OPTIMIZATION FOR L- ARABINOSE ISOMERASE PRODUCTION FROM LOCAL ISOLATE OF Bacillus stearothermophilus HB4.

Abstract

In this study twelve of purred local isolate from Bacillus stearo thermophilus were obtained among 40 isolates from different sources of Iraqi soil. They were subjected to primary and secondary screening to select the isolate which produce the highest level of L- arabinose isomerase . It was found that the isolate B4 was the highest producer of the enzyme , with enzyme activity of 35 unit /ml. According to morphological and biochemical tests this isolate was identified as Bacillus stearothermophilus and designated as HB4 . The optimum conditions for production of L- arabinose isomerase from Bacillus stearothermophilus HB4 by submerged culture were achieved on broth medium containing 1.5% glycerol as carbon source and 0.15 % of L- arabinose as inducer and 1 % of mixture of casien, beef extract and yeast extract with equal quantity of each them as nitrogen source with 0. 15 % of magnesium sulfate and 0.02 % of manganese sulfate at pH of 7.5 after 72 hours of incubation at 55 C 0 . Under these conditions The enzyme activity was 55 U/ ml with increasing about 150 % comparing with same isolate before optimization.