INTEGRATIVE VECTOR FOR STABLE TRANSFORMATION AND EXPRESSION OF A BETA-1,3-GLUCANASE GENE IN CLAVIBACTER-XYLI SUBSP CYNODONTIS

Clavibacter xyli subsp. cynodontis is an endophytic Gram-positive bact erium that is able to colonize the xylem tissue of various plants. We constructed an integrative vector that can carry foreign genes into a repetitive chromosomal element of C. xyli subsp. cynodontis. Using thi s vector, we transformed C. xyli subsp. cynodontis with a gene coding for an endoglucanase enzyme under the control of a strong promoter tha t was previously isolated from the genome of C. xyli subsp. cynodontis . The transformed bacteria efficiently expressed active glucanase and secreted it into the culture medium. The vector has the advantage of b eing stably maintained in the chromosome; the transformations were mai ntained without antibiotic selection both in in vitro culture and in b acteria growing in maize xylem. (C) 1998 Federation of European Microb iological Societies. Published by Elsevier Science B.V.