Exoenzyme

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Organelles of the secretory pathway involved in the secretion of exoenzymes Organelles of the Secretory Pathway.png
Organelles of the secretory pathway involved in the secretion of exoenzymes

An exoenzyme, or extracellular enzyme, is an enzyme that is secreted by a cell and functions outside that cell. Exoenzymes are produced by both prokaryotic and eukaryotic cells and have been shown to be a crucial component of many biological processes. Most often these enzymes are involved in the breakdown of larger macromolecules. The breakdown of these larger macromolecules is critical for allowing their constituents to pass through the cell membrane and enter into the cell. For humans and other complex organisms, this process is best characterized by the digestive system which breaks down solid food [1] via exoenzymes. The small molecules, generated by the exoenzyme activity, enter into cells and are utilized for various cellular functions. Bacteria and fungi also produce exoenzymes to digest nutrients in their environment, and these organisms can be used to conduct laboratory assays to identify the presence and function of such exoenzymes. [2] Some pathogenic species also use exoenzymes as virulence factors to assist in the spread of these disease-causing microorganisms. [3] In addition to the integral roles in biological systems, different classes of microbial exoenzymes have been used by humans since pre-historic times for such diverse purposes as food production, biofuels, textile production and in the paper industry. [4] Another important role that microbial exoenzymes serve is in the natural ecology and bioremediation of terrestrial and marine [5] environments.

Contents

History

Very limited information is available about the original discovery of exoenzymes. According to Merriam-Webster dictionary, the term "exoenzyme" was first recognized in the English language in 1908. [6] The book "Intracellular Enzymes: A Course of Lectures Given in the Physiological," by Horace Vernon is thought to be the first publication using this word in that year. [7] Based on the book, it can be assumed that the first known exoenzymes were pepsin and trypsin, as both are mentioned by Vernon to have been discovered by scientists Briike and Kiihne before 1908. [8]

Function

In bacteria and fungi, exoenzymes play an integral role in allowing the organisms to effectively interact with their environment. Many bacteria use digestive enzymes to break down nutrients in their surroundings. Once digested, these nutrients enter the bacterium, where they are used to power cellular pathways with help from endoenzymes. [9]

Many exoenzymes are also used as virulence factors. Pathogens, both bacterial and fungal, can use exoenzymes as a primary mechanism with which to cause disease.[ citation needed ] The metabolic activity of the exoenzymes allows the bacterium to invade host organisms by breaking down the host cells' defensive outer layers or by necrotizing body tissues of larger organisms. [3] Many gram-negative bacteria have injectisomes, or flagella-like projections, to directly deliver the virulent exoenzyme into the host cell using a type three secretion system. [10] With either process, pathogens can attack the host cell's structure and function, as well as its nucleic DNA. [11]

In eukaryotic cells, exoenzymes are manufactured like any other enzyme via protein synthesis, and are transported via the secretory pathway. After moving through the rough endoplasmic reticulum, they are processed through the Golgi apparatus, where they are packaged in vesicles and released out of the cell. [12] In humans, a majority of such exoenzymes can be found in the digestive system and are used for metabolic breakdown of macronutrients via hydrolysis. Breakdown of these nutrients allows for their incorporation into other metabolic pathways. [13]

Examples of exoenzymes as virulence factors

Source: [3]

Microscopic view of necrotizing fasciitis as caused by Streptococcus pyogenes Necrotizing fasciitis - intermed mag.jpg
Microscopic view of necrotizing fasciitis as caused by Streptococcus pyogenes

Necrotizing enzymes

Necrotizing enzymes destroy cells and tissue. One of the best known examples is an exoenzyme produced by Streptococcus pyogenes that causes necrotizing fasciitis in humans.

Coagulase

By binding to prothrombin, coagulase facilitates clotting in a cell by ultimately converting fibrinogen to fibrin. Bacteria such as Staphylococcus aureus use the enzyme to form a layer of fibrin around their cell to protect against host defense mechanisms.

