Microbial pectinolytic enzymes: A review
TL;DR: Pectinases are one of the most widely distributed enzymes in bacteria, fungi and plants as discussed by the authors, and they have a share of 25% in the global sales of food enzymes.
Abstract: Pectinases or petinolytic enzymes, hydrolyze pectic substances. They have a share of 25% in the global sales of food enzymes. Pectinases are one of the most widely distributed enzymes in bacteria, fungi and plants. Protopectinases, polygalacturonases, lyases and pectin esterases are among the extensively studied pectinolytic enzymes. Protopectinases catalyze the solubilization of protopectin. Polygalacturonases hydrolyze the polygalacturonic acid chain by addition of water and are the most abundant among all the pectinolytic enzymes. Lyases catalyze the trans-eliminative cleavage of the galacturonic acid polymer. Pectinesterases liberate pectins and methanol by de-esterifying the methyl ester linkages of the pectin backbone. Pectinolytic enzymes are of significant importance in the current biotechnological era with their all-embracing applications in fruit juice extraction and its clarification, scouring of cotton, degumming of plant fibers, waste water treatment, vegetable oil extraction, tea and coffee fermentations, bleaching of paper, in poultry feed additives and in the alcoholic beverages and food industries. The present review mainly contemplates on the types and structure of pectic substances, the classification of pectinolytic enzymes, their assay methods, physicochemical and biological properties and a bird's eye view of their industrial applications.
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TL;DR: An understanding of the molecular mechanism leading to biodegradation of lignocelluloses and the development of the bioprocessing potential of cellulolytic microorganisms might effectively be accomplished with recombinant DNA technology.
Abstract: In view of rising prices of crude oil due to increasing fuel demands, the need for alternative sources of bioenergy is expected to increase sharply in the coming years. Among potential alternative bioenergy resources, lignocellulosics have been identified as the prime source of biofuels and other value-added products. Lignocelluloses as agricultural, industrial and forest residuals account for the majority of the total biomass present in the world. To initiate the production of industrially important products from cellulosic biomass, bioconversion of the cellulosic components into fermentable sugars is necessary. A variety of microorganisms including bacteria and fungi may have the ability to degrade the cellulosic biomass to glucose monomers. Bacterial cellulases exist as discrete multi-enzyme complexes, called cellulosomes that consist of multiple subunits. Cellulolytic enzyme systems from the filamentous fungi, especially Trichoderma reesei, contain two exoglucanases or cellobiohydrolases (CBH1 and CBH2), at least four endoglucanases (EG1, EG2, EG3, EG5), and one β-glucosidase. These enzymes act synergistically to catalyse the hydrolysis of cellulose. Different physical parameters such as pH, temperature, adsorption, chemical factors like nitrogen, phosphorus, presence of phenolic compounds and other inhibitors can critically influence the bioconversion of lignocellulose. The production of cellulases by microbial cells is governed by genetic and biochemical controls including induction, catabolite repression, or end product inhibition. Several efforts have been made to increase the production of cellulases through strain improvement by mutagenesis. Various physical and chemical methods have been used to develop bacterial and fungal strains producing higher amounts of cellulase, all with limited success. Cellulosic bioconversion is a complex process and requires the synergistic action of the three enzymatic components consisting of endoglucanases, exoglucanases and β-glucosidases. The co-cultivation of microbes in fermentation can increase the quantity of the desirable components of the cellulase complex. An understanding of the molecular mechanism leading to biodegradation of lignocelluloses and the development of the bioprocessing potential of cellulolytic microorganisms might effectively be accomplished with recombinant DNA technology. For instance, cloning and sequencing of the various cellulolytic genes could economize the cellulase production process. Apart from that, metabolic engineering and genomics approaches have great potential for enhancing our understanding of the molecular mechanism of bioconversion of lignocelluloses to value added economically significant products in the future.
1,094 citations
Cites background from "Microbial pectinolytic enzymes: A r..."
...ronic acid chain of the pectin polymer by the addition of a water molecule [41]....
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TL;DR: This review examines the enzymes required to degrade various components of lignocellulose and the impact of pretreatments on the lignosic substrates and the enzyme required for degradation and the effect of and interaction between different hemicellulases on complex substrates.
