Simultaneous degradation of chloro- and methyl-substituted aromatic compounds: competition between Pseudomonas strains using the ortho and meta pathway or the ortho pathway exclusively

Abstract

Pseudomonas sp. D7-4 and Pseudomonas sp. B13 FR1(pFRC20P) degraded mixtures of chloro- and methyl-substituted benzoates exclusively via an extended ortho pathway, whereas in Pseudomonas putida WR201 both ortho and meta fission were induced by mixtures of 3-chloro- and 3-methylbenzoate or even by 3-chlorobenzoate alone. The competition behaviour of these strains was compared in batch and in chemostat cultures. Despite misrouting of metabolites, strain WR201 was competitive, in a lot of the competition experiments, with mixtures of these substrates. Only in a narrow range of the mixing ratio of chloro- and methylbenzoate was the presence of both the meta and ortho pathways a disadvantage for competitiveness. Outside these ranges other attributes, such as high growth rates or short lag periods, of a respective strain were even more essential for one strain to outcompete another.