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Biological conversion assay using Clostridium phytofermentans to estimate plant feedstock quality

Permanent URL:
http://handle.nal.usda.gov/10113/55915
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Abstract:
BACKGROUND: There is currently considerable interest in developing renewable sources of energy. One strategy is the biological conversion of plant biomass to liquid transportation fuel. Several technical hurdles impinge upon the economic feasibility of this strategy, including the development of energy crops amenable to facile deconstruction. Reliable assays to characterize feedstock quality are needed to measure the effects of pre-treatment and processing and of the plant and microbial genetic diversity that influence bioconversion efficiency. RESULTS: We used the anaerobic bacterium Clostridium phytofermentans to develop a robust assay for biomass digestibility and conversion to biofuels. The assay utilizes the ability of the microbe to convert biomass directly into ethanol with little or no pre-treatment. Plant samples were added to an anaerobic minimal medium and inoculated with C. phytofermentans, incubated for 3 days, after which the culture supernatant was analyzed for ethanol concentration. The assay detected significant differences in the supernatant ethanol from wild-type sorghum compared with brown midrib sorghum mutants previously shown to be highly digestible. Compositional analysis of the biomass before and after inoculation suggested that differences in xylan metabolism were partly responsible for the differences in ethanol yields. Additionally, we characterized the natural genetic variation for conversion efficiency in Brachypodium distachyon and shrub willow (Salix spp.). CONCLUSION: Our results agree with those from previous studies of lignin mutants using enzymatic saccharification-based approaches. However, the use of C. phytofermentans takes into consideration specific organismal interactions, which will be crucial for simultaneous saccharification fermentation or consolidated bioprocessing. The ability to detect such phenotypic variation facilitates the genetic analysis of mechanisms underlying plant feedstock quality.
Author(s):
Scott J Lee , Thomas A Warnick , Sivakumar Pattathil , Jesús G Alvelo-Maurosa , Michelle J Serapiglia , Heather McCormick , Virginia Brown , Naomi F Young , Danny J Schnell , Lawrence B Smart , Michael G Hahn , Jeffrey F Pedersen , Susan B Leschine , Samuel P Hazen
Subject(s):
Brachypodium distachyon , Clostridium phytofermentans , Salix , Sorghum bicolor , alcoholic fermentation , bacteria , bioassays , bioethanol , biomass , bioprocessing , biotransformation , carbohydrate metabolism , digestibility , economic feasibility , energy crops , ethanol , ethanol production , feedstocks , genetic techniques and protocols , genetic variation , grain sorghum , mutants , phenotypic variation , saccharification , xylan , yields
Source:
Biotechnology for biofuels 2012 12 v.5 no.1
Language:
English
Publisher:
Springer-Verlag
Year:
2012
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.