零换水条件下益生菌组合在凡纳滨对虾育苗生产中的应用

Effects of probiotics combination on breeding of Litopenaeus vannamei under zero-water exchange condition

摘要:

为探索应用益生菌的凡纳滨对虾零换水育苗技术，选择具有不同生态学功能的四株益生菌进行配伍形成两个益生菌组合PBE和PBN，并应用于凡纳滨对虾无节V期幼体（N5）至仔虾第五天（PL5）的育苗实验。每个实验组包含6个平行，同时设置对照组。整个实验过程不换水，PBE和PBN组的水体中连续施用益生菌组合。当幼体发育至蚤状幼体Ⅲ期（ZⅢ）、糠虾幼体Ⅲ期（MⅢ）和PL5时，检测幼体变态率、幼体体内和水体中可培养细菌总数（total culturable bacterial count，TBC）和假定弧菌总数（total presumptive Vibriobacteria，TPVB）；在实验结束时统计各实验组幼体成活率，并用Illumina测序PL5幼体体内的微生物群落。结果显示：在整个育苗周期内，未发生疫病；与对照组相比，益生菌组合显著降低了（P<0.05）TPVB在幼体体内和育苗水体中的相对含量，并显著提高了（P<0.05）ZⅢ幼体和仔虾PL5的变态率和成活率（各增加15%）。各实验组的PL5体内核心微生物群的多样性和结构并不存在显著性差异（P>0.05），红杆菌科是微生物群落中最具优势的菌群，在各实验组中的相对丰度为40%~86%。研究表明，零换水条件下，益生菌组合能够有效抑制弧菌在育苗水体和凡纳滨对虾幼体体内的过度增殖，提高幼体的成活率，实现育苗的健康生产。

Abstract:

In order to explore breeding technology with the application of probiotics combinations for Penaeus vannamei under zero-water exchange conditions, four probiotic bacteria with different ecological functions were formulated to two combinations (i.e., PBE and PEN), which were applied in the breeding experiment from nauplius larval phase V (N5) to postlarvae phase V (PL5). Each experimental group contained six parallels and the control group was set at the same time. Culturing water was not exchanged throughout the experiment, and probiotics combinations were continuously applied to the water in the PBE and PBN groups. The larval metamorphosis rate, total culturable bacterial count (TBC) and total presumptive Vibrio bacteria (TPVB) in larva and water were counted at the phases of zoea Ⅲ (ZⅢ), mysis Ⅲ (MⅢ) and PL5. At the end of the experiment, the survival rate of postlarvae in each experimental group was determined, and the microbial communities from postlarvae were sequenced using an Illumina platform. The results showed that there was no disease outbreak in each group, and that probiotics combinations significantly decreased (P<0.05) relative abundances of TPVB in postlarvae and culturing water in the groups of PBE and PBN compared to that in the control group, and significantly increased (P<0.05) the larval metamorphosis rate (15%) and survival rate (15%) at the phases of ZⅢ and PL5, respectively. There was no striking difference of microbial diversities and structures of the core populations in the microbial communities from postlarvae in the three groups, and every microbial community was dominated by Rhodobacteriaceae with the relative abundance ranging from 40% to 86%. Taking together, probiotics combinations can effectively inhibit the overabundance of Vibrio in rearing-water and postlarvae and improve the survival rate of postlarvae, thereby achieving healthy breeding of P. vannamei under zero-water exchange conditions.