Isolation and characterization of Pseudomonas stutzeri and its potential application in biological nitrification

Ammonia-oxidizing bacteria (AOB) were isolated from sediment samples of fishponds with an aim to use them for application in biological nitrification of water. Isolation of AOB was done in an inorganic medium and nitrite-producing bacterial isolates were selected. These isolates were further screened by polymerase chain reaction using specific primers forAOB. Out of 119 nitrate positive isolates, only 12 showed positive amplification and yielded a PCR product of ~465 bp. Treatment of aquaculture pond and riverwaterwith one of the bacterial isolate (HC-5) resulted in lowering of soluble ammonia level from 3.50 to 0.05 mgl(-1) and 7.5 to 0.01 mgl(-1), respectively. Partial 16S rRNA gene sequencing of isolate HC-5 identified the microorganism as Pseudomonasstutzeri.