微囊藻与硝化细菌在不同种群密度条件下的相互作用

Interactions between Microcystis sp. and Nitrifying Bacteria with Different Population Densities

作为水环境中与氮循环密切相关的两类重要微生物,藻类和细菌之间存在复杂的相互关系。实验通过藻菌共培养,研究了微囊藻与硝化细菌不同种群密度下的相互作用。结果显示:在初始氨氮(NH4+-N)为30 mg/L的硝化细菌与微囊藻共培养体系中,藻初始种群密度较小时,藻菌在实验前期同步增长,但随着氨氧化细菌(AOB)代谢产物亚硝酸盐氮(NO2--N)的快速积累,藻生长受抑制并逐渐死亡;而藻初始种群密度较大时,NO2--N被藻菌及时利用,藻菌保持同步生长直到NH4+-N消耗至较低水平。实验表明,微囊藻与AOB对NH4+-N存在竞争性利用,微囊藻对AOB的生长有明显的抑制作用。由此推断,在富营养化湖泊中,硝化细菌和微囊藻的关系主要是对营养盐的竞争利用关系。当湖泊中藻类大量繁殖时,硝化细菌的作用可能会因此而减弱。

As two kinds of important microorganisms which closely related to the nitrogen cycle in water environment,algae and bacteria have complex interrelation. This experiment analyzed the interactions between Microcystis sp. and nitrifying bacteria with different population densities under the condition of co-culture. Results indicated that in the conditions of initial ammonia nitrogen （NH4＋--N） concentration as 30 mg/L in the system of nitrifying bacteria and Microcystis sp. co-cultured,when algae initial population density was small, algae and bacteria grew simultaneously in the early period of the test,but algae growth was hampered, and gradually die, as nitrite nitrogen（NO2--N） was accumulated quickly caused by ammonia-oxidizing process; when algae initial population density was higher,algae and bacteria synchronous grew until NH4＋--N was consumed to a low level,as NO2--N was used timely by algae and nitrifying bacteri~ Results indicated that Microcystis six and AOB competitively used NHc^-N, Microcystis sp. has obvious inhibitory effect on the growth of AOB. It is concluded that the relationship between nitrifying bacteria and Microcystis sp. is mainly the competitive utilization of nutrient in eutrophic lake. And the effect of nitrifying bacteria may be weakened when algal bloom is coming.