红树林土壤微生物模块化聚酮合酶基因(簇)及其多样性研究

Modular PKS Gene(Cluster)and Its Diversity in Microorganism Community from Mangrove Soil

聚酮类化合物(Polyketide)是一类重要的具有药用价值的生物活性分子.通过宏基因组学技术获得了红树林土壤微生物中模块化聚酮合酶(Polyketide Synthase,PKS)基因(簇),并对其多样性进行了研究.首先构建了该红树林土壤微生物的16SrDNA文库,初步分析了红树林土壤样本的细菌群落组成,发现许多菌群曾经被报道存在PKS基因簇,约占整个细菌群落的75%.利用相关菌群的PKS酮基合成酶结构域(Ketosynthase,KS)的保守区域序列信息设计简并引物,并构建了KS DNA序列文库.经测序获得131条新型KS序列,该结果表明红树林土壤微生物中蕴含了许多新型的聚酮类化合物合成酶.为了进一步获得聚酮合酶基因(簇),我们通过土壤微生物宏基因组Cosmid文库的构建与筛选,得到了13个属于trans-AT PKS,cis-AT PKS,NRPS/PKS Hybrid等类型的聚酮合酶的基因(簇),并通过构建KS序列的系统进化树分析了样本中聚酮合酶的多样性组成.

Polyketides are a type of bioactive molecules with important medicinal value. Here, Modular PKS（Polyketide Synthase）gene （cluster）and its diversity in microorganism community of mangrove soil wereinvestigated. Firstly, the phylogenetic diversity of the microbial flora community from mangrove soil was studiedby comparative 16S ribosomal DNA（rDNA）sequence analysis. We found that several floras accounting for 75 M ofthe whole community which harbor genes（clusters）of PKS reported previously. After that, a pair of degenerateprimers was designed in the conservative region of KS（Ketosynthase）domain of related flora to construct KS DNAsequence library. About 131 sequences of KS obtained by sequencing were then subject to phylogenetic analysis,and results suggested several new types of PKS existed in the metagenomie community from mangrove soil. Tofurther obtain the PKS genes （clusters）, a Cosmid library of metagenomic community from mangrove soil wasconstructed and screened, and then 13 PKS genes（clusters）were obtained. The PKS of genes（clusters）could bedivided into three types, trans-AT PKS, cis-AT PKS, and NRPS/PKS Hybrid, based on their domainarrangement. In the meanwhile, the further analysis of diversity of Modular PKS from sample was carried out byconstructing the phytigenetic tree.