Aquaculture Water Quality Improvement by Mixed Bacillus and Its Effects on Microbial Community Structure

Abstract

Nutrients nitrogen and phosphorus pollution in aquaculture is one of the greatest challenges threatening the survival of aquatic organisms, which requires efficient and sustainable remediation approach. Microbial remediation, especially the application of probiotics, has recently gained popularity in improving the water quality and maintaining the health condition of aquatic animals. In the present study, two groups of mixed Bacillus (Bacillus megaterium and Bacillus subtilis (A0+BS) and Bacillus megaterium and Bacillus coagulans (A0+BC)) were applied to aquaculture system of Crucian carp to improve the treatment of nitrogenous and phosphorus compounds. The effects of mixed Bacillus on water quality, and the structure and function of microbial communities in aquaculture water were investigated. Our results showed that the improvement effect of mixed Bacillus A0+BS on water quality was better than that of A0+BC, and the NH4+-N, NO2--N, NO3--N and total phosphorus (TP) concentrations were reduced by 46.3%, 76.3%, 35.6%, and 80.3%, respectively. In addition, both groups of mixed Bacillus increased the diversity of bacterial community and decreased the diversity of fungal community. Microbial community analysis showed that mixed Bacillus A0+BS increased the relative abundance of bacteria related with nitrogen and phosphorus removal, e.g., Proteobacteria, Actinobacteria, Comamonas, and Stenotrophomonas, but decreased the relative abundance of pathogenic bacteria (Acinetobacter and Pseudomonas) and fungi (Epicoccum and Fusarium). The redundancy analysis showed that NH4+-N, NO2--N, and TP were primary environmental factors affecting the microbial community in aquaculture water. PICRUST analysis indicated that all functional pathways in the treatment groups were up-regulated, and all pathways in A0+BS group were richer than those in other groups. These results indicated that mixed Bacillus A0+BS addition produced good results in reducing nitrogenous and phosphorus compounds and shaped a favorable microbial community structure to further improve water quality.

Water Quality Improvement by Wild Bacilli Isolated from Marine Environments

“…For example, mixed Bacillus (B. megaterium and B. subtilis) reported efficiency of nitrogenous waste (ammonia, nitrite, and nitrate) reduction by approximately 35-76%. This result had good efficiency rather than compared mixture (B. megaterium and B. coagulans) [36]. Moreover, a consortium of B. cereus, B. amyloliquefaciens, and Pseudomonas stutzeri was studied with 84.89% of ammonium removal [6].…”

“…B. subtilis, B. cereus, and B. licheniformis showed phosphate reduction [34], and B. velezensis reduced total phosphorus in channel catfish pond by 19% [35]. Moreover, the mixture of B. megaterium and B. subtilis can remove total phosphorus by about 80.3% [36].…”

Values of the New Urbanist Neighborhood Planning Based on the Concept of Sustainability

“…Efforts were made to create an ecological layout pattern and to design urban villages with walkable areas whenever possible. By the 1990s, New Urbanism had become the fastest growing mainstream development model for urban communities [2].…”