Diversity within the genus Thermoanaerobacter and its potential implications in lignocellulosic biofuel production through consolidated bioprocessing

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dc.contributor.authorVerbeke, Tobin James
dc.contributor.examiningcommitteeYurkov, Vladimir (Microbiology) De Kievit, Teresa (Microbiology) Levin, David (Biosystems Engineering) Kelly, Robert (Chemical and Biomolecular Engineering, North Carolina State University)en_US
dc.contributor.supervisorSparling, Richard (Microbiology)en_US
dc.date.accessioned2014-01-15T21:17:41Z
dc.date.available2014-01-15T21:17:41Z
dc.date.issued2011-03-09en_US
dc.date.issued2011-08-30en_US
dc.date.issued2013-03-26en_US
dc.date.issued2012-12-18en_US
dc.degree.disciplineMicrobiologyen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractA major obstacle to achieving commercially viable lignocellulosic biofuels through consolidated bioprocessing (CBP) is the lack of “industry-ready” microorganisms. Ideally, a CBP-relevant organism would achieve efficient and complete hydrolysis of lignocellulose, simultaneous utilization of the diverse hydrolysis products and high yields of the desired biofuel. To date, no single microbe has been identified that can perform all of these processes at industrially significant levels. As such, thermophilic decaying woodchip compost was investigated as a source of novel lignocellulolytic, biofuel producing bacteria. From a single sample, a collection of physiologically diverse strains were isolated, which displayed differences in substrate utilization and biofuel production capabilities. Molecular characterization of these isolates, and development of a genome relatedness prediction model based on the chaperonin-60 universal target sequence, identified these isolates as strains of Thermoanaerobacter thermohydrosulfuricus. Application of this model to other Thermoanaerobacter spp. further identified that these isolates belong to a divergent and lesser characterized lineage within the genus. Based on this, the CBP-potential of a single isolate, T. thermohydrosulfuricus WC1, was selected for further investigation through metabolic, genomic and proteomic analyses. Its ability to grow on polymeric xylan, potentially catalyzed by an endoxylanase found in only a few Thermoanaerobacter strains, distinguishes T. thermohydrosulfuricus WC1 from many other strains within the genus. The simultaneous consumption of two important lignocellulose constituent saccharides, cellobiose and xylose was also observed and represents a desirable phenotype in CBP-relevant organisms. However, at elevated sugar concentrations, T. thermohydrosulfuricus WC1 produces principally lactate, rather than the desired biofuel ethanol, as the major end-product. Proteomic analysis identified that all likely end-product forming proteins were expressed at high levels suggesting that the end-product distribution patterns in T. thermohydrosulfuricus WC1 are likely controlled via metabolite-based regulation or are constrained by metabolic bottlenecks. The xylanolytic and simultaneous substrate utilization capabilities of T. thermohydrosulfuricus WC1 identify it as a strain of interest for CBP. However, for its development into an “industry-ready” strain as a co-culture with a cellulolytic microorganism, improved biofuel producing capabilities are needed. The practical implications of CBP-relevant phenotypes in T. thermohydrosulfuricus WC1 in relation to other Thermoanaerobacter spp. will be discussed.en_US
dc.description.noteFebruary 2014en_US
dc.identifier.citationSystematic and Applied Microbiology. 2011. 34: 171-179.en_US
dc.identifier.citationFEMS Microbiology Ecology. 2011. 78: 473-487.en_US
dc.identifier.citationPLoS ONE. 2013. 8 (3): e59362.en_US
dc.identifier.citationBMC Microbiology. 2012. 12: 295.en_US
dc.identifier.urihttp://hdl.handle.net/1993/23253
dc.language.isoengen_US
dc.publisherElsevier GmbHen_US
dc.publisherBlackwell Publishing Ltd.en_US
dc.publisherPLOSen_US
dc.publisherBioMed Centralen_US
dc.rightsopen accessen_US
dc.subjectThermoanaerobacteren_US
dc.subjectBiofuelsen_US
dc.subjectComparative genomicsen_US
dc.subjectProteomicsen_US
dc.subjectMicrodiversityen_US
dc.subjectChaperonin-60en_US
dc.subjectMicrobial physiologyen_US
dc.subjectConsolidated bioprocessingen_US
dc.titleDiversity within the genus Thermoanaerobacter and its potential implications in lignocellulosic biofuel production through consolidated bioprocessingen_US
dc.typedoctoral thesisen_US
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