The Isolation, Identification and Analysis of a Nitrogen-Removing Bacterium Strain From Shrimp Farming Pond Using Bio- Floc Technology

Abstract:

In a high density farming pond, the concentration of nitrite is often much higher than standard due to the excessive release of waste from feeding, breeding, and water pollutions. High nitrite is a prominent harmful factor in aquaculture. It can facilitate the growth of pathogenic bacteria, increase the stress for fishes and shrimp, render them prone to bacterial infection, and consequently lead to disease breakout. Nitrogen-removing has been widely recognized as an effective method to degrade nitrite in the water which comes from food residual and feces. An efficient nitrogen-removing bacterium strain, 201107290102, was isolated from the bio-floc in a shrimp farming pond. It was preliminarily identified as Halomonas venusta because 16S rRNA sequence analysis revealed that it shared 99% similarity in sequence with H. venusta. We next studied factors that determined the nitrogen-removing efficiency of this strain, including C/N ratio, temperature, initial pH and salinity. The optimal conditions were: C/N ratio 15, temperature 37℃, salinity 40, initial pH 10.0. Under the optimal conditions, the nitrogen-removing efficiency could be up to 91.7%. These results suggested that the strain 201107290102 could effectively degrade the nitrite. Our study provided a new tool for improving the bio-floc in shrimp culture.