Abstract
Probiotic strain Eurotium cristatum was isolated from Chinese Fuzhuan brick-tea and tested for its in vitro activity against aflatoxigenic Aspergillus flavus. Results indicated that E. cristatum can inhibit the radial growth of A. flavus. Furthermore, this inhibition might be caused by E. cristatum secondary metabolites. The ability of culture filtrate of strain E. cristatum against growth and aflatoxin B1 production by toxigenic A. flavus was evaluated in vitro. Meanwhile, the influence of filtrate on spore morphology of A. flavus was analyzed by scanning electron microscopy (SEM). Results demonstrated that both radial growth of A. flavus and aflatoxin B1 production were significantly weakened following increases in the E. cristatum culture filtrate concentration. In addition, SEM showed that the culture filtrate seriously damaged hyphae morphology. Gas chromatography mass spectrometry (GC/MS) analysis of the E. cristatum culture supernatant revealed the presence of multiple antifungal compounds. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that the expression of aflatoxin biosynthesis-related genes (aflD, aflQ, and aflS) were down-regulated. Importantly, this latter occurrence resulted in a reduction of the AflS/AflR ratio. Interestingly, cell-free supernatants of E. cristatum facilitated the effective degradation of aflatoxin B1. In addition, two degradation products of aflatoxin B1 lacking the toxic and carcinogenic lactone ring were identified. A toxicity study on the HepG2 cells showed that the degradation compounds were less toxic when compared with AFB1.
Highlights
Aflatoxins, toxic derivatives of difuran coumarin, are predominantly synthesized by Aspergillus species such as Aspergillus flavus and Aspergillus parasiticus (Karabulut et al, 2014)
Aspergillus flavus and E. cristatum were co-cultured on potato dextrose agar (PDA) plates for 5 days
We speculate that the inhibition of E. cristatum on A. flavus might be caused by the synthesis of secondary metabolites by E. cristatum
Summary
Aflatoxins, toxic derivatives of difuran coumarin, are predominantly synthesized by Aspergillus species such as Aspergillus flavus and Aspergillus parasiticus (Karabulut et al, 2014). Multifarious physical (such as artificial removal, physisorption, temperature, and humidity control) and chemical (such as alkali and oxidation treatments, chemical agents) methods have been developed to alleviate associated problems in recent decades (Torres et al, 2014; Ismail et al, 2018). These methods consume large amounts of energy, and significantly reduce the nutritional efficiency of food while adversely impacting available natural resources (Wang et al, 2015; Peng et al, 2018).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