Fibrin layer formed by Staphylococcus aureus Staphylococcus aureus, 50,000x, USDA, ARS, EMU.jpg
Fibrin layer formed by Staphylococcus aureus

Kinases

The opposite of coagulase, kinases can dissolve clots. S. aureus can also produce staphylokinase, allowing them to dissolve the clots they form, to rapidly diffuse into the host at the correct time. [14]

Hyaluronidase

Similar to collagenase, hyaluronidase enables a pathogen to penetrate deep into tissues. Bacteria such as Clostridium do so by using the enzyme to dissolve collagen and hyaluronic acid, the protein and saccharides, respectively, that hold tissues together.

Hemolysins

Hemolysins target erythrocytes, a.k.a. red blood cells. Attacking and lysing these cells harms the host organism, and provides the microorganism, such as the fungus Candida albicans , with a source of iron from the lysed hemoglobin. [15] Organisms can either by alpha-hemolytic, beta-hemolytic, or gamma-hemolytic (non-hemolytic).

Examples of digestive exoenzymes

Amylases

Pancreatic alpha-amylase 1HNY Pancreatic alpha-amylase 1HNY.png
Pancreatic alpha-amylase 1HNY

Amylases are a group of extracellular enzymes (glycoside hydrolases) that catalyze the hydrolysis of starch into maltose. These enzymes are grouped into three classes based on their amino acid sequences, mechanism of reaction, method of catalysis and their structure. [16] The different classes of amylases are α-amylases, β-amylases, and glucoamylases. The α-amylases hydrolyze starch by randomly cleaving the 1,4-a-D-glucosidic linkages between glucose units, β-amylases cleave non-reducing chain ends of components of starch such as amylose, and glucoamylases hydrolyze glucose molecules from the ends of amylose and amylopectin. [17] Amylases are critically important extracellular enzymes and are found in plants, animals, and microorganisms. In humans, amylases are secreted by the pancreas and salivary glands, with both sources of the enzyme required for complete starch hydrolysis. [18]

Lipoprotein lipase

Lipoprotein lipase (LPL) is a type of digestive enzyme that helps regulate the uptake of triacylglycerols from chylomicrons and other low-density lipoproteins from fatty tissues in the body. [19] The exoenzymatic function allows it to break down the triacylglycerol into two free fatty acids and one molecule of monoacylglycerol. LPL can be found in endothelial cells in fatty tissues, such as adipose, cardiac, and muscle. [19] Lipoprotein lipase is downregulated by high levels of insulin, [20] and upregulated by high levels of glucagon and adrenaline. [19]

Pectinase

Pectinases, also called pectolytic enzymes, are a class of exoenzymes that are involved in the breakdown of pectic substances, most notably pectin. [21] Pectinases can be classified into two different groups based on their action against the galacturonan backbone of pectin: de-esterifying and depolymerizing. [22] These exoenzymes can be found in both plants and microbial organisms including fungi and bacteria. [23] Pectinases are most often used to break down the pectic elements found in plants and plant-derived products.

Pepsin

Discovered in 1836, pepsin was one of the first enzymes to be classified as an exoenzyme. [8] The enzyme is first made in the inactive form, pepsinogen by chief cells in the lining of the stomach. [24] With an impulse from the vagus nerve, pepsinogen is secreted into the stomach, where it mixes with hydrochloric acid to form pepsin. [25] Once active, pepsin works to break down proteins in foods such as dairy, meat, and eggs. [24] Pepsin works best at the pH of gastric acid, 1.5 to 2.5, and is deactivated when the acid is neutralized to a pH of 7. [24]

Trypsin

Also one of the first exoenzymes to be discovered, trypsin was named in 1876, forty years after pepsin. [26] This enzyme is responsible for the breakdown of large globular proteins and its activity is specific to cleaving the C-terminal sides of arginine and lysine amino acid residues. [26] It is the derivative of trypsinogen, an inactive precursor that is produced in the pancreas. [27] When secreted into the small intestine, it mixes with enterokinase to form active trypsin. Due to its role in the small intestine, trypsin works at an optimal pH of 8.0. [28]

Bacterial assays

Amylase test results.png
Lipase Assay.png
Results of bacterial assays. Left:amylase bacterial assay on a starch medium. A indicates a positive result, D indicates a negative result. Right: lipase bacterial assay on an olive oil medium. 1 shows a positive result, 3 shows a negative result

