Glutathione metabolism contributes to citric acid tolerance and antioxidant capacity in Acetobacter tropicalis.

Acetobacter is one of the main species producing fruit vinegar and its tolerance mechanism to citric acid has not been fully studied. This limits fruit vinegar production from high-citric-acid fruits, which are excellent materials for fruit vinegar production. This study analyzed the metabolic differences between two strains of A. tropicalis with different citric acid tolerances using non-targeted metabolomics. Differential metabolites and metabolic pathways analysis showed that the enhanced amino acid metabolism significantly improved the citric acid tolerance of A. tropicalis and the deamination of amino acids may also play a role. In addition, the up-regulated phosphatidylcholine (PC) and N-heptanoylhonoserine lactone indicated decreased membrane permeability and enhanced quorum sensing (QS), respectively. The analysis of the interaction between pathways and metabolites indicated that Gln, Cys, and Tyr contribute to improving citric acid tolerance, which was also confirmed by the exogenous addition. After adding the amino acids, the down-regulated qdh, up-regulated ggt, and improved glutathione reductase (GR) activity in J-2736 indicated that glutathione metabolism played an important role in resisting citric acid, and cellular antioxidant capacity was increased. This study provides a theoretical basis for efficient fruit vinegar production from citric-acid-type fruits.

Evaluation of the immunomodulatory activity of probiotics mixture and sulfasalazine against acetic acid-induced colitis in a murine model.

BACKGROUND: Currently, the use of probiotics to treat inflammatory bowel diseases (IBD) is widely accepted because of their gut microbiota modulation capabilities and anti-inflammatory potential. OBJECTIVE: The aim of this study is to examine the immunomodulatory outcomes of probiotics and sulfasalazine in the acetic acid-induced colitis murine model. METHODS: The animals were randomly assigned to one of the seven groups. Following the induction of colitis, Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12, and sulfasalazine (SASP) were orally administered for 10 days. Subsequently, the in vitro anti-inflammatory effect on TNF-α and IL-10 in the supernatants of cultured spleen cells was assessed via ELISAs. Relative mRNA expression of ZO-1, MLCK, iNOS, TNFR2, ROR-γt, GATA-3, T-bet, and Foxp3 was determined using quantitative reverse­transcription polymerase chain reaction (qRT­PCR). RESULTS: The SASP plus probiotic mixture was more effective in alleviating colitis symptoms, and reducing disease activity scores, and mucosal inflammation. qRT-PCR analysis revealed a significant reduction in T-bet and RORγt levels, while Foxp3 and GATA-3 levels increased in the colons of colitis mice. In addition, the selected strains substantially inhibited the release of inflammatory markers. Administration of LA-5 + BB-12 + SASP resulted in considerably higher inhibition of NO production and cell proliferation than in the other groups (p < 0.001). Treatment with LA-5 + BB-12 + SASP also reduced TNF-α-mediated apoptosis in intestinal epithelial cells (IECs). CONCLUSIONS: Survey results highlight that the combination regimen could be a promising strategy for IBD therapy, warranting further study of its clinical application and long-term benefits.

Microbiological studies on Escherichia coli and Klebsiella pneumoniae causing vaginal and urinary tract inflammation; prevalence, antibiotics-resistance and natural products susceptibility.

