5 research outputs found
Isolation and characterization of <i>Magnetospirillum</i> sp strain 15-1 as a representative anaerobic toluene-degrader from a constructed wetland model
Previously, Planted Fixed-Bed Reactors (PFRs) have been used to investigate microbial toluene removal in the rhizosphere of constructed wetlands. Aerobic toluene degradation was predominant in these model systems although bulk redox conditions were hypoxic to anoxic. However, culture-independent approaches indicated also that microbes capable of anaerobic toluene degradation were abundant. Therefore, we aimed at isolating anaerobic-toluene degraders from one of these PFRs. From the obtained colonies which consisted of spirilli-shaped bacteria, a strain designated 15-1 was selected for further investigations. Analysis of its 16S rRNA gene revealed greatest similarity (99%) with toluene-degrading Magnetospirillum sp. TS-6. Isolate 15-1 grew with up to 0.5 mM of toluene under nitrate-reducing conditions. Cells reacted to higher concentrations of toluene by an increase in the degree of saturation of their membrane fatty acids. Strain 15-1 contained key genes for the anaerobic degradation of toluene via benzylsuccinate and subsequently the benzoyl-CoA pathway, namely bssA, encoding for the alpha subunit of benzylsuccinate synthase, bcrC for subunit C of benzoyl-CoA reductase and bamA for 6-oxocyclohex-1-ene-1-carbonyl-CoA hydrolase. Finally, most members of a clone library of bssA generated from the PFR had highest similarity to bssA from strain 15-1. Our study provides insights about the physiological capacities of a strain of Magnetospirillum isolated from a planted system where active rhizoremediation of toluene is taking place
Microscopy observation of strain 15–1 isolated from a Planted Fixed-bed Reactor (PFR).
<p>Microscopy observation of strain 15–1 isolated from a Planted Fixed-bed Reactor (PFR).</p
Neighbor joining tree of BssA amino acidic sequences.
<p>The cluster shown as a triangle represents members of a clone library obtained from a PFR closely related to <i>Magnetospirillum</i> strain TS-6 and to the isolate 15–1. Clones 57 and 78 are part of a second subgroup and C54 is shown in the <i>Thauera</i> cluster</p
Effect of toluene on growth (closed circles) and degree of saturation of membrane fatty acids (open squares) of strain 15–1.
<p>Effect of toluene on growth (closed circles) and degree of saturation of membrane fatty acids (open squares) of strain 15–1.</p
Anaerobic and aerobic growth tests of denitrifying strain 15–1 with different aromatic and non-aromatic compounds as sole carbon sources.
<p>Anaerobic and aerobic growth tests of denitrifying strain 15–1 with different aromatic and non-aromatic compounds as sole carbon sources.</p