Ochratoxin A (OTA), a widespread mycotoxin contaminant in food and feed, threatens human and animal safety and causes significant economic losses. The aims of the present study were to investigate the elimination properties of Cryptococcus podzolicus Y3 on OTA and its co-degradation efficiency on citrinin (CIT) and OTA. C . podzolicus Y3 eliminated 100% OTA (1 μg/mL) in the PM media within 5 d and in grape juice media within 3 d by intracellular substances. The results of HPLC-FLD and LC-MS showed that OTA was efficiently eliminated into non-toxic ochratoxin α (OTα). The substances responsible for OTA degradation were thermostable and worked effectively at 4 °C and 28 °C, and intracellular proteins were participated in the elimination of OTA. In addition, the results showed that C. podzolicus Y3 degraded OTA and CIT together in NYDB media, although the degradation efficiency was lower than single mycotoxin degradation. Generally, our study highlighted that C. podzolicus Y3 could be a potential strain to eliminate OTA and CIT to secure food products and enhance food safety.
Cryptococcus podzolicus Y3 is an antagonistic yeast that can control postharvest diseases of crops and mycotoxins , which is potentially valuable for ensuring food safety. Our previous study showed that C. podzolicus Y3 can efficiently degrade ochratoxin A (OTA), one of the harmful mycotoxins in the environment and food. However, the genomic information of C. podzolicus Y3 and its protein expression profile during OTA degradation are not available. In this study, whole-genome sequencing of C. podzolicus Y3 was analyzed. Protein expression during OTA degradation was investigated by the data-independent acquisition (DIA) technique. The genome size of C. podzolicus Y3 was about 29,181,249 bp length with 58.79% GC content and identified with 17 scaffolds, 9090 coding regions and 127 non-coding regions. The DIA identified 4315 proteins during OTA degradation, among which 101 proteins were significantly up-regulated and 116 were down-regulated. The differentially expressed proteins were mainly involved in reduced glutathione metabolism, phosphatidylinositol signaling system and mitogen-activated protein kinase signaling pathway, calcium ion homeostasis, endoplasmic reticulum protein processing and fatty acid metabolism. Our results provide the genome information of C. podzolicus Y3 for further functional researches. In addition, this study has revealed the toxicity and stress response mechanism of C. podzolicus Y3 during OTA degradation at the protein level.
With the increasing global climate change, ochratoxin A (OTA) pollution in food and environment has become a serious and potential risk element threatening food safety and human health. Biodegradation of mycotoxin is an eco-friendly and efficient control strategy. Still, research works are warranted to develop low-cost, efficient, and sustainable approaches to enhance the mycotoxin degradation efficiency of microorganisms . In this study, the activities of N-acetyl- L -cysteine (NAC) against OTA toxicity were evidenced, and its positive effects on the OTA degradation efficiency of antagonistic yeast, Cryptococcus podzolicus Y3 were verified. Co-culturing C. podzolicus Y3 with 10 mM NAC improved 100% and 92.6% OTA degradation rate into ochratoxin α (OTα) at 1 d and 2 d. The excellent promotion role of NAC on OTA degradation was observed even at low temperatures and alkaline conditions. C. podzolicus Y3 treated with OTA or OTA+NAC promoted reduced glutathione (GSH) accumulation. GSS and GSR genes were highly expressed after OTA and OTA+NAC treatment, contributing to GSH accumulation. In the early stages of NAC treatment, yeast viability and cell membrane were reduced, but the antioxidant property of NAC prevented lipid peroxidation. Our finding provides a sustainable and efficient new strategy to improve mycotoxin degradation by antagonistic yeasts, which could be applied to mycotoxin clearance.
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