球等鞭金藻三级培养过程中细菌群落多样性分析

球等鞭金藻三级培养过程中生长差异明显,在完全灭菌的一级培养中生长最佳,在未灭菌的三级培养中生长最差。为揭示培养过程中藻际细菌群落多样性与其生长差异的相关性,以球等鞭金藻(Isochrysis galbana)为研究对象,利用Illumina HiSeq平台通过高通量测序的方法对球等鞭金藻三级培养过程中细菌群落多样性进行研究。结果表明,一、二、三级培养组之间的藻际细菌群落组成差异明显。Shannon和Simpson指数分析说明,一级培养组中细菌群落多样性显著低于二级和三级培养组。MetaStat分析发现,一级和三级培养组之间存在两株丰度显著差异的细菌,其中麦氏交替单胞菌(Alteromonas macleodii)在三级培养下丰度显著高于一级,而红球菌(Rhodococcus erythropolis)相反。进一步通过2216E平板涂布法分离并鉴定了麦氏交替单胞菌等17株球等鞭金藻藻际环境细菌;系统进化树构建结果显示,整个进化树分成13个分支,分别对应13个属,包括交替单胞属(Alteromonas)、假交替单胞属(Pseudoalteromonas)、海杆菌属(Marinobacter)等。本研究结果为探索藻菌互作机理奠定了基础,有助于提高水产养殖过程中球等鞭金藻的产量和质量。

Analysis of Bacterial Community Diversity in Tertiary Culture of Isochrysis galbana

The growth of Isochrysis galbana was significantly different during tertiary culture, and it grew best in the fully sterilized first culture stage and the worst in the unsterilized third culture stage. To reveal the relationship between the growth of I. galbana and its bacterial communities during cultivation, the diversity and composition of bacterial communities were investigated by analyzing the 16S rRNA clone libraries using high-throughput sequencing (Illumina HiSeq). There were distinctly differences among three culture stages. With Shannon and Simpson index, the bacterial community diversity in the first culture stage was the smallest. The relative abundance of Alteromonas macleodii was significantly higher in the third culture stage than that in the first stage based on MetaStat analysis, whereas that of Rhodococcus erythropolis was higher in the first culture stage. Additionally, 17 bacterial strains in the phycosphere of I. galbana, including A. macleodii, were isolated by the 2216E plate coating method and further identified. The phylogenetic results show that the whole phylogenetic tree is divided into 13 branches, corresponding to 13 genera, including Alteromonas, Pseudoalteromonas and Marinobacter.This study lays a foundation for exploring the interaction mechanism between microalgae and bacteria, and is helpful to improve the yield and quality of I. galbana in aquaculture.