IN-VITRO FORMATION OF A CATABOLIC PLASMID CARRYING KLEBSIELLA-PNEUMONIAE DNA THAT ALLOWS GROWTH OF ESCHERICHIA-COLI K-12 ON 3-HYDROXYBENZOATE

The four enzymes needed to convert 3-hydroxybenzoate to pyruvate and f umarate via the gentisate pathway, as well as a putative positive regu lator protein, were encoded on an 8 kb Sphl fragment of Klebsiella pne umoniae DNA. The five genes were clustered in the order regulator-gent isate dioxygenase-fumarylpyruvate hydrolase-3-hydroxybenzoate monooxyg enase-maleylpyruvate isomerase (mhbRDHMI), with the catabolic genes tr anscribed in the dioxygenase to isomerase direction. 2-Hydroxybenzoate was found to be a non-metabolizable inducer analogue for the mhb gene s, supporting the view that gentisate rather than maleylpyruvate was t he physiological inducer, The plasmid pNDR20 encoding the full gentisa te catabolic pathway endowed Escherichia coil with the ability to grow on 3-hydroxybenzoate but the host cell appeared to be responsible for substrate uptake.