The combination use of Candida tropicalis HH8 and Pseudomonas stutzeri LZX301 on nitrogen removal, biofloc formation and microbial communities in aquaculture

Different effects of a marine yeast strain Candida tropicalis HH8 and an aerobic denitrifying bacteria strain Pseudomonas stutzeri LZX301 on water properties especially nitrogen removal, biofloc formation and microbial communities were investigated. Both the strain HH8 and LZX301 removed inorganic nitrogen efficiently and participated biofloc formation. The combination use of the two strains is available in aquaculture due to their specific biochemical characteristics that much of nitrogen (44.87%) was converted to organic nitrogen by assimilation and bioflocs formed rapidly were more compact in the presence of the strain HH8 while much of nitrogen (59.33%) was removed by denitrification with the strain LZX301 added. Moreover, the phytoplankton stock (chlorophyll-a) was controlled at an appropriate level with the strain HH8 added. Microbial communities of biofloc varied largely and the relative abundance of Candida and Pseudomonas decreased obviously at the end of the trial. As a result, Candida tropicalis HH8 and Pseudomonas stutzeri LZX301 could be excellent participants in biofloc technology due to high-efficient nitrogen removal and fast-rate bioflocs formation.