刺参养殖池环境细菌群落对底质改良剂的响应

运用平板培养计数法、最大或然数法和16S rRNA 基因的 PCR-DGGE 指纹图谱技术，分析发病刺参池塘环境中不同生理类群细菌数量及群落结构对底质改良剂的响应。结果显示，加入底质改良剂后，发病刺参池塘沉积环境中的总异养菌、硝化细菌、硫酸盐还原细菌等的数量在最初的2–4 d 有所上升，但升高幅度小于对照组，且在之后的2–4 d 内下降至加改良剂之前菌量；在加入底质改良剂后第2天，弧菌和硫化细菌数量便迅速下降，明显低于对照组。PCR-DGGE 图谱及测序结果显示，刺参养殖环境细菌优势菌分别属于绿弯菌门、变形菌门的莫拉菌科、柄杆菌科和气单胞菌科以及厚壁菌门的芽孢杆菌科和乳杆菌科的某种细菌，多样性指数在2.5–3.5之间。实验组加入底质改良剂后，气单胞菌属两种细菌数量逐渐下降。研究结果表明，底质改良剂可改变沉积环境中不同细菌类群的数量，降低致病菌的数量，从而改善底质环境并对“刺参腐皮综合征”起到防治作用。

Responses of Bacterial Community to the Sediment Improver in the Environment of Apostichopus japonicus Culture Ponds

Sea cucumber (Apostichopus japonicus) farming industry has been developing rapidly in North China, but at the meanwhile sea cucumber diseases has become a growing problem. The environmental deterioration was considered one of the main causes. A type of sediment improver studied by our research group has been proved to be effective in adjusting the sediment environment of the sea cucumber culture ponds. In order to detect the responses of the bacterial community to the sediment improver, we conducted experiments using the sediment from the disease-occurring sea cucumber culture ponds. The sample treated with the sediment improver was the trial group and that without the improver was the control group, and we set 3 parallels for each group. The plant counting method and the most probable number method were used to determine the change in the numbers of several bacterial groups in the sediment after the addition of the sediment improver. The bacterial diversity was analyzed using the 16S rRNA gene PCR-DGGE and the sequencing techniques. The results showed that in the trial group the numbers of the heterotrophic bacteria, the nitrifying bacteria and the sulfate- reducing bacteria in sea cucumber pond sediments increased in the first 2 to 4 days, followed by a decrease and then maintained at a low level, and the increase was significantly smaller than that in the control group. The numbers of Vibriols and sulfurizing bacteria sharply declined 1 day after the addition of the sediment improver, which were significantly lower than those in the control group. The sequencing result of DGGE bands showed that the dominant bacteria in the sea cucumber culture environment belonged to chloroflexi, moraxellaceae, Caulobacteraceae, Aeromonadaceae in proteobacteria, bacillaceae, and lactobacillaceaein in firmicutes. The bacterial diversity indexes varied between 2.5 and 3.5. The numbers of 2 species of Aeromonus were observed to decline after the addition of the sediment improver in the trial group. Therefore, we concluded that the sediment improver could adjust the numbers of different bacterial groups in the sediment environment and reduce the quantity of some pathogenic bacteria. The sediment improver may thus improve the quality of the pond sediment environment and protect A. japonicus from diseases.