【摘要】 对从红曲米中分离出来的12株红曲霉进行桔霉素产量检测,筛选出一株在大米培养基和YES培养基中均不产桔霉素的红曲霉菌株CS-5。对CS-5进行基因分析,发现在红曲霉CS-5的桔霉素合成基因簇中缺少ctnA和ctnE基因(ctnA是桔霉素合成途径中的激活基因,ctnE是脱氢酶的编码基因);红曲霉CS-5上ctnF和ctnH基因与Monascus aurantiacu(Gen Bank accession No.EU309474)同源基因(ctnF和ctnH基因分别编码变位酶和短链脱氢酶)同源性仅为71%和76%;同时发现,orf5基因(编码膜转运蛋白)在mRNA上不表达。结果表明:红曲霉的桔霉素发酵特性与其基因结构紧密相关。ctnA和ctnE基因的缺失、ctnF和ctnH基因的低同源性以及orf5基因不表达可能导致桔霉素合成途径被中断或桔霉素无法被转运到细胞膜外。这些可能是导致红曲霉CS-5不产桔霉素的关键原因。该研究为根据基因结构筛选不产桔霉素的红曲霉菌株提供了理论依据。更多还原

【Abstract】 12 strains of Monascus isolated from red-rice,and ability of citrinin production were detected,then strain CS-5 which no citrinin produced neither in rice medium nor in YES medium was screened.Results of CS-5 gene analysis showed that strain CS-5 lacks ctnA and ctnA gene(citrinin biosynthesis gene activator and dehydrogenase encoding gene respectively) in citrinin biosynthesis gene cluster,ctnF and ctnH gene(encode mutase and short-chain dehydrogenase respectively) in CS-5 on the homology of only 71% and 76% to the Monascus aurantiacu(Gen Bank accession No.EU309474).The orf5 gene(encoding a membrane transporter protein) didn’t not express on mRNA level.The citrinin fermentation characteristics were closely related to their genetic structure.Lacking of ctnA and ctnE, low homology of ctnF and ctnH,orf5 didn’t express at the mRNA level caused citrinin biosynthetic pathway interrupted or can’t be transported outside the cell membrane.These maybe the reason why Monascus CS-5 didn’t produce citrinin.This study provided a theoretical basis for screening strains of Monascus that do not produce citrinin based on genetic structure.更多还原