Recently, Professor Hongyin Zhang’s team from the School of Food and Bioengineering of Jiangsu University published a research paper entitled “Sustainable and effective method of utilizing N-acetyl-L-cysteine for complete and enhanced ochratoxin A clearance by antagonistic yeast” in the Journal of Hazardous Materials (IF=14.224) (2023, 448, 15). The effect of the antioxidant, N-acetyl-L-cysteine on ochratoxin A degradation efficiency of Cryptococcus podzolicus Y3 and the change in yeast metabolism were studied. Meilin Wei, a doctoral student in the School of Food and Bioengineering of Jiangsu University, is the first author of this paper; Professor Hongyin Zhang is the corresponding author, Associate professors Dr. Solairaj Dhanasekaran and Dr. Qiya Yang, and graduate student Qihao Ji, also participated in the research work of this paper.
OTA is one of the mycotoxins produced by Aspergillus and Penicillium fungi and is ranked group 2B carcinogen. OTA has noticeable toxic effects on kidney cells of humans, pigs, dogs and other animals, and also has different degrees of harmful effects on other cells, such as liver cells, nerve cells, germ cells, esophageal mucosal epithelial cells, cardiac cells and intestinal cells. In the context of global warming, mycotoxin pollution in the food, feed and environment is becoming more and more serious, increasing the chances of human or animal contact with mycotoxins. Not only rice and corn but also coffee, wine, meat products, dried fruit, spices, etc., are also the primary sources of OTA intake by the human body. C. podzolicus Y3 degraded OTA by intracellular protein, but the degradation efficiency is low. To improve the yeast’s degradation efficiency, N-acetyl-L-cysteine (NAC) was used, and its effect on yeast’s biochemical and molecular changes was studied.
Different concentrations of NAC (3-12.5mM) were used to help C. podzolicus Y3 degrade OTA, and the effect of different environments on the degradation of yeast was also verified. The results showed that NAC could significantly promote OTA degradation by yeast in low temperatures (20 ℃) and alkaline environments (pH 8.5). In the early phase of NAC treatment, the degradation efficiency of the yeast decreased, and cell membrane permeability increased. The results of HPLC showed that NAC promoted the metabolism process of C. podzolicus Y3 from OTA to OTα. However, NAC treatment did not induce the expression of the degradation gene (Carboxypeptide A4). Both OTA and OTA+NAC treatments promoted the accumulation of reduced glutathione (GSH), which may be attributed to the expression of GSH synthesis genes, glutathione reductase (GSR) and glutathione synthesis (GSS). This study successfully used a low-cost chemical (NAC) to improve the antagonistic yeast’s efficiency in degrading OTA. Prof. Zhang and his team provided a new perspective for enhancing the microbial degradation of mycotoxins. NAC-induced antagonistic yeast can be used to remove OTA in feed or environment and can also be used for the subsequent treatment of industrial adsorption of mycotoxins.
This study was supported by the National Natural Science Foundation of China (32072276; 31901743), the Science and Technology Planning Project of Zhenjiang-International Scientific and Technological Cooperation (GJ2021009) and the Graduate Innovative Projects of Jiangsu Province (KYCX21_3393).
(School of Food and Biological Engineering)