Great efforts have been made for controlling multidrug-resistant bacteria (MDR). The antibacterial activity of natural products is an effective strategy due to its beneficial effects on human health. This study focused on the isolation, identification, studying the prevalence and the susceptibility of Escherichia coli and Klebsiella spp. to some natural products. After isolation, the isolates primarily identified using biochemical and API tests. Then, the antibiotic susceptibility test was done to reveal the most antibiotics resistant isolates before further identification of Escherichia coli and Klebsiella pneumoniae using phoA and gyrA genes, respectively. Furthermore, the sensitivity of the most antibiotics resistant isolates to apple cider vinegar (ACV), garlic oil (GO), coconut oil (CNO), tea tree oil (TTO), and lavender oil (LO) was estimated. All tested extracts especially ACV and TTO showed good antibacterial activity against MRD selected isolates. Statistical analysis indicated that there was significant difference in ACV and TTO antibacterial response between Escherichia coli and Klebsiella pneumoniae whereas there was no significant difference between natural products activity when tested against Escherichia coli and Klebsiella pneumoniae seperatly. GC-MS spectroscopy analysis revealed the most prominent active constituents present in tested ACV and TTO. Analyzing the 16S rRNA sequence confirmed the two most MRD pathogenic isolates that showed sensitivity to ACV and TTO were Escherichia coli MS1 and Klebsiella pneumoniae MS47, respectively. Essential oils tea tree and apple cider vinegar showed good antibacterial activities against antibiotics-resistant Escherichia coli and Klebsiella pneumoniae causing vaginal and urinary tract inflammation.

Change of Cerebral Hemodynamic Signals during the Process of Swallowing Water, Acetic Acid Solution and Salt Solution in Healthy Adults: An fNIRS Study.

BACKGROUND: The aim of this preliminary study was to investigate the similarities and differences in cortical activation patterns during the swallowing of water, acetic acid solution and salt solution in healthy adults using functional near-infrared spectroscopy (fNIRS). METHODS: Eighteen right-handed healthy adults were recruited and fNIRS was used to measure changes in concentrations of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (HbR) in 35 channels during the swallowing of water, acetic acid solution and salt solution. The task-based experiment used a block-design in which participants alternated between resting blocks of 30 s and task blocks (swallowing water, acetic acid solution, or salt solution) of 30 s, repeated six times. Participants remained still during the resting blocks and performed a swallowing action every 6 s during the task blocks. Data preprocessing was conducted using NirSpark software and statistical analyses were performed using either one-sample or paired t-tests to compare differences in cortical activation in healthy participants between swallowing a water and acetic acid solution, as well as swallowing a water and salt solution. RESULTS: Compared to the resting state, nine brain regions, including primary somatosensory cortex (S1), primary motor cortex (M1), dorsolateral prefrontal cortex (DLPFC), Wernicke's area, premotor cortex (PMC), supplementary motor area (SMA), inferior frontal cortex (IFC), orbitofrontal cortex (OFC) and frontopolar area, were commonly activated during the process of swallowing water, acetic acid solution, and salt solution. The DLPFC, Broca's area, PMC and SMA showed higher activation levels during the swallowing of acetic acid solution when compared to swallowing water, with statistically significant differences (p < 0.05). The frontopolar area and OFC exhibited higher activation during the swallowing of salt solution when compared to water, also with statistically significant differences (p < 0.05). CONCLUSIONS: Multiple brain regions were activated during the swallowing of water, acetic acid solution and salt solution in healthy adults. Moreover, swallowing acetic acid solution leads to stronger activation of DLPFC, Broca's area, PMC and SMA, while swallowing salt solution leads to stronger activation of the frontopolar area and OFC.

Effects of acetic acid fermentation product and its components on defense signaling in rice.

Acetic acid fermentation product made from isomalto-oligosaccharide as the main raw material is composed of isomalto-oligosaccharide and acetic acid. In this paper, we have shown that the fermentation product enhanced the expression of disease resistance genes in rice, and that its main functional component was acetic acid. It has been reported so far that acetic acid enhances the jasmonic acid signaling pathway, while the role of isomalto-oligosaccharide in plant defense signaling remains unclear. In this study, we demonstrated the possibility that isomalto-oligosaccharide shifted part of the jasmonic acid signaling pathway, which is enhanced by acetic acid, to the salicylic acid signaling pathway, which is the other major defense pathway. Furthermore, glucose, a constituent monosaccharide of isomalto-oligosaccharide, and a disaccharide maltose had little effect on the signaling pathway, but a trisaccharide maltotriose tended to have a similar effect to isomalto-oligosaccharide on the defense signaling pathway.

