Study of Microbial Phosphate Solubilizers and their Potential Usage in Sustainable Agricultural Practices

Abstract

Phosphorus (P) is one of the essential macro elements which plays a vital role in the proper functioning of plants. So deficiency of P can diminish plant growth and development. Soil possesses total P in the form of organic and inorganic compounds, most of them remain inactive and thus unavailable to plants. Usage of synthetic Phosphate fertilizers show adverse effect and it is also expensive so many farmers cannot afford them. So there is a need to develop alternative techniques to provide P. Soil has the presence of several Phosphate solubilizing microbes (PSMs) which are beneficial microorganisms and have the capability of hydrolyzing organic and inorganic insoluble phosphorus compounds to soluble P form that can easily be assimilated by plants. . Under the present investigation identification, characterization, and optimization of the phosphate solubilizing activity of these microbes at different pH, temperature and salt concentrations was carried out. Isolation of PSMs have been carried out from the agricultural soil sample of Kankot, Rajkot. Collected soil sample undergone serial dilution followed by inoculation on Pikovskaya’s Agar (PVK) medium. Out of 7 isolates only 3 isolates showed significant zone of hydrolysis on Pikovskaya’s Agar (PVK) medium. Based on morphological and cultural characteristics, 3 isolates were tentatively identified A.niger, Penicillium sp. and Bacillus sp. Further extraction of phosphatase enzyme has been carried out and it’s activity had been determined qualitatively by zone of clearance which is measured as 5 cm for Penicillium sp. and Aspergillus sp. and quantitatively by Spectro vanadomolybdate phosphoric yellow color method which was observed and measured as the highest value 83 μg/ml for Pseudomonas sp.. Partial purification of crude alkaline phosphatase enzyme has been carried out and followed by it enzyme assay was done by using Alkaline phosphatase assay. As result we found maximum enzyme activity is 3.410 of Pseudomonas sp., 1.829 of Aspergillus sp.), and 1.783 of Penicillium sp.. Enzyme optimization has been carried out at different pH, temperature, salt concentration ,and incubation periods. As result we found that alkaline phosphatase enzyme shows the maximum result at Pseudomonas sp. 9 pH, Penicillium sp. 10 pH and Aspergillus sp. 12 pH maximum effects for temperature was carried out for Pseudomonas sp as 5.147, Penicillium sp. as 4.341, and Aspergillus sp. as 5.519 ; the maximum effect of salt concentration for Pseudomonas sp. was calculated as 7.81, Penicillium sp as 7.03, and Aspergillus sp. as 7.8. The maximum effects of incubation period was observerd as Pseudomonas sp.4.05, Penicillium sp. 4.12, and Aspergillus sp.4.36. Further these optimized enzyme was used in the in-vitro pot assay experiment to check it’s efficiency in plant growth promotion. Purpose of this review is to understand the role of PSMs in crop production as biofertilizer.