Microbial Production and Purification of Industrially Important Carbohydrases

Abstract

During commercial baking preparations glucoamylases are used for improvement in flour/dough quality, minimize dough staling, increases efficient machinability. The enzyme is also used to enrich the crust color of bread, bleach flour, enhance quality of high-fiber baked products, and lower the phytate matter in whole-grain foods (Kumar and Satyanarayana, 2008). Glucoamylases have also been used in the pharmaceutical divisions for the manufacture of digestive tablets. As medicinal formulations, the enzyme is used in combinations with various other enzymes such as maltase, peptidase, protease and lipase (Nichols et al., 2009). newlineOne of the most indispensable applications of glucoamylase is in alcohol fermentation industry. The conventional method of ethanol fermentation process involves a two-stage strategy utilizing microbial amylases and glucoamylases. Initially, the starchy materials are liquefied by bacterial amylases followed by saccharification by fungal glucoamylases. Starch rich substrates such as corn, rice, potato, cassava and wheat represents a valuable resource for ethanol production. Although many yeast strains such as Saccharomycopsis buligera, Schwanniomyces alluvius and Candida tropicalis exhibit amylolytic activity, majority of them are incapable to directly consume starch including the S. cerevisiae strains (Jamai et al., 2007). However, most of the glucoamylases reported are from fungi especially from Aspergillus sp. and Rhizopus sp. On the other hand, several fungal glucoamylases explored by far possesses optimal temperature at 60 °C or above, and exhibit low catalytic efficiency at mild or low temperatures. Certain applications in the industrial saccharification processes also prefers glucoamylases with high catalytic activity at lower/ambient temperatures, thereby to conserve energy and prevent thermal denaturation. The cold-adaptive enzymes are applicable in many industrial processes (Carrasco et al., 2017). Therefore, the recent research focuses on identification of unique properties of glucoamylases which could be beneficial for diverse industrial applications. newline