Optimization of gelatinolytic enzyme production by B. amyloliquefaciens sp. H11 through Plackett–Burman design and response surface methodology

Abstract

<em>Bacillus amyloliquefaciens</em> H11 has been proven as a potential producer of extracellular protease with capacity of hydrolyzing gelatin. Therefore, the cultivation conditions for the enhanced production of gelatinolytic enzyme from a newly isolated <em>B. amyloliquefaciens</em> H11 was investigated using Plackett–Burman design and response surface methodology. Three significant variables (agitation speed, cultivation time and fish gelatin concentration) were selected for optimization. Increases in speed of agitation and fish gelatin concentration markedly increased the production of gelatinolytic enzyme. Gelatin concentration and cultivation time showed significant interaction and both variables played the important role in enzyme production. The maximal gelatinolytic enzyme production in the basal medium was 2,801 U/mL under the following optimal condition: agitation speed of 234 rpm, 8.36 g/L of fish gelatin and 31 h of cultivation. The predicted model fitted well with the experimental results (2,734 ± 101 U/mL). Fourteen-fold increase in yield was achieved, compared with the basal condition (212 U/mL). Thus, cultivation of <em>B.</em><em>amyloliquefaciens</em> H11 under the optimal condition could enhance the production of gelatinolytic enzyme effectively.