Molecular detection and statistical optimization of Exiguobacterium sp. MSB42 alkaline metalloprotease production

Improvement of alkaline protease production, one of the most important types of industrial biocatalysts, is essential for commercial purposes. The present study’s aim was to increase alkaline protease production of MSB42, a newly isolated strain of Exiguobacterium sp., through the rotatable central composite design (RCCD). In this regard, parameters affecting MSB42 enzyme production were chosen based on the results of preliminary one-factor-at-a-time (OFAT) experiments. According to the results of RCCD, the enzyme production showed its maximum level (198.48 U/ml) in the presence of 3% w/v glucose, 3% w/v peptone, at 37 °C and pH 9. Overall, the enzyme production was 2 and 3.24 times more than OFAT experiments (98.69 U/ml) and unoptimized conditions (61.29 U/ml), respectively. A polynomial model of MSB42 alkaline protease production was obtained using the experimental date and based on the significant terms. The protease gene of this strain was also amplified using the designed primers (873 bp), and based on the sequencing results, was found to be closely related to the M6 family of metalloprotease domain.