盐度对MPN法测定沿岸海水粪大肠菌群数的影响

Effect of Salinity on Densities of Fecal Coliform in Coastal Water Using MPN Method

粪大肠菌群是在44℃温度下能生长并发酵乳糖产酸产气的微生物生理群，是总大肠菌群中的一部分，水质污染的生物学指标之一。文中使用五管发酵MPN法研究了培养液和稀释水盐度在5，10，15，20，25，30，35七个盐度梯度下对沿岸海水粪大肠菌群数量的影响，结果表明：5～35的七个盐度梯度间的粪大肠菌群数量差异极显著（P〈0．01），在盐度为10～25时，粪大肠菌群数量较为丰富，而在两端盐度的范围，粪大肠菌群数量较少，表明使用MPN法测定近岸海水的粪大肠菌群数量时，培养液和稀释水的盐度不宜过高和过低。调查站位间粪大肠菌群数的水平差异与陆源排污及其影响有关。

Fecal coliform are a group of the microbes which can grow at 44℃, form acid and produce gas. They are one part of total E.coli group and biological indicator in water pollution. The abundance of fecal coliform in coastal water is researched using the method of MPN at salinity of 5, 10, 15,20,25,30,35. The results show that the difference in densities of fecal coliform is significant （P〈0.01）when salinity ranging from 5 to 35, the fecal coliform are more abundant at salinity of 10-25, while they are few at both sides of the salinity gradient. The lower and higher salinity of media and dilution water both unfit fecal coliform When their densities are measured by MPN method. The horizontal difference in densities of fecal coliform among stations is related to terrestrial drainages and their effects.