Nitrification Potential of Achromobacter xylosoxidans Isolated from Fresh Water Finfish Farms of Kerala, India

Abstract

A heterotrophic strain ACM-1, isolated from Pangasius spp fish farms showed an ability to convert ammonium to nitrate under aerobic conditions. Based on the molecular phylogenetic analysis 16S rRNA gene sequence ACM-1 matched similarity to Achromobacter xylosoxidans (100 percentage) ACM-1 showed amplification for Betaproteobacterial 16S AOB gene (465 bp) confirming the characteristic feature of ammonia oxidation. Sodium pyruvate (1 percentage) was confirmed as the probable carbon source for the luxurious growth of Achromobacter xylosoxidans among the six carbon sources tested. At 30 degree celsius 5 percentage preculture and 120 rpm in shaker, ACM-1 could able to remove 100 percentage ammonium within 36h. The ammonium removal rate was reported to be 1.3 NH4- N mg per litre per hour at 30 degree celsius. The rate of ammonium removal at different temperature (20 degree celsius, 25 degree celsius, 37 degree celsius) ranged between 0.9 to 1.33 NH4- N mg per litre per hour The nitrite produced during this experiment remained at constant rate and nitrate concentration increased after the initial hours of experiment. Therefore, the results demonstrate that Achromobacter xylosoxidans ACM-1 can remove ammonium in batch cultures and could be applied in aquaculture farms as a biological nitrifier.