The types and pollution status of mycotoxins in different fermented condiments vary both domestically and internationally, which can be attributed to the disparities in raw materials, geographical locations, seasons, and other factors. Microorganisms can convert mycotoxins into low-toxicity or non-toxic substances through the adsorption of cell walls or enzymatic catalysis, thus ensuring the safety of fermented condiments for consumption. With the deepening of research on mycotoxin decontamination, many efficient strains for degrading mycotoxins have been selected. However, there is a relative dearth of studies focusing on safe mycotoxin-degrading microbes isolated from foods. This article summarizes the current status of mycotoxin contamination in fermented condiments, with a focus on mycotoxin-degrading strains from different sources and mycotoxin-degrading enzymes in microbial cells in order to offer insights for reducing harmful fungi and mycotoxin contamination in fermentation condiments.

In this study, a strain of Wickerhamiella versatilis capable of degrading aflatoxin B₁ (AFB₁) was obtained. The removal conditions of AFB₁ by this strain were optimized and important physiological and metabolic processes were elucidated using transcriptomics. The results single factor experiments indicated that pH, temperature, and inoculum size had the most significant influence on the degradation rate of AFB₁. Using response surface methodology (RSM), the optimal fermentation conditions that provided maximum AFB₁ removal rate of 96.01% were obtained as follows: pH 5.6, 30 ℃, and inoculum size of 10%. Transcriptomic results revealed that 525 genes were differentially expressed under the stress of AFB₁, including 397 up-regulated and 128 down-regulated ones. Gene annotation was particularly notable in carbon metabolism and the phosphatidylinositol-3-kinase-protein kinase B (PI3K/Akt) signal pathway. Among these genes, the genes coding for lipoxygenase (LOX2S), glutathione S-transferase (GST), adenosylhomocysteinase (AHCY), aromatic amino acid aminotransferase I (ARO8), S-adenosylmethionine decarboxylase (speD) promoted the formation of AFB₁-exo-8,9-epoxide-glutathione (AFBO-GSH) conjugates, disrupted the double bond of the furan ring of AFB₁, and reduced its toxicity. Moreover, mass spectrometric analysis showed that in the presence of AFB₁, the GSH synthesis process of this strain was accelerated, and a large amount of the intermediate substance acetyl homoserine was generated. In summary, this study has practical significance for future research on intracellular removal of AFB₁.

In order to reduce the content of ethyl carbamate (EC), a harmful by-product in the fermentation process of Baijiu, this study isolated bacteria and yeasts with EC-degrading ability and excellent fermentation performance from Daqu, and the co-fermentation conditions for the two microbial species were optimized by response surface methodology and applied to the fermentation of Baijiu. The results showed that 5 strains of yeast and 4 strains of bacteria with high EC-degrading activity were obtained from Baijiu Daqu and screened for ester production ability and protease activity. Bacillus amyloliquefaciens (JX2-10) and Wickerhamomyces anomalus (QX-2) with excellent fermentation performance were obtained. The degradation rates of 200 μg/L EC by JX2-10 and QX-2 were 85% and 35% after 24 h culture, respectively. Using single factor experiments and response surface methodology (RSM) with protease activity and total ester concentration as response variables, the optimal co-fermentation conditions were determined to be 5.6, 30.1 ℃ and 3.9% for initial pH, culture temperature, and ethanol concentration, respectively. Under these conditions, the activity of protease was 41.59 U/mL, and the total ester concentration was 5.85 g/L. EC contents in fermented grains and Baijiu produced using the co-culture decreased by 12.7% and 10.8%, respectively, compared with those of the control group, and the content of volatile flavor substances in Baijiu increased. This study provides a data basis for the degradation of EC during the fermentation of Baijiu.