Selenobacteria selected from the rhizosphere as a potential tool for Se biofortification of wheat crops

Abstract

Cereal production in southern Chile is based on ash-derived volcanic Andisols, which present suboptimal levels of available selenium (Se). Strategies are needed to improve Se content in cereal crops and concomitantly improve the nutritional quality of grain. Here, we investigated the occurrence of Se-tolerant bacteria (STB) in Andisols and evaluated Se tolerance and accumulation in STB. The inoculation of wheat with STB and the contributions of these bacteria to Se content in plants were also evaluated under greenhouse conditions. The results showed that Se amendment of Andisols stimulated some bacterial groups (Paenibacillaceae and Brucellaceae) but inhibited others (Clostridia, Burkholderiales, Chitinophagaceae and Oxalobacteraceae), as revealed by denaturing gradient gel electrophoresis. Furthermore, we found four STB isolates that displayed 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase activity) and that carried the acdS gene as revealed by PCR. The selected STB were characterised as Stenotrophomonas, Bacillus, Enterobacter and Pseudomonas according to partial sequencing of the 16S rRNA gene. After 24 h of culture in nutrient broth, the selected STB showed the ability to grow in high Se concentrations (5 and 10 mM) and to accumulate elemental Se in micro-and nanospherical deposits, transforming 50-80 % of the Se initially added. Greenhouse experiments with wheat showed that Se associated with STB (micro-and nanospheres of elemental Se and other intracellular forms) can be translocated into leaves of wheat plantlets.

Effect of rhizobacterial consortia from undisturbed arid- and agro-ecosystems on wheat growth under different conditions

“…The results revealed a positive effect on plant biomass by consortia inoculation, with C2 exhibiting a statistically significant (P ≤ 0Á05; Tukey's test) higher biomass than the uninoculated control. The positive effect of the C2 is in good agreement with earlier observations with individual inoculation strain effect (Acuña et al 2013;Jorquera et al 2013;Mart ınez et al 2015) and hence confirms the performance of C2 as possible biofertilizer in wheat crops. Interestingly, addition of inocula from arid ecosystems (C1) also resulted in higher biomass compared with uninoculated control, but not statistically significant.…”

“…The positive effect of the C2 is in good agreement with earlier observations with individual inoculation strain effect (Acuña et al . ; Jorquera et al . ; Martínez et al .…”

“…N0‐29PA, which showed multiple PGP activity and separately improved wheat biomass in previous inoculation studies (Acuña et al . ; Jorquera et al . ; Martínez et al .…”

Effects of biochar on copper immobilization and soil microbial communities in a metal-contaminated soil

“…The composition on microbial communities (bacteria and fungi) was analyzed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE), according to the method described by Acuña et al (2013). Total DNA of five soil samples from BC treatments was extracted using FastDNA SPIN Kit for Soil (MP Biomedicals) according to manufacturer's guide.…”

Inoculation with selenobacteria and arbuscular mycorrhizal fungi to enhance selenium content in lettuce plants and improve tolerance against drought stress

“…The photosynthetic performance of PGPB inoculated plants increased, thus indicating the microbial influence on photosynthetic machinery (Gururani et al 2013). In addition, microorganisms with PGPB capacity have been recently used for selenium (Se) biofortification with certain bacteria called selenobacteria that can reduce inorganic Se to elemental Se nanospheres (NanoSe) and other important organic Se forms (Acuña et al 2013;Durán et al 2013;Durán et al 2014;Durán et al 2015).…”