Amylolytic Yeasts: Producers of α-amylase and Pullulanase

Amylases are among the most important enzymes used in various industries. They represent approximately 30% of the world enzyme production. These are of ubiquitous occurrence and hold the maximum market share of enzyme sales. These comprise hydrolases, which hydrolyze starch to diverse products as dextrins, and progressively smaller polymers composed of glucose units. They are highly demanded in various arrays such as food, pharmaceuticals, textiles, detergents, etc. However, enzymes from mold and bacterial source have dominated applications in industrial sectors while few species of yeast were studied for the amylases production. This review focuses on the amylolytic yeasts and their enzymes and we were interested at αamylase and pullulanase, their distribution, structural-functional aspects, physical and chemical parameters, and the use of these enzymes in industrial applications. Key-wordsAmylolytic yeast, α-amylase, Pullulanase, Industrial application -------------------------------------------------IJLSSR----------------------------------------------INTRODUCTION Different amylases catalyze the enzymatic hydrolysis of starch as α -amylases (EC3.2.1.1), glucoamylases (EC 3.2.1.3), β-amylases (EC 3.2.1.2.) and debranching enzymes such as pullulanases (EC 3.2.1.41). However, with the advances in biotechnology, the amylase application has expanded in many fields such as clinical, medicinal and analytical chemistry, as well as their widespread application in starch saccharification and in the textile, food, detergent, brewing and distilling industries [1-2]. Although they can be derived from several sources, such as plants, animals and microorganisms, fungi and bacteria have been extensively screened for amylases production [1]. Recently, some amylases from yeasts have been found to have the ability to hydrolyze starch: α-amylase and glucoamylase from Schwanniomyces castelli [3], glucoamylases from S. fibuligera [4] and Candida antarctica [5], α-amylase from Cryptococcus sp. S-2 [6], Access this article online Quick Response Code: Website: www.ijlssr.com DOI: 10.21276/ijlssr.2016.2.4.6 Candida lusitaniae, Candida famata [7], amylopullulanase from Clavispora lusitaniae ABS7 [8] and pullulanase from Aureobasidium pullulans [9]. A number of reviews exist on bacterial and fungal amylases and their applications, however, none specifically covers yeast amylases. α-amylases and pullulanase are one of the most popular and important form of industrial amylases and the present review highlights the various aspects of these yeast amylases. Industrial use yeasts or their enzymes Yeasts are used by humans for thousands of years with wide application, both fundamental and industrial, in science, food, medical and agricultural. Yeasts are traditionally involved in many food fermentations and manufacturing products such as beers, ciders, wines, sake, baked goods, cheese, sausages and other fermented foods. Industrial processes involve long since yeast in the production of fuel ethanol from single cell protein (SCP) for animal feed or industrial enzymes, vaccine production and carotenoids [10-11] (Table 1). The yeast extract is an important nutrient (nitrogen source and intake of essential vitamins group B), particularly favorable to the growth of most microorganisms. Yeasts are also involved in the development of agricultural and industrial waste for the production of proteins, enzymes and "SPC" [12]. The enzymes of yeast are increasingly Review Article (Open access) Int. J. Life. Sci. Scienti. Res., VOL 2, ISSUE 4 http://ijlssr.com IJLSSR © 2015 All rights are reserved Page 340 used in industries to facilitate the process and reduce the energy cost of the finished product particularly in the food industry. The search for new yeast enzymes having an industrial application potential continues to grow. Yeasts such as Pichia pastoris, Saccharomyces cerevisiae and Hansenula polymorpha are currently used for the industrial production of proteins and enzymes, including pharmaceutical proteins [13]. The yeast Yarwinia lipolytica and Rhodotorula glutinis are used due to their ability to produce lipase in petroleum industries, laundry, detergent industry and the IAA [14]. Table 1: Industrial Enzymes produced by yeasts [13,15-16] Enzyme Yeasts Industry Chymosine Klyveromyces sp. Food processing Saccharomyces cerevisiae Galactosidase Saccharomyces sp. Food applications Glutaminase Zygosaccharomyces rouxii Therapeutic analysis Inulinases Candida sp. Food applications Klyveromyces marxianus Invertase Saccharomyces cerevisiae Food applications Lactase Candida pseudotropicalis Food processing