Regulation of Lactobacillus plantarum on the reactive oxygen species related metabolisms of Saccharomyces cerevisiae

Hexadecanoic acid produced in the co-culture of S. cerevisiae and E.coli promotes oxidative stress tolerance of the S.cerevisiae cells

Co-fermentation performed by Saccharomyces cerevisiae and Escherichia coli or other microbes has been widely used in industrial fermentation. Meanwhile, the co-cultured microbes might regulate each other's metabolisms or cell behaviors including oxidative stress tolerance through secreting molecules. Here, results based on the co-culture system of S. cerevisiae and E. coli suggested the promoting effect of E. coli on the oxidative stress tolerance of S. cerevisiae cells. The co-cultured E. coli could enhance S. cerevisiae cell viability through improving its membrane stability and reducing the oxidized lipid level. Meanwhile, promoting effect of the co-cultured supernatant on the oxidative stress tolerance of S. cerevisiae illustrated by the supernatant substitution strategy suggested that secreted compounds contained in the co-cultured supernatant contributed to the higher oxidative stress tolerance of S. cerevisiae. The potential key regulatory metabolite (i.e., hexadecanoic acid) with high content difference between co-cultured supernatant and the pure-cultured S. cerevisiae supernatant was discovered by GC-MS-based metabolomics strategy. And exogenous addition of hexadecanoic acid did suggest its contribution to higher oxidative stress tolerance of S. cerevisiae. Results presented here would contribute to the understanding of the microbial interactions and provide the foundation for improving the efficiency of co-fermentation performed by S. cerevisiae and E. coli.

Regulation of the PFK1 gene on the interspecies microbial competition behavior of Saccharomyces cerevisiae

Saccharomyces cerevisiae is a widely used strain for ethanol fermentation; meanwhile, efficient utilization of glucose could effectively promote ethanol production. The PFK1 gene is a key gene for intracellular glucose metabolism in S. cerevisiae. Our previous work suggested that although deletion of the PFK1 gene could confer higher oxidative tolerance to S. cerevisiae cells, the PFK1Δ strain was prone to contamination by other microorganisms. High interspecies microbial competition ability is vital for the growth and survival of microorganisms in co-cultures. The result of our previous studies hinted us a reasonable logic that the EMP (i.e., the Embden-Meyerhof-Parnas pathway, the glycolytic pathway) key gene PFK1 could be involved in regulating interspecies competitiveness of S. cerevisiae through the regulation of glucose utilization and ethanol production efficiency. The results suggest that under 2% and 5% glucose, the PFK1Δ strain showed slower growth than the S288c wild-type and TDH1Δ strains in the lag and exponential growth stages, but realized higher growth in the stationary stage. However, relative high supplement of glucose (10%) eliminated this phenomenon, suggesting the importance of glucose in the regulation of PFK1 in yeast cell growth. Furthermore, during the lag growth phase, the PFK1Δ strain displayed a decelerated glucose consumption rate (P < 0.05). The expression levels of the HXT2, HXT5, and HXT6 genes decreased by approximately 0.5-fold (P < 0.05) and the expression level of the ZWF1 exhibited a onefold increase in the PFK1Δ strain compared to that in the S. cerevisiae S288c wild-type strain (P < 0.05).These findings suggested that the PFK1 inhibited the uptake and utilization of intracellular glucose by yeast cells, resulting in a higher amount of residual glucose in the medium for the PFK1Δ strain to utilize for growth during the reverse overshoot stage in the stationary phase. The results presented here also indicated the potential of ethanol as a defensive weapon against S. cerevisiae. The lower ethanol yield in the early stage of the PFK1Δ strain (P < 0.001) and the decreased expression levels of the PDC5 and PDC6 (P < 0.05), which led to slower growth, resulted in the strain being less competitive than the wild-type strain when co-cultured with Escherichia coli. The lower interspecies competitiveness of the PFK1Δ strain further promoted the growth of co-cultured E. coli, which in turn activated the ethanol production efficiency of the PFK1Δ strain to antagonize it from E. coli at the stationary stage. The results presented clarified the regulation of the PFK1 gene on the growth and interspecies microbial competition behavior of S. cerevisiae and would help us to understand the microbial interactions between S. cerevisiae and other microorganisms. KEY POINTS: • PFK1Δ strain could realize reverse growth overshoot at the stationary stage • PFK1 deletion decreased ethanol yield and interspecific competitiveness • Proportion of E. coli in co-culture affected ethanol yield capacity of yeast cells.

