[Regulation of the enzyme activity of para-xylene catabolism in a spontaneous para-xylene-negative variant of Pseudomonas aeruginosa 2x79].

: A spontaneous variant of Pseudomonas aeruginosa 2x unable to grow on p-xylene as the sole source of carbon and energy has been isolated. p-Xylenenegative variant of P. aeruginosa 2x79 differs from the wild type strain by the character of growth on the p-xylene oxidation intermediates p-toluate and protocatochuate. The cell of 2x79 variant inability to grow on p-xylene has been shown to be accompanied by the elimination of the activities of three enzymes - p-xylene methylhydroxylase, p-cresol methylhydroxylase and metapyrocatechase and by the considerable alteration in the regulation of orto-cleavage aromatic ring enzymes activity pyrocatechase and protocatechuate-3,4-dioxygenase. Possible reasons for appearing spontaneous variants 2x79 in the population of P. aeruginosa 2x growing on the p-xylene are being discussed.