Bacterial complexes of Bacillus subtilis and Pseudomonas stutzeri alter the microbial composition in grass carp water.

The current study was designed to evaluate the effects of bacterial complexes (BC, a combination of Bacillus subtilis SC02 and Pseudomonas stutzeri F1M) on nitrogen removal and microbial composition in grass carp culture water. The results of the study showed that the addition of BC could significantly decrease the level of harmful nitrogen compounds and improve the water quality in grass carp culture water over an extended period of time. The 454-pyrosequencing results showed that BC could significantly increase (p < 0.05) the abundance of the genera Hydrogenophaga and Cloacibacterium on the 6th day and 15th day, respectively. LefSe analysis (LDA Score [log10] > 4) indicated that BC enriched in the taxa Firmicutes, Hydrogenophaga, and Pseudomonas, while the CK was enriched in the genus Rhodobacter on the 6th day. On the 15th day, the CK microbiome was characterized by a preponderance of Betaproteobacteria in the water, but no biomarker was identified in the BC group; therefore, the addition of a combination of Bacillus subtilis SC02 and Pseudomonas stutzeri F1M can improve water quality and change the microbiota in grass carp water. [ABSTRACT FROM AUTHOR]