Synergistic proteins for the enhanced enzymatic hydrolysis of cellulose by cellulase

Kim, In Jung; Lee, Hee Jin; Choi, In Geol; Kim, Kyoung Heon

doi:10.1007/s00253-014-6001-3

Cited by 106 publications

(71 citation statements)

References 97 publications

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“…6). These processes could, for example, include the production and attachment of yellow affinity substance, together with the production and activity of bacterial endoglucanases or other cellulose hydrolysis-enhancing proteins (Kim et al 2014), which are probably less well detected than exo-glucanases and β-glucosidases by the cellulase activity assay used (Coleman et al 2007). Regardless of the prior processes involved, there was a clear correlation between the onset of registered cellulase activity and biogas production from the cellulose substrate, indicating that much of the cellulase activity recorded in the assay is derived from expression of β-glucosidases, which are thus presumably the critical enzymes induced between days 4 and 6.…”

Section: Dashed Lines Indicate Fitted Datamentioning

confidence: 99%

Applying theories of microbial metabolism for induction of targeted enzyme activity in a methanogenic microbial community at a metabolic steady state

Speda

Johansson

Jonsson

et al. 2016

Appl Microbiol Biotechnol

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Novel enzymes that are stable in diverse conditions are intensively sought because they offer major potential advantages in industrial biotechnology, and microorganisms in extreme environments are key sources of such enzymes. However, most potentially valuable enzymes are currently inaccessible due to the pure culturing problem of microorganisms. Novel metagenomic and metaproteomic techniques that circumvent the need for pure cultures have theoretically provided possibilities to identify all genes and all proteins in microbial communities, but these techniques have not been widely used to directly identify specific enzymes because they generate vast amounts of extraneous data.In a first step towards developing a metaproteomic approach to pinpoint targeted extracellular hydrolytic enzymes of choice in microbial communities, we have generated and analyzed the necessary conditions for such an approach by the use of a methanogenic microbial community maintained on a chemically defined medium. The results show that a metabolic steady state of the microbial community could be reached, at which the expression of the targeted hydrolytic enzymes were suppressed, and that upon enzyme induction a distinct increase in the targeted enzyme expression was obtained. Furthermore, no cross talk in expression was detected between the two focal types of enzyme activities under their respective inductive conditions. Thus, the described approach should be useful to generate ideal samples, collected before and after selective induction, in controlled microbial communities to clearly discriminate between constituently expressed proteins and extracellular hydrolytic enzymes that are specifically induced, thereby reducing the analysis to only those proteins that are distinctively up-regulated.

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Section: Dashed Lines Indicate Fitted Datamentioning

confidence: 99%

Applying theories of microbial metabolism for induction of targeted enzyme activity in a methanogenic microbial community at a metabolic steady state

Speda

Johansson

Jonsson

et al. 2016

Appl Microbiol Biotechnol

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“…Thus, to achieve anaerobic digestion as completely as possible, very long retention times in the anaerobic digester are required [3, 4], which make the capital costs of large volume digesters high. Part of the recalcitrance to hydrolysis can be attributed to the crystallinity of cellulose, which can only be efficiently hydrolyzed, in its simplest form, by a combination of endo- and exo-glucanases together with β-glucosidases [5]. However, it has been found that the crystallinity of cellulose does not completely preclude hydrolysis because it can proceed if appropriate enzymes can access the crystalline cellulose [1].…”

Section: Introductionmentioning

confidence: 99%

Enhanced biomethane production rate and yield from lignocellulosic ensiled forage ley by in situ anaerobic digestion treatment with endogenous cellulolytic enzymes

Speda

Johansson

Odnell

et al. 2017

Biotechnol Biofuels

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BackgroundEnzymatic treatment of lignocellulosic material for increased biogas production has so far focused on pretreatment methods. However, often combinations of enzymes and different physicochemical treatments are necessary to achieve a desired effect. This need for additional energy and chemicals compromises the rationale of using enzymes for low energy treatment to promote biogas production. Therefore, simpler and less energy intensive in situ anaerobic digester treatment with enzymes is desirable. However, investigations in which exogenous enzymes are added to treat the material in situ have shown mixed success, possibly because the enzymes used originated from organisms not evolutionarily adapted to the environment of anaerobic digesters. In this study, to examine the effect of enzymes endogenous to methanogenic microbial communities, cellulolytic enzymes were instead overproduced and collected from a dedicated methanogenic microbial community. By this approach, a solution with very high endogenous microbial cellulolytic activity was produced and tested for the effect on biogas production from lignocellulose by in situ anaerobic digester treatment.ResultsAddition of enzymes, endogenous to the environment of a mixed methanogenic microbial community, to the anaerobic digestion of ensiled forage ley resulted in significantly increased rate and yield of biomethane production. The enzyme solution had an instant effect on more readily available cellulosic material. More importantly, the induced enzyme solution also affected the biogas production rate from less accessible cellulosic material in a second slower phase of lignocellulose digestion. Notably, this effect was maintained throughout the experiment to completely digested lignocellulosic substrate.ConclusionsThe induced enzyme solution collected from a microbial methanogenic community contained enzymes that were apparently active and stable in the environment of anaerobic digestion. The enzymatic activity had a profound effect on the biogas production rate and yield, comparable with the results of many pretreatment methods. Thus, application of such enzymes could enable efficient low energy in situ anaerobic digester treatment for increased biomethane production from lignocellulosic material.

