Mathematical model based estimation of volumetric oxygen transfer coefficient(s) in the production of proteolytic enzymes in Bacillus amyloliquefaciens

Abstract

Alkaline protease is a class of important hydrolytic enzymes having wide applications in bioprocess industries. Their optimum pH in the alkaline range and stability at higher temperatures make them ideal in detergent and leather processing industries. These enzymes have excellent depilating capacity. The present study aims at process optimization for the production of alkaline protease from Bacillus amyloliquefaciens ATCC 23844. Information on the optimal operating temperature and pH were elicited from speci®c growth rates and alkaline protease yields. It was also observed that besides pH and temperature, the oxygen transfer rate is another important limiting variable for the production of protease. Volumetric oxygen transfer coef®cient (k L a) was estimated at various impeller speeds and aeration rates. The optimal impeller speed and aeration rates were determined from k L a and the relative protease yield data. It was understood that the oxygen transfer rate is one of the crucial parameters for the production of proteolytic enzymes by B. amyloliquefaciens. List of symbols mkinematic viscosity of the culture broth (m 2 s A1 ) g dynamic viscosity of the culture broth (kg s A1 m A1 ) q density of the culture broth (kg m A3 ) g acceleration due to gravity (m s A2 ) P energy transferred per time unit from the stirrer to the¯uid (N m s A1 ) V volume of the culture (m 3 ) F volumetric gas¯ow rate (m 3 s A1 ) D vessel diameter (m) k L a volumetric oxygen transfer coef®cient (h A1 ) B gasi®cation parameter (dimensionless) (P g /V) à power parameter (dimensionless) k L a à mass transfer parameter (dimensionless)

A two-stage oxygen supply control strategy for enhancing milk-clotting enzyme production by Bacillus amyloliquefaciens

“…This was consistent with the observations of Bajaj and Singhal [25] who reported that higher K L a values enhanced growth, but not poly (c-glutamic acid) (PGA) accumulation in B. licheniformis. Furthermore, Sachidanandham [26] demonstrated that excess dissolved oxygen in the culture medium would lead to the inhibition of protease production. In previous study, metabolite production was influenced by excess availability of dissolved oxygen via the variation of energy metabolism [24].…”

Scale-up of biopesticide production processes using wastewater sludge as a raw material

“…The benefit of small bubbles is the slow rising velocity, which keeps air bubbles in the liquid longer, allowing more time for the oxygen to dissolve [11]. Furthermore, small air bubbles provided a higher interfacial area (a) than large air bubbles [26].…”

“…This could be due to strong shear rates, which could lead to deterioration of the cells and hence the enzyme yield [26].…”

Evaluation of Various Unstructured Kinetic Models for the Production of Protease by Bacillus sphaericus MTTC511

“…Microbial proteases are the important hydrolytic enzymes that have been extensively studied since the advent of enzymology. Commercially produced proteases are of microbial origin and hold around 50 % of the total enzyme market [1]. The proteolytic enzymes produced by Bacillus species have commercial importance such as in detergent, brewing, food, dairy industry and leather industries and have traditionally held the predominant share of the industrial enzyme market.…”

“…There are many papers on the microbial production of protease, but very little information on the kinetic analysis of its production is available in the literature [8,9]. Sachidanandham et al [1] studied the process optimization for the production of alkaline protease from Bacillus amyloliquefaciens ATCC 23844. Information on the optimal operating temperature and pH were elicited from the specific growth rates and alkaline protease yields.…”