Quantitative and Qualitative Analysis of Organic Acids Produced by Phosphate Solubilizing Fungi

Abstract

The aim of this study was to identify and quantity the organic acids produced by phosphate solubilizing fungi using high performance liquid chromatography (HPLC) apparatus. Eight phosphate solubilizing fungi (PSF) were selected from 23 fungal isolates according to their potential to solubilize tricalcium phosphate in broth Pikovskaya,s medium. These fungal isolates were collected from culture bank in Botany and Microbilolgy department, Beni-suef University. PSF were identified as Aspergillus, penicillium and Trichoderma. The PSF isolates decreased the initial pH of the media when they were incubated for seven days. The pH of the media decreased from 6.3 to 2.4 in case of Aspergillus japonicus2. The decreased pH clearly indicated the production of organic acids. The highest total concentration of organic acids was secreted by Aspergillus japonicus 2 (2642.1 mg/l). By using high performance liquid chromatography (HPLC) seven different organic acids were detected (salicylic, ascorbic, citric, formic, lactic, oxalic, and malic acids). Salicylic acid was the highest quantitatively produced organic acid by all PSF; its concentration was 1823.8 mg/ l by Aspergillus japonicus2. There was a significant positive correlation between the titrable acidity and phosphate solublization (r = 0.34, p = ≤ 0.05) and a negative significant correlation between pH and phosphate solublization (r = - 0.27, P≤ 0.05).The immobilized phosphorus was negatively correlated with titrable acidity(r = - 0.24, P ≤ 0.05).