Studies on the sucrose utilization system of Clostridium beijerinckii NCIMB 8052
Doctoral Thesis
1997
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University of Cape Town
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Abstract
Solventogenic clostridial strains were used extensively in the industrial acetone-butanolethanol (ABE) fermentation during the first half of this century. This fermentation was based predominantly on two substrates: corn mash (rich in starch) and molasses (rich in sucrose). Taxonomically distinct strains were used for ABE fermentations based on the two substrates. Although starch . utilization by amylolytic solventogenic clostridial strains had been investigated, sucrose utilization by saccharolytic solventogenic clostridial strains had not been comprehensively studied. This provided the impetus for the present study. The primary aim of the project was to provide a molecular and physiological characterization of the sucrose utilization system of Clostridium beijerinckii NCIMB 8052. The C. beijerinckii sucrose utilization operon, scrARBK, was cloned in three stages. In the first stage a C. beijerinckii genomic library was screened in Escherichia coli for clones able to utilize sucrose. Using this approach, a truncated scr operon was isolated. The remainder of the operon was isolated in the second and third stages by recovering a plasmid integrated into the scrB gene, and inverse-PCR respectively. The four genes of the scrARBK operon were prowsed to encode an Enzyme1IBC1ucrose protein of the PTS (ScrA); a transcriptional repressor of the GalR-Lacl family (ScrR), a sucrose-6-phosphate hydrolase of the glucosyl hydrolase family 32 (ScrB) and an ATP-dependent fructokinase of the ribokinase/pfkB sugar kinase family (ScrK).
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Bibliography: pages 117-130.
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Leat, N. 1997. Studies on the sucrose utilization system of Clostridium beijerinckii NCIMB 8052. University of Cape Town.