Cloning and Characterization of Aerobactin Biosynthesis Genes of the Biological Control Agent Enterobacter cloacae.
Five strains of Enterobacter cloacae that are biological control agents of Pythium damping-off diseases produced the hydroxamate siderophore aerobactin under iron-limiting conditions. Genes determining aerobactin biosynthesis of the biocontrol strain E. cloacae EcCT-501 were localized to a 12.3-kb region, which conferred aerobactin production to Escherichia coli DH5alpha. The aerobactin biosynthesis genes of E. cloacae hybridized to those of the pColV-K30 plasmid of E. coli, but restriction patterns of the aerobactin regions of pColV-K30 and E. cloacae differed. A derivative strain with a deletion in the aerobactin biosynthesis locus was as effective as strain EcCT-501 in biological control of Pythium damping-off of cucumber. Thus, aerobactin production did not contribute significantly to the biological control activity of EcCT-501 under the conditions of this study.
Loper
J E
JE
Horticultural Crops Research Laboratory, Agricultural Research Service, United States Department of Agriculture, 3420 N.W. Orchard Avenue, and Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97330.
Ishimaru
C A
CA
Carnegie
S R
SR
Vanavichit
A
A