Acetic and citric acids effect the type II secretion system and decrease the metabolic activities of salmon spoilage-related Rahnella aquatilis KM05.

Rahnella aquatilis causes seafoods to spoil by metabolizing sulfur-containing amino acids and/or proteins, producing H2S in products. The type II secretion system (T2SS) regulates the transport of proteases from the cytoplasm to the surrounding environment and promotes bacterial growth at low temperatures. To prevent premature fish spoilage, new solutions for inhibiting the T2SS of bacteria should be researched. In this study, global transcriptome sequencing was used to analyze the spoilage properties of R. aquatilis KM05. Two of the mapped genes/coding sequences (CDSs) were matched to the T2SS, namely, qspF and gspE, and four of the genes/CDSs, namely, ftsH, rseP, ptrA and pepN, were matched to metalloproteases or peptidases in R. aquatilis KM05. Subinhibitory concentrations of citric (18 µM) and acetic (41 µM) acids caused downregulation of T2SS-related genes (range from - 1.0 to -4.5) and genes involved in the proteolytic activities of bacteria (range from - 0.5 to -4.0). The proteolytic activities of R. aquatilis KM05 in vitro were reduced by an average of 40%. The in situ experiments showed the antimicrobial properties of citric and acetic acids against R. aquatilis KM05; the addition of an acidulant to salmon fillets limited microbial growth. Citric and acetic acids extend the shelf life of fish-based products and prevent food waste.

Mining and characterization of novel antimicrobial peptides from the large-scale microbiome of Shanxi aged vinegar based on metagenomics, molecular dynamics simulations and mechanism validation.

The study aimed to mine and characterize novel antimicrobial peptides (AMPs) from the Shanxi aged vinegar microbiome. Utilizing machine learning techniques, AlphaFold2 structure prediction and molecular dynamics simulations, six novel AMPs were innovatively mined from 98,539 peptides based on metagenomic data, of which one peptide secreted by Lactobacillus (named La-AMP) was experimentally validated to have remarkable bactericidal effects against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with high stability and no hemolytic activity. Scanning electron microscopy revealed that La-AMP caused irreversible damage to cell membranes of S. aureus and E. coli, a finding further confirmed by calcein-AM/propidium iodide staining. Additionally, La-AMP induced nucleic acid leakage and reactive oxygen species accumulation in bacterial cells. It was found to bind to DNA gyrase through salt bridges, hydrogen bonds, and hydrophobic interactions, ultimately inducing apoptosis. Thus, La-AMP exhibited encouraging promise as a valuable bioactive component for the development of natural preservatives.

Modelling the colony growth dynamics of Listeria monocytogenes single cells after exposure to peracetic acid and acidic conditions.

Studies of classical microbiology rely on the average behaviour of large cell populations without considering that clonal bacterial populations may bifurcate into phenotypic distinct sub-populations by random switching mechanisms.Listeria monocytogenes exposure to sublethal stresses may induce different physiological states that co-exist (i.e., sublethal injury or dormancy) and present variable resuscitation capacity. Exposures to peracetic acid (PAA; 10-30 ppm; for 3 h), acetic acid and hydrochloric acid (AA and HCl; pH 3.0-2.5; for 5 h) at 20 °C were used to induce different physiological states in L. monocytogenes, Scott A strain. After stress exposure, colony growth of single cells was monitored, on Tryptic Soy Agar supplemented with 0.6 % Yeast Extract, using time-lapse microscopy, at 37 °C. Images were acquired every 5 min and were analyzed using BaSCA framework. Most of the obtained growth curves of the colonies were fitted to the model of Baranyi and Roberts for the estimation of lag time (λ) and maximum specific growth rate (µmax), except the ones obtained after exposure to AA pH 2.7 and 2.5 that were fitted to the Trilinear model. The data of λ and µmax that followed a multivariate normal distribution were used to predict growth variability using Monte Carlo simulations. Outgrowth kinetics after treatment with AA (pH 2.7 and 2.5; for 5 h at 20 °C), PAA (30 ppm; for 3 h at 20 °C) revealed that these stress conditions increase the skewness of the variability distributions to the right, meaning that the variability in lag times increases in favour of longer outgrowth. Exposures to AA pH 2.5 and 30 ppm PAA resulted in two distinct subpopulations per generation with different growth dynamics. This switching mechanism may have evolved as a survival strategy for L. monocytogenes cells, maximizing the chances of survival. Simulation of microbial growth showed that heterogeneity in growth dynamics is increased when cells are recovering from exposure to sublethal stresses (i.e. PAA and acidic conditions) that may induce injury or dormancy.

