Isolation and Characterization of Epilithic and Endolithic Bacteria from Murree Hills and Role of These Bacteria in Mineralization and Weathering of Rocks

Abstract

In this study, I focused on the isolation of phosphate solubilizing bacteria from rocks of Murree, lower Himalaya, Pakistan. Bacteria from outer and inner surface of the rocks were screened for their ability to solubilize phosphate. Three strains of bacteria were selected on the basis of halozone formation in National Botanical Research Institute for Phosphate medium (NBRIP) supplemented with TCP (tribasic calcium phosphate). The solubilization index for these bacteria was recorded as 4.29, 4.03 and 3.99. pH of the medium also dropped from the initial 7.0 to 4.0 units after 5 days of growth in liquid NBRIP medium with continuous shaking at 150 rpm. The strain P26 which is closely related to Pseudomonas species and identified as Pseudomonas putida strain (KT004384) showed maximum solubilizing activity in the given medium (161.70 mg/L) after 3 days of incubation. The other two strains P4 and N27 were identified as Pseudomonas grimontii (KT223621) and Alcaligenes faecalis (KT004385). The capability of solubilizing inorganic phosphate by these strains is attributed to the production of organic acids. The presence of these organic acids is determined by high performance liquid chromatography. Three different type of acids, gluconic, oxalic and malic acid were the dominant acids found in the culture medium. This was the first report on phosphate solubilizing (PSB) strains isolated from the rocks of lower Himalaya range Pakistan. It may be assumed that these bacteria can play a role in weathering of rocks as well.