Microbial community of biofilm inoculated from activated sludge on solubilization of phosphate rock

Microorganisms enriched from activated sludge were found to attach to phosphate rock (PR) through biofilm formation. In the present study with a column bioreactor, the microorganisms both in biofilm and solution were characterized by Illumina high-throughput sequencing. The results from Illumina 16S rRNA gene MiSeq analysis revealed Alphaproteobacteria being the dominant bacterial group at the class level in the biofilm and solution. Compared with solution, the biofilm featured higher bacterial species diversity and richness, but the solution featured higher Alphaproteobacteria abundance than the biofilm. The results from Illumina 18S rRNA gene MiSeq analysis showed a relatively lower richness but higher diversity of the fungal community in the biofilm than in the solution. At the class level, Saccharomycetes were the only dominant fungi both in the biofilm and solution, with their abundance in the biofilm being significantly higher than in the solution. The 18S rRNA analysis also revealed the presence of non-fungal organisms, such as Chrysophyceae, Trebouxiophyceae and Colpodea, in the column bioreactor. The results in this study provide new insights into our understanding of microbial community structures of biofilm and solution in the column bioreactor for the solubilization of PR.