Diversity and characteristics of culturable phosphate-solubilizing bacteria of Indian Ocean

[Objective] The aim of this study is to screen culturable phosphate-solubilizing bacteria from water samples of the Indian Ocean, and tackle their mechanism of regenerating phosphate from organics and their phylogenetic diversity in the region. [Methods] Phosphate-solubilizing bacteria were selected by inoculating bacteria isolated from the Indian Ocean waters onto solid lecithin medium, and the phosphate-solubilizing bacteria were identified according to their 16 S r RNA genes. Three strains of high phosphate-solubilizing activities were studied for their alkaline phosphatase production and phosphate-solubilizing in fermentation liquid. [Results] A total of 99 phosphate-solubilizing strains from 16 genera were selected from the 916 available bacteria strains. The dissolved inorganic phosphate(DIP) concentration presented N-type curves in cultures of all the three active phosphate-solubilizing stains India-BSP-1(Cobetia sp.), India-BSP-21(Pelagibaca sp.), India-BSP-23(Pelagibacterium sp.), and the alkaline phosphatase was detected after DIP production. [Conclusion] Phosphate-solubilizing bacteria of the Indian Ocean waters presented rich species diversity and three candidate new species. The characteristics of bacterial regeneration of phosphate from organics were influenced by both DIP and alkaline phosphatase.