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Heliyon May 2024A γ-aminobutyric acid (GABA)-producing strain JC30 was isolated from traditional kimchi, which was identified as by 16S rDNA sequencing. . JC30 was highly tolerant to...
A γ-aminobutyric acid (GABA)-producing strain JC30 was isolated from traditional kimchi, which was identified as by 16S rDNA sequencing. . JC30 was highly tolerant to acid, bile salt, and high temperatures. The survival rate of JC30 in MRS medium (pH 2.5) for 3 h was 60.96 %. Furthermore, the survival rate of JC30 in MRS medium with 3 mg/mL bile salt for 24 h was 86.62 %. The survival rate of JC30 in MRS medium at 56 °C and 58 °C for 10 min was 97.17 % and 78.20 %, respectively. When 2 % v/v JC30 (8.0 log10 CFU/mL) was added to prepare sourdough and the sourdough was then used to make bread, the bread had a higher specific volume (5.13 ± 0.12 mL/g) and GABA content (3.32 ± 0.04 mg/g DW) than the control.
PubMed: 38803853
DOI: 10.1016/j.heliyon.2024.e31236 -
Brazilian Journal of Microbiology :... May 2024Pediocin PA-1, an antimicrobial peptide derived from Pediococcus acidilactici PAC1.0, has a potential application as a food preservative thanks to its strong inhibitory...
OBJECTIVE
Pediocin PA-1, an antimicrobial peptide derived from Pediococcus acidilactici PAC1.0, has a potential application as a food preservative thanks to its strong inhibitory activity against the foodborne pathogen L. monocytogenes. This study aimed to produce Pediocin PA-1 from the yeast P. pastoris and evaluate its characteristics.
METHODS
Gene encoding Pediocin PA-1 was integrated into P. pastoris X33 genome to establish the strain X33::ped, which could produce and secrete this peptide into culture medium. The antimicrobial activity of Pediocin PA-1 was examined using agar diffusion assay. The stability of pediocin PA-1 was determined based on its remaining antibacterial activity after exposure to proteases and extreme pH and temperatures. The potential use of this bacteriocin in food preservation was demonstrated using the L. monocytogenes infected pork bologna. The anticancer activity of Pediocin PA-1 was also investigated on some cancer cells using MTT assay.
RESULTS
We established the yeast P. pastoris X33::ped capable of producing pediocin PA-1 with antimicrobial activity against L. monocytogenes and some other harmful bacteria. Pediocin PA-1 was stable at 100˚C and resistant against pH 1-12 for 1 h, but susceptible to trypsin, α-chymotrypsin, and proteinase K. This peptide could reduce the number of L. monocytogenes in pork bologna by 3.59 log CFU/g after 7 days of storage at 4˚C. Finally, Pediocin PA-1 (25 µg/ml) inhibited the proliferation of A549 and Hela cancer cells.
CONCLUSION
We succeeded in producing active Pediocin PA-1 from P. pastoris and demonstrated its potential use in food preservation and pharmaceutical industry.
PubMed: 38801640
DOI: 10.1007/s42770-024-01388-w -
Journal of Applied Microbiology May 2024To develop antifungal lactic acid bacteria (LAB) and investigate their antifungal mechanisms against Aspergillus flavus in aflatoxin (AF) production.
AIMS
To develop antifungal lactic acid bacteria (LAB) and investigate their antifungal mechanisms against Aspergillus flavus in aflatoxin (AF) production.
METHODS AND RESULTS
We isolated 179 LABs from cereal-based fermentation starters and investigated their antifungal mechanism against A. flavus through liquid chromatography-mass spectrometry and co-culture analysis techniques. Of the 179 isolates, antifungal activity was identified in Pediococcus pentosaceus, Lactobacillus crustorum, and Weissella paramesenteroides. These LABs reduced AF concentration by (i) inhibiting mycelial growth, (ii) binding AF to the cell wall, and (iii) producing antifungal compounds. Species-specific activities were also observed, with P. pentosaceus inhibiting AF production and W. paramesenteroides showing AF B1 binding activity. In addition, crucial extracellular metabolites for selecting antifungal LAB were involved in the 2',3'-cAMP-adenosine and nucleoside pathways.
CONCLUSIONS
This study demonstrates that P. pentosaceus, L. crustorum, and W. paramesenteroides are key LAB strains with distinct antifungal mechanisms against A. flavus, suggesting their potential as biological agents to reduce AF in food materials.
Topics: Aspergillus flavus; Coculture Techniques; Antifungal Agents; Metabolomics; Lactobacillales; Fermentation; Aflatoxins; Edible Grain; Pediococcus pentosaceus; Antibiosis; Food Microbiology
PubMed: 38794887
DOI: 10.1093/jambio/lxae112 -
Animals : An Open Access Journal From... May 2024This study was conducted to investigate the genotypic and phenotypic characteristics of lactic acid bacteria (LAB) associated with forage plants in the native grassland...
