• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.172-178
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• 1997

Xanthmonas campestris pv. campestris, causal agent of Black rot of crucifers, were isolated and identified from crucifer host. In order to determine the characters of X. c. pv. campestris associated with pathogenicity, Tn5 mutagenesis was carried out by conjugating with E. coli pJB4J1. Transconjugants were plate- assayed for missing cellulase, protease and amylase activity. A cellulase negative mutant was selected and tested for pathogenicity. Light microscopy and Scanning electron microscopy revealed that substomatal tissues were colonized by mutant, but was far less extensive than those by wild type. Stomatal surface and substomatal tissue appeared to have degraded by only wild type in 24 hrs and progression of pathogenesis was distinct in 48 hrs. In 6 days, wild type proliferated well in the tissue facilitated by cellulase activity. As a result, cellulase was determined as the important factor in pathogenesis.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.275-281
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• 1995

From the plasmid pYA300 carring a CMCase of Rhizobium fredii USDA193 plasmid was subcloned into pBluescript II KS(+)/pBluescript II SK(+) vectors and designated pYA500 and pYA600, respectively. Escherchia coli cells transformed with pYA500 porduced the CMCase more than with pYA600. The orientation of the cloned fragment in pBluescript vector had the effect on gene expression in E. coli background. When the 1.7 kb CMCase gene fragment of R. fredii USDA193 was hybridized to EcoRI-digested total DNA from R. meliloti and R. fredii USDA 191 the unique bands hybridized respectively, indicating that some genetic diversity exists in the EcoRI restriction enzyme site for CMCase gene in Rhizobium strains. The optimum pH of enzyme activity was 7 and the optimum temperature of that was nearly 37$\circ$C. The cellulase-minus derivatives of pYA500 were constructed by Tn5 insertional mutation. Among 6000 transconjugants, two mutant plasmids (designated pYA500::Tn5a and pYA500::Tn5b) were detected from the cellulase- negative transconjugants. The product of CMCase gene was analyzed by one dimensional SDS- PAGE of the cell extracts. About 45 kDa protein was considered to be a product of CMCase gene.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.5
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• pp.802-810
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• 2007

Fibrobacter succinogenes, a Gram-negative, anaerobic ruminal bacterium is a major fibre digesting species in the rumen. It intensively degrades plant cell walls by an erosion type of mechanism, burrowing its way through the complex matrix of cellulose and hemicellulose with the release of digestible and undigested cell wall fragments. The enzymes involved in this process include a combination of glucanases, xylanases, arabinofuranosidase(s) and esterases. The genome of the bacterium has been sequenced and this has revealed in excess of 100 putative glycosyl hydrolase, pectate lyase and carbohydrate esterase genes, which is greater than the numbers reported present in other major cellulolytic organisms for which genomes have been sequenced. Modelling of the amino acid sequences of two glycanases, CedA and EGB, by reference to crystallized homologs has enabled prediction of the major features of their tertiary structures. Two dimensional gel electrophoresis in conjunction with mass spectroscopy has permitted the documentation of proteins over expressed in F. succinogenes grown on cellulose, and analysis of the cell surfaces of mutant strains unable to bind to cellulose has enabled the identification of candidate proteins with roles in adhesion to the plant cell wall substrate, the precursor to cellulose biodegradation.