Effects of different marination conditions on the physico-chemical and microbiological quality of anchovy (Engraulis encrasicolus) fillets inoculated with Morganella psychrotolerans during cold storage.

This study is aimed to determine the effects of different marination conditions (1, 2, 3, 4% acetic and 6, 8, 10% NaCl) on the anchovy fillets inoculated with Morganella psychrotolerans during refrigerated storage (4±1°C) for three months. According to the results of study, marination has great inhibitory effects on the growth of M. psychrotolerans. Total psychrophilic bacteria, total lactic acid bacteria, total yeast and mold, Total Enterobacteriaceae and M. psychrotolerans growth were not observed in the groups treated with 3 and 4% acetic acid. Control groups and fillets marinated with 1% acetic acid showed lower sensory scores. Those groups were rejected on 30th, 45th and 60th days of the storage, respectively, while the groups marinated with 2%, 3%, and 4% acetic acid had higher sensory scores and they were still acceptable until at the end of the study. According to peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) assessment, lipid oxidation was delayed in the fillets marinated with high acetic acid concentrations (3 and 4%) comparing with the control and other inoculated fillets. From this research it can be revealed that high acetic acid and salt concentrations suppress the bacteria growth in the anchovy fillets. Thus, marination process can be recommended to be used as a preservation method to inhibit bacterial growth in anchovy fillets for a safe consumption.

Antibiofilm Effect of Sequential Application of Ozonated Water, Acetic Acid and Lactic Acid on Salmonella Typhimurium and Staphylococcus aureus Biofilms In Vitro.

Biofilms are highly resistant to disinfectants and antimicrobials and are known as the primary source of food contamination. Salmonella Typhimurium (S. Typhimurium) and Staphylococcus aureus (S. aureus) have an excellent ability to form biofilm. This study aimed to evaluate the antibiofilm activity of ozonated water (O), acetic acid (AA), and lactic acid (LA), individually and sequentially, against biofilms of S. Typhimurium and S. aureus formed on the polystyrene surfaces. The antibiofilm effects of the treatments were evaluated using crystal violet staining and the viable count determination methods. In the staining method, the highest percentage of biofilm mass reduction was induced by successive use of ozonated water and acetic acid (O-AA), which reduced S. aureus biofilm mass by 44.36%. The sequential use of ozonated water and lactic acid (O-LA) could decrease S. Typhimurium biofilm mass by 57.26%. According to the viable count method, the most effective treatment was the sequential use of ozonated water and lactic acid (O-LA), which reduced S. aureus and S. Typhimurium biofilms by 1.76 and 4.06 log, respectively. It was concluded that the sequential use of ozonated water and organic acids can be considered a practical and environmentally friendly approach to control biofilms.

The ldh Gene Plays a Crucial Role in Mediating the Pathogen Control of Lactiplantibacillus plantarum AR113.

