一株高产油脂丝状真菌的形态学及rDNA-ITS2分子鉴定

Morphological and Molecular Identification of a High Oleaginous Filamentous Fungi by rDNA-ITS2 Sequence

从采集的土样中分离获得45株产油脂菌株,其中丝状真菌7-4的原始油脂含量最高,达到46.80%.分别采用传统形态学鉴定方法及rDNA-ITS2序列克隆进行鉴定.形态学鉴定的结果初步表明该真菌为卷枝毛霉(Mucorcircinelloides),采用rDNA-ITS2序列进行复核表明该菌与卷枝毛霉(M.circinelloides)同源性为98.00%,而与易脆毛霉(M.fragilis)同源性达到100.00%.从构建的系统进化树中可以看出,该菌与易脆毛霉共同构成一个分支,并与卷枝毛霉聚成一大枝.结合形态学鉴定的结果确定菌株7-4为易脆毛霉(M.fragilis).其脂肪酸组成与植物相似,以棕榈酸、亚油酸、油酸为主,不饱和脂肪酸含量达91.77%.

A filamentous fungal strain 7-4, which was screened out from 45 strains, was capable of producing high-yield lipids up to 46.8%, and identified by rDNA-ITS2 sequence and morphological observation. The sequence data was compared with the published sequences of relative filamentous fungal strains in Genbank. The results indicated that the homology of the rDNA-ITS2 sequences of strain 7-4 with those of several Mucor strains was more than 98.0%. As shown in the phylogenetic tree, strain7-4 and M. fragilis constituted a branch and they constituted a branch together with M. circinelloides. Furthermore, the strain 7-4 was similar to M. circinelloides in morphological character. Thus, the strain 7-4 was preliminarily determined to be belonged to the species of M. fragilis. The results showed that its composition of lipids was similar to vegetable oil and its unsaturated fatty acid content was 91.77%. This research therefore suggested that these microbes could be provided as raw material resource for microbial oil production.