Isolation and identification of heterotrophic nitrosobacteria from bio-flocs and analysis of their characteristics

Abstract:

Two strains of nitrosobacteria with high ammonia transformation rate were isolated by enrichment and selective culture from bio-flocs of shrimp culture ponds. Sequences of 16S rRNA indicated that both strains belonged to the genus Halomonas sp., while strain 2011072708 was identified as H. alimentaria with 99% similarity, and strain 2011072709 as H. shengliensis with 100% similarity. Ammonia transformation rates of the two strains were compared under different temperatures, salinities, pH, and C/N ratios. The ammonia transformation rate of strain 2011072708 reached the highest level at 37 ℃, 30~40, pH 8, and C/N ratio of 28, while that of strain 2011072709 reached the maximum at 27~42 ℃, 40~50, pH 6, and C/N ratio of 21. The present study showed high ammonia transformation rates in both nitrosobacteria strains isolated from bio-flocs. Strain H. shenliensis (2011072709) had better adaptability to temperature, salinity, pH, and C/N ratio than H. alimentaria (2011072708), and may be more suitable for application in bio-flocs technology.