AimsTo identify bacteria with high selenium tolerance and reduction capacity for bioremediation of wastewater and nanoselenium particle production. Methods and ResultsA 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 (973% nucleotide identity) and named P.moraviensis stanleyae. The isolate exhibited extreme tolerance to SeO32- (up to 120mmoll(-1)) and SeO42- (>150mmoll(-1)). Selenium oxyanion removal from growth medium was measured by microchip capillary electrophoresis (detection limit 95nmoll(-1) for SeO32- and 13nmoll(-1) for SeO42-). Within 48h, P.moraviensis stanleyae aerobically reduced SeO32- to red Se(0) from 10mmoll(-1) to below the detection limit (removal rate 027mmolh(-1) at 30 degrees C); anaerobic SeO32- removal was slower. No SeO42- removal was observed. Pseudomonas moraviensis stanleyae stimulated the growth of crop species Brassica juncea by 70% with no significant effect on Se accumulation. ConclusionsPseudomonas 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 StudyPseudomonas moraviensis subsp. stanleyae may be useful for stimulating plant growth and for the treatment of Se-laden wastewater.