Effectively managing foodborne pathogens is imperative in food processing, where probiotics play a crucial role in pathogen control. This study focuses on the Lactiplantibacillus plantarum AR113 and its gene knockout strains, exploring their antimicrobial properties against Escherichia coli O157:H7 and Staphylococcus aureus. Antimicrobial assays revealed that the inhibitory effect of AR113 increases with its growth and the potential bacteriostatic substance is acidic. AR113Δldh, surpassed AR113Δ0273&2024, exhibited a complete absence of bacteriostatic properties, which indicates that lactic acid is more essential than acetic acid in the bacteriostatic effect of AR113. However, the exogenous acid validation test affirmed the equivalent superior bacteriostatic effect of lactic acid and acetic acid. Notably, AR113 has high lactate production and deletion of the ldh gene not only lacks lactate production but also affects acetic production. This underscores the ldh gene's pivotal role in the antimicrobial activity of AR113. In addition, among all the selected knockout strains, AR113ΔtagO and ΔccpA also had lower antimicrobial effects, suggesting the importance of tagO and ccpA genes of AR113 in pathogen control. This study contributes insights into the antimicrobial potential of AR113 and stands as the pioneering effort to use knockout strains for comprehensive bacteriostatic investigations.

Differential impacts of furfural and acetic acid on the bioenergetics and fermentation performance of Scheffersomyces stipitis.

Lignocellulosic material is a leading carbon source for economically viable biotechnological processes; however, compounds such furfural and acetic acid exhibit toxicity to yeasts. Nonetheless, research about the molecular mechanism of furfural and acetic acid toxicity is still scarce in yeasts like Scheffersomyces stipitis. Thus, this study aims to elucidate the impact of furfural and acetic acid on S. stipitis regarding bioenergetic and fermentation parameters. Here, we provide evidence that furfural and acetic acid induce a delay in cell growth and extend the lag phase. The mitochondrial membrane potential decreased in all treatments with no significant differences between inhibitors or concentrations. Interestingly, reactive oxygen species increased when the inhibitor concentrations were from 0.1 to 0.3 % (v/v). The glycolytic flux was not significantly (p > 0.05) altered by acetic acid, but furfural caused different effects. Ethanol production decreased significantly (4.32 g·L-1 in furfural and 5.06 g·L-1 in acetic acid) compared to the control (26.3 g·L-1). In contrast, biomass levels were not significantly different in most treatments compared to the control. This study enhances our understanding of the effects of furfural and acetic acid at the mitochondrial level in a pentose-fermenting yeast like S. stipitis.

Silver-nanoparticle-modified nanocellulose synthesized by pyroligneous acid: cytotoxicity towards HaCat cells.

In the present study, pyroligneous acid, also known as wood vinegar, has been employed as reducing and stabilizing agent in the synthesis of silver nanoparticles (AgNPs) anchored on nanocellulose (NC). The idea is to confer the latter bactericidal properties for its typical uses such as in cosmetics and food-packing. It has been demonstrated that AgNPs can be directly produced onto NC in one-pot fashion while dramatically enhancing the kinetics of AgNPs synthesis (2 h for reaction completion) in comparison to the NC-less counterpart (10 days for reaction completion). Furthermore, NC allowed for a narrower size distribution of AgNPs. NC-supported and non-supported AgNPs had sizes of 5.1 ± 1.6 nm and 16.7 ± 4.62 nm, respectively. Immortalized human keratinocytes (HaCat) cells were then employed as model to evaluate the cytotoxicity of the AgNPs-NC compound. The latter was found not to impact cell proliferation at any formulation, while decreasing the viability by only 6.8% after 72 h. This study contributes to the development of more environmentally benign routes to produce nanomaterials and to the understanding of their impact on cells.

Investigating inhibiting factors affecting seed germination index in kitchen waste compost products: Soluble carbon, nitrogen, and salt insights.

