Growth and expression of relevant metabolic genes of Clostridium thermocellum cultured on lignocellulosic residues.
The plant cell wall is a source of fermentable sugars in second-generation bioethanol production. However, cellulosic biomass hydrolysis remains an obstacle to bioethanol production in an efficient and low-cost process. Clostridium thermocellum has been studied as a model organism able to produce enzymatic blends that efficiently degrade lignocellulosic biomass, and also as a fermentative microorganism in a consolidated process for the conversion of lignocellulose to bioethanol. In this study, a C. thermocellum strain (designated B8) isolated from goat rumen was characterized for its ability to grow on sugarcane straw and cotton waste, and to produce cellulosomes. We also evaluated C. thermocellum gene expression control in the presence of complex lignocellulosic biomasses. This isolate is capable of growing in the presence of microcrystalline cellulose, sugarcane straw and cotton waste as carbon sources, producing free enzymes and residual substrate-bound proteins (RSBP). The highest growth rate and cellulase/xylanase production were detected at pH 7.0 and 60 °C, after 48 h. Moreover, this strain showed different expression levels of transcripts encoding cellulosomal proteins and proteins with a role in fermentation and catabolic repression.
Laboratory of Enzymology, Department of Cell Biology, University of Brasília (UnB), Brasília, DF, 70910-900, Brazil.
Vanessa O
VO
Leitão
Laboratory of Enzymology, Department of Cell Biology, University of Brasília (UnB), Brasília, DF, 70910-900, Brazil. enoronha@unb.br.
Eliane F
EF
Noronha
Laboratory of Enzymology, Department of Cell Biology, University of Brasília (UnB), Brasília, DF, 70910-900, Brazil.
Brenda R
BR
Camargo
Laboratory of Enzymology, Department of Cell Biology, University of Brasília (UnB), Brasília, DF, 70910-900, Brazil.
Pedro R V
PRV
Hamann
Laboratory of Enzymology, Department of Cell Biology, University of Brasília (UnB), Brasília, DF, 70910-900, Brazil.
Andrei S
AS
Steindorff
Embrapa-Agroenergy, Brasília, DF, Brazil.
Betania F
BF
Quirino
Laboratory of Biochemistry and Chemistry of Proteins, Department of Cell Biology, University of Brasília (UnB), Brasília, DF, Brazil.
Marcelo Valle
MV
de Sousa
Laboratory of Enzymology, Department of Cell Biology, University Federal Goiás, Goiania, GO, Brazil.
Cirano J
CJ
Ulhoa
Laboratory of Enzymology, Department of Cell Biology, University of Brasília (UnB), Brasília, DF, 70910-900, Brazil.
Carlos R
CR
Felix
D000818:Animals; D018533:Biomass; D002480:Cellulase / Q000378:metabolism; D044603:Cellulosomes / Q000378:metabolism; D048013:Acetivibrio thermocellus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D005285:Fermentation / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006041:Goats; D008031:Lignin / Q000378:metabolism*; D014995:Xylosidases / Q000378:metabolism
C036909:lignocellulose; D008031:Lignin; D014995:Xylosidases; D002480:Cellulase
Agro-industrial residues; Biofuel; Cellulosome; Clostridium thermocellum