Biosolubilization of Low-Grade Rock Phosphate by Native Microbial Consortia from Phosphate Mines: Effect of Sampling Sources and Culture Media

Abstract

Two native microbial consortia were isolated from the soil and drainage in the phosphate mines, and their abilities to solubilize low-grade rock phosphate (RP) in two different culture media, namely Pikovskaya (PKV) and National Botanical Research Institute’s phosphate (NBRIP) medium, respectively, were estimated. Results showed that the two microbial consortia could grow steadily in the solution and continuously released soluble phosphate from the RP during 14 d of experiments. This process was accompanied by a drop in pH of the solution. The microbial consortium isolated from the soil achieved the largest release of soluble phosphate and pH reduction in the PKV medium among the four microbial consortia named PS, NS, PD, and ND, respectively. Fourier transform infrared spectroscopy (FTIR) analysis of RP indicated that hydroxyl, alkyl C-H bond, amide, and carboxyl were involved in the RP solubilization, and significant changes of them were observed after the experiments. The four microbial consortia were sampled before and after the experiments for the analysis of their bacterial and fungal community structures by Illumina MiSeq sequencing. Results showed that the relative diversities and abundances of the dominant bacteria and fungi varied with different sampling sources (soil and drainage) and culture media (PKV and NBRIP medium).