Microbial dysbiosis and the aging process: a review on the potential age-deceleration role of Lactiplantibacillus plantarum

Gut microbiota dysbiosis has been a serious risk factor for several gastric and systemic diseases. Recently, gut microbiota's role in aging was discussed. Available preclinical evidence suggests that the probiotic bacteria Lactiplantibacillus plantarums (LP) may influence the aging process via modulation of the gut microbiota. The present review summarized compelling evidence of LP's potential effect on aging hallmarks such as oxidative stress, inflammation, DNA methylation, and mitochondrial dysfunction. LP gavage modulates gut microbiota and improves overall endurance in aging animal models. LP cell constituents exert considerable antioxidant potential which may reduce ROS levels directly. In addition, restored gut microbiota facilitate a healthy intestinal milieu and accelerate multi-channel communication via signaling factors such as SCFA and GABA. Signaling factors further activate specific transcription factor Nrf2 in order to reduce oxidative damage. Nrf2 regulates cellular defense systems involving anti-inflammatory cytokines, MMPs, and protective enzymes against MAPKs. We concluded that LP supplementation may be an effective approach to managing aging and associated health risks.

Multi-omics analysis reveals the microbial interactions of S. cerevisiae and L. plantarum on Suanyu, Chinese traditional fermented fish

S. cerevisiae and L. plantarum play important roles in Suanyu fermentation. This study investigated the interaction between S. cerevisiae and L. plantarum during fermentation and its impact on metabolic pathways. Co-culturing S. cerevisiae and L. plantarum increased pH to 5.72, reduced TVB-N to 9.47 mg/mL, and achieved high utilization rates of sugars (98.9%) and proteins (73.7%). During microbial interactions, S. cerevisiae and L. plantarum produced antibiotics, including phenyllactate and Gentamicin C1a, inhibiting the growth of each other. S. cerevisiae used S-adenosyl-l-methionine to counteract acid production of L. plantarum, establishing dominance in Suanyu fermentation. Microbial interactions influenced carbohydrate and energy metabolism pathways, such as nicotinate and nicotinamide metabolism and purine metabolism. S. cerevisiae significantly impacted gene expression in protein synthesis and cell growth pathways, including ribosome, SNARE interactions, basal transcription factors, and MAPK signaling. These findings offer insights into microbial interactions and metabolic processes during Suanyu fermentation.

The Impact in Intestines and Microbiota in BALB/c Mice Through Consumption of Milk Fermented by Potentially Probiotic Lacticaseibacillus casei SJRP38 and Limosilactobacillus fermentum SJRP43

The present study aimed to evaluate the effect of consumption of milk fermented by Lacticaseibacillus (Lc.) casei SJRP38 and Limosilactobacillus (Lm.) fermentum SJRP43 on bacterial translocation, stool analysis, and intestinal morphology of healthy BALB/c mice. Potentially probiotic lactic acid bacteria, Lc. casei SJRP38, and Lm. fermentum SJRP43 were evaluated and analyzed for translocation, fecal analysis, and intestinal morphology of four groups of mice: water control (WC), milk control (MC), milk fermented by Lc. casei SJRP38 (FMLC), and milk fermented by Lm. fermentum SJRP43 (FMLF), in co-culture with Streptococcus thermophilus ST080. The results of the animal assay indicate that the population of Lactobacilli and Bidobacterium sp. in the gastrointestinal tract of BALB/c mice was greater than 6.0 log10 CFU/g, and there was no evidence of bacteremia due to the low incidence of bacterial translocation. Ingesting fermented milk containing Lc. casei SJRP38 and Lm. fermentum SJRP43 was found to promote a healthier microbiota, as it led to a reduction in Clostridium sp. and an increase in Lactobacilli and Bifidobacterium sp. in feces. Furthermore, the dairy treatments (MC, FMLC, and FMLF) resulted in taller intestinal villi and an increase in the frequency of goblet cells in the intestines. Overall, the consumption of fermented milk containing Lc. casei SJRP38 and Lm. fermentum SJRP43 strains was deemed safe and demonstrated beneficial effects on the intestines of BALB/c mice.

