Effects of Naphthalene Degradative Plasmids on the Physiological Characteristics of Rhizosphere Bacteria of the Genus Pseudomonas

We studied the specific growth rate, duration of the lag phase, stability of plasmids, and activities of the key enzymes involved in naphthalene biodegradation in rhizosphere pseudomonades carrying the structurally similar plasmids pOV17 and pBS216. It was demonstrated that these plasmids determined various levels of catechol-2,3-dioxygenase activities. The structural rearrangements in the plasmid pBS216 could “switch off” the genes of the catechol oxidation meta-pathway. It was shown that certain combinations of degradative plasmids and bacterial hosts, such as Pseudomonas chlororaphis PCL1391(pBS216), P. chlororaphis PCL1391(pOV17), and P. putida 53a(pOV17), were considerably more efficient than natural variants in their growth characteristics and the stability of the biodegradation activity, having a potential for bioremediation of soils polluted with polycyclic aromatic hydrocarbons (PAHs).