Autotrophic Growth of Gas Vacuolate Strains of Microcyclus aquaticus on Methanol and Hydrogen

Characterization of a Pseudomonas sp. Capable of Aniline Degradation in the Presence of Secondary Carbon Sources

Pseudomonas strain K1 is a gram-negative rod which grows aerobically on minimal media containing aniline with a doubling time of 2 h at 30 degrees C. The half-saturation parameter for aniline metabolism by aniline-grown cells was 3.8 mumol . liter. Concentrations of aniline as low as 50 nM were metabolized. Neither substituted anilines nor other aromatic compounds (other than aromatic amino acids) supported growth. Cells grew as fast on aniline as on nonaromatic substrates such as lactate. The aromatic ring was cleaved via the meta pathway. Catechol 2,3-oxygenase activity was induced by aniline, even in cultures containing alternative carbon sources such as lactate. Cultures grown on a mixture of aniline and lactate mineralized aniline in the presence of the second substrate. Lactate-grown cultures lacked catechol oxygenase activity, and resting cells from these cultures did not respire aniline. Resting cells from aniline-grown cultures exhibited high respiratory activity upon the addition of aniline or catechol, some activity with toluidine, and no activity after addition of a wide variety of other aromatic compounds, including dihydroxybenzylamine, chloroanilines, ethylanilines, aminophenols, aminobenzoates, and dihydroxybenzoates. Although substituted anilines were not metabolized, 3-or 4-chloroaniline did induce the enzymes for aniline oxidation.