Construction of improved vectors and cassettes containing gusA and antibiotic resistance genes for studies of transcriptional activity and bacterial localization

Broad-host-range, conjugative vectors with a constitutively expressed gusA gene combined with different antibiotic resistance (tetracycline, gentamici n, kanamycin) genes have been constructed. These plasmids are designed for tracking Gram-negative bacterial strains without the risk of random mutagen esis. We also constructed a set of cassettes containing a promoterless gusA gene linked with different antibiotic resistance genes for making transcri ptional fusions and for cassette mutagenesis. New plasmids and cassettes ca n be useful tools for studying gene expression, interaction of bacteria wit h plants and monitoring bacteria in the environment. (C) 2001 Elsevier Scie nce B.V. All rights reserved.