Phenanthrene-degrading Sphingobium xenophagum are widely distributed in the western Pacific Ocean.

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Author: Tokuro Iwabuchi
Date: May 2022
From: Canadian Journal of Microbiology(Vol. 68, Issue 5)
Publisher: NRC Research Press
Document Type: Report
Length: 8,508 words
Lexile Measure: 1340L

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Abstract :

Six phenanthrene-degrading bacteria were isolated from surface seawater sampled from the western Pacific Ocean. They were identified as Sphingobium xenophagum (formerly Sphingomonas xenophaga) based on morphological, biochemical, and chemical characteristics, and 16S rRNA sequences. The salinity ranges for the growth of these isolates were broader than those of the seven reported Sphingomonas strains isolated from soil, and the optimum NaCl concentration in the growth medium was higher than that for soil sphingomonads. These isolates also exhibited higher phenanthrene-degrading activity under briny conditions than that of a phenanthrenedegrading Sphingomonas strain isolated from soil. A DNA fragment carrying nah genes, which are encoded on the naphthalene-catabolic plasmid NAH of Pseudomonas putida PpG7, hybridised less strongly with the total DNA of all isolates. Certain genes involved in phenanthrene degradation were also preliminarily characterised in all isolates. This is the first demonstration that S. xenophagum strains, which are able to degrade phenanthrene, are widely distributed in marine environments, and that the growth and phenanthrene-degrading activity of these strains are adapted to briny conditions. The results also suggest that genes for phenanthrene degradation, which are dissimilar to nah genes, were also ubiquitously distributed in marine strains. Key words: phenanthrene, Sphingobium xenophagum, marine environment, marine bacteria, biodegradation. Six bacteries degradant le phenanthrene ont ete isolees de l'eau de mer de surface echantillonnee dans l'ocean Pacifique occidental. Elles ont ete identifiees comme etant Sphingobium xenophagum (anciennement Sphingomonas xenophaga) selon les caracteristiques morphologiques, biochimiques et chimiques et les sequences de l'ARNr 16S. Les plages de salinite permettant la croissance de ces isolats etaient plus larges que celles de sept souches rapportees de Sphingomonas isolees du sol, et la concentration optimale de NaCl dans le milieu de croissance etait plus elevee que celle des sphingomonades du sol. Ces isolats montraient egalement une plus grande activite de degradation du phenanthrene dans des conditions saumatres que celle d'une souche de Sphingomonas degradant le phenanthrene, isolee du sol. Un fragment d'ADN portant les genes nah, codes sur le plasmide de catabolisme du naphtalene NAH de Pseudomonas putida PpG7, s'hybridait moins fortement avec l'ADN total de tous les isolats. Certains genes de degradation du phenanthrene ont egalement ete caracterises de maniere preliminaire dans tous les isolats. Il s'agit de la premiere demonstration que les souches de S. xenophagum, capables de degrader le phenanthrene, sont largement distribuees dans les environnements marins, et que la croissance et l'activite de degradation du phenanthrene de ces souches sont adaptees aux conditions saumatres. Les resultats suggerent aussi que les genes de degradation du phenanthrene, qui sont dissemblables des genes nah, etaient egalement distribues de maniere ubiquiste dans les souches marines. [Traduit par la Redaction] Mots-cles : phenanthrene, Sphingobium xenophagum, environnement marin, bacteries marines, biodegradation.

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Gale Document Number: GALE|A703478108