SCREENING AND IDENTIRICATION OF DEGREADING AMMONIA-NITROGEN BACTERIA AND ITS EFFECT ON WATER QUALITY CONTROL

Excessive ammonia nitrogen in the aquaculture waters can impact immunity, growth, and morbidity and mortality of the cultured animals. The ammonia nitrogen in aquaculture waters is mainly removed by microbial degrada-tion. In this study, two ammonium removal strains were screened from a mixture of water and sediment in variety aquaculture ponds and identified as Bacillus coagulans. The degradation rate of the two strains were 97.8% and 98.5%, respectively. Two strains could adapt high pH value and C/N range, and have high resistance to high temperature and high salt. The oral administration trials verified that the two strains were safe for cultured aquatic animals. The two screened strains and the previously obtained mutagenic strain B38 in our lab were mixed with 1 鲶1 鲶1 ratio to make a probiotics complex, and its effects on the amount of ammonia nitrogen, nitrite and algae were evaluated by 18 days farming trials. Compared with the four commercial probiotics (Photosynthetic Bacteria, Yeast, EM and Bacillus), ammonia nitrogen decreased greatly in the ponds using probiotics complex. The number of algae in the ponds using probiotics complex and Bacillus from the 9^th day was higher than other groups, and the amount of algae were about twice as much as the other groups on the 14^th day. The probiotics complex can reduce ammonia nitrogen and increase the number of algae. This study provides a foundation for the development of complex probiotics.