Isolation and evaluation of probiotics from traditional Chinese foods for aflatoxin B1 detoxification: Geotrichum candidum XG1 (yeast) and mechanistic insights.

Identifying aflatoxin-detoxifying probiotics remains a significant challenge in mitigating the risks associated with aflatoxin contamination in crops. Biological detoxification is a popular technique that reduces mycotoxin hazards and garners consumer acceptance. Through multiple rounds of screening and validation tests, Geotrichum candidum XG1 demonstrated the ability to degrade aflatoxin B1 (AFB1) by 99-100%, exceeding the capabilities of mere adsorption mechanisms. Notably, the degradation efficiency was demonstrably influenced by the presence of copper and iron ions in the liquid medium, suggesting a potential role for proteases in the degradation process. Subsequent validation experiments with red pepper revealed an 83% reduction in AFB1 levels following fermentation with G. candidum XG1. Furthermore, mass spectrometry analysis confirmed the disruption of the AFB1 furan ring structure, leading to a subsequent reduction in its toxicity. Collectively, these findings establish G. candidum XG1 as a promising candidate for effective aflatoxin degradation, with potential applications within the food industry.

Antifungal mechanisms of binary combinations of volatile organic compounds produced by lactic acid bacteria strains against Aspergillusflavus.

Aspergillus flavus（A. flavus）, a common humic fungus known for its ability to infect agricultural products, served as the subject of investigation in this study. The primary objective was to assess the antifungal efficacy and underlying mechanisms of binary combinations of five volatile organic compounds (VOCs) produced by lactic acid bacteria, specifically in their inhibition of A. flavus. This assessment was conducted through a comprehensive analysis, involving biochemical characterization and transcriptomic scrutiny. The results showed that VOCs induce notable morphological abnormalities in A. flavus conidia and hyphae. Furthermore, they disrupt the integrity of the fungal cell membrane and cell wall, resulting in the leakage of intracellular contents and an increase in extracellular electrical conductivity. In terms of cellular components, VOC exposure led to an elevation in malondialdehyde content while concurrently inhibiting the levels of total lipids, ergosterol, soluble proteins, and reducing sugars. Additionally, the impact of VOCs on A. flavus energy metabolism was evident, with significant inhibition observed in the activities of key enzymes, such as Na+/K+-ATPase, malate dehydrogenase, succinate dehydrogenase, and chitinase. And they were able to inhibit aflatoxin B1 synthesis. The transcriptomic analysis offered further insights, highlighting that differentially expressed genes (DEGs) were predominantly associated with membrane functionality and enriched in pathways about carbohydrate and amino acid metabolism. Notably, DEGs linked to cellular components and energy-related mechanisms exhibited down-regulation, thereby corroborating the findings from the biochemical analyses. In summary, these results elucidate the principal antifungal mechanisms of VOCs, which encompass the disruption of cell membrane integrity and interference with carbohydrate and amino acid metabolism in A. flavus.

Antifungal mechanisms of volatile organic compounds produced by Pseudomonas fluorescens ZX as biological fumigants against Botrytis cinerea.

To explore the antifungal mechanisms of volatile organic compounds (VOCs) produced by Pseudomonas fluorescens ZX against Botrytis cinerea, biochemical analyses and transcriptomic techniques were employed in this work. The results showed that P. fluorescens ZX-producing VOCs can increase the cell membrane permeability of B. cinerea and disrupt cell membrane integrity, resulting in leakage of the pathogen's cellular contents, inhibition of ergosterol biosynthesis (about 76%), and an increase in malondialdehyde (MDA) content. Additionally, for B. cinerea respiration, P. fluorescens ZX-producing VOCs (1 × 109 CFU /mL) significantly inhibited the activities of ATPase (55.7%), malate dehydrogenase (MDH) (33.1%), and succinate dehydrogenase (SDH) (57.9%), seriously interfering with energy metabolism and causing accumulation of reactive oxygen species (ROS). Furthermore, transcriptome analysis of B. cinerea following exposure to VOCs revealed 4590 differentially expressed genes (DEGs) (1388 upregulated, 3202 downregulated). Through GO analysis, these DEGs were determined to be enriched in intrinsic components of membrane, integral components of membrane, and membrane parts, while KEGG analysis indicated that they were enriched in many amino acid metabolism pathways. Significantly, the DEGs related to ergosterol biosynthesis, ATPase, mitochondrial respiratory chain, malate dehydrogenase, and cell membrane showed down-regulation, corroborating the biochemical analyses. Taken together, these results suggest that the antifungal activity of P. fluorescens ZX-producing VOCs against B. cinerea occurs primary mechanisms: causing significant damage to the cell membrane, negatively affecting respiration, and interfering with amino acid metabolism.

