ABSTRACT
Microbial proteases are among the most important hydrolytic enzymes and have been studied extensively since the advent of enzymology. There is renewed interest in the study of proteolytic enzymes, which not only play an important role in the cellular metabolic process but have also gained considerable attention in the industrial community. Moreover, proteases are the most important category of industrial enzymes, accounting for more than 65% of the total industrial enzyme market (Banik et al. 2004). Microbial proteases are a group of enzymes that can have application in numerous industries (Gulrajani et al. 2000; Gupta et al. 2002; Naja… et al. 2005; Prakash et al. 2005), and they are important tools in medical and pharmaceutical processes (Bhaskar et al. 2007; In et al. 2002). In the food-processing industry, the proteolytic activity of microorganisms is associated with a wide variety of processes such as fermented foods (Casaburi et al. 2008; Hayashi et al. 1990; Mauriello et al. 2002; Oneca et al. 2007), oil extraction (Kashyap et al. 2007), bakery (Lauer et al. 2000), clari…cation of juices (Dawes et al. 1994), and waste treatments (Sudeepa et al. 2007; Wang et al. 1997). Bacteria, molds, and yeast are some of the microorganisms that are able to produce proteases. Microorganisms elaborate a large array of proteases, which are intracellular and/or extracellular. Intracellular proteases are important for various cellular and metabolic processes, such as sporulations, differentiation protein turnover, maturation of enzymes and hormones, and maintenance of the cellular protein pool. The extracellular ones are important for protein hydrolysis in cell free environments and able the cell to absorb and utilize hydrolytic products. At the same time, these extracellular proteases have also been commercially exploited to assist protein degradation in various industrial processes (Salem et al. 2009). Microbes represent an excellent protease source due to their broad biochemical diversity (Godfrey and West 1996), their rapid growth, the limited space,
45.1 Sources of Commercial Proteolytic Bacteria and Applications .................................................. 731 45.2 Proteolytic Activity of Bacteria Isolated from Fresh and Fermented Vegetables ....................... 732
45.2.1 Isolation and Characterization of Proteolytic Bacteria from Fresh and Fermented Cabbage ........................................................................................................................... 732
45.2.2 Characterization of Bacillus cereus Isolated from Fermented Cabbage and Conventional Optimization of Extracellular Protease Production .................................. 734
45.2.3 Simultaneous Optimization of Biomass and Protease Biosynthesis by a Local Isolated Pseudomonas sp. ............................................................................................... 740 45.2.3.1 Selection of Main Medium Components and Operating Conditions .............. 740 45.2.3.2 Response Surface Optimization Using Box-Behnken Design ........................ 746
45.2.4 Conclusions ...................................................................................................................... 751 45.3 Use of Proteolytic Bacteria in Food Processing .......................................................................... 752 References .............................................................................................................................................. 753
or strain has its own special conditions for maximum enzyme production. Extracellular protease production by microorganisms is highly in”uenced by media components, variation in carbon/nitrogen ratio, presence of some easily metabolizable sugars, such as glucose (Beg et al. 2003), and presence of metal ions (Secades et al. 1999). Several others factors, such as aeration, inoculums density, pH, temperature, and incubation time also affect the amount of protease production and their interaction plays an important role in the synthesis of these enzymes (Puri et al. 2002).