The production of a particular digestive exoenzyme by a bacterial cell can be assessed using plate assays. Bacteria are streaked across the agar, and are left to incubate. The release of the enzyme into the surroundings of the cell cause the breakdown of the macromolecule on the plate. If a reaction does not occur, this means that the bacteria does not create an exoenzyme capable of interacting with the surroundings. If a reaction does occur, it becomes clear that the bacteria does possess an exoenzyme, and which macromolecule is hydrolyzed determines its identity. [2]

Amylase

Amylase breaks down carbohydrates into mono- and disaccharides, so a starch agar must be used for this assay. Once the bacteria is streaked on the agar, the plate is flooded with iodine. Since iodine binds to starch but not its digested by-products, a clear area will appear where the amylase reaction has occurred. Bacillus subtilis is a bacterium that results in a positive assay as shown in the picture. [2]

Lipase

Lipase assays are done using a lipid agar with a spirit blue dye. If the bacteria has lipase, a clear streak will form in the agar, and the dye will fill the gap, creating a dark blue halo around the cleared area. Staphylococcus epidermidis results in a positive lipase assay. [2]

Biotechnological and industrial applications

Microbiological sources of exoenzymes including amylases, proteases, pectinases, lipases, xylanases, and cellulases are used for a wide range of biotechnological and industrial uses including biofuel generation, food production, paper manufacturing, detergents and textile production. [4] Optimizing the production of biofuels has been a focus of researchers in recent years and is centered around the use of microorganisms to convert biomass into ethanol. The enzymes that are of particular interest in ethanol production are cellobiohydrolase which solubilizes crystalline cellulose and xylanase that hydrolyzes xylan into xylose. [29] One model of biofuel production is the use of a mixed population of bacterial strains or a consortium that work to facilitate the breakdown of cellulose materials into ethanol by secreting exoenzymes such as cellulases and laccases. [29] In addition to the important role it plays in biofuel production, xylanase is utilized in a number of other industrial and biotechnology applications due to its ability to hydrolyze cellulose and hemicellulose. These applications include the breakdown of agricultural and forestry wastes, working as a feed additive to facilitate greater nutrient uptake by livestock, and as an ingredient in bread making to improve the rise and texture of the bread. [30]

Generic Biodiesel Reaction. Lipases can serve as a biocatalyst in this reaction Generic Biodiesel Reaction1.gif
Generic Biodiesel Reaction. Lipases can serve as a biocatalyst in this reaction

Lipases are one of the most used exoenzymes in biotechnology and industrial applications. Lipases make ideal enzymes for these applications because they are highly selective in their activity, they are readily produced and secreted by bacteria and fungi, their crystal structure is well characterized, they do not require cofactors for their enzymatic activity, and they do not catalyze side reactions. [31] The range of uses of lipases encompasses production of biopolymers, generation of cosmetics, use as a herbicide, and as an effective solvent. [31] However, perhaps the most well known use of lipases in this field is its use in the production of biodiesel fuel. In this role, lipases are used to convert vegetable oil to methyl- and other short-chain alcohol esters by a single transesterification reaction. [32]

Cellulases, hemicellulases and pectinases are different exoenzymes that are involved in a wide variety of biotechnological and industrial applications. In the food industry these exoenzymes are used in the production of fruit juices, fruit nectars, fruit purees and in the extraction of olive oil among many others. [33] The role these enzymes play in these food applications is to partially breakdown the plant cell walls and pectin. In addition to the role they play in food production, cellulases are used in the textile industry to remove excess dye from denim, soften cotton fabrics, and restore the color brightness of cotton fabrics. [33] Cellulases and hemicellulases (including xylanases) are also used in the paper and pulp industry to de-ink recycled fibers, modify coarse mechanical pulp, and for the partial or complete hydrolysis of pulp fibers. [33] Cellulases and hemicellulases are used in these industrial applications due to their ability to hydrolyze the cellulose and hemicellulose components found in these materials.

