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Title: Pseudomonas seleniipraecipitatus sp. nov.: A selenite reducing -proteobacteria isolated from soil

item Hunter, William
item Manter, Daniel

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2010
Publication Date: 2/1/2011
Citation: Hunter, W.J., Manter, D.K. 2011. Pseudomonas seleniipraecipitatus sp. nov.: A selenite reducing - proteobacteria isolated from soil. Current Microbiology. 62(2):565-569.

Interpretive Summary: The paper describes a new species of soil bacteria that is of interest because of its unusually ability to reduce (bioremediate) large amounts of selenite and its high resistance to both selenite and selenate. Selenite is a natural compound that can be toxic to humans and animals if ingested in amounts that exceed 850 µg Se day -1. There are a number of natural and industrial sources of selenite and selenite may be present as a contaminant of irrigation or drinking waters. Methods (and organisms) that can remove selenite from water are needed. Biological approaches, that use microorganisms to remove selenite, offer great promise. For this study we isolated, characterized, and identified a bacterium that is unusual in its ability to remove very large amounts of selenite from water. The organism reduces toxic selenite to elemental red selenium. Reduction effectively removes selenite from the water because elemental selenium is not soluble. Based on rDNA sequence and on fatty acid makeup this bacteria belongs to the bacterial genus Pseudomonas of the class '-Proteobacteria, order Pseudomonadales and family Pseudomonadaceae. However, this new bacteria does not belong to any named species within the genus Pseudomonas and we propose that the organism be named Pseudomonas seleniipraecipitatus sp. nov. due to its ability to remove selenite from water. The organism may have value as an inoculum for the in situ remediation of groundwater.

Technical Abstract: Abstract: A Gram-negative, yellow pigmented bacterium designated strain CA5 that reduced selenite to elemental red selenium (Se0) was isolated from soil. 16S rRNA gene sequence alignment identified the isolate as a novel Pseudomonas sp. with P. argentinensis, P. flavescens and P. straminea as its closest relatives. Sequence alignments show that the 16S rRNA gene of strain CA5 differed from that of P. argentinensis, P. flavescens and P. straminea by 1.3, 1.5 and 1.7%, respectively. The G + C content was 62.8 mol%, similar to that of P. flavescens but slightly higher than that of P. straminea and significantly higher than of P. argentinensis. The major cellular fatty acids present in the CA5 strain were 18:1 '7c (41.1%), C16:1 (25.7%), C16:0 (12.0%), 12:0 (8.0%), 12:0 3-OH (4.4%), 10:0 (2.2%), 17:1 '8c (1.0%),15:0 (0.9%), 17:0 (0.8%), and C18:0 (0.7%). The cellular fatty acid profile, GC content, phenotypic properties and biochemical characteristics were consistent with its placement. The name Pseudomonas seleniipraecipitatus is proposed for these bacteria.