TRANSFER OF THE CATABOLIC PLASMID RP4TN4371 TO INDIGENOUS SOIL BACTERIA AND ITS EFFECT ON RESPIRATION AND BIPHENYL BREAKDOWN

The catabolic plasmid RP4::Tn4371, containing the genes for biphenyl a nd 4-chlorobiphenyl catabolism, was transferred from Enterobacter aggl omerans DMK3 to indigenous bacteria in biphenyl amended sandy soil, al though the donor survived for only 3 days. Proliferation of transconju gants above a detectable lever required presence of the concomitant po llutant biphenyl. Different Gram-negative bacterial species, tentative ly identified as Pseudomonas chlororaphis, Pseudomonas corrugata and C omamonas sp., had taken up the plasmid and were able to express the bi phenyl degradation genes. These genera have, until now, not been repor ted to express the biphenyl degradative genes. The soil had a high nat ural catabolic capacity for biphenyl. Notwithstanding this, out of 8 t rials in which DMK3 was inoculated, 2 were found not to respond but 6 had an increased biphenyl degradation and concomitant increased oxygen consumption. The results indicate that seeding of RP4::Tn4371 generat es a variety of transconjugants and holds potential for increasing the soil biodegradation capacity towards chlorinated biphenyl analogues.