COMAMONAS-ACIDOVORANS UCC61 CATABOLIZES O-PHTHALATE VIA A 4,5-OXYGENATION PATHWAY THAT IS ENCODED ON A 70 KBP SECTION OF PLASMID POPH1 BOUNDED BY DIRECTLY REPEATED SEQUENCES
Jr. Dutton et al., COMAMONAS-ACIDOVORANS UCC61 CATABOLIZES O-PHTHALATE VIA A 4,5-OXYGENATION PATHWAY THAT IS ENCODED ON A 70 KBP SECTION OF PLASMID POPH1 BOUNDED BY DIRECTLY REPEATED SEQUENCES, Microbiology, 141, 1995, pp. 1673-1682
Twenty-three bacteria capable of growing with o-phthalate as sole carb
on source were isolated from sewage sludge. One of these, named UCC61,
was identified as a strain of Comamonas acidovorans and was selected
for further study. UCC61 was found to carry a single plasmid (named pO
PH1) of about 270 kbp in size. The phthalate-utilizing phenotype of UC
C61 was unstable and could be lost either by complete curing of pOPH1,
or by the deletion of a specific 70 kbp segment from pOPH1. This segm
ent, termed the Pht element, was extensively restriction mapped (using
four restriction endonucleases), and was found to be flanked by direc
tly repeated sequences greater than 1.9 kbp in length. Data from compa
rative restriction analysis of pOPH1 and its deleted derivative were c
onsistent with a deletion mechanism that involves homologous recombina
tion between the direct repeats. UCC61 was found to catabolize o-phtha
late via 4,5-oxygenation, dehydrogenation and decarboxylation to proto
catechuate. These three activities were encoded within the Pht element
, with the genes clustered near the right-hand terminus. Protocatechua
te metabolism was chromosomally encoded, as also was the ability to ca
tabolize the m- and p-isomers of phthalate.