UTILIZATION OF HALOGENATED BENZENES, PHENOLS, AND BENZOATES BY RHODOCOCCUS-OPACUS GM-14

Strain GM-14 was isolated by selective enrichment from contaminated so il with chlorobenzene as the sole source of carbon and energy. It util izes an exceptionally wide spectrum of haloaromatic substrates. It is a gram-positive, weakly acid-fast actinomycete, with a morphological c ycle from cocci and short rods to long rods and branched filaments; it grew optimally at 28 degrees C; and it tolerated 5% NaCl in rich medi um. The chemotaxonomic characteristics, the diagnostic biochemical tes ts, the whole-cell fatty acid composition, and 16S rDNA analysis were consistent with Rhodococcus opacus. R. opacus GM-14 grew on 48 of 117 different aromatic and haloaromatic compounds. It utilized phenol at c oncentrations up to 1.2 g/liter, 3- and 4-methylphenols up to 0.5 g/li ter, 2- and 4-chloropbenols up to 0.25 g/liter, and 3-chlorophenol up to 0.1 g/liter. It grew in saturated aqueous solutions of benzene, chl orobenzene, and 1,-3 and 1,4-dichlorobenzene (up to 13, 3, 0.5, and 0. 5 g/liter, respectively). The specific growth rate of strain GM-14 on phenol and 3- and 4-chlorophenols in batch culture was 0.27 to 0.29 h( -1), and that on benzene and chlorobenzene was similar to the rate on fructose, i.e., 0.2 h(-1). The growth yield on benzene and on chlorobe nzene (less than or equal to 0.4 g liter(-1)) was 40 to 50 g (dry weig ht) per mol of substrate consumed, equalling 8 g of dry weight biomass per mol of substrate carbon, similar to that obtained on acetate. Dur ing growth of strain GM-14 on chlorobenzene, 1,3-dichlorobenzene, and ail isomers of monochlorophenol, stoichiometric amounts of chloride we re released, and 50% of the stoichiometric amount was released from 1, 4-dichlorobenzene.