Fermentation of Persimmon Leaves Extract by Lactiplantibacillus plantarum and Saccharomyces cerevisiae

Persimmon leaves usually as agricultural and forestry waste were fermented by Lactiplantibacillus plantarum and Saccharomyces cerevisiae. Growth and metabolic performances of L. plantarum and S. cerevisiae, as well as the effect of fermentation on the antioxidant abilities of the extract was investigated, including the content of flavonoids, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical clearance rates. Growth of L. plantarum was limited, even though the acid production was sustainable, while S. cerevisiae was more suitable to inhabit in the persimmon leaves extract. A symbiotic relationship was observed between the two microbes, reflected in aspects of growth of S. cerevisiae, pH reduction, and ethanol production. The DPPH radical clearance rates of all groups decreased at the early period, and increased later. The co-culture group reached the second highest value of DPPH radical clearance rate only next to the single group of L. plantarum at 9 h. All groups showed an overall downward trend of the hydroxyl radical clearance rates during the 9 h-fermentation. These findings highlight the promising industrial application of fermentation of the plant-based materials with Lactiplantibacillus and Saccharomyces species to improve the biological properties.

Chestnuts in Fermented Rice Beverages Increase Metabolite Diversity and Antioxidant Activity While Reducing Cellular Oxidative Damage

Foods containing chestnuts (Castanea mollissima Blume) are relatively uncommon, despite the high nutrient and starch contents and purported health benefits. In this study, we examine the flavor-related metabolites, volatile compounds, and amino acids in a traditional glutinous rice fermented beverage supplemented with chestnuts as a fermentation substrate for lactic acid bacteria (LAB). Changes in antioxidant activity towards free radicals and effects on cellular oxidative stress are compared between beverages with or without chestnuts. The fermented chestnut-rice beverage (FCRB) has higher sensory scores and a wider range of volatiles and flavor-related compounds (74 vs. 38 species compounds), but lower amino acid contents, than the traditional fermented glutinous rice beverage (TFRB). In free radical scavenging assays, the FCRB exhibits higher activity than the TFRB in vitro. Furthermore, while neither beverage induces cytotoxity in Caco-2 cells at concentrations up to 2 mg/mL, pretreatment with the FCRB results in lower rates of apoptosis and necrosis and higher overall viability in cells with H₂O₂-induced oxidative stress compared to pretreatment with the TFRB. The enhanced reactive oxygen species neutralization in vitro and protection against oxidative damage in cells, coupled with increased diversity of volatiles and flavor-related metabolites of LAB, support the addition of chestnuts to enhance flavor profile and antioxidant properties of fermented functional foods.

Oxidative stress response pathways in fungi

Fungal response to any stress is intricate, specific, and multilayered, though it employs only a few evolutionarily conserved regulators. This comes with the assumption that one regulator operates more than one stress-specific response. Although the assumption holds true, the current understanding of molecular mechanisms that drive response specificity and adequacy remains rudimentary. Deciphering the response of fungi to oxidative stress may help fill those knowledge gaps since it is one of the most encountered stress types in any kind of fungal niche. Data have been accumulating on the roles of the HOG pathway and Yap1- and Skn7-related pathways in mounting distinct and robust responses in fungi upon exposure to oxidative stress. Herein, we review recent and most relevant studies reporting the contribution of each of these pathways in response to oxidative stress in pathogenic and opportunistic fungi after giving a paralleled overview in two divergent models, the budding and fission yeasts. With the concept of stress-specific response and the importance of reactive oxygen species in fungal development, we first present a preface on the expanding domain of redox biology and oxidative stress.