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ISOLATION AND IDENTIFICATION OF THERMOLYSIN PRODUCING ISOLATES OF Bacillus stearothermophilus FROM IRAQI SOIL AND DETERMINATION OF NUTRITION FACTORS | ||
| IRAQ JOURNAL OF AGRICULTURE | ||
| Article 1, Volume 14, Issue 4, 2009, Pages 0-0 | ||
| Author | ||
| K. A. Al-Khafaji | ||
| Abstract | ||
| Bacillus stearothermophilus spores are the most resistant for extreme environmente, their spores are abundant in all soil types at hot and cold regions. This species produce Thermolysin (extracellular metalloprotease) which resist high temperature. The production of thermolysin is affected positively or negatively by the addition of some nutrition factors to basal medium. This research was conducted to isolate and identify B. stearothermophilus from different Iraqi soils and the determination of nutrition factors that affect the enzyme production. Thirty three thermophilic bacterial isolates identified as B. stearothermophilus from twenty five different Iraqi soil samples. The production of thermolysin enzyme was screened qualitatively and quantitavely and the isolates showed different quantity of enzyme production. The isolate designed as B. stearothermophilus SK 422 produced the highest amount of thermolysin reached to 900 unit/ ml. The complex basal medium contained tryptone and yeast extract was used and the ideal concentration of each tryptone and yeast extract for enzyme production was determined to be 0.65% and 0.5% respectively. Soytone (soy bean digest) or peptone or pantone could replaced the tryptone without any clear effect on enzyme production. The effect of some salts concentration was determined separately or as mixture and found that the best concentration was 0.25% for NaCl and KCl, while it was 0.5% for MgSO4, CaCl2 and (NH4)2SO4. A mixture of 0.25% KCl, 0.5% (NH4)2SO4 gave higher enzyme production compared with using the salts separately. The effect of adding sugars (hexose ,pentose, polysaccharide, polyole)to the basal medium was studied on the enzyme production .The sugars which have positive effect was 0.25% glucose then 0.5% galactose. | ||
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