Bioremediation applications

Water pollution from runoff of soil and fertilizer Runoff of soil & fertilizer.jpg
Water pollution from runoff of soil and fertilizer

Bioremediation is a process in which pollutants or contaminants in the environment are removed through the use of biological organisms or their products. The removal of these often hazardous pollutants is mostly carried out by naturally occurring or purposely introduced microorganisms that are capable of breaking down or absorbing the desired pollutant. The types of pollutants that are often the targets of bioremediation strategies are petroleum products (including oil and solvents) and pesticides. [34] In addition to the microorganisms ability to digest and absorb the pollutants, their secreted exoenzymes play an important role in many bioremediation strategies. [35]

Fungi have been shown to be viable organisms to conduct bioremediation and have been used to aid in the decontamination of a number of pollutants including polycyclic aromatic hydrocarbons (PAHs), pesticides, synthetic dyes, chlorophenols, explosives, crude oil, and many others. [36] While fungi can breakdown many of these contaminants intracellularly, they also secrete numerous oxidative exoenzymes that work extracellularly. One critical aspect of fungi in regards to bioremediation is that they secrete these oxidative exoenzymes from their ever elongating hyphal tips. [36] Laccases are an important oxidative enzyme that fungi secrete and use oxygen to oxidize many pollutants. Some of the pollutants that laccases have been used to treat include dye-containing effluents from the textile industry, wastewater pollutants (chlorophenols, PAHs, etc.), and sulfur-containing compounds from coal processing. [36]

Exocytic vesicles move along actin microfilaments toward the fungal hyphal tip where they release their contents including exoenzymes A simplified model for myosin V (MyoE) function at the hyphal tip in Aspergillus nidulans - journal.pone.0031218.g009A.png
Exocytic vesicles move along actin microfilaments toward the fungal hyphal tip where they release their contents including exoenzymes

Bacteria are also a viable source of exoenzymes capable of facilitating the bioremediation of the environment. There are many examples of the use of bacteria for this purpose and their exoenzymes encompass many different classes of bacterial enzymes. Of particular interest in this field are bacterial hydrolases as they have an intrinsic low substrate specificity and can be used for numerous pollutants including solid wastes. [37] Plastic wastes including polyurethanes are particularly hard to degrade, but an exoenzyme has been identified in a Gram-negative bacterium, Comamonas acidovorans, that was capable of degrading polyurethane waste in the environment. [37] Cell-free use of microbial exoenzymes as agents of bioremediation is also possible although their activity is often not as robust and introducing the enzymes into certain environments such as soil has been challenging. [37] In addition to terrestrial based microorganisms, marine based bacteria and their exoenzymes show potential as candidates in the field of bioremediation. Marine based bacteria have been utilized in the removal of heavy metals, petroleum/diesel degradation and in the removal of polyaromatic hydrocarbons among others. [38]

Related Research Articles

Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. Mechanical digestion takes place in the mouth through mastication and in the small intestine through segmentation contractions. In chemical digestion, enzymes break down food into the small compounds that the body can use.

A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism. It can also cover substances that are present in much higher concentrations than are usual. Natural compounds can also become xenobiotics if they are taken up by another organism, such as the uptake of natural human hormones by fish found downstream of sewage treatment plant outfalls, or the chemical defenses produced by some organisms as protection against predators. The term "xenobiotic" is also used to refer to organs transplanted from one species to another.

<span class="mw-page-title-main">Bioremediation</span> Process used to treat contaminated media such as water and soil

Bioremediation broadly refers to any process wherein a biological system, living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluents etc., in natural or artificial settings. The natural ability of organisms to adsorb, accumulate, and degrade common and emerging pollutants has attracted the use of biological resources in treatment of contaminated environment. In comparison to conventional physicochemical treatment methods bioremediation may offer advantages as it aims to be sustainable, eco-friendly, cheap, and scalable.

<span class="mw-page-title-main">Digestive enzyme</span> Class of enzymes

Digestive enzymes take part in the chemical process of digestion, which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes in the mouth, stomach, pancreas, and duodenum, before being able to be absorbed into the bloodstream. Initial breakdown is achieved by chewing (mastication) and the use of digestive enzymes of saliva. Once in the stomach further mechanical churning takes place mixing the food with secreted gastric acid. Digestive gastric enzymes take part in some of the chemical process needed for absorption. Most of the enzymatic activity, and hence absorption takes place in the duodenum.

Endo-1,4-β-xylanase is any of a class of enzymes that degrade the linear polysaccharide xylan into xylose, thus breaking down hemicellulose, one of the major components of plant cell walls:

<i>Halobacterium</i> Genus of archaea

Halobacterium is a genus in the family Halobacteriaceae.

