不同 OTUs 划分阈值对湖泊浮游细菌α多样性的影响

摘要

Theα-diversity of bacterioplankton community in lake is generally evaluated based on OTUs (op-eration taxonomy units).This study investigated the effects of different OTUs cutoff values or genus level onα-diversity and detected the approximation of OTUs cutoff values which was corresponding to taxonomic level of genera for bacteria.By 454 high-throughput sequencing technology,the bacterioplankton communities of Mo-chou Lake,Qian Lake,Xuanwu Lake,and Zixia Lake in Nanjing city were studied.Different OTUs cutoff values were assumed to explore the variation of OTUs,Chao1,Invsimpson,Shannon indexes.Results showed that, OTUs and Chao1 indexes showed a consistent change with the variation of OTUs cutoff values,while Invsimp-son and Shannon indexes showed a consistent change.Along with the distribution of OTUs cutoff values,OTUs and Chao1 indexes of four lakes remained monotonous compared to each other in different seasons,whereas the results of Invsimpson and Shannon indexes differed with fluctuated values.The taxonomic level of genera was roughly corresponding to differentiation threshold of 0.06~0.08.The well-known thresholds of 0.03 or 0.1 as cutoffs to analyze microbial sequenceα-diversity was reasonable.Method for analyzingα-diversity of the micro-bial community was comprehensive and reliable.%微生物研究中,湖泊浮游细菌微生物群落的α多样性通过 OTUs(operation taxonomy units)来分析评价。考察了现有手段下不同 OTUs 划分阈值或分类单元“属”水平对α多样性大小和趋势的影响,并推断了分类单元“属”所对应的 OTUs 划分阈值。通过454高通量测序技术研究了南京莫愁湖、前湖、玄武湖、紫霞湖4个湖泊的浮游细菌微生物群落,探讨了不同 OTUs 划分阈值对α多样性指数 OTUs、Chao1、Invsimpson、Shannon 的影响。结果发现,OTUs 划分阈值不同,OTUs 和 Chao1指数变化一致,Invsimpson 和 Shannon 指数变化一致；在不同的 OTUs 划分阈值下,4个湖泊的 OTUs 和 Chao1指数在不同季节的排序基本保持不变,Invsimpson 和 Shannon 指数在不同季节的排序发生改变。表明,分类单元“属”所对应的 OTUs 划分阈值在0.06~0.08范围内；原有的以0.03或0.1阈值划分 OTUs 来分析α多样性是合理的；所用的分析微生物群落α多样性方法是全面的、可靠的。