虾池沉积物中3类主要细菌的垂直分布特征

Vertical distribution of three main bacteria in sediment of shrimp ponds

采用平板涂布法和MPN法测定了虾池底质下 0到 30cm深度范围内 3类主要细菌类群的垂直分布情况。结果表明 ,底泥中细菌主要集中于 0到 5cm的表层范围内 ,随深度增加 ,数量急剧减少 ,至 30cm深处所测到菌量已很少。底泥中的总菌量随养殖时间推移 ,逐渐增加 ,到养殖中后期 ,表层菌量增加至 10 6CFU/g ,表层以下 10～2 0cm的总异养菌量和硝酸盐还原菌数量也增加至 10 5CFU/ g以上。弧菌仍集中于表层。

The shrimp ponds were stocked with 50 000 juvenile shrimps with body length 3.5 cm. The bottom mud was sampled before the stock, during the culture (the early stage, middle stage and post stage of the culture) and at the end of the culture. Spread plant method and multiple possible number (MPN) method were used to determine the distribution of the bacteria. The results show that most of the bacteria in the sediments focus on the surface layer within 0-5 cm in depth and the bacterium number drops rapidly with the increase of depth under the bottom, and at the depth of 30 cm, almost no bacteria can be detected. The total number of bacteria increases with the cultural time, and up to the final stage of the culture season, the heterotrophic bacteria and nitrate reducing bacteria on the surface layer of the sediments increase to 10 6 CFU/g and those of under layer within the depth of 10-20 cm also get to over 10 5 CFU/g, while the vibrio bacteria mostly distribute on the surface layer. The vertical distribution of bacteria numbers correlates with the distribution of organic matter and dissolved oxygen.