Degradation of high loads of crystalline cellulose and of unpretreated plant biomass by the thermophilic bacterium Caldicellulosiruptor bescii

• Published in: Bioresource technology Vol. 152; pp. 384 - 392
• Main Authors: Basen, Mirko, Rhaesa, Amanda M., Kataeva, Irina, Prybol, Cameron J., Scott, Israel M., Poole, Farris L., Adams, Michael W.W.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.01.2014; Elsevier
• Subjects: Ammonium Compounds - pharmacology; Biodegradation, Environmental - drug effects; Biological and medical sciences; Biomass; Biomass conversion; Bioreactors - microbiology; Biotechnology; Caldicellulosiruptor; Carbon; Cellulose - metabolism; Consolidated bioprocessing; Crystalline cellulose; Degradation; Fermentation - drug effects; Fundamental and applied biological sciences. Psychology; Gram-Positive Bacteria - drug effects; Gram-Positive Bacteria - growth & development; Gram-Positive Bacteria - metabolism; High substrate loads; Hydrogen-Ion Concentration - drug effects; Inhibitors; Lignin - metabolism; Organic acids; Panicum - drug effects; Panicum - growth & development; Panicum - metabolism; Plants (organisms); Temperature; Thermophiles; Vitamins; Caldicellulosiruptor; Biomass conversion; High substrate loads; Consolidated bioprocessing; Thermophiles; Degradation; Substrate; Cellulose; Bacteria; Thermophily; Biomass; Biological treatment
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2013.11.024

•C. bescii degrades 60% of 50gL−1 crystalline cellulose.•C. bescii grows on industrially relevant loads of unpretreated biomass (200gL−1).•Growth is inhibited by low concentrations (20gL−1) of acid-treated switchgrass.•Carbon balances are closed after degradation of crystalline cellulose and switchgrass.•Growth on crystalline cellulose was limited by nitrogen and vitamin availability. The thermophilic bacterium Caldicellulosiruptor bescii grows at 78°C on high concentrations (200gL−1) of both crystalline cellulose and unpretreated switchgrass, while low concentrations (<20gL−1) of acid-pretreated switchgrass inhibit growth. Degradation of crystalline cellulose, but not that of unpretreated switchgrass, was limited by nitrogen and vitamin (folate) availability. Under optimal conditions, C. bescii solubilized approximately 60% of the crystalline cellulose and 30% of the unpretreated switchgrass using initial substrate concentrations of 50gL−1. Further fermentation of crystalline cellulose and of switchgrass was inhibited by organic acid end-products and by a specific inhibitor of C. bescii growth that did not affect other thermophilic bacteria, respectively. Soluble mono- and oligosaccharides, organic acids, carbon dioxide, and microbial biomass, quantitatively accounted for the crystalline cellulose and plant biomass carbon utilized. C. bescii therefore degrades industrially-relevant concentrations of lignocellulosic biomass that have not undergone pretreatment thereby demonstrating its potential utility in biomass conversion.