Management of enzyme diversity in high-performance cellulolytic cocktails (original) (raw)
Related papers
Applied Biochemistry and Biotechnology
We evaluated various agricultural lignocellulosic biomass and variety of fungi to produce cellulolytic enzymes cocktail to yield high amount of reducing sugars. Solid-state fermentation was performed using water hyacinth, paddy straw, corn straw, soybean husk/tops, wheat straw, and sugarcane bagasse using fungi like Nocardiopsis sp. KNU, Trichoderma reesei, Trichoderma viride, Aspergillus flavus, and Phanerochaete chrysosporium alone and in combination to produce cellulolytic enzymes. Water hyacinth produced (U ml −1) endoglucanase (51.13) and filter paperase (0.55), and corn straw produced (U ml −1) β-glucosidase (4.65), xylanase (113.32), and glucoamylase (41.27) after 7-day incubation using Nocardiopsis sp. KNU. Production of cellulolytic enzymes was altered due to addition of various nitrogen sources, metal ions, vitamins, and amino acids. The maximum cellulolytic enzymes were produced by P. chrysosporium (endoglucanase; 166.32 U ml −1 and exoglucanase; 12.20 U ml −1), and by T. viride (filter paperase; 1.57 U ml −1). Among all, co-culture of T. reesei, T. viride, A. flavus, and P. chrysosporium showed highest β-glucosidase (17.05 U ml −1). The highest xylanase (1129 U ml −1) was observed in T. viride + P. chrysosporium co-culture. This study revealed the dependency on substrate and microorganism to produce good quality enzyme cocktail to obtain maximum reducing sugars.
Production of Cellulolytic Enzymes
Bioprocessing of Renewable Resources to Commodity Bioproducts, 2014
For the conversion of plant biomass into various bioproducts, a significant bottleneck is enzymatic hydrolysis of lignocelluloses to soluble sugars. These sugars are then metabolized through various natural or engineered pathways toward products of interest. The success of projected biorefinery processes depend to a large extent on the economics of hydrolytic enzyme production. Presently, mesophilic fungal strains Bioprocessing of Renewable Resources to Commodity Bioproducts, First Edition. Edited by Virendra S. Bisaria and Akihiko Kondo.
AMB Express, 2016
Various enzymatic cocktails were produced from two Trichoderma reesei strains, a cellulase hyperproducer strain and a strain with β-glucosidase activity overexpression. By using various carbon sources (lactose, glucose, xylose, hemicellulosic hydrolysate) for strains growth, contrasted enzymatic activities were obtained. The enzymatic cocktails presented various levels of efficiency for the hydrolysis of cellulose Avicel into glucose, in presence of xylans, or not. These latter were also hydrolyzed with different extents according to cocktails. The most efficient cocktails (TR1 and TR3) on Avicel were richer in filter paper activity (FPU) and presented a low ratio FPU/β-glucosidase activity. Cocktails TR2 and TR5 which were produced on the higher amount of hemicellulosic hydrolysate, possess both high xylanase and β-xylosidase activities, and were the most efficient for xylans hydrolysis. When hydrolysis of Avicel was conducted in presence of xylans, a decrease of glucose release occurred for all cocktails compared to hydrolysis of Avicel alone. Mixing TR1 and TR5 cocktails with two different ratios of proteins (1/1 and 1/4) resulted in a gain of efficiency for glucose release during hydrolysis of Avicel in presence of xylans compared to TR5 alone. Our results demonstrate the importance of combining hemicellulase and cellulase activities to improve the yields of glucose release from Avicel in presence of xylans. In this context, strategies involving enzymes production with carbon sources comprising mixed C5 and C6 sugars or combining different cocktails produced on C5 or on C6 sugars are of interest for processes developed in the context of lignocellulosic biorefinery.
