A Review on Microbial Alkaline Proteases: Optimization of Submerged Fermentative Production, Properties, and Industrial Applications

Abstract—Due to the growing need for alkaline proteases in various industrial applications, the preference for microbial sources, such as bacteria and fungi, has surged in comparison to plant and animal-derived alternatives. These microorganisms which can be isolated from natural alkaline habitats have emerged as promising candidates for large-scale industrial production. To meet this demand, greater attention is being given to improving the enzyme yields by optimizing culture conditions employing various approaches, viz., optimization of environmental and nutritional factors, statistical methodologies for screening, strain improvement, etc. Although acidic and neutral proteases are currently in industrial use, this review focuses on alkaline proteases from various sources because of their catalytic abilities at extreme pH values. While acidic proteases do possess distinctive and valuable catalytic capabilities at extreme pH values, they are predominantly utilized in the food industry for specific applications and are primarily produced by fungi, in contrast to alkaline proteases. Considering this, the present review focuses extensively on various environmental and nutritional factors affecting alkaline protease production in submerged fermentation. Additionally, the purification methodologies adopted, and properties of alkaline proteases obtained from different sources are discussed, and the industrial applications of alkaline proteases are also highlighted.