Isolation and Characterization of a High Efficiency Aerobic Denitrifier

Abstract:

Twenty two bacterial strains with a capacity of denitrification were isolated from fish pond, of which eight strains have the high rate of denitrification while one strain named HS-N62 has the strongest effect of denitrification. The results showed that the denitrifying rate of strain HS-N62 reached 96% in 12 hours with initial nitrate nitrogen concentration of 140 mg/L and no nitrite nitrogen accumulation. The growth rate and characteristics of HS-N62 were further studied, and the results showed that the optimum growth temperature ranged from 30°C to 37°C, pH value from 6.0 to 8.0 and the optimal C/N ratio 10:1. Meanwhile strain HS-N62 could utilize a variety of carbon sources for growth. The most suitable denitrification condition for strain HS-N62 was confirmed by using a series of the orthogonal test. This denitrifying strain HS-N62 also has good ability of phosphorus removal, and the removal rate within 12 hours was up to 67.7% (at initial phosphate concentration 57 mg/L). Strain HS-N62 showed 99% 16S rRNA gene sequence similarity to many Pseudomonas strains. Based on the morphological characteristics, physiological and biochemical characteristics, the strain HS-N62 was identified as Pseudomonas sp.