Industrial fermentation is the intentional use of fermentation in manufacturing processes. In addition to the mass production of fermented foods and drinks, industrial fermentation has widespread applications in chemical industry. Commodity chemicals, such as acetic acid, citric acid, and ethanol are made by fermentation. Moreover, nearly all commercially produced industrial enzymes, such as lipase, invertase and rennet, are made by fermentation with genetically modified microbes. In some cases, production of biomass itself is the objective, as is the case for single-cell proteins, baker's yeast, and starter cultures for lactic acid bacteria used in cheesemaking.

Microbial genetics is a subject area within microbiology and genetic engineering. Microbial genetics studies microorganisms for different purposes. The microorganisms that are observed are bacteria and archaea. Some fungi and protozoa are also subjects used to study in this field. The studies of microorganisms involve studies of genotype and expression system. Genotypes are the inherited compositions of an organism. Genetic Engineering is a field of work and study within microbial genetics. The usage of recombinant DNA technology is a process of this work. The process involves creating recombinant DNA molecules through manipulating a DNA sequence. That DNA created is then in contact with a host organism. Cloning is also an example of genetic engineering.

<span class="mw-page-title-main">Glycoside hydrolase</span> Class of enzymes which break glycosidic bonds via hydrolysis

In biochemistry, glycoside hydrolases are a class of enzymes which catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes, with roles in nature including degradation of biomass such as cellulose (cellulase), hemicellulose, and starch (amylase), in anti-bacterial defense strategies, in pathogenesis mechanisms and in normal cellular function. Together with glycosyltransferases, glycosidases form the major catalytic machinery for the synthesis and breakage of glycosidic bonds.

Neocallimastigomycota is a phylum containing anaerobic fungi, which are symbionts found in the digestive tracts of larger herbivores. Anaerobic fungi were originally placed within phylum Chytridiomycota, within Order Neocallimastigales but later raised to phylum level, a decision upheld by later phylogenetic reconstructions. It encompasses only one family.

Microbial biodegradation is the use of bioremediation and biotransformation methods to harness the naturally occurring ability of microbial xenobiotic metabolism to degrade, transform or accumulate environmental pollutants, including hydrocarbons, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), heterocyclic compounds, pharmaceutical substances, radionuclides and metals.

<span class="mw-page-title-main">Extracellular polymeric substance</span> Gluey polymers secreted by microorganisms to form biofilms

Extracellular polymeric substances (EPSs) are natural polymers of high molecular weight secreted by microorganisms into their environment. EPSs establish the functional and structural integrity of biofilms, and are considered the fundamental component that determines the physicochemical properties of a biofilm. EPS in the matrix of biofilms provides compositional support and protection of microbial communities from the harsh environments. Components of EPS can be of different classes of polysaccharides, lipids, nucleic acids, proteins, lipopolysaccharides, and minerals.

<span class="mw-page-title-main">Phototrophic biofilm</span> Microbial communities including microorganisms which use light as their energy source

Phototrophic biofilms are microbial communities generally comprising both phototrophic microorganisms, which use light as their energy source, and chemoheterotrophs. Thick laminated multilayered phototrophic biofilms are usually referred to as microbial mats or phototrophic mats. These organisms, which can be prokaryotic or eukaryotic organisms like bacteria, cyanobacteria, fungi, and microalgae, make up diverse microbial communities that are affixed in a mucous matrix, or film. These biofilms occur on contact surfaces in a range of terrestrial and aquatic environments. The formation of biofilms is a complex process and is dependent upon the availability of light as well as the relationships between the microorganisms. Biofilms serve a variety of roles in aquatic, terrestrial, and extreme environments; these roles include functions which are both beneficial and detrimental to the environment. In addition to these natural roles, phototrophic biofilms have also been adapted for applications such as crop production and protection, bioremediation, and wastewater treatment.

<span class="mw-page-title-main">Lipase</span> Class of enzymes which cleave fats via hydrolysis

In biochemistry, lipase refers to a class of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; however, these are usually treated separately from "conventional" lipases. Unlike esterases, which function in water, lipases "are activated only when adsorbed to an oil–water interface". Lipases perform essential roles in digestion, transport and processing of dietary lipids in most, if not all, organisms.

