Enzymes are biocatalysts that play an important role at all stages of metabolism and biochemical reactions. They are of particular interest and are used as organic catalysts in numerous industrial scale processes. This article provides an overview of microbial enzymes and their classification.
Introduction
Different bioindustries require enzymes with specific characteristics for their use in the processing of substrates and raw materials. Microbial enzymes act as biocatalysts to carry out reactions in biological processes in an economical and environmentally friendly manner compared to the use of chemical catalysts. Their special characteristics are used for commercial interest and industrial applications. Enzymes are very specific, they catalyze about 4000 biochemical reactions. Nobel laureate Emil Fischer suggested that this is because both the enzyme and the substrate have specific complementary geometries that are preciselyfit into each other.
Definition
Enzymes are large biological molecules responsible for all those important chemical interchanges that are necessary to sustain life. They are highly selective catalysts that can greatly accelerate both the rate and specificity of metabolic reactions that range from food digestion to DNA synthesis. All metabolic processes occurring in them depend on what enzymes are formed in the cells of microorganisms.
History
In 1877, Wilhelm Friedrich Kuehne, professor of physiology at the University of Heidelberg, first used the term "enzyme", which comes from the Latin word fermentum, meaning "in leaven". Obtaining enzymes of microorganisms began in ancient Greece. They were used to preserve food and drink.
In 1783, the famous Italian Catholic priest Lazzaro Spallanzani first mentioned the importance of this biomolecule in his work on biogenesis.
In 1812, Gottlieb Sigismund Kirchhoff investigated the procedure for converting starch into glucose. In his experiment, he highlights the use of enzymes as a catalyst.
In 1833, French chemist Anselm Payen discovered the first enzyme, diastase.
Decades later, in 1862, while studying the fermentation of sugar to alcohol, Louis Pasteur came to the conclusion that it was catalyzed by the life force contained in the yeast cells.
Biomolecules found in naturehave been widely used since ancient times in the manufacture of products such as linen, leather and indigo. All these processes were caused by microorganisms - enzyme producers.
Meaning
Enzymes are needed to facilitate chemical reactions. Their role in the life of microorganisms is very important. It consists in ensuring metabolic processes, respiration, digestion and other types of life. When enzymes function properly, homeostasis is maintained. Another role of enzymes in microorganisms is to speed up metabolism.
Special Features
Microorganism enzyme properties include:
- heat resistance;
- thermophilic nature;
- tolerance to changing pH range;
- activity stability when changing temperatures and pH;
- other stringent reaction conditions.
They are classified as thermophilic, acidophilic or alkaliphilic. Microorganisms with thermostable enzyme systems reduce the possibility of microbial contamination in large scale industrial reactions of long duration. Microbial enzymes help in increasing mass transfer and reducing the viscosity of the substrate during the hydrolysis process of the raw material.
Classification
Because of the wide range of activities based on the nature of their reaction, enzymes are classified according to catalysis:
- Oxidoreductases. Oxidation reactions involve the transfer of electrons from a single moleculeto another. In biological systems, this is the removal of hydrogen from the substrate.
- Transferases. This class of enzymes catalyzes the transfer of groups of atoms from one molecule to another. Aminotransferases or transaminases facilitate the transfer of an amino group from an amino acid to an alpha-oxo acid.
- Hydrolases. Catalyze hydrolysis, splitting of substrates with water. The reactions include the cleavage of peptide bonds in proteins, glycosidic bonds in carbohydrates, and ester bonds in lipids. Generally, larger molecules break down into smaller fragments.
- Liase. Catalyze the addition of groups to double bonds or the formation of the latter by removing the former. For example, pectate lyases cleave glycosidic bonds by beta elimination.
- Isomerases. They catalyze the transfer of groups from one position to another in the same molecule. Change the structure of the substrate, rearranging its atoms.
- Ligases. Connect molecules together with covalent bonds. They participate in biosynthetic reactions, where new bond groups are formed. Such reactions require an input of energy in the form of cofactors.
Application
Fermentation is used in the preparation of many foods. The use of microbial enzymes in the food industry is a long-standing process. The following types are widely used:
- Amylase. Liquefaction of starch, improvement of bread quality, clarification of fruit juices.