Effect of the lactic acid fermentation by probiotic strains on the sour cherry juice and its bioactive compounds.

Nowadays, demand for products which beyond the overall nutritional value have a feature that protects the consumers health, have increased. Several studies have proved fruit juices can become suitable carrier or medium for probiotic organisms. Therefore the aim of our study was to investigate the possibility of the probiotication of sour cherry juice by lactic acid fermentation with probiotic starter culture. In the fermentation 9 Lactobacillus strains were used and two cultivars of sour cherry as raw material. The pH adjustment and supplement of nutrients were necessary and to reach the recommended probiotic cell count we also investigated the effect of dilution of sour cherry juice. Due to the optimized combination of the pH adjustment, supplementation and dilution, the investigated strains reached the desired 9 log cfu/mL cell density in sour cherry juices, however a significant difference was observed between the number of viable cells of some Lactobacillus strains. In the Újfehértói fürtös sour cherry L. acidophilus La-5 (9.43 log cfu/mL), while in the Petri species L. acidophilus 150 (9.60 log cfu/mL) resulted in the highest probiotic cell number. The lactic acid fermentation can increase the phenolic compounds, but in case of the bioactive compounds significant differences were not general between the strains.

Lactobacillus plantarum KFY02 enhances the relieving effect of gardenoside on montmorillonite induced constipation in mice.

Lactobacillus plantarum KFY02 (KFY02), isolated from naturally fermented milk yoghurt in Korla, Xinjiang, Northwest of China, showed gardenoside action for the intestinal regulation of constipated mice. Comparatively, the effects of KFY02 (0.5 × 108 CFU kg-1, by body weight (BW)), gardenoside (50 mg kg-1, BW), and KFY02 (0.5 × 108 CFU kg-1, BW) + gardenoside (50 mg kg-1, BW) on intestinal regulation in mice with montmorillonite-induced constipation were also studied. Enzyme linked immunoassay, hemotoxylin and eosin (H&E) staining, quantitative polymerase chain reaction (qPCR) assay and high performance liquid chromatography (HPLC) analysis were used for the study. Compared with the model group, KFY02 + genipin (combined group) increased the propelling rate of activated carbon in the small intestines of mice and accelerated the discharge of the first black stool in mice. At the same time, the combination group reduced the levels of motilin (MTL), substance P (SP) and endothelin-1 (ET-1) in the serum, and increased the somatostatin (SS), vasoactive intestinal peptide (VIP), acetylcholinesterase (AchE) and gastrin (Gastrin) levels in the serum, which made these parameters close to those of the normal group. Using qPCR analysis, it was observed that the combined group up-regulated the mRNA expression of endothelial nitric oxide synthase (eNOS), stem cell factor (SCF), stem cell factor receptor (c-Kit), glutathione (GSH), catalase and manganese-superoxide dismutase (Mn-SOD) and down-regulated the expression of inducible nitric oxide synthase (iNOS) and transient receptor potential vanilloid receptor 1 (TRPV1). The combination increased the Bacteroides and Akkermansia abundances and decreased the Firmicutes abundance in the feces of the constipated mice and decreased the Firmicutes/Bacteroides ratio. The expression of the above genes was similar to that of the normal group. The results indicate that KFY02 produced ß-glucosidase to hydrolyze the gardenoside glycosidic bond to produce genipin and can effectively promote the regulation of gastrointestinal hormones and intestinal peristalsis and reduce oxidative tissue damage in constipated mice. This study also confirmed that KFY02 has similar relieving effects to gardenoside for constipation in mice.