Abstract: Lignocellulose is a complex substrate which requires a variety of enzymes, acting in synergy, for its complete hydrolysis. These synergistic interactions between different enzymes have been investigated in order to design optimal combinations and ratios of enzymes for different lignocellulosic substrates that have been subjected to different pretreatments. This review examines the enzymes required to degrade various components of lignocellulose and the impact of pretreatments on the lignocellulose components and the enzymes required for degradation. Many factors affect the enzymes and the optimisation of the hydrolysis process, such as enzyme ratios, substrate loadings, enzyme loadings, inhibitors, adsorption and surfactants. Consideration is also given to the calculation of degrees of synergy and yield. A model is further proposed for the optimisation of enzyme combinations based on a selection of individual or commercial enzyme mixtures. The main area for further study is the effect of and interaction between different hemicellulases on complex substrates.
851 citations
TL;DR: This review describes the effector repertoires of 84 plant-colonizing fungi and focuses on the mechanisms that allow these fungal effectors to promote virulence or compatibility, discuss common plant nodes that are targeted by effectors, and provide recent insights into effector evolution.
Abstract: Plants can be colonized by fungi that have adopted highly diverse lifestyles, ranging from symbiotic to necrotrophic. Colonization is governed in all systems by hundreds of secreted fungal effector molecules. These effectors suppress plant defense responses and modulate plant physiology to accommodate fungal invaders and provide them with nutrients. Fungal effectors either function in the interaction zone between the fungal hyphae and host or are transferred to plant cells. This review describes the effector repertoires of 84 plant-colonizing fungi. We focus on the mechanisms that allow these fungal effectors to promote virulence or compatibility, discuss common plant nodes that are targeted by effectors, and provide recent insights into effector evolution. In addition, we address the issue of effector uptake in plant cells and highlight open questions and future challenges.
797 citations
TL;DR: existing and potential applications of thermophiles and thermostable enzymes with focus on conversion of carbohydrate containing raw materials are discussed and strategies that enhance thermostablity of enzymes both in vivo and in vitro are assessed.
Abstract: In today's world, there is an increasing trend towards the use of renewable, cheap and readily available biomass in the production of a wide variety of fine and bulk chemicals in different biorefineries. Biorefineries utilize the activities of microbial cells and their enzymes to convert biomass into target products. Many of these processes require enzymes which are operationally stable at high temperature thus allowing e.g. easy mixing, better substrate solubility, high mass transfer rate, and lowered risk of contamination. Thermophiles have often been proposed as sources of industrially relevant thermostable enzymes. Here we discuss existing and potential applications of thermophiles and thermostable enzymes with focus on conversion of carbohydrate containing raw materials. Their importance in biorefineries is explained using examples of lignocellulose and starch conversions to desired products. Strategies that enhance thermostablity of enzymes both in vivo and in vitro are also assessed. Moreover, this review deals with efforts made on developing vectors for expressing recombinant enzymes in thermophilic hosts.
536 citations
Cites background from "Microbial pectinolytic enzymes: A r..."
...11) de-esterify the methyl ester linkages of the pectin backbone [139]....
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...82) hydrolysing the polygalacturonic acid chain by addition of water, are all classified under GH28, and are the most abundant among all the pectinolytic enzymes [128,139]....
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TL;DR: Pectin structure, sources and extraction procedures have been discussed focussing on the properties of the polysaccharide that can be tuned to optimize the gels for a desired application and possess a fundamental role in application of pectin in the biomedical field.
Abstract: Pectin, due to its simple and cytocompatible gelling mechanism, has been recently exploited for different biomedical applications including drug delivery, gene delivery, wound healing and tissue engineering. Recent studies involving pectin for the biomedical field are reviewed, with the aim to capture the state of art on current research about pectin gels for biomedical applications, moving outside the traditional fields of application such as the food industry or pharmaceutics. Pectin structure, sources and extraction procedures have been discussed focussing on the properties of the polysaccharide that can be tuned to optimize the gels for a desired application and possess a fundamental role in application of pectin in the biomedical field.
