Assessment of Microbial Profile and Plankton Composition of Biofloc Water under Different Carbon Sources

Biofloc technology (BFT) is a microbial-based culture system that works by adding different carbon sources. This is commonly accomplished by adding an organic carbon source to the water or, less commonly, by raising the carbon level. A 10-week experiment was conducted to assess the microbial profile and planktonic composition of biofloc water from different carbon sources. Four treatments, including Control (C), Glycerol (G), Sucrose (S), and Wheat bran (W), were generated. The experiment was carried out in a 100 L plastic bowl, and it was performed in triplicate. Water samples were collected before the stocking of experimental fish for microbial analysis, and after the experimental trials for microbial and plankton composition. The microbial composition of the biofloc water before fish stocking revealed diverse bacterial taxa, with E. coli, Bacillus, Citrobacter, and Enterobacter consistently detected across all treatments, while S. aureus, Pseudomonas, and Salmonella were detected in selective systems. The plankton composition of bioflocs developed with different carbon sources showed marked differences in species richness and relative abundance. The complex carbon sources were effectively utilized, resulting in improved water quality, a highly diverse microbial community, and the highest plankton abundance and richness. Overall, this study demonstrated that bioflocs grown on different carbon sources exhibit distinct qualities and suggested that the choice of carbon source is of prime importance. The present study indicated that different carbon sources could affect the bacterial composition, morphostructure, and microbial community of biofloc. This result may provide a theoretical basis for the biofloc technology used in aquaculture.