The safety analysis on mycotoxins of Rhizopus chinensis based on whole genomic sequences

Abstract:

[Objective] Based on the bioinformations of the whole genomic sequences, we assessed biosynthetic pathway of mycotoxins and antibiotics in Rhizopus chinensis CCTCCM201021, an important fungus isolated from Daqu, a leaven used in the production of traditional Chinese liquor. [Methods] The sequencing was done using Solexa sequencing technology. The genome was assembled by using SOAP de novo software. Key synthetic pathways and genes of rhizoxin and rhizonin, as well as mycotoxins metabolism were analyzed, including PKS, NRPS and PKS-NRPS hybrid metabolic pathways, terpenoid metabolism and other metabolic pathways. [Results] The genome of R. chinensis has a total size of 45.70 Mb and a GC content of 36.99%. Compared with the genomes of the Zygomycetes, the sequence similarity is low, whereas the similarity of the homologous gene is about 60%. The genome differences between Rhizopus and the fungi belonging to the Zygomycete class were significant. By the analysis of typical mycotoxins synthesis pathways and genes based on the genome data, a few polyketide biosynthetic pathway metabolism and terpenoid metabolism genes were found in R. chinensis, but there were great quantity genes of xenobiotics biodegradation pathways. [Conclusion] R. chinensis cannot produce mycotoxins, and its products are generally considered as safe.