COMPETITION OF PLASMID-HEARING PSEUDOMONAS-PUTIDA STRAINS CATABOLIZING NAPHTHALENE VIA VARIOUS PATHWAYS IN CHEMOSTAT CULTURE

Plasmid-carrying Pseudomonas putida strains degrade naphthalene throug h different biochemical pathways. The influence of various combination s of host bacteria and plasmids on growth characteristics and competit iveness of P. putida strains was studied in chemostat culture at a low dilution rate (D = 0.05 h(-1)) with naphthalene as the sole source of carbon and energy. Under naphthalene limitation, the plasmid-bearing strains degrading naphthalene that use catechol 1,2-dioxygenase for ca techol oxidation (ortho pathway), were the most competitive. The strai ns bearing plasmids that control naphthalene catabolism via catechol 2 ,3-dioxygenase (meta pathway), were less competitive. Under these cond itions the strain carrying plasmid pBS4, which encodes for naphthalene catabolism via gentisic acid, was the least competitive.