Genotypic and Phenotypic Characteristics of Lactic Acid Bacteria Associated with Forage Plants in the Native Grassland of Western Inner Mongolia and Their Application for Alfalfa Silage Fermentation.
This study was conducted to investigate the genotypic and phenotypic characteristics of lactic acid bacteria (LAB) associated with forage plants in the native grassland of western Inner Mongolia and to evaluate their effects on alfalfa silage fermentation. Forage plants and their spontaneous fermentation silages were analysed using culture-based techniques for LAB isolation; the phenotypic properties and 16S rDNA and S or A gene sequences of the isolates were evaluated; alfalfa was ensiled with four additive combinations: subsp. (GI19), subsp. and (GI19+GI51), GI19 and 20 g/kg fresh matter of sucrose (GI19+S), and GI19+GI51+S, for 60 d. A total of 73 strains belonging to 16 species were isolated. All isolates grew at 5-45 °C and in 3.0% NaCl, and most of them grew in 6.5% NaCl. and were 26.03% and 17.81% of the total isolates, respectively. All additives improved the silage quality, while GI19+S was more effective for alfalfa ensiling with a higher lactic acid content and lower pH, undesirable microorganism counts, and acetic acid and NH-N contents than remnant additives. In conclusion, the LAB species were diverse, and most of them possessed good cryotolerance and osmotolerance; GI19+S was the optimal inoculant for alfalfa fermentation improvement.
PubMed: 38791612
DOI: 10.3390/ani14101394 -
International Journal of Molecular... May 2024The search for new substances of natural origin, such as flavonoids, is necessary in the fight against the growing number of diseases and bacterial resistance to...
The search for new substances of natural origin, such as flavonoids, is necessary in the fight against the growing number of diseases and bacterial resistance to antibiotics. In our research, we wanted to check the influence of flavonoids with chlorine or bromine atoms and a nitro group on pathogenic and probiotic bacteria. We synthesized flavonoids using Claisen-Schmidt condensation and its modifications, and through biotransformation via entomopathogenic filamentous fungi, we obtained their glycoside derivatives. Biotransformation yielded two new flavonoid glycosides: 8-amino-6-chloroflavone 4'---D-(4″--methyl)-glucopyranoside and 6-bromo-8-nitroflavone 4'---D-(4″--methyl)-glucopyranoside. Subsequently, we checked the antimicrobial properties of the aforementioned aglycon flavonoid compounds against pathogenic and probiotic bacteria and yeast. Our studies revealed that flavones have superior inhibitory effects compared to chalcones and flavanones. Notably, 6-chloro-8-nitroflavone showed potent inhibitory activity against pathogenic bacteria. Conversely, flavanones 6-chloro-8-nitroflavanone and 6-bromo-8-nitroflavanone stimulated the growth of probiotic bacteria ( and ). Our research has shown that the presence of chlorine, bromine, and nitro groups has a significant effect on their antimicrobial properties.
Topics: Flavonoids; Chlorine; Biotransformation; Bromine; Microbial Sensitivity Tests; Anti-Infective Agents; Bacteria; Anti-Bacterial Agents
PubMed: 38791577
DOI: 10.3390/ijms25105540 -
Brazilian Journal of Microbiology :... May 2024Pediococcus pentosaceus ST65ACC is a bacteriocinogenic lactic acid bacteria (LAB) isolated from Brazilian artisanal cheese that is capable of inhibiting different food...
Pediococcus pentosaceus ST65ACC is a bacteriocinogenic lactic acid bacteria (LAB) isolated from Brazilian artisanal cheese that is capable of inhibiting different food pathogens, mainly Listeria monocytogenes. The production of bacteriocins can be influenced by several growth conditions, such as temperature, pH, and medium composition. This study aimed to evaluate the effect of different culture media on the production of bacteriocins and antimicrobial activity of P. pentosaceus ST65ACC on L. monocytogenes Scott A. The strains were inoculated alone and in coculture in four different media: BHI broth, MRS broth, meat broth, and reconstituted skim milk (RSM) 10% (w/v). The culture media were then incubated at 37 °C for 96 h, and count analysis, pH measurement, and bacteriocin production were performed at 0, 24, 48, 72 and 96 h. L. monocytogenes was inhibited to nondetectable levels in coculture with P. pentosaceus ST65ACC in MRS broth within 96 h, consistent with the high production of bacteriocin throughout the analysis period (3,200-12,800 AU/mL). However, lower inhibitory activities of P. pentosaceus ST65ACC on L. monocytogenes Scott A were recorded in BHI, RSM, and meat broth, with low or no production of bacteriocins at the analyzed times. The composition of these culture media may have repressed the production and activity of bacteriocins and, consequently, the antagonist activity of P. pentosaceus ST65ACC on L. monocytogenes Scott A. The results showed that the antimicrobial activity was more effective in MRS broth, presenting greater production of bacteriocins and less variability when compared to the other media analyzed.
PubMed: 38789904
DOI: 10.1007/s42770-024-01391-1 -
Bioresources and Bioprocessing May 2024Biodetoxification fungus selectively degrades toxic inhibitors generated from pretreatment of lignocellulose without consuming fermentable sugars. However, one barrier...
