Evaluation of the ability of some local soil fungi to produce oxalic acid under different conditions

Abstract

The aim of this study was to isolate fungi from soil and evaluate their ability to produce oxalic acid, then determine the most productive fungal isolate and the optimal conditions for acid production. All fungal isolates were oxalate producers, and the most efficient fungal species was A.niger, followed by A.flavus, then Rizoctonia solani with production rates of 4.05% , 3.54% , and 3.42% respectively , the rest isolates gave variable productivity. The optimum conditions for oxalate production were as follows ; (4%) sucrose as the best carbon source, (0.25%) ammonium sulfate as a best nitrogen source, (0.1%) hydrated magnesium sulfate as a best salt , (3%) which is equal to 1×106 spores/ml was the best inoculum size, the optimal pH value was equal to 6.5 , and 25°C represent an optimal temperature degree , for 7 days incubation period.