The seed germination index (GI) serves as the principal determinant that impedes the integration of aerobic composting products into agricultural lands. The current research work predominantly focuses on exploring the correlation between physical and chemical indicators of the compost products and GI, neglecting the fundamental cause. This study systematically analyzed the composition of GI aqueous extracts from compost products derived from kitchen waste under various composting methodologies, with nitrogen, carbon, and inorganic salt as critical factors. The analytical work concluded that acetic acid, formic acid, and ammonium were the inhibitory factors influencing GI. Validation experiments introduced inhibitory factors, yielding a functional relationship formula depicting GI variations due to a single influential factor. This study conclusively identified acetic acid as the primary constraint, establishing that its inhibitory concentration corresponded to 70 % GI stands at 85 mg/L. This study will provide guidelines for the future research on enhancing aerobic composting techniques.

Induction into viable but non culturable state and outgrowth heterogeneity of Listeria monocytogenes is affected by stress history and type of growth.

Exposure to sublethal stresses related to food-processing may induce a heterogenous mixture of cells that co-exist, comprising healthy, sublethally injured, dormant and dead cells. Heterogeneity in survival capacity and dormancy of single cells may impede the detection of foodborne pathogens. In this study, we exposed Listeria monocytogenes Scott A strain, to peracetic acid (PAA; 20-40 ppm) and to acidic conditions (hydrochloric (HCl) and acetic (AA) acid, adjusted to pH 2.7-3.0, to evaluate the resuscitation capacity and outgrowth kinetics of metabolically active cells in two different media. Injury and the viable-but-non-culturable (VBNC) status of cells were assessed by flow cytometry using CFDA (metabolically active) and PI (dead) staining. Stressed CFDA+PI- cells were sorted on Tryptic Soy (TS) Agar or in TS broth, both supplemented with 0.6 % Yeast Extract (TSAYE or TSBYE), to evaluate culturability. Resuscitation capacity of CFDA+PI-sorted cells (10 events/well) was monitored by visual inspection on TSAYE and by optical density measurement in TSBYE for 5 days. Sorting of L. monocytogenes viable cells (CFDA+PI-) in Ringer's solution on TSAYE and TSBYE showed 100 % recovery in both media (control condition), while the mean lag time in TSBYE was 9.6 h. Treatment with 20 ppm PAA for 90 and 180 min resulted in 74.79 % and 85.82 % of non-culturable cells in TSBYE and increased the average lag time to 41.7 h and 43.8 h, respectively, compared to the control (9.6 h). The longest average lag time (79.5 h) was detected after treatment with 30 ppm PAA for 90 min, while at the same condition sorting of CFDA+PI- cells resulted in 95.05 % and 93.94 % non-culturable cells on TSAYE and TSBYE, respectively. The highest percentage of wells with non-culturable cells (96.17 %) was detected on TSAYE after treatment with 40 ppm PAA for 30 min. Fractions of VBNC cells were detected in TSBYE after treatment with HCl pH 3.0 for 60 and 240 min, and in TSAYE and TSBYE after exposure to AA pH 2.7. Treatment with AA pH 2.7 for 150-300 min increased the range of recorded lag time values compared to 60 min, from 8.6 h up to 13.3 h, as well as the mean lag times in TSBYE. Modelling of the outgrowth kinetics comparing the two types of stress (oxidative vs acid) and the two systems of growth (colonial vs planktonic) revealed that low starting concentrations hindered the detection of viable L. monocytogenes cells, either due to VBNC induction or cell heterogeneity.

Inhibition of Clostridium perfringens and Bacillus cereus by Dry Vinegar and Cultured Sugar Vinegar During Extended Cooling of Uncured Beef and Poultry Products.