Biodetoxification fungus selectively degrades toxic inhibitors generated from pretreatment of lignocellulose without consuming fermentable sugars. However, one barrier for practical application is the sustained cell viability in the consequent fermentation step to compete the fermentable sugars with fermenting strains, resulting in sugar loss and reduced target product yield. This study investigated the competitive growth property between the biodetoxification fungus Paecilomyces variotii FN89 and the L-lactic acid bacterium Pediococcus acidilactici ZY271 under varying temperature and lactic acid osmatic stress. The results show that the L-lactic acid bacterium Ped. acidilactici ZY271 showed less thermotolerance to Pae. variotii FN89 at high temperature of 45 °C to 50 °C in both synthetic medium and wheat straw hydrolysate. In the higher temperature environment, the growth of the biodetoxification strian failed to compete with the lactic acid fermentation strain and was quickly eliminated from the fermentation system. The high temperature fermentation facilitated a fast transition from the detoxification stage to the fermentation stage for higher production of L-lactic acid.
PubMed: 38780813
DOI: 10.1186/s40643-024-00772-6 -
Journal of Food Science Jul 2024Addition of soybean in raw materials could improve the flavor of chi-flavor Baijiu (CFB) in production. For investigating the mechanism of flavor improvement during...
Addition of soybean in raw materials could improve the flavor of chi-flavor Baijiu (CFB) in production. For investigating the mechanism of flavor improvement during fermentation, the changes of volatile flavors and their relationship with microbial community were analyzed. The results showed that the average contents of lactic and acetic acid in EG (added with hydrolyzed soybean) samples were higher those of CK (without hydrolyzed soybean) samples. The contents of main volatile esters, including ethyl acetate, ethyl palmitate, and ethyl benzoate, in EG samples were higher than those in CK samples at the end of fermentation. The content of alcohols in EG sample was 140.55 mg/L, higher than that in CK sample at the end of fermentation. Especially, the average content of characteristic flavor β-phenylethanol in EG samples increased 17.6% in comparison with that in CK samples during fermentation. Lactobacillus and Pediococcus were the dominant bacterial genera, whereas Saccharomyces, Mortierella, and Trichosporon were dominant fungal genera in both CK and EG samples. Lactobacillus and Weissella confusa showed strong positive correlation with β-phenylethanol, ethyl acetate, and ethyl benzoate. This study provides an in-depth analysis of the effects of hydrolyzed soybeans on the volatile flavor compounds and microbial communities of CFB and theoretical guidance for improving the quality of CFB.
Topics: Glycine max; Fermentation; Volatile Organic Compounds; Flavoring Agents; Microbiota; Taste; Fermented Foods; Bacteria; Hydrolysis; Alcoholic Beverages; Fungi; Food Microbiology
PubMed: 38778551
DOI: 10.1111/1750-3841.17132 -
Food & Function Jun 2024The literature regarding the role of probiotics in critically ill patients who have undergone mechanical ventilation (MV) is unclear; therefore, this umbrella systematic... (Meta-Analysis)
Meta-Analysis Review
The literature regarding the role of probiotics in critically ill patients who have undergone mechanical ventilation (MV) is unclear; therefore, this umbrella systematic review and meta-analysis was carried out to clarify the effects of probiotics on the clinical outcomes of mechanically ventilated patients. The Scopus, PubMed/Medline, ISI Web of Science, and Google Scholar online databases were searched up to February 2023. All meta-analyses evaluating the impact of probiotics in patients under MV were considered eligible. The assessment of multiple systematic reviews (AMSTAR) questionnaire was used to evaluate the quality of the studies. Data were pooled using the random-effects approach. Thirty meta-analyses and nine clinical outcomes were re-analyzed. Probiotics significantly decreased ventilator-associated pneumonia (VAP) incidence, nosocomial infections, intensive care unit (ICU) length of stay, hospital length of stay, ICU mortality, hospital mortality, MV duration, duration of antibiotic use, and diarrhea. The obtained results of the current umbrella meta-analysis indicate that probiotic administration could be considered an adjunct therapy for critically ill patients; however, no specific probiotic treatment regimen can be recommended due to the diverse probiotics used in the included meta-analyses. The following microorganisms were used at various doses and combinations throughout the studies: , , , , , , , , , , , , , , , , , GG, , , , , , , , , , and .
Topics: Probiotics; Humans; Respiration, Artificial; Critical Illness; Pneumonia, Ventilator-Associated; Intensive Care Units; Length of Stay
PubMed: 38771159
DOI: 10.1039/d3fo04653b -
Food Research International (Ottawa,... Jul 2024Single 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,...
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.
Topics: Fermentation; Animals; Food Microbiology; Tilapia; Fish Products; Hydrogen-Ion Concentration; Latilactobacillus sakei; Lactobacillales; Pediococcus acidilactici; Fermented Foods; Meat Products
PubMed: 38763686
DOI: 10.1016/j.foodres.2024.114456