BioChem - DOS

Consolidated bioprocessing of transgenic switchgrass by an engineered and evolved Clostridium thermocellum strain

Biotechnology for biofuels

Yee, Kelsey L; Rodriguez Jr, Miguel; Thompson, Olivia A; Fu, Chunxiang; Wang, Zeng-Yu; Davison, Brian H; Mielenz, Jonathan R

<P><B>Background</B></P><P>Switchgrass is an abundant and dedicated bioenergy feedstock, however its inherent recalcitrance is one of the economic hurdles for producing biofuels. The downregulation of the caffeic acid O-methyl transferase (COMT) gene in the lignin pathway of switchgrass reduced lignin content and S/G ratio, and the transgenic lines showed improved fermentation yield with <I>Saccharomyces cerevisiae</I> and wild-type <I>Clostridium thermocellum</I> (ATCC 27405) in comparison to the wild-type switchgrass.</P><P><B>Results</B></P><P>Here we examine the conversion and yield of the COMT transgenic and wild-type switchgrass lines with an engineered and evolved <I>C. thermocellum</I> (M1570) strain. The fermentation of the transgenic switchgrass by M1570 had superior conversion relative to the wild-type control switchgrass line with an increase in conversion of approximately 20% and ethanol being the primary product accounting for 90% of the total metabolites measured by HPLC analysis.</P><P><B>Conclusions</B></P><P>The engineered and evolved <I>C. thermocellum</I> M1570 was found to respond to the apparent reduced recalcitrance of the COMT switchgrass with no substrate inhibition, producing more ethanol on the transgenic feedstock than the wild-type substrate. Since ethanol was the main fermentation metabolite produced by an engineered and evolved <I>C. thermocellum</I> strain, its ethanol yield on a transgenic switchgrass substrate (gram/gram (g/g) glucan liberated) is the highest produced thus far. This result indicates that the advantages of a modified feedstock can be combined with a modified consolidated bioprocessing microorganism as anticipated.</P>

2014

BioMed Central

1754-6834

7

pp.75-75

10.1186/1754-6834-7-75

http://click.ndsl.kr/servlet/OpenAPIDetailView?keyValue=05787966&target=NART&cn=NART71770148

Transgenic; Switchgrass; Metabolic engineering; Clostridium thermocellum; Consolidated bioprocessing; Feedstock; Cellulosic ethanol