Microbial cellulose utilization: fundamentals and biotechnology.
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TLDR
A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.Abstract:
Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for "consolidated bioprocessing" (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.read more
Citations
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TL;DR: It is suggested that it is timely to revisit and reinvigorate functional modeling of cellulose hydrolysis and that this would be highly beneficial if not necessary in order to bring to bear the large volume of information available on cellulase components on the primary applications that motivate interest in the subject.
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References
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TL;DR: In this paper, the inhibitory effects of methylcellulose on the growth of Ruminococcus flavefaciens FD1 were concentration dependent, with complete inhibition at 0.1% (wt/vol).
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D. E. Brown,M. A. Zainudeen +1 more
TL;DR: Specific oxygen uptake rates were correlated with specific growth rates and absorption coefficients were shown to be a function of dilution rate independent of pH, and some data on cellulase biosynthesis were examined and correlated in terms of a maturation time model.
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Characterisation of cellulolytic activities in commercial Trichoderma reesei preparations: An approach using small, chromogenic substrates
Marc Claeyssens,Guido Aerts +1 more
TL;DR: A comparison of the cellulolytic activities found in three commercial Trichoderma reesei preparations is presented and it was found that Novo (Denmark) cellulase is particularly poor in β-glucosidase activity, an IFP (France) preparation is maximally active on the classical substrates in contrast to the Genencor (USA) cellul enzyme with high activity against the small, chromophoric substrates.
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Elucidation of adsorption processes of cellulases during hydrolysis of crystalline cellulose
Mitsuo Tanaka,Hiroko Nakamura,Masayuki Taniguchi,Takuo Morita,Ryuichi Matsuno,Tadashi Kamikubo +5 more
Abstract: To elucidate the effect of adsorption of cellulases during hydrolysis of crystalline cellulose, the relationship between the rate of hydrolysis and the adsorption of crude cellulases onto crystalline cellulose was investigated under various experimental conditions. Several phases of adsorption have been proposed to explain the process of cellulose hydrolysis by these enzymes. The process of hydrolysis calculated on the basis of these phases fitted well with that obtained experimentally.
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Protoplast transformation of Bacillus stearothermophilus NUB36 by plasmid DNA.
Lijun Wu,N. E. Welker +1 more
TL;DR: Chloramphenicol-resistant and tetracycline-resistant transformants were obtained when competent cells of Bacillus subtilis were transformed with pLW05 and pTHT15 and these plasmids are shuttle vectors for mesophilic and thermophilic bacilli.