Biotechnological potential of microbial α-galactosidases

The enzyme alpha-galactosidase (alpha-D-galactoside galactohydrolase; EC 3.2.1.22) catalyzes the hydrolysis of alpha-1,6-linked galactose residues in oligosaccharides and polymeric galactomannan. The alpha-galactosidases are of particular interest in view of their many potential biotechnological and medical applications. These enzymes have found wide use in various industries such as food and feed, sugar and paper and pulp for the removal of raffinose and stachyose. They are also important medically for blood group conversion and in the treatment of Fabry disease. Most of the research on alpha-galactosidases has focused on their isolation from various microbial sources. In the last decade, cloning of novel alpha-galactosidase genes and their heterologous expression has gained momentum. The present review focuses on the production of alpha-galactosidases from bacteria, fungi and yeast, and discusses their properties. Recent progress on cloning and heterologous expression in various hosts is summarized with special emphasis on their application in various fields.