高通量测序分析凡纳滨对虾育苗期水体菌群结构特征

为了解凡纳滨对虾育苗期正常苗池水体菌群结构和多样性变化,实验采用Illumina MiSeq高通量测序水体细菌16S rDNA V4区,比较幼体在无节V期(N5)、溞状Ⅱ期(Z2)、糠虾Ⅰ期(M1)与仔虾Ⅰ期(P1)时的水体菌群特征。结果显示,水体菌群Shannon多样性指数随幼体发育先降后升,而Pielou均匀度指数除在N5时稍高外,在其余阶段都很接近。育苗期间,变形菌门为水体绝对优势菌群(50.0%~88.0%),尤其红杆菌科从N5到P1阶段分别占24.2%、61.6%、43.3%和51.8%;拟杆菌门在各期丰度均9.7%,其中腐螺旋菌科以5.3%~16.9%优势分布于后3个阶段;放线菌门在后3个期都为优势类群,并以微杆菌科为主,丰度分别达5.6%、37.6%和10.8%;而疣微菌门只在P1时表现为优势(5.3%)。苗池水体核心菌属主要由洛克氏菌、海命菌、栖东海菌、亚硫酸杆菌和2个分类未定属构成。可见水体菌群呈高度多样而动态变化,且N5菌群明显区别于后3个阶段。育苗期间水体主要环境因子总体波动较小,对优势操作分类单元(OTU)丰度分布无显著影响。研究表明,凡纳滨对虾健康苗池水体菌群随幼体发育和饵料投喂而明显更替,其中核心菌群的潜在功能对维持水体生态系统稳定起重要作用,可为对虾育苗益生菌与健康苗池指示菌的筛选提供依据。

Characterization of aquatic bacterial community of Litopenaeus vannamei larvae during hatchery period with high-throughput sequencing

In order to characterize the bacterial community structure and diversity in rearing water of healthy Litopenaeus vannamei larvae during hatchery period, the genomic DNA of aquatic microbiota from larval stages of nauplius 5 (N5), zoea 2 (Z2), mysis 1(M1) and postlarvae 1 (P1) was amplified with 16S rDNA V4 primers and sequenced by a high-throughput Illumina MiSeq platform. The results showed that the bacterial Shannon diversity index increased at P1 stage after declined gradually from stages N5 to M1, the Pielou evenness index at N5 stage was a little higher than those of the following three stages, which were approximated closely. During the entire larviculture period, the phylum Proteobacteria was overwhelmingly dominated in rearing water with high abundance up to 50.0%-88.0%, especially, the family Rhodobacteraceae of which had high abundances of 24.2%, 61.6%, 43.3%, and 51.8% at stages N5, Z2, M1, and P1, respectively. Bacteroidetes thrived in various stages with abundance higher than 9.7%, and the family Saprospiraceae of this phylum existed significantly (5.3%-16.9%) in the later three phases. Actinobacteria presented also dominantly in rearing water except for the N5 stage, and the family Microbacteriaceae with abundances of 5.6%, 37.6% and 10.8% for Z2, M1, and P1 stages, respectively. The phylum Verrucomicrobia dominated only at P1 stage (5.3%). In the larviculture water, the core microbiota at genus level consisted of Loktanella, Marivita, Donghicola, Sulfitobacter, and two unclassified candidates. Thus the microbiota in larval rearing water harbors a high diversity and presents dynamic succession, which differed obviously between N5 stage and the latter three stages. Overall, the main environmental factors in larviculture water varied slightly and exhibited no significant effect on abundance of dominant OTUs (operational taxonomic units). In conclusion, the bacterial community in rearing water of healthy L. vannamei larvae shifts in composition and abundance with larval development and diet feeding. And the core microbiota with potential functions play an important role in maintaining homeostasis in the larviculture system, which could be served as candidates for autochthonous probiotics, as well as healthy indicator for shrimp larviculture.