Patel Flores, Maximiliano J. Blamey Kazy, Dhiraj Paul, Angana Sarkar Singh, Rushit J. Shukla, Bhavtosh A. Kikani Nisha, Tulasi Satyanarayana The increasing interest in this field is reflected by the growing information on the discovery, purification, and characterization of REases from thermophilic sources. The properties associated with these enzymes offer additional advantages over their mesophilic counterparts.
Chitin is the second most abundant polysaccharide, next to cellulose, occurring nature in the fungal cell walls, insect exoskeletons, while the shells of crustaceans contribute significantly to the availability of renewable biopolymer. Several enzymes are known to degrade different forms of chitin mostly produced by bacteria, fungi, and plants. Deacetylated polymer of chitosan and chitin is chemically hydrolyzed to generate oligomers and monomers for variety of applications that include pharmaceutical, environmental, agricultural, and cosmetic sectors.
It would be possible to select from natural sources or modify the natural sources of chitinases to develop industrial processes that could replace the chemical processes for production of the chitooligomers, dimers, and monomers. Thermostable chitinases would give an added advantage for such industrial processes, and therefore there is a need to identify sources of such chitinases. In this chapter we have examined the availability of microbial sources of chitinases with a special attention to the thermostable chitinases.
The approaches used in modifying chitinases and other related enzymes have been discussed to present the possible biotechnological approaches to generate novel thermostable enzymes. However, there was limited information available for chitinases indicating the need to focus research in that direction. Thermostable enzymes are receiving considerable attention because of their usefulness in high-temperature catalysis of various enzymatic industrial processes. The phosphorus thus liberated is used in metabolic pathways.
The phosphatases have been considered to be one of the most versatile groups of hydrolases because of their adaptability under different environmental extremes such as high-temperature regimes and regulate phosphate metabolism for maintaining phosphorus economy of the cell for fulfilling its growth as well as bioenergetic requirements.
The reduction of phytic acid content in the foods and feeds by enzymatic hydrolysis using phytase is desirable, because the physical and chemical methods of phytate removal negatively affect their nutritional value. These enzymes, therefore, have potential applications in food and feed industries for mitigating their phytic acid content to liberate available inorganic phosphate and improve digestibility as a result of elimination of antinutrient characteristics. In this review, the attention is focused on the production, characteristics and potential biotechnological aspects of phytases and phosphatases from thermophilic microbes.
Represented by archeal, bacterial, and fungal species, thermophilic organisms have been isolated from all types of terrestrial and marine hot environment. Pectinase from these organisms thermophilic pectinase developed unique structure—function properties of high thermostability and optimal activity at higher temperature.
The advantage of using thermostable enzymes for various industrial applications is of course the intrinsic thermostability, and hence low activity losses during the raw material pretreatment at the elevated temperatures. Industrial applications of thermophilic pectinolytic enzyme have drawn a great deal of attention for use as biocatalysts because most of the industrial processes are carried out at higher temperature zone. Their potential to carry out myriads of biochemical reactions even at stringent conditions makes their use eco-friendly and best alternative to polluting chemical technologies.
The role of acidic pectinases in extraction and clarification of fruit juices is well established. Recently, these have emerged as suitable candidate for biobleaching of wood pulp, desizing and bioscouring of cotton, degumming of plant fibers and biomass conversion, etc. Thermostable carbohydrate-degrading enzymes are of special interest for many industrial applications as the solubility of carbohydrates at elevated temperatures sharply increases.
Gellan is among the microbial exopolysaccharides found recently extensive use in food, microbial cultivation media, and pharmaceutical industries. Enzyme modification of gellan could change its molecular weight, hardness of its gel, and its elasticity and in such a way might broaden its current spectrum of application. Several reports on mesophilic bacterial strains producing gellan lyases are known, and only one thermophilic bacterial producer,. In this chapter, the source microorganism and properties of the thermostable gellan lyase are discussed in relation to those of mesophilic producers.
Even though the accumulated knowledge on the structural and catalytic properties of the gellan lyase is still very limited, the results obtained clearly demonstrate that it is a new enzyme with interesting characteristics, which could add to the commercial value of gellan as an emulsifier, stabilizer, gel agent, thickener and suspending agent, and application in the future are also suggested. Thermophilic fungi and actinomycetes have been extensively studied in vegetal biomass bioconversion processes for the formulation of industrial enzymatic pools and as gene donors for the heterologous expression of thermostable enzymes.
The production of second-generation biofuels and the application in industries such as the textile are of particular interest. In this chapter, we have reviewed the gene structure, gene regulation, biochemical properties, and biotechnological applications of lignocellulolytic enzymes and other potential industrial hydrolases of thermophilic fungi and actinobacteria. The renewed interest in cellulase biotechnology is drawing the attention of researchers globally due to their diverse range of applications. The major applications of cellulases E.
Another most promising application of cellulases is in the bioconversion of renewable lignocellulosic biomass into fermentable sugar constituents that are subsequently used for the production of value-added chemicals after the fermentation reaction with appropriate microorganisms. The success of ethanol-based biorefinery truly depends upon the efficiency of cellulase titers stable at high temperature and their cost at shop floor.
