Identification of a Moderate Halophilic Phosphate-dissolving Bacterium and Its Phosphate-solubility

Abstract:

A aerobic moderate halophilic phosphate-dissolving bacterium, named QW1011, was isolated from the plant rhizospheres grown on the wall of ancient brine well located in Zigong city, Sichuan Province, China. The results showed that its cell was line shaped (0.8 μm×30 μm~100 μm), gram positive. The strain required aerobic conditions for growth and grew well with an optimum concentration at 10% NaCl (W/V) at pH 7.0 and tolerated up to 15% NaCl. And it could also hydrolyze gelatin and starch but not casein. 16S rRNA analysis revealed that its sequence sharing 100% similarity to B. Megaterium ATCC 14581. However, compared with B. Megaterium ATCC 14581 and B. Megatherium var. phosphaticum DSM 3228, QW1011 exhibited several differences in the phenotypic, physiological characteristics and ISR. Based on the phenotypic distinctiveness, molecular and ISR genetic evidence, it was proposed that QW1011 can be classified as genus Bacillus. The strain showed high phosphate-dissolving ability for Ca3(PO4)2 with the capacity of 62.42 μg/mL~71.34 μg/mL in Ca3(PO4)2 liquid medium at 24°C~36°C, 5%~10% sodium (W/V) and pH 6.5~8.0 after incubation for 60 h. And its activity for Ca3(PO4)2 was higher than for lecithin.

Key words:Moderate halophilic phosphorbacteria, Phosphate-solubility, Phenotypic analysis, 16S rRNA, 16S-23S rRNA ISR