Pediococcus acidilactici MRS-7 could absorb up to 67% of inorganic Se and convert most of it into organic Se; about 75% of organic Se was selenoprotein, 2.7% was Se-polysaccharide, and 4.6% was Se-nucleic acid. Additionally, Se-enriched treatment increased the levels of amino acids and essential elements in P. acidilactici MRS-7. Finally, after Se enrichment, Se nanoparticles (SeNPs) were found on the surface of P. acidilactici MRS-7, but they had no harmful effect on its morphology, and its survival during gastrointestinal digestion was not affected, indicating that SeP has potential probiotic value in the food industry.

Inhibitory Effect of Bacterial Lysates Extracted from Pediococcus acidilactici on the Differentiation of 3T3-L1 Pre-Adipocytes.

Postbiotics, including bacterial lysates, are considered alternatives to probiotics. The aim of the current study was to investigate the effect of bacterial lysates (BLs) extracted from Pediococcus acidilactici K10 (K10 BL) and P. acidilactici HW01 (HW01 BL) on the differentiation of 3T3-L1 pre-adipocytes. Both K10 and HW01 BLs significantly reduced the accumulation of lipid droplets and the amounts of cellular glycerides in 3T3-L1 cells (p < 0.05). However, another postbiotic molecule, peptidoglycan of P. acidilactici K10 and P. acidilactici HW01, moderately inhibited the accumulation of lipid droplets, whereas heat-killed P. acidilactici did not effectively inhibit the lipid accumulation. The mRNA and protein levels of the transcription factors, peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α, responsible for the differentiation of 3T3-L1 cells, were significantly inhibited by K10 BL and HW01 BL (p < 0.05). Both K10 and HW01 BLs decreased adipocyte-related molecules, adipocyte fatty acid-binding protein and lipoprotein lipase, at the mRNA and protein levels. Furthermore, both K10 and HW01 BLs also downregulated the mRNA expression of leptin, but not resistin. Taken together, these results suggest that P. acidilactici BLs mediate anti-adipogenic effects by inhibiting adipogenic-related transcription factors and their target molecules.

Proteomic Profiling and Stress Response in Pediococcus acidilactici under Acetic Acid.

Lactic acid bacteria are indispensable functional microorganisms for cereal vinegar brewing, but cell activities are inhibited by the dominant acetic acid stress. Herein, an acetic-acid-tolerant strain isolated previously was identified as Pediococcus acidilactici, which also exhibited good resistance to other stresses during vinegar brewing. Proteomics analysis evidenced that differentially expressed proteins involved in the glycolysis and gluconeogenesis pathway, pyruvate metabolism, and sugar phosphotransferase system were all downregulated. Meanwhile, saturation of fatty acids and antioxidant enzymes was strengthened. The effects of several proteins on the resistance of P. acidilactici and Lactobacillus lactis relied on the types of strain and stress. AccA and AcpP participating in fatty acid metabolism and biosynthesis and Mnc related to stress response were found to protect cells by modifying fatty acid compositions and reinforcing the antioxidant defense system. Our works deepen the mechanisms of P. acidilactici under acetic acid and offer targets for engineering cell tolerance.

Renoprotective Effect of Pediococcus acidilactici GKA4 on Cisplatin-Induced Acute Kidney Injury by Mitigating Inflammation and Oxidative Stress and Regulating the MAPK, AMPK/SIRT1/NF-κB, and PI3K/AKT Pathways.

