Identification of aerobic-denitrifying Psychrobacter cryohalolentis strain F5-6 and its nitrate removal at low temperature

Biological denitrification is suppressed when temperature is lower than 10 degrees C. In this study, Psychrobacter cryohalolentis F5-6 was isolated from Harbin region and showed high aerobic-denitrifying rate at low temperature. It contained high percentage of unsaturated fatty acids (87.32%) and short chain saturated acid (3.4% C10:0 and 4.0% C12:0 3-OH). Acetate was the best carbon source for the strain F5-6 performing denitrification. Aerobic denitrification (napA gene) and nitrate assimilation (nasA gene) were the nitrate metabolism processes for the strain F5-6. Its biological nitrate removal (BNR) rate at 10 degrees C showed fit with Monod equation (R2 = 0.9808). The maximum BNR rate was 23.71 mg NO3- -N g- 1DW h-1 and KS was 116.96 mg L-1. The optimal denitrifying condition was pH 7.5, 15 degrees C with shaking speed of 180 rpm and C/N of 2. Results of this study supplied a bacterial resource for improving nitrate removal from low C/N water at low temperature.

Automated summary

In this study, a strain called Psychrobacter cryohalolentis F5-6 was isolated and found to have a high aerobic-denitrifying rate at low temperatures. It has a high percentage of unsaturated fatty acids and short chain saturated acids. The strain prefers acetate as the carbon source for denitrification. The study also showed the nitrate metabolism processes of the strain and determined the optimal conditions for denitrification. This research provides valuable information and a potential bacterial resource for improving nitrate removal from low C/N water at low temperatures.