Preliminary Function Study Of A Hypothetical Biotin Biosynthetic Gene BioC In Aspergillus Flavus

Biotin also known as vitamin H is an important enzyme cofactor that functions as a prosthetic group of many carboxylases,such as acetyl-CoA carboxylase and pyruvate carboxylase.We investigated whether biotin played roles in the development and secondary metabolism of Aspergillus flavus.We identified an malonyl-[ACP]O-methyltransferase BioC and its enzymatic product as one of the precursors for biotin biosynthetic pathway from A.flavus.We produced a bioC knock-out mutant(?bioC)by completely replacing the bioC coding sequence with the pyrG(whey nucleoside-5'-phosphoric acid decarboxylase gene)selectable marker.Additionally,through E.coli-Aspergillus chromosomal integrating shuttle vector pPTR I,the complementary strain of AbioC(C?bioC)was constructed.Our results revealed that the bioC deletion strain exhibited a drastic decrease in growth,conidiation production,aflatoxin(AF)biosynthesis and stress response,compared to the wild-type(WT)strain and the complementation strain(C?bioC).In addition,we found that BioC was necessary for the normal maturation of sclerotia.The depletion of bioC also caused a significant reduction in virulence on colonizing peanut seeds.Furthermore,adding exogenous biotin could rescue the phenotype defect of AbioC mutant,suggesting that bioC might be a biotin biosynthetic gene.Thus,our findings indicated that bioC,a biotin biosynthetic gene,contributed to asexual development,aflatoxin biosynthesis,sclerotial production,virulence and stress response in A.flavus.