Abstract:
The best cultivation medium for production of lipase from Bacillus subtilis was performed by selection the optimum medium formulation. The results showed that this formulation for the highest activity were composed of basic formular 1, 0.5% (w/v) yeast extract, o.2% (w/v) ammonium nitrate and 0.33% (v/v) castor oil. The optimum conditions for cultivation of Bacillus subtilis were at agitation speed 200 rpm, OD 600 nm equal to 0.1, pH at the beginning of cultivation equal to 6.8, temperature 30 ํC, cultivation time 6 hours. The optimum conditions for detection the extracellular lipase activity from Bacillus subtilis were found at incubation time 30 minutes, volume of enzyme 0.5 ml, temperature 45 ํC, acetate buffer pH 4.8, and 1% olive oil in emulsion as a substrate. The lipase was inhibited compled completely by EDTA and HgCl2 and partially inhibited by FeCl3 and NiCl2. The experiment was aimed to use raw materials in Thailand instead of carbon sources and nitrogen sources for cultivation. The result showed that only 1% glucose or fructose could replaced 0.33% castor oil (v/v) for carbon source. In addition, soybean meal with total 0.3%N could replace 0.5% (w/v) yeast extract with total 0.18%N for nitrogen source. After culture in the best medium, the enzyme was precipitated from the broth as a powder with 80% (v/v) ethanol and dried at room temperature (25 ํC) for 8-12 hours with 6.5 unit/mg protein. The enzyme powders were stored between -20 ํC to 60 ํC for at least 28 days. It was found that storage temperatures between -20 ํC to 30 ํC were not lost the activity