高通量测序分析DNA提取引起的对虾肠道菌群结构偏差

【目的】通过高通量测序技术,评价不同DNA试剂盒提取引起的对虾肠道菌群结构偏差,了解健康凡纳滨对虾肠道菌群结构特征。【方法】分别以细菌、粪便和组织DNA试剂盒3次重复提取凡纳滨对虾肠道总DNA(分别编号为SIB,SIS和SIT),检测DNA含量、纯度及其16S r DNA V4区可扩增性,进一步采用Illumina Mi Seq高通量测序比较SIB和SIS样品菌群组成和多样性。【结果】细菌试剂盒提取的虾肠总DNA效果最好,粪便试剂盒次之,而组织试剂盒所提DNA含量低且难以被扩增。从SIB和SIS样品分别获得52151±5085和55296±5147条有效序列,同一(46800条)测序深度下,SIS样品OTU(operational taxonomic unit)数量和Shannon多样性指数均显著高于SIB的,而SIB样品间OTU重复性则优于SIS样品间的。从SIB和SIS样品鉴定的优势门一致,均包括变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)、浮霉菌门(Planctomycetes)、放线菌门(Actinobacteria)和蓝细菌门(Cyanobacteria),但不同分类水平上绝大多数优势菌群丰度在两种样品间差异明显。【结论】高通量测序分析表明对虾肠道菌群结构因DNA提取方法不同而呈现显著偏差;本研究健康凡纳滨对虾肠道核心菌群主要由发光杆菌属(Photobacterium),乳球菌属(Lactococcus),弧菌属(Vibrio),Aliivibrio和3个分类未定属构成。

Biases on community structure during DNA extraction of shrimp intestinal microbiota revealed by high-throughput sequencing

Objectives] High-throughput sequencing technology is increasingly applied in intestinal microbiota of aquatic animals including shrimp. However, there is a lack of standard method or kit for DNA isolation from shrimp intestinal microbiota, and little is known about the effectiveness and biases regarding DNA extraction based on high-throughput sequencing. The aim of this study was to study the biases of different DNA extraction kits on community structure of shrimp intestinal microbiota through high-throughput sequencing, and to better understand the structure and composition of bacterial flora associated with healthy Litopenaeus vannamei.Methods] We extracted the total DNA of intestinal microbiota from L. vannamei with three commercial kits designed for DNA extraction from bacteria, stool and tissue(Omega, USA). DNA quality was evaluated based on the absorbance ratios of 260/280 nm by NanoDrop, while DNA concentration was quantified using PicoGreen. Then Illumina MiSeq high-throughput sequencing was used to examine the intestinal bacterial communities following PCR amplification of 16S rDNA V4 region.Results] The yield and purity of the DNA from the Bacterial Kit(SIB) were superior to those from the Stool Kit(SIS), whereas the DNA from Tissue Kit(SIT) presented too small amount to be amplified efficiently. The average sequence reads obtained from SIB and SIS samples were 52151±5085 and 55296±5147 respectively. After resampling at the same depth of 46800 reads, the operational taxonomic unit(OTU) number and Shannon diversity index of SIS samples were significantly higher than those of SIB samples. By contrast, the reproducibility of OTU among SIB replicates was higher than that among SIS replicates. The dominant phyla of SIS and SIB samples were identical, including Proteobacteria, Firmicutes, Bacteroidetes, Planctomycetes, Actinobacteria, and Cyanobacteria. However, the relative abundances of almost all the dominant groups at various taxonomic levels differed greatly between these two samples.Conclusion] Significant biases on community structure of shrimp intestinal microbiota were detected which originated from DNA extraction. And the core microbiota of the healthy L. vannamei in this study was mainly composed of genera Photobacterium, Lactococcus, Aliivibrio, Vibrio, as well as three other unclassified groups.