Acute kidney injury (AKI) describes a sudden loss of kidney function and is associated with a high mortality. Pediococcus acidilactici is a potent producer of bacteriocin and inhibits the growth of pathogens during fermentation and food storage; it has been used in the food industry for many years. In this study, the potential of P. acidilactici GKA4 (GKA4) to ameliorate AKI was investigated using a cisplatin-induced animal model. First, mice were given oral GKA4 for ten days and intraperitoneally injected with cisplatin on the seventh day to create an AKI mode. GKA4 attenuated renal histopathological alterations, serum biomarkers, the levels of inflammatory mediators, and lipid oxidation in cisplatin-induced nephrotoxicity. Moreover, GKA4 significantly decreased the expression of inflammation-related proteins and mitogen-activated protein kinase (MAPK) in kidney tissues. Eventually, GKA4 also increased the levels of related antioxidant enzymes and pathways. Consistently, sirtuin 1 (SIRT1) upregulated the level of autophagy-related proteins (LC3B, p62, and Beclin1). Further studies are needed to check our results and advance our knowledge of the mechanism whereby PI3K inhibition (wortmannin) reverses the effect of GKA4 on cisplatin-treated AKI. Taken together, GKA4 provides a therapeutic target with promising clinical potential after cisplatin treatment by reducing oxidative stress and inflammation via the MAPK, AMP-activated protein kinase (AMPK)/SIRT1/nuclear factor kappa B (NF-κB), and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) axes.

Pediococcus acidilactici Strain Alleviates Gluten-Induced Food Allergy and Regulates Gut Microbiota in Mice.

Wheat flour, the most important source of food globally, is also one of the most common causative agents of food allergy. Wheat gluten protein, which accounts for 80% of the total wheat protein, is a major determinant of important wheat-related disorders. In this study, the effects of Pediococcus acidilactici XZ31 against gluten-induced allergy were investigated in a mouse model. The oral administration of P. acidilactici XZ31 attenuated clinical and intestinal allergic responses in allergic mice. Further results showed that P. acidilactici XZ31 regulated Th1/Th2 immune balance toward Th1 polarization, which subsequently induced a reduction in gluten-specific IgE production. We also found that P. acidilactici XZ31 modulated gut microbiota homeostasis by balancing the Firmicutes/Bacteroidetes ratio and increasing bacterial diversity and the abundance of butyrate-producing bacteria. Specifically, the abundance of Firmicutes and Erysipelotrichaceae is positively correlated with concentrations of gluten-specific IgE and may act as a fecal biomarker for diagnosis. The evidence for the role of P. acidilactici XZ31 in alleviating gluten-induced allergic responses sheds light on the application of P. acidilactici XZ31 in treating wheat allergy.

Selenium-Enriched Pediococcus acidilactici MRS-7 Alleviates Patulin-Induced Jejunum Injuries in Mice and Its Possible Mechanisms.

Patulin (PAT) is a common mycotoxin. Oral ingestion of PAT could damage the intestinal mucosa. Both selenium and probiotics can alleviate intestinal damage, but there are few reports on selenium-enriched probiotics. Here, we studied the protective effects of a new selenium-enriched Pediococcus acidilactici MRS-7 (SeP) on PAT-induced jejunum injuries in mice. Results show that PAT induced jejunum injuries such as loss of crypts, ulceration of the mucosa, and intestinal epithelial barrier function impairment. However, SeP could protect against PAT-induced jejunum injuries and significantly inhibit the reduction of goblet cell numbers. SeP could not only alleviate PAT-induced oxidative stress by decreasing malondialdehyde (MDA) and increasing superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) levels in the jejunum tissues but also alleviate the inflammatory response caused by PAT by reducing the levels of inflammatory factors (interleukin (IL)-6 snd IL-1ß and tumor necrosis factor-α (TNF-α)) in the serum and jejunum tissues. In addition, SeP also inhibited the expression of nuclear factor-κB (NF-κB) and Toll-like receptor 4 (TLR-4), increased the expression of tight junction proteins (occludin, ZO-1, and claudin-1), and increased the selenium content in the jejunum, thereby antagonizing the jejunum injuries caused by PAT exposure. Finally, SeP rebalanced the intestinal microbiota and improved probiotic abundance such as Turicibacter, Bifidobacterium, Ileibacterium, and Pediococcus in PAT-treated mice. These results support the possibility of SeP as a novel protective agent to mitigate the toxicity of PAT.

Pediococcus acidilactici CECT9879 (pA1c) Counteracts the Effect of a High-Glucose Exposure in C. elegans by Affecting the Insulin Signaling Pathway (IIS).

