Isolation and Characterization of a High Efficiency Aerobic Denitrifier

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.