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Curr Microbiol (2011) 62:565569
DOI 10.1007/s00284-010-9745-8
Pseudomonas seleniipraecipitatus sp. nov.: A Selenite Reducing c-Proteobacteria Isolated from Soil
William J. Hunter Daniel K. Manter
Received: 12 April 2010 / Accepted: 13 August 2010 / Published online: 3 September 2010 US Government 2010
Abstract A Gram-negative, yellow pigmented bacterium designated strain CA5T that reduced selenite to elemental red selenium was isolated from soil. 16S rRNA gene sequence alignment identied the isolate as a novel Pseudomonas species with P. argentinensis, P. avescens, andP. straminea as its closest relatives. Sequence alignments show that the 16S rRNA gene of strain CA5T differed from that of P. argentinensis, P. avescens, and P. straminea by1.3, 1.5, and 1.7%, respectively. The G?C content was62.8 mol%, similar to the 62.763 mol% reported for P. avescens but slightly higher than the 62.562.6 mol% ofP. straminea and signicantly higher than the57.558.0 mol% of P. argentinensis. The major cellular fatty acids present in the CA5T strain were C18:1 x7c(41.1%), C16:1 x6c and C16:1 x7c (25.7%), C16:0 (12.0%),
C12:0 (8.0%), C12:0 3-OH (4.4%), and C10:0 3-OH (2.9%). The cellular fatty acid prole, GC content, phenotypic properties, and biochemical characteristics were consistent with its placement within the genus Pseudomonas. The name P. seleniipraecipitatus is proposed for these bacteria.
Introduction
The genus Pseudomonas of the class c-Proteobacteria, order Pseudomonadales and family Pseudomonadaceae, accommodates a number of species of heterotrophic, Gram-negative, non-spore forming, rod-shaped aerobic bacteria. Within this biochemically diverse group of
organisms are free-living members as well as species that are capable of causing plant and animal disease [14].
Pseudomonas sp. strain CA5T has shown an unusual resistance to the toxic effects of selenate and selenite. Selenate, at 64 mM, had no measurable inuence on the growth of the strain and the strains minimum inhibitory concentration (MIC) for selenite was found to exceed 150 mM, an unusual level of resistance. Its resistance to selenite likely comes, in part, from the ability of this strain to reduce and precipitate large amounts of the oxyanion selenite to elemental selenium [8]. As elemental selenium is insoluble, it is not biologically available, thus its toxicity is greatly reduced [23]. The CA5T strain may have future value as a tool for removing heavy metals from contaminated soils and water. In this article we describe the...