Review on Role of Phosphate Solubilizing Microorganisms in Sustainable Agriculture

Most of soil microorganisms are known for their ability to solubilize insoluble phosphorous compounds for releasing soluble phosphate to make phosphorous available for plant absorption. Releasement of this soluble phosphorous is very important in increasing plant growth and plant product yields. Inoculating plant seeds with phosphate solubilizing microorganisms is very effective and environmentally useful to decrease the side effect of chemical fertilizers on soil microbes and other organisms. A large number of microbial organisms including bacteria, fungi, actinomycetes, and algae exhibit phosphate solubilization and mineralization ability. Many soil bacteria have been recognized for their ability to solubilize insoluble phosphate. These strains of bacteria include: Pseudomonas spp., Agrobacterium spp., and Bacillus circulans. Other phosphorus solubilizing and mineralizing bacteria include various strains of Azotobacter, Bacillus, Burkholderia, Enterobacter, Erwinia, Kushneria, Paenibacillus, Ralstonia, Rhizobium, Rhodococcus, Serratia, Bradyrhizobium, Salmonella, Sinomonas, and Thiobacillus. The strains of fungi with P solubilisation ability are: Achrothcium, Alternaria, Arthrobotrys, Aspergillus, Cephalosporium, Cladosporium, Curvularia, Cunninghamella, Chaetomium, Fusarium, Glomus, Helminthosporium, Micromonospora, Mortierella, Myrothecium, Oidiodendron, Paecilomyces, Penicillium, Phoma, Pichia fermentans, Populospora, Pythium, Rhizoctonia, Rhizopus, Saccharomyces, Schizosaccharomyces, Schwanniomyces, Sclerotium, Torula, Trichoderma, and Yarrowia. Different species of fungi can solubilise rock phosphate, aluminium phosphate and tricalcium phosphate. For the application of phosphate solubilizing Microorganisms to seeds, the seeds should be surface sterilized, rinsed with sterile water and dried. The surface disinfected seeds can be coated by soaking seeds in liquid culture medium of phosphate solubilizing fungi for 2 hr. While inoculation of the seed using plant and both Aspergillus niger + Penicillium notatum is recommended. Therefore, the application of phosphate solubilizing fungi is recommended as a sustainable way for increasing crop yield.