Biotechnology for biofuels, 2014
Enzymatic hydrolysis of pretreated lignocellulosic biomass is an essential process for the production of fermentable sugars for industrial use. A better understanding of fungal cellulase systems will provide clues for maximizing the hydrolysis of target biomass. Talaromyces cellulolyticus is a promising fungus for cellulase production and efficient biomass hydrolysis. Several cellulolytic enzymes purified from T. cellulolyticus were characterized in earlier studies, but the core enzymes critical for hydrolysis of lignocellulosic biomass remain unknown. Six cellulolytic enzymes critical for the hydrolysis of crystalline cellulose were purified from T. cellulolyticus culture supernatant using an enzyme assay based on synergistic hydrolysis of Avicel. The purified enzymes were identified by their substrate specificities and analyses of trypsin-digested peptide fragments and were classified into the following glycosyl hydrolase (GH) families: GH3 (β-glucosidase, Bgl3A), GH5 (endoglucana...
Fungal Biology and Biotechnology, 2017
Background: The industrial applications of cellulases are mostly limited by the costs associated with their production. Optimized production pathways are therefore desirable. Based on their enzyme inducing capacity, celluloses are commonly used in fermentation media. However, the influence of their physiochemical characteristics on the production process is not well understood. In this study, we examined how physical, structural and chemical properties of celluloses influence cellulase and hemicellulase production in an industrially-optimized and a non-engineered filamentous fungus: Trichoderma reesei RUT-C30 and Neurospora crassa. The performance was evaluated by quantifying gene induction, protein secretion and enzymatic activities. Results: Among the three investigated substrates, the powdered cellulose was found to be the most impure, and the residual hemicellulosic content was efficiently perceived by the fungi. It was furthermore found to be the least crystalline substrate and consequently was the most readily digested cellulose in vitro. In vivo however, only RUT-C30 was able to take full advantage of these factors. When comparing carbon catabolite repressed and de-repressed strains of T. reesei and N. crassa, we found that cre1/cre-1 is at least partially responsible for this observation, but that the different wiring of the molecular signaling networks is also relevant. Conclusions: Our findings indicate that crystallinity and hemicellulose content are major determinants of performance. Moreover, the genetic background between WT and modified strains greatly affects the ability to utilize the cellulosic substrate. By highlighting key factors to consider when choosing the optimal cellulosic product for enzyme production, this study has relevance for the optimization of a critical step in the biotechnological (hemi-) cellulase production process.
Novel perspectives for evolving enzyme cocktails for lignocellulose hydrolysis in biorefineries
Sustainable Chemical Processes, 2013
The unstable and uncertain availability of petroleum sources as well as rising cost of fuels have shifted global efforts to utilize renewable resources for the production of greener energy and a replacement which can also meet the high energy demand of the world. Bioenergy routes suggest that atmospheric carbon can be cycled through biofuels in carefully designed systems for sustainability. Significant potential exists for bioconversion of biomass, the most abundant and also the most renewable biomaterial on our planet. However, the requirements of enzyme complexes which act synergistically to unlock and saccharify polysaccharides from the lignocellulose complex to fermentable sugars incur major costs in the overall process and present a great challenge. Currently available cellulase preparations are subject to tight induction and regulation systems and also suffer inhibition from various end products. Therefore, more potent and efficient enzyme preparations need to be developed for...
Stable Carbohydrolases of Extremophilic Mycelia Fungi
2013
Enzymatic hydrolysis of cellulose to fermentable glucose is the most important technological process among all possible enzyme technologies. Thermophilic fungi are potential sources of enzymes with the view of scientific and commercial interests. From the collection of microscophic fungi isolated from the ecological niches of Georgia at Durmishidze Institute of Biochemistry and Biotechnology of Agricultural University. Thermophilic micromycetes active producers of stable Four endoglucanases were purified to homogeneity from Sporotrichum pulverulentum J-3, Aspergillus wentii S-6, Aspergillus versicolor D-3, Chaetomium thermophile P-21 culture medium. Some kinetic, physical and chemical properties of purified endoglucanases (molecular mass, isoelectric point, carbohydrates content, pH, temperature optimums, Km, Kcat, Vmax, Ki, Henries constant Kp, substrate specificity) were studied.© 2013 Bull. Georg. Natl. Acad. Sci.
