Effect of Environmental Conditions on Denitrification of Pseudomonas sp.

Abstract:

A bacterial strain with high denitrification activity isolated from a shrimp pond was designated strain 2906. The effects on denitrification efficacy of environmental conditions including carbon/nitrogen (C/N) ratio, pH, and salinity were determined using sucrose and ammonia as carbon and nitrogen sources, respectively. The effects of carbon sources (glucose, sucrose, maltose, sodium succinate, sodium citrate, lactose and soluble starch) on the denitrification efficacy of strain 2906 were assessed. The maximal NH4+-N removal rate of strain 2906 was achieved at a C/N ratio1520, an initial pH of 78, and salinity of 515. Sodium citrate was the optimal carbon source, with which the NH4+-N removal rate reached 100%. In the process of denitrification, there was a strong correlation between bacterial density and denitrification efficiency (R=0.94). A sequencing and phylogenetic analysis of the 16S rRNA of strain 2906 showed it was closely related to Pseudoalteromonas spp. The biosafety of strain 2906 was also tested on juvenile shrimp through an immersion challenge, with the result showing that the 50% lethal concentration of strain 2906 for juvenile shrimp was 2.8×107 CFU/ml, which indicates that strain 2096 has no virulence to shrimp. The results provide a theoretical basis for the development and utilization of the bacterium.