Naphthalene plasmids in Pseudomonads

Connors, Margaret Anne Morris (1986) Naphthalene plasmids in Pseudomonads. Masters thesis, Memorial University of Newfoundland.

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Abstract

The Pseudomonas strains NCIB 9816, PG, ATCC 17483 and ATCC 17484 were examined for the involvement of plasmids in the degradation of naphthalene. The role of a plasmid was demonstrated in strains NCIB 9816 and PG by conjugation. It was not possible to demonstrate the involvement of plasmids in the degradation of naphthalene in strains ATCC 17483 and ATCC 17484 either by curing or conjugation. -- A published method was modified to permit the screening of wild type strains for the presence of plasmids. Strains NCIB 9816, PG and ATCC 17484 contained multiple plasmids. It was not possible to demonstrate the presence of any plasmids in ATCC 17483. It was the largest of the pair of plasmids in NCIB 9816 and PG (designated NAH2 and NAH3 respectively) which determined the degradation of naphthalene. -- The patterns of restriction enzyme fragments from digestion with Hind III or BAM HI were identical for NAH2 and NAH3, but were very different from those of NAH, the plasmid described by Dunn and Gunsalus (1973). Nevertheless, NAH3 hydridized extensively with NAH. -- Some aspects of the regulation of the naphthalene pathway were investigated. An examination of mutants generated by exposure to N-methyl-N'-nitro-N-nitrosoguanidine enabled the identification of salicylaldehyde as the first possible inducer of the pathway in strain ATCC 17483. The unusual regulatory characteristics of the meta enzymes for the degradation of catechol in strains NCIB 9816 and PG were transferred by conjugation, and are therefore specified by plasmids NAH2 and NAH3 respectively. However, differences in the regulation of plasmids NAH2 and NAH3 and plasmid NAH may not be as great as it would first appear.

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