An Ecofriendly and Efficient Strategy for Cost Effective Production of Lignocellulotic Enzymes
Waste and Biomass Valorization, 2017
is used in distillery plants whereas surplus residue is disposed off as such or burnt in environment which invites several brutal ecological problems. A foremost solution to fight these problems is to utilize surplus residue for producing commodity products including lignocellulases which are capable of hydrolyzing biomass to fermentable sugars for bioethanol production. These are considered as cheap energy sources for microbial fermentation and enzyme production [5]. Due to renewable nature nowadays they are becoming a centre of attention for researchers. Sugarcane bagasse has also been employed in many other studies for enzyme production using different microbes (Table 1). But high production cost and low hydrolysis efficiency are the major bottlenecks in commercialization of these enzymes for biofuel production. Such kind of infirmities can be unraveled up to a greater extent by enzyme production through co-culturing using cheap, renewable and easily available lignocellulosic wastes [15]. Co-culturing means to culture two microorganisms together and simultaneously in same medium [16]. In the precedent literature coculturing is reported to increase the quantity and quantity of desirable components [17]. Strain compatibility is the most determining factors for successful co culturing and mixed culturing. Strains may found to be incompatible i.e. one fungus may secrete some metabolites that are antagonistic to other. However, if strains are compatible there is a probability for synergy between metabolic pathways of involved strains. Recalcitrant nature of the biomass also poses a great obstacle. Consequently a pretreatment step is required for delignification to disrupt the highly ordered lignin-carbohydrate complex [18]. Considering the major challenges associated with commercialization of lignocellulotic enzymes present study was designed to develop a cost effective production strategy.
Reviews in Environmental Science and Bio/Technology, 2020
Lignocellulosic biomass is the earth's most abundant renewable feedstock alternative that comprises of cellulose, hemi-cellulose and lignin. The synergistic action of cellulolytic/xylanolytic enzymes produced by lignocellulolytic microorganisms such as bacteria, algae and fungi are capable of robust cellulosic biomass deconstruction. Most of the microorganisms dwelling in extreme environmental habitats such as rumen environment, hot/cold springs, deep ocean trenches, acidic/alkaline pH environment have been considered as an attractive producers of hemi/cellulolytic lignocellulolytic and other biotechnological enzymes with enhanced biochemical properties essential for industrial bioconversion processes. However, the potential microbial sources of cellulolytic enzymes and the underlying mechanism to achieve this is not fully elucidated. In this review article, first we detail the composition of lignocellulosic biomass. Next, we describe the structure and functions of divergent hydrolytic enzymes (cellulolytic and xylanolytic enzymes) involved in cellulosic biomass degradation. Third, we analyze, outline and unveil the prospective source of microbes encoding exceptionally diverse set of biotechnologically relevant cellulolytic enzymes which are critical to answer the specific ecological question of by whom, where and how cellulosic biomass is degraded in the environment. Finally, this review article features the snapshot about the future developments and perspectives on microbial enzymes, high-throughput techniques and molecular tools that could be exploited to derive those enzymes from the potential sources.
Enzymes Prospection from Fungi and Biomass Pretreatment for Biorefinery Application
A detailed description of the microbial glycoside hydrolases able to degrade lignocellulosic biomass is very important for a better understanding of the new processes involving biorefinery the conversion of biomass into biofuels. Cellulose and hemicellulose, the major carbohydrates of plant biomass, together with lignin, constitute the most abundant organic compounds present in nature. Cellulose and hemicellulose are converted enzymatically into glucose, xylose or other sugars, which may be fermented by yeasts into second-generation bioethanol or other chemicals. In order to process the lignocellulosic biomass in biorefinery, the use of efficient degrading enzymes is essential for the bioconversion. In this chapter we describe recent advances in the characterization of glycoside hydrolases, auxiliary activities and synergism between cellulases and accessory proteins involved in cellulose hydrolysis. Furthermore, considering that pretreatments are necessary for efficient biomass degradation and exposition of the lignocellulosic components, a detailed description of several physical, chemical, physicochemical, biological and integrated pretreatments is also presented. Modern and classical methods, including spectroscopy, coupled chromatography, electron microscopy, MALDI-imaging MS, and others, are also discussed as strategies for improving both fiber characterization and understanding of the saccharification of lignocellulose and subsequent biofuel production.