3 ) a heterotrophic nitrifier , named strain hn , was isolated from the greenhouse soil . the cells of isolates were gram positive , rod or coccus 一3 ）从土壤中分离到一株异养型硝化细菌，命名为菌株hn ，分离菌株为革兰氏染色阳性，球状或杆状。
2.
Because there are a great quantity ' s heterotrophic bacteria in the breeding pool , which will have the repulsion action to the insufficient quantity ' s nitrifier and prevent the nitrification , the situation will bring the accumulating of nitrite which is the middle substance of nitrification in water , the long term accumulated nitrite can debase fish and shrimp ' s disease - resistant and decrease the growth and even die 由于养殖池中存在大量的异养菌，受到异养性细菌排斥，本身无足够数量的硝化菌，硝化作用往往受阻，结果就会引起硝化作用的中间产物亚硝酸盐在水体内的累积、亚硝酸盐长期蓄积会使鱼虾等抗病力降低、生长受阻、严重者中毒死亡。
