Concomitant production of detergent compatible enzymes by Bacillus flexus XJU-1

A soil screened Bacillus flexus XJU-1 was induced to simultaneously produce alkaline amylase, alkaline lipase and alkaline protease at their optimum levels on a common medium under submerged fermentation. The basal cultivation medium consisted of 0.5% casein, 0.5% starch and 0.5% cottonseedoil as an inducer forprotease, amylase, and lipase, respectively. The casein also served as nitrogen source for all 3 enzymes. The starch was also found to act as carbon source additive for both lipase and protease. Maximum enzyme production occurred on fermentation medium with 1.5% casein, 1.5% soluble starch, 2% cottonseed oil, 2% inoculum size, initial pH of 11.0, incubation temperature of 37 °C and 1% soybean meal as a nitrogen source supplement. The analysis of time course study showed that 24 h was optimum incubation time for amylase whereas 48 h was the best time for both lipase and protease. After optimization, a 3.36-, 18.64-, and 27.33-fold increase in protease, amylase and lipase, respectively was recorded. The lipase was produced in higher amounts (37.72 U/mL) than amylase and protease about 1.27 and 5.85 times, respectively. As the 3 enzymes are used in detergent formulations, the bacterium can be commercially exploited to secrete the alkaline enzymes for use in detergent industry. This is the first report for concomitant production of 3 alkaline enzymes by a bacterium.

Buffering capacity and membrane H+ conductance of protease producing facultative alkaliphilic bacterium Bacillus flexus from mangrove soil. Indian Journal of Biochemistry & Biophysics. 2009 June; 46(3): 261-265.

A facultative alkaliphilic protease-producing gram-positive rod-shaped bacteria (EMGA 5) was isolated from mangrove soil and confirmed as Bacillus flexus by the 16S rDNA sequence. Buffering capacity and membrane H+ conductance of this alkaliphilic isolate were investigated for the cells grown at pH 7.2 and 10.5 using acid pulse technique. Suspensions of B. flexus cells grown in poly peptone yeast glucose medium at pH 10.5 exhibited higher cytoplasmic membrane buffering capacity values (70 µmol H+/pH unit/mg protein at pH 9.9) than the cells grown at pH 7.2 (41 µmol H+/pH unit/mg protein at pH 9.9). B. flexus grown aerobically at pH 7.2 showed higher H+ conductance values than the cells grown at pH 10.5 (0.032 µmol H+/s/pH unit/mg protein at pH 9.9 and 0.028 µmol H+/s/pH unit/mg protein at pH 9.8, respectively). The present study revealed that the buffering capacity and membrane H+ conductance of the B. flexus isolates were influenced by pH of the medium.