Abstract
The protease myroilysin is the most abundant protease secreted by marine sedimental bacterium Myroides profundi D25. As a novel elastase of the M12 family, myroilysin has high elastin-degrading activity and strong collagen-swelling ability, suggesting its promising biotechnological potential. Because myroilysin cannot be maturely expressed in Escherichia coli, it is important to be able to improve the production of myroilysin in the wild strain D25. We optimized the culture conditions of strain D25 for protease production by using single factor experiments. Under the optimized conditions, the protease activity of strain D25 reached 1137 ± 53.29 U/mL, i.e., 174% of that before optimization (652 ± 23.78 U/mL). We then conducted small scale fermentations of D25 in a 7.5 L fermentor. The protease activity of strain D25 in small scale fermentations reached 1546.4 ± 82.65 U/mL after parameter optimization. Based on the small scale fermentation results, we further conducted pilot scale fermentations of D25 in a 200 L fermentor, in which the protease production of D25 reached approximately 1100 U/mL. These results indicate that we successfully set up the small and pilot scale fermentation processes of strain D25 for myroilysin production, which should be helpful for the industrial production of myroilysin and the development of its biotechnological potential.
Highlights
Particulate organic nitrogen is abundant in marine sediments, and bacterial enzymatic activity in sediments is generally the initial and rate-limiting step in nitrogen recycling [1]
The fermentation medium we previously developed for the production of myroilysin in strain D25 contained (w/v) 2% corn powder, 2% bean powder, 1% wheat bran, 0.4% Na2HPO4, 0.03% KH2PO4, 0.1% CaCl2, and artificial seawater [14]
Optimizing culture conditions is important for improving bacterial enzyme production, and setting up small and pilot fermentation processes provides an important basis for the industrial production of bacterial enzymes
Summary
Particulate organic nitrogen is abundant in marine sediments, and bacterial enzymatic activity in sediments is generally the initial and rate-limiting step in nitrogen recycling [1]. Marine sediments are good resources for exploiting novel proteases with biotechnological potential. CF6-2 is a novel elastase of the M23 family [3,11] These studies indicate that the bacterial proteases from marine sediments usually have some novel characteristics, and may have promosing potential in various industries, such as detergents, food processing and pharmaceutical engineering. Due to its promising biotechnological potential, it is necessary to improve the production of myroilysin for its application. Heterogenous expression, such as in Escherichia coli, is the common way to improve enzyme production [19,20]. The results lay a good foundation for developing the biotechnological potential of myroilysin
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