Formation of ethanol by bacteria. A pledge for the use of extreme thermophilic anaerobic bacteria in industrial ethanol fermentation processes

Wiegel, Juergen

doi:10.1007/bf01960144

Cited by 117 publications

(51 citation statements)

References 55 publications

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“…(11,335,338), and involved a mixture of C. thermocellum and C. thermosaccharolyticum (78). This combination forms closely associated, syntrophic, and very stable dual cultures (345). Cellulose is broken down by the cellulase complex of C. thermocellum to cellobiose and cellodextrins, which are then utilized by the organisms to produce ethanol; unfortunately, acetate and lactate are also formed.…”

Section: Clostridial Coculturesmentioning

confidence: 99%

Cellulase, Clostridia, and Ethanol

Demain

Newcomb

2005

Microbiol Mol Biol Rev

804

579

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SUMMARY Biomass conversion to ethanol as a liquid fuel by the thermophilic and anaerobic clostridia offers a potential partial solution to the problem of the world's dependence on petroleum for energy. Coculture of a cellulolytic strain and a saccharolytic strain of Clostridium on agricultural resources, as well as on urban and industrial cellulosic wastes, is a promising approach to an alternate energy source from an economic viewpoint. This review discusses the need for such a process, the cellulases of clostridia, their presence in extracellular complexes or organelles (the cellulosomes), the binding of the cellulosomes to cellulose and to the cell surface, cellulase genetics, regulation of their synthesis, cocultures, ethanol tolerance, and metabolic pathway engineering for maximizing ethanol yield.

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Section: Clostridial Coculturesmentioning

confidence: 99%

Cellulase, Clostridia, and Ethanol

Demain

Newcomb

2005

Microbiol Mol Biol Rev

804

579

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“…Glucose (25,50,75, 100, and 150 mg/liter) was used as the standard. Samples (200 l) were diluted to the appropriate concentrations and mixed with 200 l 5% phenol and 1 ml of 98% H 2 SO 4 .…”

Section: Whole-genome Sequencing and Analysis (I) Organism Source Anmentioning

confidence: 99%

Correlation of Genomic and Physiological Traits of Thermoanaerobacter Species with Biofuel Yields

Hemme

Fields

et al. 2011

Appl Environ Microbiol

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Thermophilic anaerobic noncellulolytic Thermoanaerobacter species are of great biotechnological importance in cellulosic ethanol production due to their ability to produce high ethanol yields by simultaneous fermentation of hexose and pentose. Understanding the genome structure of these species is critical to improving and implementing these bacteria for possible biotechnological use in consolidated bioprocessing schemes (CBP) for cellulosic ethanol production. Here we describe a comparative genome analysis of two ethanologenic bacteria, Thermoanaerobacter sp. X514 and Thermoanaerobacter pseudethanolicus 39E. Compared to 39E, X514 has several unique key characteristics important to cellulosic biotechnology, including additional alcohol dehydrogenases and xylose transporters, modifications to pentose metabolism, and a complete vitamin B 12 biosynthesis pathway. Experimental results from growth, metabolic flux, and microarray gene expression analyses support genome sequencing-based predictions which help to explain the distinct differences in ethanol production between these strains. The availability of whole-genome sequence and comparative genomic analyses will aid in engineering and optimizing Thermoanaerobacter strains for viable CBP strategies.Global energy demands will increase significantly in coming decades (16), and renewable energy sources such as biofuels have been proposed to help reduce dependence upon fossil energy (8,23,27,49). Current efforts focus on biofuel production from renewable lignocellulosic feedstock (e.g., switchgrass), which constitutes ϳ50% of the world's biomass (2,8,23,27,49). Although intensive research and development have been performed on the effective utilization of lignocellulose, problems associated with practical use of this material have not been resolved fully (13). When enzymatic hydrolysis is adopted for cellulosic ethanol production, different levels of process integration can be visualized: (i) separate (or sequential) hydrolysis and fermentation (SHF), where the enzymes (cellulases) are used separately from fermentation tanks; (ii) simultaneous saccharification and fermentation (SSF), which consolidates enzymatic hydrolysis with fermentation of hexose or pentose; (iii) simultaneous saccharification and cofermentation (SSCF), which further combines the fermentation of hexose and pentose together; and (iv) consolidated bioprocessing (CBP), where all required enzymes and ethanol are produced in a single reactor (1,13,24,29,46,51). While these production schemes represent increasing levels of simplification through process consolidation, consolidation of multiple steps often results in a loss of process efficiency. Thus, improving the efficiency of individual steps, such as cellulose hydrolysis and ethanol fermentation, remains an important task for the development of economically feasible cellulosic bioethanol.Recent efforts have focused on metabolic engineering and (more recently) synthetic biology to produce strains or consortia capable of producing biofuels. Efforts to ...

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“…Temperature shifts affect a variety of cellular processes including protein translation rate, membrane fluidity, RNA stability, rescue enzyme activity, impacting cell growth (Lee et al, 2012) and eventually decreasing fermentation yield and byproduct quality (Salvado et al, 2011). Although the use of thermophilic bacteria in ethanol fermentation has been reported (Wiegel et al, 1980), the yeast S. cerevisiae is the most widely used microorganism in fuel ethanol production. Several cost reductions could be achieved if fermentation could be performed with thermotolerant yeasts at higher temperatures (Abdel-Banat et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Saccharomyces cerevisiae KNU5377 Stress Response during High-Temperature Ethanol Fermentation

Kim

et al. 2013

Molecules and Cells

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Formation of ethanol by bacteria. A pledge for the use of extreme thermophilic anaerobic bacteria in industrial ethanol fermentation processes

Cited by 117 publications

References 55 publications

Cellulase, Clostridia, and Ethanol

Cellulase, Clostridia, and Ethanol

Correlation of Genomic and Physiological Traits of Thermoanaerobacter Species with Biofuel Yields

Saccharomyces cerevisiae KNU5377 Stress Response during High-Temperature Ethanol Fermentation

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