| Abstract |
Arsenic (As) contamination of rice grain is a serious problem worldwide. The objective of this study was to mitigate As toxicity and accumulation in hydroponically grown KDML105 rice seedlings using bacteria isolated from heavy metal-contaminated soils. Seven strains (KKU2500-1, -2, -3, -9, -12, -16 and -22) of 24 cadmium (Cd)-tolerant bacteria produced high levels of inorganic sulfide and thiol-rich compounds in As-supplemented media. The strains were allowed to colonize rice seedlings growing in arsenite [As(III)]- or arsenate [As(V)]-supplemented Hoagland’s solutions. Colonization by strains KKU2500-3 and -12 led to increases in plant growth parameters and similarly reduced As translocation into shoots [translocation factor (TF) = 0.05] in the As(V)-supplemented solution. Strains KKU2500-12 also greatly reduced As translocation into shoots (TF = 0.16) in As(III)-supplemented solution. KKU2500-3 and -12 co-colonized onto seedlings with the As(III)-oxidizing isolates 4.25, 4.27, 4.40 and 4.44, and the strain combinations KKU2500-12/4.25, KKU2500-3/4.25, KKU2500-3/4.27 and KKU2500-3/4.44 resulted in higher growth parameters for plants grown in As [As(III)+As(V)]-supplemented solution than other combinations. Moreover, the combinations KKU2500-3/4.25 and KKU2500-3/4.44 greatly reduced As translocation (TF = 0.15 and 0.12, respectively), and this decreased As accumulation in shoots was significantly correlated with increased sulfide stimulation in roots and nutrient solution. These results indicate that these coinoculated bacteria can mitigate As toxicity, translocation and accumulation in KDML105 seedlings and thus demonstrate synergistic activity in rice plants, and this effect can be further developed in field trials. |
Publication
Journal Publication
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