Cloning and expression of cellulase and xylanase genes in Lactobacillus plantarum
1990
Scheirlinck, T. | Meutter, J. de | Arnaut, G. | Joos, H. | Claeyssens, M. | Michiels, F.
Eleven cellulase genes from Gram-positive bacteria were cloned in a Lactobacillus plantarum silage inoculum. Eight of these genes were expressed as active enzymes from their original promoters and translation signals. Where tested, the enzymes produced by transformed L. plantarum had the same temperature and pH optimum as enzymes produced in the original host, or in transformed Escherichia coli. Using chloramphenicol acetyltransferase as a cell-internal marker enzyme, it could be demonstrated that at least endoglucanase D from Clostridium thermocellum was actively secreted by transformed L. plantarum. In growing L. plantarum cultures, most of the enzymes were irreversibly inactivated when the pH decreased below 4.5. If the transformed strains were to be applied as an inoculum in silage, this pH inactivation might be useful in preventing overdigestion of the crop fibre.
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