Disclosed is a biologically pure bacterial culture of XSB375 (Bacillus firmus) (ATCC# PTA-120309). Also disclosed is a method of increasing plant growth and/or yield comprising: inoculating with phosphate solubilising plant growth promoting rhizobacteris (PGPR) XSB375 (Bacillus firmus) (ATCC# PTA-120309) in soil environment or potting mixture; and growing a plant in the soil environment or potting mixture.