Fibrolytic bacteria constitute a group of microorganisms that are able to process complex plant polysaccharides thanks to their capacity to synthesize cellulolytic and hemicellulolytic enzymes. Polysaccharides are present in plant cellular cell walls in a compact fiber form where they are mainly composed of cellulose and hemicellulose.

<span class="mw-page-title-main">Fungal extracellular enzyme activity</span> Enzymes produced by fungi and secreted outside their cells

Extracellular enzymes or exoenzymes are synthesized inside the cell and then secreted outside the cell, where their function is to break down complex macromolecules into smaller units to be taken up by the cell for growth and assimilation. These enzymes degrade complex organic matter such as cellulose and hemicellulose into simple sugars that enzyme-producing organisms use as a source of carbon, energy, and nutrients. Grouped as hydrolases, lyases, oxidoreductases and transferases, these extracellular enzymes control soil enzyme activity through efficient degradation of biopolymers.

Penicillium occitanis is a species of fungus in the genus Penicillium which produces cellulase and pectinase. The mutant Pol6 produces a very high amount of cellulase and pectinase. This mutant might be used for industrial use.

<i>Rhizopus oryzae</i> Species of fungus

Rhizopus oryzae is a filamentous heterothallic microfungus that occurs as a saprotroph in soil, dung, and rotting vegetation. This species is very similar to Rhizopus stolonifer, but it can be distinguished by its smaller sporangia and air-dispersed sporangiospores. It differs from R. oligosporus and R. microsporus by its larger columellae and sporangiospores. The many strains of R. oryzae produce a wide range of enzymes such as carbohydrate digesting enzymes and polymers along with a number of organic acids, ethanol and esters giving it useful properties within the food industries, bio-diesel production, and pharmaceutical industries. It is also an opportunistic pathogen of humans causing mucormycosis.

Thermomyces lanuginosus is a species of thermophilic fungus that belongs to Thermomyces, a genus of hemicellulose degraders. It is classified as a deuteromycete and no sexual form has ever been observed. It is the dominant fungus of compost heaps, due to its ability to withstand high temperatures and use complex carbon sources for energy. As the temperature of compost heaps rises and the availability of simple carbon sources decreases, it is able to out compete pioneer microflora. It plays an important role in breaking down the hemicelluloses found in plant biomass due to the many hydrolytic enzymes that it produces, such as lipolase, amylase, xylanase, phytase, and chitinase. These enzymes have chemical, environmental, and industrial applications due to their hydrolytic properties. They are used in the food, petroleum, pulp and paper, and animal feed industries, among others. A few rare cases of endocarditis due to T. lanuginosus have been reported in humans.

Bioremediation of petroleum contaminated environments is a process in which the biological pathways within microorganisms or plants are used to degrade or sequester toxic hydrocarbons, heavy metals, and other volatile organic compounds found within fossil fuels. Oil spills happen frequently at varying degrees along with all aspects of the petroleum supply chain, presenting a complex array of issues for both environmental and public health. While traditional cleanup methods such as chemical or manual containment and removal often result in rapid results, bioremediation is less labor-intensive, expensive, and averts chemical or mechanical damage. The efficiency and effectiveness of bioremediation efforts are based on maintaining ideal conditions, such as pH, RED-OX potential, temperature, moisture, oxygen abundance, nutrient availability, soil composition, and pollutant structure, for the desired organism or biological pathway to facilitate reactions. Three main types of bioremediation used for petroleum spills include microbial remediation, phytoremediation, and mycoremediation. Bioremediation has been implemented in various notable oil spills including the 1989 Exxon Valdez incident where the application of fertilizer on affected shoreline increased rates of biodegradation.

