Plant Growth Promotion and Selenium Accumulation in Zea mays by Rhizobacteria Isolated from Natural Seleniferous Soils

Selenium (Se) is essential for life's basic functions but its sources are limited. Plant growth promoting bacteria is a potential source to increase Se accumulation and plant growth. Bacteria are isolated from native seleniferous soils,. and based on 16S rRNA (ribosomal RNA) sequenceanalysis, two plant growth promoting and selenium tolerant bacteria are selected. They are identified as Leclercia adecarboxylata (B49) and Cedecea neteri (B71). L. adecarboxylata and C. neteri produce indole acetic acid of 93 +/- 3.2 and 68 +/- 2.9 mg L-1 and a phosphate solubilization index of 1.26 +/- 0.3 and 3.29 +/- 0.2, respectively. L. adecarboxylata and C. neteri tolerate up to 350 mm of selenite with an inhibitory concentration 50 value of 225.6 +/- 14 and 236.6 +/- 14 mm, respectively. Inoculation of bacteria significantly increases the growth of Zea mays plants in seleniferous soil. Plant growth promotion is 36.6% more in C. neteri inoculated plants compared to L. adecarboxylata. Se accumulation significantly increases in plant tissues inoculated with C. neteri (20.2 mu g g(-1)) than L. adecarboxylata (12.1 mu g g(-1)). This study has provided evidence that microbial Se biotransformation through bacterial inoculation is an alternative way to improve the Se uptake in crops and maintain human health.