茯茶中冠突曲霉的分离及比较基因组研究

Isolation and Comparative Genome of Aspergillus cristatus in Fuzhuan Tea

为研究市售茯茶产品中的发酵菌株,从产自湖南长沙、湖南益阳、陕西西安和陕西咸阳地区的8个茯茶样品中分离真菌,进行形态学观察、全基因组序列比较,基因家族分析及次级代谢产物基因簇预测分析。结果表明:从8个茯茶样品分离出8株优势真菌,均为冠突曲霉(Aspergillus cristatus),8株菌在菌株及显微形态上相似,与参考菌株全基因组比对相似性均为99%;基因家族Venn图分析表明菌株F1、F3、F4、F7、F8基因家族相同,F2有34个特有的基因家族,F5有3个特有的基因家族,参考菌株有32个特有的基因家族,不同来源茯砖茶中的冠突曲霉具有高度的同源性;以AntiSMASH 6.0软件对分离菌株和参考菌株进行次生代谢产物基因簇预测分析,结果表明8株菌和参考菌株都预测到相同的6个次级代谢产物基因簇,其中曲霉内酯和克拉维酸有抑菌活性,这也解释了茯茶发酵过程中冠突曲霉会成为单一的发酵菌株。研究表明湖南和陕西地区茯茶中的“金花”菌没有显著区别,与其他研究结果一致。结合形态学和比较基因组学分析,8株分离菌株相似度极高,可能为相同来源菌株。

In order to study the fermentation microorganism in the commercial products of Fuzhuan tea,fermentation strains were isolated from 8 samples of Fuzhuan tea production in Changsha,Yiyang of Hunan and Xi’an,Xianyang of Shaanxi.Therefore,the morphological observation,whole genome sequence comparison,gene family analysis and prediction analysis of secondary metabolic gene cluster were carried out.The results showed that eight dominant fungi were isolated from 8 samples of Fuzhuan tea,all of which were Aspergillus cristatus.All of those 8 strains were similar in micromorphology and the similarity of genome was 99%compared with the reference strains.Gene family Venn diagram analysis showed that strains F1,F3,F4,F7 and F8 had the same gene families.F2 had 34 unique gene families,F5 had 3 unique genes families,and reference strains had 32 unique genes families.Predicted with AntiSMASH 6.0,those 8 strains and reference strain had same six secondary metabolites gene cluster,including aspergillus lactone and clavulanic acid,which possessed antibacterial activity.Those analysis explains why A.cristatus could be the unique fermentation strain in end of fermentation of Fuzhuan tea.Combined with morphological and comparative genomic analysis,the 8 isolates were highly similar,and were probably from the same source.