Identification of a catabolic transposon, Tn4371, carrying biphenyl and 4-chlorobiphenyl degradation genes in Alcaligenes eutrophus A5.
Alcaligenes eutrophus A5 catabolizes biphenyl to CO2 via benzoate and 4-chlorobiphenyl to 4-chlorobenzoate. In curing and conjugation experiments, the A5 endogenous 51-kb IncP1 plasmid pSS50 was found to be dispensable for biphenyl and 4-chlorobiphenyl catabolism. Transfer of the biphenyl- and 4-chlorobiphenyl-degrading phenotype by means of pSS50 was observed at a frequency of 10(-5) per transferred plasmid in matings of A5 with other A. eutrophus strains. Transconjugants harbor enlarged pSS50 derivatives which contain additional genetic information governing the oxidation of biphenyl and 4-chlorobiphenyl to benzoate and 4-chlorobenzoate and originating from the chromosome of strain A5. The following observations indicate that the catabolic genes reside on a 59-kb large transposon (Tn4371) for which a restriction map is presented. (i) Tn4371 transposes between different replicons and at different locations of the same replicon. (ii) Transposition was observed in a Rec- strain of A. eutrophus. (iii) Tn4371 transposes as a single, contiguous piece of DNA. Although an RP4::Tn4371 plasmid was stably maintained in different hosts, the plasmid conferred growth on biphenyl only when present in strains of A. eutrophus and in an Acinetobacter sp. strain.
Laboratory of Genetics and Biotechnology, SCK/CEN-VITO, Mol, Belgium.
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Springael
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Kreps
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Mergeay
D000421:Alcaligenes / Q000235:genetics* / Q000378:metabolism; D001713:Biphenyl Compounds / Q000378:metabolism*; D015139:Blotting, Southern; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D005798:Genes, Bacterial; D015394:Molecular Structure
D001713:Biphenyl Compounds; D004251:DNA Transposable Elements; C006983:4-chlorobiphenyl