Optimization of mannanase production by Bacillus sp. HDYM-05 through factorial method and response surface methodology

Abstract

Bacillus sp. HDYM-05 was separated from flax retting liquid and identified as Bacillus cereus which was a new source of microbial mannanase. To optimize the medium components and condition of shake flask experiment for a higher mannanase production, factorial method and response surface methodology were used to obtain the maximal productivity by this species originally. The optimal medium components were: konjaku flour 8.81%, yeast extract 0.5%, NaNO3 0.5%, K2HPO4 0.5%, MgSO4·7H2O 0.02%. The optimal condition of shake flask experiment was: 75 ml medium in 500 ml flask, inoculum volume 1%, initial pH 8.0 and 140 rpm with the cultivation temperature and time at 37°C and 32.05 h, respectively. The maximum enzyme activity of Bacillus sp. HDYM-05 achieved 6777.4 U/ ml, 1.4 folds under the optimal culture conditions as compared to the initial control. Key words: Mannanase, Bacillus cereus, optimization, factorial method, response surface methodology.