Lignocellulose fermentation and residual solids characterization for senescent switchgrass fermentation by <i>Clostridium thermocellum</i> in the presence and absence of continuous <i>in situ</i> ball-milling

Balch, Michael L.; Holwerda, Evert K.; Davis, Mark F.; Sykes, Robert; Happs, Renee M.; Kumar, Rajeev; Wyman, Charles E.; Lynd, Lee R.

doi:10.1039/c6ee03748h

Cited by 71 publications

(50 citation statements)

References 56 publications

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“…While not yet completely understood, the effectiveness of C. thermocellum at lignocellulose solubilization has been attributed to the ability to splay ends of cellulose fibers [21] and the presence of multiple cellulase modalities [22 ]. C. thermocellum has also been shown to be capable of carrying out soluble sugar fermentation in the presence of aggressive ball milling, whereas yeast has not [23]. Wildtype strains of C. thermocellum and other thermophilic, saccharolytic anaerobes produce organic acids, in particular acetic acid, in addition to ethanol and do not exhibit high ethanol tolerance.…”

Section: An Illustrative Examplementioning

confidence: 99%

Cellulosic ethanol: status and innovation

Lynd

Liang

Biddy

et al. 2017

Current Opinion in Biotechnology

334

199

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Although the purchase price of cellulosic feedstocks is competitive with petroleum on an energy basis, the cost of lignocellulose conversion to ethanol using today's technology is high. Cost reductions can be pursued via either in-paradigm or new-paradigm innovation. As an example of new-paradigm innovation, consolidated bioprocessing using thermophilic bacteria combined with milling during fermentation (cotreatment) is analyzed. Acknowledging the nascent state of this approach, our analysis indicates potential for radically improved cost competitiveness and feasibility at smaller scale compared to current technology, arising from (a) R&D-driven advances (consolidated bioprocessing with cotreatment in lieu of thermochemical pretreatment and added fungal cellulase), and (b) configurational changes (fuel pellet coproduction instead of electricity, gas boiler(s) in lieu of a solid fuel boiler).

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Section: An Illustrative Examplementioning

confidence: 99%

Cellulosic ethanol: status and innovation

Lynd

Liang

Biddy

et al. 2017

Current Opinion in Biotechnology

334

199

View full text Add to dashboard Cite

show abstract

“…Inspired by the positive effect of rumination on feed digestibility, Balch et al (2017) investigated the impact of continuous ball milling on the solubilization of senescent switchgrass in fermentations by C. thermocellum. The authors demonstrated that the total carbohydrate solubilization could be increased from 45% without ball milling to 88% by in situ ball milling.…”

Section: Fundamental Investigations On Defined Anaerobic Cellulolyticmentioning

confidence: 99%

Impacts of biofilms on the conversion of cellulose

Brethauer

Shahab

Studer

2020

Appl Microbiol Biotechnol

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Lignocellulose is a widely available renewable carbon source and a promising feedstock for the production of various chemicals in biorefineries. However, its recalcitrant nature is a major hurdle that must be overcome to enable economic conversion processes. Deconstruction of lignocellulose is part of the global carbon cycle, and efficient microbial degradation systems have evolved that might serve as models to improve commercial conversion processes. Biofilms-matrix encased, spatially organized clusters of microbial cells and the predominating lifestyle in nature-have been recognized for their essential role in the degradation of cellulose in nature, e.g., in soils or in the digestive tracts of ruminant animals. Cellulolytic biofilms allow for a high concentration of enzymes at the boundary layer between the solid substrate and the liquid phase and the more complete capture of hydrolysis products directly at the hydrolysis site, which is energetically favorable. Furthermore, enhanced expression of genes for carbohydrate active enzymes as a response to the attachment on solid substrate has been demonstrated for cellulolytic aerobic fungi and anerobic bacteria. In natural multispecies biofilms, the vicinity of different microbial species allows the creation of efficient food webs and synergistic interactions thereby, e.g., avoiding the accumulation of inhibiting metabolites. In this review, these topics are discussed and attempts to realize the benefits of biofilms in targeted applications such as the consolidated bioprocessing of lignocellulose are highlighted. Key Points & Multispecies biofilms enable efficient lignocellulose destruction in the biosphere. & Cellulose degradation by anaerobic bacteria often occurs by monolayered biofilms. & Fungal biofilms immobilize enzymes and substrates in an external digestion system. & Surface attached cultures typically show higher expression of cellulolytic enzymes.

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“…5 Biomass modification is essential through either physical/chemical pretreatment or cotreatment of biomass to achieve high solubilization of polysaccharides by biological systems. [6][7][8][9][10][11] For ethanol production via a biological route, enzymatic hydrolysis of cellulose is a heterogeneous reaction in which enzymes derived from † These authors contributed equally to this work.…”

Section: Introductionmentioning

confidence: 99%