Isolation and characterization of catechol 2,3-dioxygenase genes from phenanthrene degraders Sphingomonas, sp. ZP1 and Pseudomonas sp. ZP2

Abstract

Two bacterial strains, Sphingomonas sp. ZP1 and Pseudomonas stutzeri sp ZP2, were identified as having phenanthrene-degrading ability and were characterized. The activity of catechol-2,3-dioxygenase (C23O) of both strains was measured. With degradation of phenanthrene with an initial concentration of 250 ppm, the C23O activity of both strain ZP1 and ZP2 increased. The ZP1 strain consumed all phenanthrene at day 6, and strain ZP2 degraded 250 ppm of phenanthrene at around day 5; C23O activity in strain ZP1 reached its peak of 6.92 U at day 6, and C23O activity in strain ZP2 achieved 7.80 U as its peak at day 5. After all phenanthrene (250 ppm) was consumed, C23O activity in both Sphingomonas sp. ZP1 and Pseudomonas stutzeri ZP2 decreased. Analysis of the C23O gene sequence indicated that gene PhnZP1 from strain ZP1 has close sequence similarity with the C23O gene from the nearest strain Sphingomonas. sp. KMG 425 (98% identity), 97% similarity with the C23O gene catA from S. paucimobilis sp. TZS-7, and 94% similar with catE gene from S. sp. HV3. The sequence of the C23O gene PhnZP2 of strain ZP2 has 98% similarity with the cmpE gene from strain S. sp., 92% similarity with the phnE gene from P. sp. DJ77 strain, and 90% similarity with all selected C23O genes from Pseudomonas genus strains.