一株芽孢杆菌的分离鉴定及在生物絮团对虾养殖中的应用

Isolation and Identification of a Bacillus sp. Strain and Its Role in Bioflocs for the Shrimp Culture System

关键词:  芽孢杆菌  凡纳滨对虾  生物絮团技术  氨氮  亚硝酸氮  存活率  弧菌

Key words:  Bacillus sp.  Litopenaeus vannamei  Biofloc technology  Ammonia-N  Nitrite-N  Survival rate  Vibrio

摘要:

从对虾养殖池中分离到1株细菌(编号2013042402，简称菌株02)，分别用16S rDNA序列比对法和细菌全细胞脂肪酸气相色谱法对该菌进行鉴定。结果显示，菌株02为芽孢杆菌(Bacillus sp.)。为探讨该芽孢杆菌在生物絮团对虾养殖中的使用效果，实验分别设置加菌加糖组(菌株02的量为2.0×104 CFU/ml，蔗糖量为饵料的70%)、加菌组、加糖组(生物絮团组)及空白对照组，研究了菌株02对养殖水质(温度、盐度、溶氧、pH、氨氮及亚硝酸氮)、对虾存活率及水体中主要菌群组成等指标的影响。结果显示，加菌加糖组能显著降低养殖水体中的氨氮和亚硝酸氮浓度，提高对虾存活率。生物絮团对虾养殖系统中添加菌株02，能够改善菌群结构，抑制弧菌生长。研究结果可为生物絮团对虾养殖中定向培养有益微生物提供技术支持。

Abstract:

In recent years there have been a number of outbreaks of lethal shrimp diseases caused by viral and bacterial infections in many countries, which hinders the development of shrimp culture industry. To protect shrimp from diseases, a lot have been done to improve the shrimp germplasm against disease, the shrimp culture technology, as well as the aquaculture environment. One example is the bioflocs technology (BFT) that helps eliminate harmful nitrogen sources, reduce water exchange rate, and increase the feed utilization rate. Probiotics such as Bacillus sp. could also improve water quality in the shrimp culture pond. In this study, we isolated a strain named 2013042402 (Strain 02) from a shrimp pond. Strain 02 was identified as Bacillus sp. using 16S rDNA sequencing and gas chromatographic analysis of the whole cell fatty acids. To investigate the function of Strain 02 in bioflocs for the shrimp culture system, we added three groups into the culture system that were Strain 02(2.0×104 CFU/ml) combined with sucrose (70% of feed), strain 02 alone, and sucrose alone. Then we measured a series of physicochemical parameters of the culture system including temperature, salinity, dissolved oxygen, pH, floc volume, ammonia-N and nitrite-N. We also examined the growth rate and the survival rate of shrimps, and the compositions of dominant bacterial communities in the water body. We found that the Strain 02-sucrose combination significantly reduced the concentrations of ammonia-N and nitrite-N in the water and improved the survival rate and growth rate of shrimps. This suggested that Strain 02 added to the bioflocs could improve the aquaculture water quality, optimize the structure of bacterial communities, and inhibit the growth of vibrio, therefore elevate the survival rate and growth rate of shrimps. Our study implied that the bioflocs technology could be highly improved by the addition of probiotics.