Reducing arsenic in rice grains by leonardite and arsenic–resistant endophytic bacteria
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Author list: Dolphen R., Thiravetyan P.
Publisher: Elsevier
Publication year: 2019
Journal: Chemosphere (0045-6535)
Volume number: 223
Start page: 448
End page: 454
Number of pages: 7
ISSN: 0045-6535
Languages: English-Great Britain (EN-GB)
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Abstract
Arsenic contaminated in rice plants can cause many physiological, biochemical and productivity in rice. This also had a negative impact on human health. To decrease arsenic in grains, a combination of leonardite as amendment and arsenic-resistance endophytic bacteria was investigated. The results showed that 1% (w/v) leonardite (91.86 ± 2.04%) had the highest efficiency in adsorbing initial arsenic concentration of 2 mg L−1, which was higher than bagasse fly ash (16.25 ± 3.97%), rice husk ash (10.36 ± 1.28%), and sawdust fly ash (63.00 ± 5.67%) under the same condition. This was due to the higher aluminium and iron contents of leonardite strongly binding to arsenic anions. Meanwhile, Bacillus pumilus had an ability to decrease arsenic accumulation in rice grains to levels below those achieved by Pseudomonas sp. and Bacillus thuringiensis. This was possibly due to B. pumilus producing higher siderophore. Interestingly, a combination of microbe and leonardite addition could decrease arsenic accumulation in grains to below the permissible limit (0.2 mg As kg−1 for inorganic arsenic). It could also reduce oxidative stress and showed down-regulation of Lsi1, Lsi2 and OsPT4 at the heading stage, which coincided with low arsenic and high silicon accumulation in roots. Therefore, this result could be used to decrease arsenic accumulation in grains in arsenic-contaminated paddy fields, improved rice plants defense and endured of arsenic stress, and increased rice productivity. © 2019 Elsevier Ltd
Keywords
Bacillus pumilus, Leonardite, Rice plant
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