The 2021 FSIS Stabilization Guidelines for Meat and Poultry Products (Appendix B) Option 1.2 limits Phase 1 cooling from 48.8 to 26.7 °C in uncured meats to 1 h. However, this time restriction is impractical to achieve in large-diameter whole-muscle products. The objective of this study was to compare the inhibitory effect of commercial dry vinegars (DVs) and cultured sugar-vinegar blends (CSVs) on Clostridium perfringens and Bacillus cereus in uncured beef and poultry products during extended cooling. Treatments (beef: 72-73% moisture, pH 6.2-6.3, 0.85-0.95% NaCl; turkey: 76-77% moisture, pH 6.5-6.7, 1.3-1.6% NaCl) included Controls without antimicrobials, and four DV and four CSV, each tested at 0.75 and 1.25%. Batches were inoculated with 2.5-log C. perfringens or B. cereus spores, vacuum-packaged, and cooked to 73 °C. Packages were cooled from 48.8 to 27 °C (Phase 1) in 3, 4, or 5 h; Phase 2 (27-12.8 °C) and Phase 3 (12.8-4 °C) were standardized for 5-h cooling each. Pathogens were enumerated on selective agar in triplicate samples assayed at precook, postcook, and at the end of Phase 1, 2, and 3 cooling. Experiments were conducted twice. B. cereus did not grow (<0.5-log increase) in any treatment when Phase 1 cooling was extended to 5 h. C. perfringens grew rapidly (2.5 to >4.5 log) in Control treatments when Phase 1 cooling was extended to ≥3 h. All 1.25% DV ingredients limited C. perfringens growth to ≤1-log when Phase 1 cooling was extended to 3 h but supported a >1-log increase when Phase 1 cooling was extended to 5 h. All 1.25% CSV inhibited growth under 3-h Phase 1 cooling; 1.25% CSV-A and ≥0.75% CSV-D inhibited growth in turkey during 5-h Phase 1 cooling, but inhibition with 1.25% CSV-C was inconsistent in beef. This study revealed that formulating uncured meats with 1.25% DV or certain CSV can extend Phase 1 cooling to 3 h. Although all ingredients inhibited growth when used at 0.75% or greater compared to a control, greater variability of inhibition was observed among CSV than for DV.

Mining novel gene targets for improving tolerance to furfural and acetic acid in Yarrowia lipolytica using whole-genome CRISPRi library.

Abundant renewable resource lignocellulosic biomass possesses tremendous potential for green biomanufacturing, while its efficient utilization by Yarrowia lipolytica, an attractive biochemical production host, is restricted since the presence of inhibitors furfural and acetic acid in lignocellulosic hydrolysate. Given deficient understanding of inherent interactions between inhibitors and cellular metabolism, sufficiently mining relevant genes is necessary. Herein, 14 novel gene targets were discovered using clustered regularly interspaced short palindromic repeats interference library in Y. lipolytica, achieving tolerance to 0.35 % (v/v) acetic acid (the highest concentration reported in Y. lipolytica), 4.8 mM furfural, or a combination of 2.4 mM furfural and 0.15 % (v/v) acetic acid. The tolerance mechanism might involve improvement of cell division and decrease of reactive oxygen species level. Transcriptional repression of effective gene targets still enabled tolerance when xylose was a carbon source. This work forms a robust foundation for improving microbial tolerance to lignocellulose-derived inhibitors and revealing underlying mechanism.

Acetic acid affects porcine oocyte metabolism and improves oocyte developmental ability.

Improvement in vitro maturation culture conditions has been achieved by mimicking in vivo culture environments such as the follicular fluid. Acetic acid is an energy substrate that is abundantly present in the follicular fluid but has not been considered in vitro maturation. This study examined the effects of acetic acid on oocyte quality during nuclear maturation. Cumulus cells and oocyte complexes were collected from the porcine antral follicles of gilt ovaries and matured with 0, 0.1 or 1 mmol/L of acetic acid. After 44 h of in vitro maturation, the energy status, mitochondrial quality and function and embryonic developmental rate following parthenogenetic activation were determined. RNA-sequencing and protein expression analyses were conducted to predict the effects of acetic acid. Supplementation of the in vitro maturation medium with acetic acid (1 mmol/L) improved embryonic development. Oocytes matured with acetic acid had low adenosine triphosphate and lipid contents, mitochondrial membrane potential and reactive oxygen species levels. RNA-sequencing revealed differential expression of genes associated with the adenosine monophosphate-activated protein kinase signalling pathway. Immunostaining revealed that acetic acid increased the levels of phospho-adenosine monophosphate-activated protein kinase, phospho-acetyl-coenzyme A carboxylase, and sirtuin 1 and decreased those of fatty acid synthase and acetyl-coenzyme A synthetase 1. In summary, the use of acetic acid during oocyte maturation improved oocyte developmental ability and metabolism by altering mitochondrial activity and lipid metabolism.

