GROWTH-PERFORMANCE AND PATHWAY FLUX DETERMINE SUBSTRATE PREFERENCE OFALCALIGENES-EUTROPHUS DURING GROWTH ON ACETATE PLUS AROMATIC COMPOUNDMIXTURES

During batch growth of Alcaligenes eutrophus on various aromatic compo unds in the presence of acetate, several distinct behaviour patterns w ere observed, The utilization of substrates of the meta pathway (pheno l or p-cresol) was inhibited by acetate. When the aromatic was a subst rate of the p-hydroxybenzoate branch of the ortho pathway, growth was mixotrophic, i.e. both substrates were consumed simultaneously. For th e substrates of the gentisate pathway or the benzoate branch of the or tho pathway, substrate preference was governed by growth performance, Aromatic compounds enabling growth rate and yields higher than those o btained on acetate alone (i.e. benzoate, benzaldehyde, m-hydroxybenzoa te and gentisate) inhibited acetate utilization, while acetate was the substrate consumed preferentially in mixtures containing aromatic com pounds supporting only slow growth (i.e. benzoyl formate and 4-fluorob enzoate).