Pseudomonas moraviensis subsp. stanleyae, a bacterial endophyte of hyperaccumulator Stanleya pinnata, is capable of efficient selenite reduction to elemental selenium under aerobic conditions

L. C. Staicu, C. J. Ackerson, P. Cornelis, L. Ye, R. L. Berendsen, W. J. Hunter, S. D. Noblitt, C. S. Henry, J. J. Cappa, R. L. Montenieri, A. O. Wong, L. Musilova, M. Sura-de Jong, E. D. van Hullebusch, P. N L Lens, R. J B Reynolds, Elizabeth A H Pilon-Smits*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Aims: To identify bacteria with high selenium tolerance and reduction capacity for bioremediation of wastewater and nanoselenium particle production. Methods and Results: A bacterial endophyte was isolated from the selenium hyperaccumulator Stanleya pinnata (Brassicaceae) growing on seleniferous soils in Colorado, USA. Based on fatty acid methyl ester analysis and multi-locus sequence analysis (MLSA) using 16S rRNA, gyrB, rpoB and rpoD genes, the isolate was identified as a subspecies of Pseudomonas moraviensis (97·3% nucleotide identity) and named P. moraviensis stanleyae. The isolate exhibited extreme tolerance to SeO<inf>3</inf><sup>2-</sup> (up to 120 mmol l<sup>-1</sup>) and SeO<inf>4</inf><sup>2-</sup> (>150 mmol l<sup>-1</sup>). Selenium oxyanion removal from growth medium was measured by microchip capillary electrophoresis (detection limit 95 nmol l<sup>-1</sup> for SeO<inf>3</inf><sup>2-</sup> and 13 nmol l<sup>-1</sup> for SeO<inf>4</inf><sup>2-</sup>). Within 48 h, P. moraviensis stanleyae aerobically reduced SeO<inf>3</inf><sup>2-</sup> to red Se(0) from 10 mmol l<sup>-1</sup> to below the detection limit (removal rate 0·27 mmol h<sup>-1</sup> at 30°C); anaerobic SeO<inf>3</inf><sup>2-</sup> removal was slower. No SeO<inf>4</inf><sup>2-</sup> removal was observed. Pseudomonas moraviensis stanleyae stimulated the growth of crop species Brassica juncea by 70% with no significant effect on Se accumulation. Conclusions: Pseudomonas moraviensis stanleyae can tolerate extreme levels of selenate and selenite and can deplete high levels of selenite under aerobic and anaerobic conditions. Significance and Impact of the Study: Pseudomonas moraviensis subsp. stanleyae may be useful for stimulating plant growth and for the treatment of Se-laden wastewater.

Original languageEnglish
Pages (from-to)400-410
Number of pages11
JournalJournal of Applied Microbiology
Volume119
Issue number2
DOIs
Publication statusPublished - 1 Aug 2015

Keywords

  • Pseudomonas moraviensis
  • Stanleya pinnata
  • Aerobic selenite reduction
  • Elemental selenium nanoparticles
  • Microchip capillary electrophoresis
  • Multi-locus sequence analysis

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