Isolation from soil of bacteria producing extracellular alpha galactosidase

Abstract

Extracellular alpha galactosidase (alpha galactosidase galactoydrolase EC 3.2.1.22) producing bacteria were isolated from soil by the enrichment culture technique using raffinose as the inducer. Six bacterial species were isolated by this method based on their morphological characteristics. Their raffinose utilization rate varied from 11 mg/h to 27 mg/h. Enzyme acivity present in the supernatant varied from 2-11 mU/ml. Two of the isolated species did not show any alpha galactosidase activity. Three bacterial species having high alpha galactosidase activity were identified as Klebsiella pneumoniue. Citrobucter freundii and Escherichia coli by their colony morphology and biochemical tests. They were cultivated at different pH values with peptone and ammonium sulphate as the nitrogen source. From those studies, it was shown that the highest extracellular alpha galactosidase activity of 14.7 mU/ml could be obtained from Citrobucter freundii after 18h of cultivation in a culture medium with an initial pH of 8 containing peptone as the nitrogen source. Extracellular enzyme production was increased up to 19mU/ml by the cultivation of Citrobucter freundii in pH8 phosphate buffer for 36h with peptone as the nitrogen source.