title: Characterization of the metabolic pathway and catabolic gene expression in biphenyl degrading marine bacterium Pseudomonas aeruginosa JP-11.
abstract: Metabolic pathway of biphenyl assimilation and the catabolic gene expression in a marine bacterium Pseudomonas aeruginosa JP-11, isolated from the coastal sediments of Odisha, India have been studied. This strain utilized 98.86% ± 2.29% of biphenyl within 72 h when supplied as the sole source of carbon, however, preferential utilization of glucose was observed over catechol and biphenyl when grown in a complex medium. Combination of chromatographic and spectrophotometric techniques confirmed the catechol pathway and identified 2-Hydroxy-6-oxo-6-phenylhexa-2, 4-dienoate as the intermediate metabolic product. Assimilation of biphenyl was initiated by its dioxygenation, forming cis-2, 3-dihydro-2, 3-dihydroxybiphenyl subsequently transformed to 2-hydroxy-6-oxo-6-phenylhexa-2, 4-dienoate. In the lower pathway, cis-1, 6-dihydroxy-2, 4-cyclohexadiene-1-carboxylic acid was detected which formed catechol before entering into the Krebs cycle. Detection of key enzyme catechol-1, 2-dioxygenase in the cell-free extract of P. aeruginosa JP-11 supported the proposed degradation pathway. The primary enzyme for biphenyl assimilation, biphenyl dioxygenase encoded by bphA gene was found in the genome of the isolate. On increasing biphenyl stress (50, 100, 150 and 200 mg L(-1)), bphA gene showed a significant (P < 0.01) up-regulation upto 43.5 folds. Production of biosurfactant was confirmed and the rhamnolipid synthesizing gene rhlAB was amplified. This gene also showed a significant (P < 0.01) up-regulation upto 258 folds on increasing biphenyl stress.
authors.affiliation: Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, 769 008, Odisha, India.
authors.forename: Jaya
authors.initials: J
authors.lastname: Chakraborty
authors.affiliation: Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, 769 008, Odisha, India. Electronic address: surajit@nitrkl.ac.in.
authors.forename: Surajit
authors.initials: S
authors.lastname: Das
mesh_terms: D001713:Biphenyl Compounds / Q000032:analysis / Q000378:metabolism*; D002396:Catechols; D049308:Dioxygenases / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D005798:Genes, Bacterial; D019015:Geologic Sediments / Q000382:microbiology*; D007194:India; D053858:Metabolic Networks and Pathways / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015854:Up-Regulation; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D001713:Biphenyl Compounds; D002396:Catechols; D049308:Dioxygenases; D014874:Water Pollutants, Chemical; C010574:biphenyl; C034221:catechol
keywords: Biphenyl; Biphenyl dioxygenase; Catechol pathway; Gene expression; Marine bacteria