Study on Phosphate Solubilizing Bacteria Isolated from Ghulkin Glacier, Hunza Valley

Abstract

Phosphorus (P) stands out as a vital macronutrient essential for the growth and reproductive processes of plants. Plants absorb P from the soil solution as phosphate anions. However, due to their high reactivity, phosphate anions can precipitate with cations such as Fe3+, Al3+, Mg2+, and Ca2+, contingent on the particular properties of the soil. since of this, plants cannot use the phosphate since it is so extremely insoluble. To promote plant development and P uptake, phosphate-solubilizing bacteria (PSB) have been used as fertilizer. Improving soil fertility is a commonly used strategy to increase agricultural productivity. Maintaining high levels of available phosphorus (P) and nitrogen (N), the two nutrients that limit soil fertility the most, is still a major undertaking. For the first time, we isolated and characterized psychrophilic PSB from Ghulkhin Glacier that had strong solubilizing capacities for calcium phosphate (Ca-P), hydroxyapatite (H-Ap), and tricalcium phosphate (TCP). Optimizing for the solubilization of phosphate (P) by the isolates Pseudomonas frederiksbergensis GA23 and Acinetobacter johnsonii GB30 was done. Phosphate solubilizing efficiency (PSE) capabilities were assessed using a variety of insoluble P sources, including TCP, Ca-P, H-Ap, Al-P, and Fe-P. Temperature of 5 degrees Celsius, pH values of 3 for Pseudomonas frederiksbergensis GA23 and 15 for Acinetobacter johnsonii GB30, fructose for Pseudomonas frederiksbergensis GA23 and xylose for Acinetobacter johnsonii GB30, ammonium sulphate for Pseudomonas frederiksbergensis GA23 and ammonium nitrate for Acinetobacter johnsonii GB30, potassium nitrate for Pseudomonas frederiksbergensis GA23 and potassium chloride for Acinetobacter johnsonii GB30, and 10% salt stress for both Pseudomonas frederiksbergensis GA23 and Acinetobacter johnsonii GB30 were found to be the ideal conditions. Nonetheless, the highest increase in Drought stress was 6% for Pseudomonas frederiksbergensis GA23 and 5% for Acinetobacter johnsonii GB30. The release of organic acids in culture was observed to be correlated with phosphate solubilization (PS). The presence of organic acids is confirmed by the TLC plate when an orange, yellow, blue background appears. For additional assurance, FTIR analysis was carried out. Three known acids (oxalic, acetic, and formic acid) and ten unknown acids were found by HPLC analysis of the culture broth after 48 hours of incubation, whereas five known organic acids (citric, oxalic, acetic, gluconic, and formic acids) were found by HPLC analysis of xi Acinetobacter johnsonii GB30 after 96 hours of incubation. These organic acids help to promote plant growth and solubilize inorganic phosphate to soluble phosphate. Glacier samples exhibited high productivity of organic acids, which could be utilized as biofertilizers to enhance agricultural growth in the cold regions of Pakistan.