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25,389 citations
TL;DR: In this paper, the reliability of the various Somogyi-Shaffer-Hartmann (SHH) copper reagents for glucose determination in biological material has been established, which can be accomplished by omission of the iodide and iodate in their preparation, since these interfere with the molybdate color reagents.
Abstract: The reliability of the various Somogyi-Shaffer-Hartmann (1, 2) copper reagents for glucose determination in biological material has been established. Adaptation of these reagents to calorimetric use may be accomplished by omission of the iodide and iodate in their preparation, since these interfere with the molybdate color reagents. This omission produces no especial change in the character of the reagents. KI, however, inhibits the autoreduction of the copper and in its absence an unstable reagent results. Nevertheless, if the copper is added to the rest of the reagent on the day of its use, this difficulty is avoided. When the Somogyi micro reagent (2) is used in this way with almost any of the various phosphomolybdate reagents, very satisfactory proportionality is found between color density and glucose taken over a wide range of values. However, all of the phosphomolybdate reagents tried left much to be desired in reproducibility from time to time and lacked the desired stability of color. We therefore tried various color reagents, which led to the development of a new arsenomolybdate reagent. When this reagent was used with Somogyi’s micro reagent, it gave satisfactory stability and reproducibility of color. By this means it has been possible to utilize the copper reagents in a photometric procedure for practically all the uses to which the titrimetric procedures are adapted. These include tissue sugar, glycogen, urine reduction equivalent, maltose, glucuronic acid, etc. However, diastase determinations have not been successful because of the effect of the undigested starch on the clarity of the final colored solution. The reactions involved in the molybdenum blue reaction are uncertain and beyond the scope of this report. Woods and Mellon (3) discuss and give references to the various interpretations of the reaction. Reagents-Analytical reagent grade or the equivalent. 1. Copper Reagent A. Dissolve 25 gm. of N&C03 (anhydrous), 25 gm. of Rochelle salt, 20 gm. of NaHCOs, and 200 gm. of NaiSOa (anhydrous) in about 800 ml. of water and dilute to 1 liter. Filter if necessary.’ This
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19 Mar 1998
TL;DR: Encyclopedia of Chemical Technology The Third Edition of the Encycled encyclopedia of chemical technology as mentioned in this paper is built on the solid foundation of the previous editions of the encyclopedia, which has been updated and updated and many new subjects have been added to reflect changes in chemical technology through the 1970s.
Abstract: Encyclopedia of Chemical Technology The Third Edition of the Encyclopedia of Chemical Technology is built on the solid foundation of the previous editions All of the articles have been rewritten and updated and many new subjects have been added to reflect changes in chemical technology through the 1970s The new edition, however, will be familiar to users of the earlier editions comprehensive, authoritative, accessible, lucid The Encyclopedia remains an indispensable information source for all producers and users of chemical products and materials In the Third Edition, emphasis is given to major present-day topics of concern to all chemists, scientists, and engineers--energy, health, safety, toxicology, and new materials New subjects have been added, especially those related to polymer and plastics technology, fuels and energy, inorganic and solid-state chemistry, composite materials, coating, fermentation and enzymes, pharmaceuticals, surfactant technology, fibers and textiles New features include the use of SI units as well as English units, Chemical Abstracts Service's Registry Numbers, and complete indexing based on automated retrieval from a machine-readable composition system Once again this classic serves as an unrivaled library of information for the chemical and allied industries Some comments about Kirk-Othmer-- The First Edition "No reference library worthy of the name will be without this series It is simply a must for the chemist and chemical engineer" --Chemical and Engineering News The Second Edition "A necessity for any technical library" --Choice
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TL;DR: This review discusses various types of pectinases and their applications in the commercial sector.
Abstract: Pectinases are one of the upcoming enzymes of fruit and textile industries. These enzymes break down complex polysaccharides of plant tissues into simpler molecules like galacturonic acids. The role of acidic pectinases in bringing down the cloudiness and bitterness of fruit juices is well established. Recently, there has been a good number of reports on the application of alkaline pectinases in the textile industry for the retting and degumming of fiber crops, production of good quality paper, fermentation of coffee and tea, oil extractions and treatment of pectic waste water. This review discusses various types of pectinases and their applications in the commercial sector.
1,001 citations