References

  1. ↑ Kong F, Singh RP (June 2008). "Disintegration of solid foods in human stomach". Journal of Food Science. 73 (5): R67–80. doi: 10.1111/j.1750-3841.2008.00766.x . PMID   18577009.
  2. 1 2 3 4 Roberts, K. "Exoenzymes". Prince George's Community College. Archived from the original on 13 June 2013. Retrieved 8 December 2013.
  3. 1 2 3 Duben-Engelkirk, Paul G. Engelkirk, Janet (2010). Burton's microbiology for the health sciences (9th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. pp. 173–174. ISBN   9781605476735.{{cite book}}: CS1 maint: multiple names: authors list (link)
  4. 1 2 Thiel, ed. by Joachim Reitner, Volker. Encyclopedia of geobiology. Dordrecht: Springer. pp. 355–359. ISBN   9781402092121.{{cite book}}: |first= has generic name (help)CS1 maint: multiple names: authors list (link)
  5. ↑ Arnosti C (15 January 2011). "Microbial extracellular enzymes and the marine carbon cycle". Annual Review of Marine Science. 3 (1): 401–25. Bibcode:2011ARMS....3..401A. doi:10.1146/annurev-marine-120709-142731. PMID   21329211.
  6. ↑ "Merriam-Webster" . Retrieved 2013-10-26.
  7. ↑ "Lexic.us" . Retrieved 2013-10-26.
  8. 1 2 Vernon, Horace. "Intracellular Enzymes: A Course of Lectures Given in the Physiological" . Retrieved 2013-10-26.
  9. ↑ Kaiser, Gary. "Lab 8: Identification of Bacteria Through Biochemical Testing". Biol 230 Lab Manual. Archived from the original on 11 December 2013. Retrieved 9 December 2013.
  10. ↑ Erhardt M, Namba K, Hughes KT (November 2010). "Bacterial nanomachines: the flagellum and type III injectisome". Cold Spring Harbor Perspectives in Biology. 2 (11): a000299. doi:10.1101/cshperspect.a000299. PMC   2964186 . PMID   20926516.
  11. ↑ McGuffie EM, Fraylick JE, Hazen-Martin DJ, Vincent TS, Olson JC (July 1999). "Differential sensitivity of human epithelial cells to Pseudomonas aeruginosa exoenzyme S". Infection and Immunity. 67 (7): 3494–503. doi:10.1128/IAI.67.7.3494-3503.1999. PMC   116536 . PMID   10377131.
  12. ↑ Lodish, Harvey (2008). Molecular cell biology (6th ed., [2nd print.]. ed.). New York [u.a.]: Freeman. ISBN   978-0716776017.
  13. ↑ Andrews, Lary. "Supplemental Enzymes for Digestion". Health and Healing Research. Archived from the original on 27 July 2013. Retrieved 9 December 2013.
  14. ↑ Todar, Kenneth. "Mechanisms of Bacterial Pathogenicity". Todar's Online Textbook of Bacteriology. Kenneth Todar, PhD. Retrieved 12 December 2013.
  15. ↑ Favero D, Furlaneto-Maia L, França EJ, Góes HP, Furlaneto MC (February 2014). "Hemolytic factor production by clinical isolates of Candida species". Current Microbiology. 68 (2): 161–6. doi:10.1007/s00284-013-0459-6. PMID   24048697. S2CID   253807898.
  16. ↑ Sharma A, Satyanarayana T (2013). "Microbial acid-stable alpha-amylases: Characteristics, genetic engineering and applications". Process Biochemistry. 48 (2): 201–211. doi:10.1016/j.procbio.2012.12.018.
  17. ↑ Pandey A, Nigam P, Soccol CR, Soccol VT, Singh D, Mohan R (2000). "Advances in microbial amylases". Biotechnol. Appl. Biochem. 31 (2): 135–52. doi:10.1042/ba19990073. PMID   10744959.
  18. ↑ Pandol, Stephen (2010). "The Exocrine Pancreas". Colloquium Series on Integrated Systems Physiology: From Molecule to Function. 3 (2). Morgan & Claypool Life Sciences: 1–64. doi:10.4199/C00026ED1V01Y201102ISP014. PMID   21634067 . Retrieved 25 November 2013.
  19. 1 2 3 Mead JR, Irvine SA, Ramji DP (December 2002). "Lipoprotein lipase: structure, function, regulation, and role in disease". Journal of Molecular Medicine. 80 (12): 753–69. doi:10.1007/s00109-002-0384-9. PMID   12483461. S2CID   40089672.