- Glucoamylases. Production of beer and syrups with high glucose and fructose content.
- Protease. Tenderizationmeat, milk coagulation.
- Lactase. Reduction of lactose intolerance in humans, prebiotic nutritional supplements.
- Lipase. Production of cheddar cheese.
- Phospholipases. Production of lipolyzed milk fat.
- Esterase. Improvement of taste and aroma in fruit juice. Deesterification of dietary fiber. Production of short chain esters.
- Cellulases. Animal feed.
- Glucose oxidase. Improving food shelf life.
- Laccases. Removal of polyphenols from wine.
- Catalases. Food preservation. Removal of hydrogen peroxide from milk prior to cheese production.
- Peroxidase. Development of taste, color and quality of food.
Protease
Proteases derived from microbial systems are of three types: acidic, neutral and alkaline. Alkaline serine proteases have the greatest application in the bioindustry. They have high activity and stability under abnormal conditions of extreme physiological parameters. Alkaline proteases have the property of high stability of enzymatic activity when used in detergents. They have found wide application in the bioindustry:
- production of washing powders;
- food industry;
- leather processing;
- pharmaceuticals;
- research in molecular biology and peptide synthesis.
Amylase
This is an enzyme of microorganisms that catalyzes the breakdown of starch into sugars. He wasdiscovered and isolated by Anselm Peyen in 1833. All amylases are glycoside hydrolases. They are widely used in industry and account for nearly 25% of the enzyme market. Used in industries such as:
- food;
- bakery;
- paper and textile;
- sweeteners and fruit juices;
- glucose and fructose syrups;
- detergents;
- fuel ethanol from starches;
- alcoholic drinks;
- digestive aid;
- stain remover in dry cleaning.
Also used in clinical, medical and analytical chemistry.
Xylanase
Hemicellulose is one of the main constituents of agricultural residues along with cellulose, lignin and pectin. Xylan is its main component. The importance of xylanase has increased significantly due to its biotechnological applications for the production of pentose, the purification of fruit juices, the improvement of digestion, and the bioconversion of lignocellulosic agricultural waste into fuels and chemicals. It has found its application in the food, textile and pulp and paper industries, agricultural waste disposal, ethanol production and animal feed.
Laccase
Liginolytic enzymes are useful in the hydrolysis of lignocellulosic agricultural residues, especially for the degradation of the complex and non-pumping constituent lignin. They are very versatile in nature and can be used in a number of industrial processes. The lignolytic enzyme system is used in cellulose biodecoloration and other industries such as wine and fruit juice stabilization, denim laundering, cosmetics and biosensors.
Lipase
This is an enzyme of microorganisms that catalyzes the breakdown and hydrolysis of fats. Lipases are a subclass of esterases. They play a significant role in digestion, transport and processing of fats. Most of the lipases are involved in a certain position on the glycerol backbone of the fatty substrate, especially in the small intestine. Some of them are expressed by secreted pathogenic organisms during an infectious disease. Lipases are considered the main group of biotechnologically valuable enzymes, mainly due to the versatility of their applied properties and ease of mass production.
Lipase application
These enzymes are involved in a variety of biological processes, ranging from routine triglyceride metabolism in the diet to signaling and cell inflammation. Some lipase activities are restricted to certain compartments within cells, while others work in extracellular spaces:
- Pancreatic lipases are secreted into extracellular spaces where they serve to convert dietary lipids into simpler forms that are transported throughout the body.
- Facilitate the absorption of nutrients from the environment.
- Increased lipase activity replacesconventional catalysts in biodiesel processing.
- Used in areas such as baking, laundry detergents, as biocatalysts.
- In the textile industry, it is used to increase the absorbency of the fabric and evenness when dyeing.
- To modify food taste by synthesizing esters of short chain fatty acids and alcohols.
- The presence or high levels of lipases may indicate a specific infection or disease and can be used as a diagnostic tool.
- Have a bactericidal effect. Can be used in the treatment of malignant tumors.
- Have great commercial value in cosmetics and pharmaceuticals (skin care products, hair curlers).