Potential and utilization of thermophiles and thermostable enzymes in biorefining
Recent developments on the proteomics, genomics, and fermentation strategies have paved the way for searching more efficient and novel thermostable cellulase titers from thermophilic microorganisms of different habitats. Some of the major applications of this enzyme are in bleaching of pulp and paper, food and feed sector, etc.
For several of these applications, enzymes from thermophilic sources are preferred. In this chapter, we present information on classification of family 11 xylanases, used in pulp and paper industry.
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Based on these principles, protein engineering approaches to achieve thermostability of fungal xylanases are reviewed. Our own work on development of hyper-xylanase-producing mutant and process strategies adopted to enhance production of this enzyme from a thermophilic fungus. Additives, currently in use, to make stable xylanase preparation are also described.
Special emphasis is laid on downstream processing, which includes role of carriers and binders in producing the product of desired quality. Hemicellulose is the second most abundant component in lignocellulosics available in nature. It is a storage polymer occurring in seeds and a prominent structural component of cell walls in plants. Monomers of various hemicelluloses are useful in various biotechnological processes like the production of different antibiotics, alcohols, animal feeds, and biofuels.
Insight into thermophiles and their wide-spectrum applications
Xylan is the most abundant of all hemicelluloses. Immense interest in the enzymatic hydrolysis of xylan has been due to the applications of hydrolysates in feedstocks, production of biochemicals, and paper pulp bleaching.
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Biodegradation of xylan requires action of several enzymes, among which xylanases play a key role. A wide variety of microorganisms are known to produce xylanases. The interest in thermostable xylanases has markedly increased due to their potential applications in pulping and bleaching processes, in food and feed industry, textile processing, enzymatic saccharification of lignocellulosic materials, and waste treatment.
Since elevated temperatures have a significant influence on the bioavailability and solubility of organic compounds, most of these processes are carried out at high temperatures. The elevation in temperature is accompanied by a decrease in viscosity and an increase in the diffusion coefficient of organic compounds, and thus, higher rates of reactions are expected. Thermophilic organisms are of special interest as sources of thermostable xylanases.
The development of new analytical techniques and the commercial availability of new matrices have led to the purification and characterization of a large number of xylan-degrading bacterial enzymes. The recombinant DNA technology has permitted selection and overproduction of xylanolytic enzymes that are suitable for industrial applications.
The developments in cloning and expression, directed evolution, physicochemical and functional characteristics, and biotechnological applications and commercialization of thermostable xylanases of bacterial origin have been reviewed. Proteases are one of the largest selling enzymes in the world. This is rationalised by their extensive usage in the detergent, food, pharmaceutical, leather and textile industries. Thermostability in industrial enzymes remains a desirable attributes for 1 achieving faster conversion rates, 2 greater catalytic efficiencies and 3 protection from microbial contamination while operating at higher temperatures.
Proteases endowed with such characteristics are all the more needed for baking and textile processing. In general, most of the industrial proteases are sourced from. Thermostability in protease is accorded by protein engineering or appropriate immobilisation methods. Proteases from hyperthermophiles and thermophiles are natural choice for exploring the inherent heat stability. Few classical thermostable proteases especially those from. Heat stability in these cases has been attributed to large proportion of hydrophobic residue, extensive hydrogen bonding and increased share of disulphide bonds.
Extensive screening of large range of unexplored thermophiles is well called for.
Thermophilic Microbes in Environmental and Industrial Biotechnology
Understanding their protein architecture may enable rationale design for heat-stable proteases in future. This chapter highlights the enzymatic characteristics and novel properties of known thermostable proteases and focuses on their structure—function relationship. Diverse microorganisms that belong to Eukarya, bacteria, and Archaea produce these enzymes. A large number of Bacilli, Actinobacteria, and fungi are reported to produce keratinases. Microbial keratinases present great diversity in their biochemical and biophysical properties. They are robust enzymes with wide temperature and pH activity range.
Studies with specific substrates and inhibitors indicated that keratinases preferentially act on hydrophobic and aromatic residues at P1 position. Keratinases have several current and potential applications in agro-industrial, pharmaceutical, and biomedical fields. These enzymes are useful in processes related with the bioconversion of keratin waste into feed and fertilizers.
Other promising applications are enzymatic dehairing for leather and cosmetic industry, detergent industry, and development of biopolymers from keratin fibers. The use of keratinases to enhance drug delivery in some tissues and hydrolysis of prion proteins arises as novel outstanding applications. Their use in biomass conversion into biofuels may address the increasing concern on energy conservation and recycling. Looking into their biotechnological impetus, they are being cloned and expressed in a variety of heterologous hosts.
In this technology-oriented world, when every phase is going green, enzymes have found tremendous applications. Thousands of enzymes have been identified and are being used commercially. However, microbial origin enzymes have gained more relevance than those from other sources. Among others, lipases are spectacular enzymes known for their unique attributes and significant industrial potential. They are one of the most important biocatalysts known for their applications in the biotechnology industry. Since these enzymes find massive applications, with the passage of time, the trend has shifted towards the identification of thermostable lipases which could be used in the industries which require harsh conditions to work in.
Thermostable lipases have found applications in various areas such as in pharmaceuticals, food, and chemical industries. The following article talks about the thermophilic lipases derived from various microorganisms and their applications. Springer Professional.
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Back to the search result list. Table of Contents Frontmatter. Thermophiles in the Environment Frontmatter Chapter 1.