  20. ↑ Kiens B, Lithell H, Mikines KJ, Richter EA (October 1989). "Effects of insulin and exercise on muscle lipoprotein lipase activity in man and its relation to insulin action". The Journal of Clinical Investigation. 84 (4): 1124–9. doi:10.1172/JCI114275. PMC   329768 . PMID   2677048.
  21. ↑ Jayani, Ranveer Singh; Saxena, Shivalika; Gupta, Reena (1 September 2005). "Microbial pectinolytic enzymes: A review". Process Biochemistry. 40 (9): 2931–2944. doi:10.1016/j.procbio.2005.03.026.
  22. ↑ Alimardani-Theuil, Parissa; Gainvors-Claisse, Angélique; Duchiron, Francis (1 August 2011). "Yeasts: An attractive source of pectinases—From gene expression to potential applications: A review". Process Biochemistry. 46 (8): 1525–1537. doi:10.1016/j.procbio.2011.05.010.
  23. ↑ Gummadi, Sathyanarayana N.; Panda, T. (1 February 2003). "Purification and biochemical properties of microbial pectinases—a review". Process Biochemistry. 38 (7): 987–996. doi:10.1016/S0032-9592(02)00203-0.
  24. 1 2 3 "Encyclopædia Britannica" . Retrieved November 14, 2013.
  25. ↑ Guldvog I, Berstad A (1981). "Physiological stimulation of pepsin secretion. The role of vagal innervation". Scandinavian Journal of Gastroenterology. 16 (1): 17–25. PMID   6785873.
  26. 1 2 Worthington, Krystal. "Trypsin". Worthington Biochemical Corporation. Retrieved 26 November 2013.
  27. ↑ "Trypsin". Free Dictionary. Retrieved 26 November 2013.
  28. ↑ "Trypsin Product Information". Worthington Biochemical Corporation. Retrieved 26 November 2013.
  29. 1 2 Alper H, Stephanopoulos G (October 2009). "Engineering for biofuels: exploiting innate microbial capacity or importing biosynthetic potential?". Nature Reviews. Microbiology. 7 (10): 715–23. doi:10.1038/nrmicro2186. PMID   19756010. S2CID   7785046.
  30. ↑ Juturu V, Wu JC (1 November 2012). "Microbial xylanases: engineering, production and industrial applications". Biotechnology Advances. 30 (6): 1219–27. doi:10.1016/j.biotechadv.2011.11.006. PMID   22138412.
  31. 1 2 Jaeger, Karl-Erich; Thorsten Eggert (2002). "Lipases for biotechnology". Current Opinion in Biotechnology. 13 (4): 390–397. doi:10.1016/s0958-1669(02)00341-5. PMID   12323363.
  32. ↑ Fan X, Niehus X, Sandoval G (2012). "Lipases as Biocatalyst for Biodiesel Production". Lipases and Phospholipases. Methods in Molecular Biology. Vol. 861. pp. 471–83. doi:10.1007/978-1-61779-600-5_27. ISBN   978-1-61779-599-2. PMID   22426735.
  33. 1 2 3 Bhat, M.K. (2000). "Cellulases and related enzymes in biotechnology". Biotechnology Advances. 18 (5): 355–383. CiteSeerX   10.1.1.461.2075 . doi:10.1016/s0734-9750(00)00041-0. PMID   14538100.
  34. ↑ "A Citizen's Guide to Bioremediation". United States Environmental Protection Agency. September 2012. Retrieved 5 December 2013.
  35. ↑ Karigar CS, Rao SS (2011). "Role of microbial enzymes in the bioremediation of pollutants: a review". Enzyme Research. 2011: 1–11. doi: 10.4061/2011/805187 . PMC   3168789 . PMID   21912739.
  36. 1 2 3 Harms H, Schlosser D, Wick LY (March 2011). "Untapped potential: exploiting fungi in bioremediation of hazardous chemicals". Nature Reviews. Microbiology. 9 (3): 177–92. doi:10.1038/nrmicro2519. PMID   21297669. S2CID   24676340.
  37. 1 2 3 Gianfreda, Liliana; Rao, Maria A (September 2004). "Potential of extra cellular enzymes in remediation of polluted soils: a review". Enzyme and Microbial Technology. 35 (4): 339–354. doi:10.1016/j.enzmictec.2004.05.006.
  38. ↑ Dash HR, Mangwani N, Chakraborty J, Kumari S, Das S (Jan 2013). "Marine bacteria: potential candidates for enhanced bioremediation". Applied Microbiology and Biotechnology. 97 (2): 561–71. doi:10.1007/s00253-012-4584-0. PMID   23212672. S2CID   253773148.
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