Laccase production in gamma-proteobacterium JB was enhanced 13-fold by adding 0.1 mM CuSO4 24 h after the onset of growth. Ethidium bromide (2.5 muM), Malachite Green, Phenol Red and Thymol Blue (10 muM each) enhanced laccase production 17-, 19-, 4- and 2-fold, respectively. Among the fourteen aromatic/organic compounds tried, p-aminobenzoic acid and an industrial effluent, from where the organism was isolated, showed 1.2- and 1.26-fold increases in production.