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“…Synergistic action of these enzymes is vital for complete breakdown of cellulose into soluble sugars (Kim et al 2014). Extensive basic and applied research on cellulases revealed their commercial significance and diverse industrial applicability, especially in bioethanol production (Bajpai 1999;Harman and Kubicek 1998;Uhlig 1998).…”

Section: Introductionmentioning

confidence: 99%

Use of combined UV and chemical mutagenesis treatment of Aspergillus terreus D34 for hyper-production of cellulose-degrading enzymes and enzymatic hydrolysis of mild-alkali pretreated rice straw

Kumar

Parikh

Singh

et al. 2015

Bioresour. Bioprocess.

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Background: Microbial production of cellulose-degrading enzymes could be significantly improved using traditional mutagenesis treatment. Development of high-titre cellulase producing mutants drastically reduces the costs involved in cellulase production and downstream processing in commercial-scale enzyme production. Here, we have evaluated the efficacy of different Aspergillus terreus D34 mutants for hyper-production of improved cellulase enzymes utilizing locally available lignocellulosic biomass residues as growth substrates in solid state fermentation conditions. Further, enzymatic hydrolysis of mild-alkali pre-treated rice straw was performed using the improved cellulases.Results: A 4.9-fold higher β-glucosidase activity was obtained from ethyl methyl sulphonate (EMS) treated mutant strain (EMS2) when grown on mixed rice straw/sugarcane bagasse (RSBG) biomass growth substrate. Similarly with the EMS2 mutant and BG-grown culture extract a 1.1-fold higher xylanase activity was observed. Irrespective of the growth substrates and the mutant strains, the maximum cellulase (FPase, carboxymethyl cellulase, avicelase, β-glucosidase) and xylanase activities (U mL −1 ) were 2.34, 39.8, 2.46, 19.9 and 655, respectively. Further, external supplementation of 20% bovine serum albumin (BSA), 3% tween 80 and 20% polyethylene glycol (PEG) 6000 to the crude enzyme extract increased the FPase activity nearly 4.0-, 2.8-and 2.2-fold. Addition of 0.05% sodium benzoate marginally increased the stability of cellulase enzyme and retained more than 60% of the initial activity after 96 h incubation at 37°C. While at 4°C, no loss in enzyme activity was observed even after prolonged incubation period (up to 90 days). Further, maximum reducing sugars of 0.842 g g −1 at a rate of 0.25 mM g −1 h −1 at 10% biomass loading of mild-alkali pretreated rice straw was produced using the BG-grown culture extract of EMS2 mutant strain. Conclusion:The extracellular protein production and corresponding cellulase activities of A. terreus D34 were significantly enhanced after combined UV and chemical mutagenesis treatments. In the present study, besides accelerating the rate of cellulase production, we have also demonstrated production of high reducing sugars by enzymatic saccharification of pretreated lignocellulosic biomass using hyper-produced cellulase enzymes. Due to high enzyme activity of the cellulase enzymes produced from the mutant strains, the volume of enzyme loadings in enzymatic hydrolysis could be reduced up to 7-fold. These studies clearly show the potential of the developed hyper-cellulase producing mutants in decreasing the overall process economics of cellulosic ethanol technology.

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Synergistic proteins for the enhanced enzymatic hydrolysis of cellulose by cellulase

Cited by 106 publications

References 97 publications

Applying theories of microbial metabolism for induction of targeted enzyme activity in a methanogenic microbial community at a metabolic steady state

Applying theories of microbial metabolism for induction of targeted enzyme activity in a methanogenic microbial community at a metabolic steady state

Enhanced biomethane production rate and yield from lignocellulosic ensiled forage ley by in situ anaerobic digestion treatment with endogenous cellulolytic enzymes

Use of combined UV and chemical mutagenesis treatment of Aspergillus terreus D34 for hyper-production of cellulose-degrading enzymes and enzymatic hydrolysis of mild-alkali pretreated rice straw

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