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Bioresour Technol. 2014;152:384-92. doi: 10.1016/j.biortech.2013.11.024. Epub 2013 Nov 19.

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

Author information

1
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: mbasen@uga.edu.
2
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: rhaesa13@uga.edu.
3
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: kataeva@uga.edu.
4
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: cprybol1@uga.edu.
5
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: imscott357@gmail.com.
6
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: fpoole@bmb.uga.edu.
7
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: adams@bmb.uga.edu.

Abstract

The thermophilic bacterium Caldicellulosiruptor bescii grows at 78 °C on high concentrations (200 g L(-1)) of both crystalline cellulose and unpretreated switchgrass, while low concentrations (<20 g L(-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 50 g L(-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.

KEYWORDS:

Biomass conversion; Caldicellulosiruptor; Consolidated bioprocessing; High substrate loads; Thermophiles

PMID:
24316482
DOI:
10.1016/j.biortech.2013.11.024
[Indexed for MEDLINE]

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