A transcriptional fusion for an Aeromonas caviae chitinase gene was constructed under the control of a constitutive
promoter of the kanaraycin resistance gene (PKmR
). The construct was inserted into a medium copy number broad host
range plasmid vector to yield recombinant plasmid pAM340, which harbored transcriptional fusion PKmR
- chi. Another
transcriptional fusion, Ptac-chi, in a recombinant plasmid pAM630, was conducted as comparison. Triparental mating of E.
coli  carrying the recombinant plasmids with Pseudomotws fluorescens  5100, a phyllosphere bacterium, was performed.
Pseudomonas fluorescens  5100 exconjugants were examined for constitutive expression of chitinase employing a
spectrophotometric assay; they showed stronger chitin degradation activity than Escherichia coli transformants. Using a fungal
antagonism plate assay, this chitinolytic P. fluorescens, however, could not inhibit selected phytopathogenic fungi.