Protective effect of Lactobacillus fermentum CQPC04 on dextran sulfate sodium-induced colitis in mice is associated with modulation of the nuclear factor-κB signaling pathway.

Colitis severely affects the quality of life of patients, and lactic acid bacteria have been reported to be able to improve or treat colitis. In this study, we selected a strain of Lactobacillus fermentum (CQPC04) with good resistance in vitro to evaluate its effect on improvement in mice with dextran sulfate sodium (DSS)-induced colitis. We analyzed the effects of L. fermentum CQPC04 on mice with colitis macroscopically via colon length and histopathology. We also used conventional biochemical and ELISA kits, real-time quantitative PCR (RT-qPCR), and Western blotting to analyze microscopically the effects of L. fermentum CQPC04 on related oxidant indices and pro- and anti-inflammatory cytokines in serum and colon tissue of mice. The results indicated that L. fermentum CQPC04 notably increased colon length and ameliorated pathological damage of colon tissue in colitic mice. Serum indices showed that L. fermentum CQPC04 increased the enzyme activity of total superoxide dismutase (T-SOD) and catalase (CAT) and decreased the content of malondialdehyde (MDA) and the activity of myeloperoxidase (MPO). In addition, it inhibited the release of the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), IFN-γ, IL-1ß, IL-6, and IL-12, and increased the release of the anti-inflammatory cytokine IL-10 in serum. The RT-qPCR experiments confirmed that L. fermentum CQPC04 downregulated the expression of pro-inflammatory cytokine nuclear factor-κB-p65 (NF-κBp65), NF-κB inhibitor-α (IκB-α), TNF-α, IFN-γ, IL-1ß, IL-6, cyclooxygenase 2 (COX-2), and inducible nitric oxide synthase (iNOS), and upregulated the expression of IL-10 in colon tissue. Western blot analysis indicated that L. fermentum CQPC04 significantly reduced expression of NF-κBp65, TNF-α, IL-1ß, COX-2, and iNOS in mouse colon tissues, and increased expression of IκB-α and superoxide dismutase 2 (SOD2). Thus, L. fermentum CQPC04 could effectively alleviate the symptoms of DSS-induced colitis mice and is a potential probiotic for human experiments.

Sensorically and antimicrobially active metabolite production of Lactobacillus strains on Jerusalem artichoke juice.

BACKGROUND: In the tubers of Jerusalem artichoke (Helianthus tuberosus L.) the main carbohydrate is the well-known prebiotic inulin, which is a good growth substrate for gut microorganisms. Jerusalem artichoke tuber is traditionally consumed boiled or pickled rather than in fermented form. Lactic acid bacteria are traditionally used in the production of fermented foods; nevertheless their behavior and metabolite production are considerably influenced by the substrate. The purpose of this study was to investigate the growth and production of the most important sensorically and antimicrobially active metabolites of different Lactobacillus strains on Jerusalem artichoke juice. RESULTS: All investigated strains grew well (in the range 10(9) cfu mL(-1) ) in the media. The organic acids (lactic acid, 110-337 mmol L(-1) ; acetic acid, 0-180 mmol L(-1) ; and succinic acid, 0-79 mmol L(-1) ), hydrogen peroxide (0.25-1.77 mg L(-1) ), mannitol (0.06-3.24 g L(-1) ), acetoin and diacetyl production of strains varies not only according to the species but also from strain to strain, which will be demonstrated and discussed in the paper. CONCLUSION: Our results showed that lactobacilli can be used for the fermentation of Jerusalem artichoke, which in this form could be used, alone or mixed with other raw food material, as a new synbiotic functional food.