Construction And Functional Analysis Of The CtnG And CtnH Gene Disruption Mutants In Monascus Aurantiacus AS3.4384

The filamentous fungus Monascus is a traditional fungus use for food fermentation, which can produce a variety of bioactive metabolites, and applied to food, health products and pharmaceutical industries fields. However, some Monascus strains can produce citrinin-a kind of fungal toxins, So the safety of Monascus products are called for evaluation.In this paper, the ctnG gene disruption mutants in Monascus aurantiacus AS3.4384 were constructed. It provides a theoretical basis for elucidating the citrinin biosynthetic pathway. The major findings were expounded as follows:1.Through the bioinformatics analysis, supposed ctnG gene encodesβ-carbonic anhydrase, ctnH gene encodes the short-chain dehydrogenase, and predicted ctnG and ctnH genes may be involved in the PKS-modifying of citrinin biosynthetic pathways.2.Two replacement vectors, pCTNG-HPH and pCTNH-HPH were constructed which have hygromycin B resistance gene in the middle of two homologous arm sequence fragments.3.The replacement vector pCTNG-HPH and pCTNH-HPH were respectively transformed into protoplast of M. aurantiacus AS3.4384 to disrupt target gene. Then, methods of hygromycin resistance, Dot blot analysis and Southern blot analysis were performed on selected clones. Three ctnG gene disruption mutants were gained. The ctnH gene disruption mutants are screened.4.The citrinin of the ctnG gene disruption mutants were analysised by HPLC and the pigments were anlysised by UV Spectrophotometer. The citrinin production of three ctnG gene disruption mutants were respectively decreased by 50.3%,49.8% and 50.8%.So confirmed that ctnG was a citrinin synthesis-related gene and to predicted ctnG gene involved in the PKS-modifying of citrinin biosynthetic pathways.