Identifying and characterization of novel broad-spectrum bacteriocins from the Shanxi aged vinegar microbiome: Machine learning, molecular simulation, and activity validation.

Shanxi aged vinegar microbiome encodes a wide variety of bacteriocins. The aim of this study was to mine, screen and characterize novel broad-spectrum bacteriocins from the large-scale microbiome data of Shanxi aged vinegar through machine learning, molecular simulation and activity validation. A total of 158 potential bacteriocins were innovatively mined from 117,552 representative genes based on metatranscriptomic information from the Shanxi aged vinegar microbiome using machine learning techniques and 12 microorganisms were identified to secrete bacteriocins at the genus level. Subsequently, employing AlphaFold2 structure prediction and molecular dynamics simulations, eight bacteriocins with high stability were further screened, and all of them were confirmed to have bacteriostatic activity by the Escherichia coli BL21 expression system. Then, gene_386319 (named LAB-3) and gene_403047 (named LAB-4) with the strongest antibacterial activities were purified by two-step methods and analyzed by mass spectrometry. The two bacteriocins have broad-spectrum antimicrobial activity with minimum inhibitory concentration values of 6.79 µg/mL-15.31 µg/mL against Staphylococcus aureus and Escherichia coli. Furthermore, molecular docking analysis indicated that LAB-3 and LAB-4 could interact with dihydrofolate reductase through hydrogen bonds, salt-bridge forces and hydrophobic forces. These findings suggested that the two bacteriocins could be considered as promising broad-spectrum antimicrobial agents.

Induction of Salmonella Enteritidis into a Viable but Nonculturable State by Cinnamaldehyde and Its Resuscitation.

Trans-cinnamaldehyde (TC), a typical plant-derived compound, has been widely used in the control of foodborne pathogen contamination. Nevertheless, the risk associated with the occurrence of viable but nonculturable (VBNC) bacteria induced by TC remains unclear. The results of this study showed that Salmonella Enteritidis (S. Enteritidis) entered the VBNC state after being induced by TC at a minimum inhibitory concentration of 312.5 µg/mL and survived for at least 22 days under TC treatment. Enhanced resistance was found against heat treatment (75°C, 30 s), antibiotics (i.e., ampicillin, ceftriaxone sodium, chloramphenicol), and hydrogen peroxide (3%) in VBNC S. Enteritidis. A synergistic effect against VBNC S. Enteritidis occurred when TC was combined with acid treatment, including lactic acid and acetic acid (pH = 3.5). VBNC and resuscitated S. Enteritidis by sodium pyruvate treatment (100 mM) were found to retain the infectious ability to Caco-2 cells. Relative expression levels of the stress-related genes relA, spoT, ppx, lon, katG, sodA, dnaK, and grpE were upregulated in VBNC S. Enteritidis. Accumulation of reactive oxygen species (ROS) and protein aggregates was observed in VBNC cells. Besides, the resuscitation of VBNC cells was accompanied with clearance of ROS and protein aggregates. In summary, this study presents a comprehensive characterization of stress tolerance and resuscitation of VBNC S. Enteritidis induced by cinnamaldehyde, and the results provide useful information for the development of effective control strategy against VBNC pathogenic bacteria in food production.