Journal of Biotechnology & Biomaterials
Open Access

Microbial enzymes, Microorganisms, Fermentation

Microorganisms have been utilized in meal fermentation since extinct times and fermentation processes are still applied in the preparation of several of the meal items.

1. Microbial enzymes play an important role in meal industries because they're more steady than plant and animal enzymes. They can be generated by means of fermentation strategies in a cost-effective manner with less time and space requirement, and due to their tall consistency, process modification and optimization can be done extremely easily.

2. Countless of these enzymes locate many applications in several industrial sectors, e.g. amylolytic enzymes locate applications in food, detergent, money and textile industries.

3. They're utilized for the making of glucose syrups, crystalline glucose, elevated fructose corn syrups, maltose syrups, etc. In detergent industry, they're utilized as additives to remove starch-based stains. In notes industry, they're utilized for the reduction of starch viscosity for appropriate coating of money [1].

In textile industry, amylases are utilized for warp sizing of textile fibres. Similarly, enzymes love proteases, lipases or xylanases have wide applications in meal sectors. The following sections provide detailed and updated databases about several meal enzymes of microbial origin (Table 1).

Α-Amylases

α-Amylases (EC 3.2.1.1) are starch-degrading enzymes capable of hydrolyzing α-1,4 glycosidic bonds of polysaccharides, which results in the production of short-chain dextrins . These enzymes are widely distributed in all living organisms. Majority of α-amylases are metalloenzymes and require calcium ions for their activity, stability as well as integrity.Wide applications of α-amylases in food industry include baking, brewing, starch liquefaction as well as a digestive aid. They are widely used in baking industry as flavour enhancement and antistaling agent to improve bread quality. During baking, α-amylases are added to the dough for conversion of starch to smaller dextrins, which are subsequently fermented by yeast. It improves the taste, crust colour and toasting qualities of bread.α-Amylases are also used in the manufacture of high-molecular-mass branched dextrins. They are used as a glazing agent for the production of rice cakes and powdery foods. In starch industry, they also find application for starch liquefaction, which converts starch into glucose and fructose syrups. Enzymatic conversion of starch involves three steps: gelatinization, liquefaction and saccharification. Gelatinization involves formation of a viscous suspension by dissolution of starch granules. This is followed by a liquefaction process, which reduces viscosity and involves partial hydrolysis. Glucose and maltose are further produced by saccharification. This requires highly thermostable enzymes and most of the starch saccharification is carried out with α-amylases from Bacillus amyloliquefaciencs, Bacillus stearothermophilus or Bacillus licheniformis .For the production of ethanol, starch is converted to fermentable sugars by the action of α-amylases and further fermentation of the sugars to alcohol is carried out by Saccharomyces cerevisiae. Other applications of α-amylases include clarification of fruit juices, which is carried out in the presence of cellulases and pectinases to improve yield as well as to make the process costeffective [2].

Glucoamylases

Glucoamylases (EC 3.2.1.3) are exo-acting enzymes which catalyze the hydrolysis of polysaccharide starch from the non-reducing end, releasing β-glucose. They are also called saccharifying enzymes and are widely distributed in all living organisms. These enzymes are produced mainly by Aspergillus niger and Aspergillus awamori, but the one produced by Rhizopus oryzae is widely used for industrial applications. Majority of glucoamylases are stable at low temperature. At higher temperatures, they lose activity due to conformational change. Glucoamylases find wide range of applications in food industry, such as for the production of high-glucose syrups and high-fructose syrups. They also find application in baking industry to improve flour quality, reduce dough staling, as well as to improve bread crust colour and the quality of high fibre baked products. Glucoamylases convert the starch present in the flour to maltose and fermentable sugars. Fermentation by yeast leads to dough rise. These enzymes are also used for the production of glucose, which upon fermentation with Saccharomyces cerevisiae yields ethanol. Glucoamylases play an important role in the production of sake and soya sauce, as well as in the production of light beer. They metabolize dextrins and convert them to fermentable sugars with reduced calorific value and alcohol content in the beer [3,4].

Enzymes which catalyze the hydrolysis of peptide bonds present in proteins and polypeptides. They are widely used in detergent and pharmaceutical, followed by food industries. They represent 60% of industrial enzymes on the market. The global demand for protease enzyme market has been growing at a compound annual growth rate (CAGR) of 5.3% during the period 2014-2019. Their demand is expected to increase much further as they find applications in leather processing as well as bioremediation processes. Proteases can be classified based on their origin, catalytic activity and nature of the reactive group in the catalytic site. The major sources of protease enzymes are animals, plant and microorganisms (both bacterial and fungal). Proteases are divided into two groups: exopeptidases and endopeptidases, based on the site of action on polypeptide chains. The exopeptidases act on the ends of polypeptide chains and endopeptidases act randomly in the inner regions of polypeptide chains. The endopeptidases are further classified into six groups, based on the catalytic residue present in the active site: serine, aspartic, cysteine, metallo, glutamic acid and threonine protease. Plant proteases such as bromelain, ficin and papain are widely used in food industry for various applications such as brewing, tenderization of meat, coagulation of milk and as a digestive aid.