The increasing prevalence of metabolic syndrome-related diseases, including type-2 diabetes and obesity, makes it urgent to develop new alternative therapies, such as probiotics. In this study, we have used Caenorhabditis elegans under a high-glucose condition as a model to examine the potential probiotic activities of Pediococcusacidilactici CECT9879 (pA1c). The supplementation with pA1c reduced C. elegans fat accumulation in a nematode growth medium (NGM) and in a high-glucose (10 mM) NGM medium. Moreover, treatment with pA1c counteracted the effect of the high glucose by reducing reactive oxygen species by 20%, retarding the aging process and extending the nematode median survival (>2 days in comparison with untreated control worms). Gene expression analyses demonstrated that the probiotic metabolic syndrome-alleviating activities were mediated by modulation of the insulin/IGF-1 signaling pathway (IIS) through the reversion of the glucose-nuclear-localization of daf-16 and the overexpression of ins-6 and daf-16 mediators, increased expression of fatty acid (FA) peroxisomal ß-oxidation genes, and downregulation of FA biosynthesis key genes. Taken together, our data suggest that pA1c could be considered a potential probiotic strain for the prevention of the metabolic syndrome-related disturbances and highlight the use of C. elegans as an appropriate in vivo model for the study of the mechanisms underlying these diseases.

Anti-Obesity Efficacy of Pediococcus acidilactici MNL5 in Canorhabditis elegans Gut Model.

In the present study, thirty two lactic acid bacteria (LAB) were isolated from fermented Indian herbal medicine. In comparison to other strains, MNL5 had stronger bile salt hydrolase (BSH) and cholesterol-lowering properties. Furthermore, it can withstand the extreme conditions found in the GI tract, due to, e.g., pepsin, bile salts, pancreatin, and acids. Pediococcus acidilactici MNL5 was identified as a probiotic candidate after sequencing the 16S rRNA gene. The antibacterial activity of P. acidilactici MNL5 cell-free supernatants (CFS) against Escherichia coli, Staphylococcus aureus, Helicobacter pylori, Bacillus cereus, and Candida albicans was moderate. A Caenorhabditis elegans experiment was also performed to assess the effectiveness of P. acidilactici MNL5 supplementation to increase life span compared to E. coli supplementation (DAF-2 and LIU1 models) (p < 0.05). An immense reduction of the lipid droplets of C. elegans was identified through a fluorescent microscope. The drastic alteration of the expression of fat genes is related to obesity phenotypes. Hence, several paths are evolutionary for C. elegans; the results of our work highlight the nematode as an important model for obesity.

High-Efficiency Genome Editing Based on Endogenous CRISPR-Cas System Enhances Cell Growth and Lactic Acid Production in Pediococcus acidilactici.

Pediococcus acidilactici is commonly used for pediocin production and lactic acid fermentation. However, a high-efficiency genome editing tool is unavailable for this species. In this study, we constructed endogenous subtype II-A CRISPR-Cas system-based genome interference plasmids which carried a "repeat-spacer-repeat" cassette in the pMG36e shuttle vector. These plasmids exhibited self-interference activities in P. acidilactici LA412. Then, the genome-editing plasmids were constructed by cloning the upstream/downstream donor DNA into the corresponding interference plasmids to exert high-efficiency markerless gene deletion, gene integration, and point mutation in P. acidilactici LA412. We found that endogenous CRISPR-mediated depletion of the native plasmids enhanced the cell growth and that integration of an l-lactate dehydrogenase gene into the chromosome enhanced both cell growth and lactic acid production. IMPORTANCE A rapid and precise genome editing tool will promote the practical application of Pediococcus acidilactici, one type of lactic acid bacterium with excellent stress tolerance and probiotic characteristics. This study established a high-efficiency endogenous CRISPR-Cas system-based genome editing tool for P. acidilactici and achieved different genetic manipulations, including gene deletion, gene insertion, mononucleotide mutation, and endogenous plasmid depletion. The engineered strain edited by this tool showed significant advantages in cell growth and lactic acid fermentation. Therefore, our tool can satisfy the requirements for genetic manipulations of P. acidilactici, thus making it a sophisticated chassis species for synthetic biology and bioindustry.