Analysis of microbial community differences during wastewater treatment of gelatin production plants based on high-throughput sequencing

In order to understand the structural differences of bacterial flora in the treatment process of gelatin processing wastewater, the 16S rRNA V3-V4 region of bacterial community in four sampling points of wastewater (initial settling water, aerobic water, secondary sedimentary sludge and discharge water) were investigated by high throughput sequencing using Illumina Hiseq sequencing platform. The results demonstrated that the dominant bacteria of initial settling water were Proteobacteria (69.62%) and Firmicutes (29.77%) at phylum level, Uncultured bacterium WS6 (34.48%, 22.75%) and Proteobacteria (24.85%, 22.88%) were dominated in aerobic water and secondary sedimentary sludge, Saccharibacteria (8.89%) and Proteobacteria (16.49%) were dominated in discharge water. At the genus level, the dominant bacteria of initial settling water were Hydrogenophaga(37.57%), while the dominant bacteria in aerobic wastewater and secondary sedimentary sludge were uncultured bacterium p WS6 (34.48%, 22.76%), and the dominant bacteria of discharge water was uncultured bacterium p Saccharibacteria (28.89%). There were significant differences of bacterial community diversity of four wastewater samples. The bacterial communities structure in wastewater treatment system was significantly correlated with water quality environmental factors (P< 0.05). Rheinheimera was positively correlated with pH and the content of Ca²⁺, ammonia nitrogen (P< 0.05). Alkalibacterium was positively correlated with the content of total nitrogen and chemical oxygen demand (P< 0.05). In summary, the environmental factors of wastewater were closely related to the structure of microbial communities, and the functions of key bacterial community in wastewater treatment was ascertained by the established relationship between environmental factors and microbial communities.