Isolates of nitrifying and denitrifying bacteria activities that derived from catfish, Pangasius sp. culture pond

Nitrifying and denitrifying bacteria are very fruitful for controlling water quality in fish culture because they have a role in converting toxic chemical compounds into non-toxic compounds. The purpose of this experiment is to determine the isolates of nitrifying and denitrifying bacteria in terms of oxidizing ammonia, accumulating total nitrite, and accumulating total nitrate activities. Eight isolates of bacteria consist of four nitrifying bacteria (NP1, NP2, NP3, and NP4), and four denitrifying bacteria (DP1, DP2, DP3, and DP4) were inoculated with the density of 10 2 CFU/ml. The result showed that NP1, NP2, NP3, and NP4 isolates have almost similar ability to oxidize ammonium of 99.57, 99.37, 99.89, and 99.83%, respectively. The NP1-NP4 isolates on the total nitrite accumulated were 0.06, 0.05, 0.06, and 0.06%, while the total nitrate accumulated were 1.56, 1.65, 2.08, and 1.65%, respectively. The isolates of DP1, DP2, DP3, and DP4 can reduce total nitrate by 99.9, 100.0, 99.9, and 99.9%, respectively, while accumulated total nitrite was 0.01, 0.04, 0.00, and 0.00%. Isolates of NP2 and DP2 are recommended for controlling chemical compounds in the pond water.