1. Down regulation of biofilm formation by Cd2+ on Bacillus subtilis 1JN2 affected its biocontrol efficiency against Ralstonia wilt on tomato.
- Author
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Wei Yang, Haixia Yan, Shimo Li, Yuming Gao, Wei Xu, Jinshan Shang, and Yuming Luo
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EFFECT of cadmium on plants ,BACILLUS subtilis ,TOMATO diseases & pests ,GREENHOUSES ,BIOFILMS - Abstract
Bacillus subtilis 1JN2 can serve as an effective biocontrol agent against Ralstonia wilt on tomato, but the efficiency of control depends on the levels of heavy metals in the rhizosphere soil. Here, we investigated how the heavy metal Cd
2+ affects the biocontrol efficacy of B.subtilis 1JN2 on Ralstonia wilt. We found that low Cd2+ content of 2mM or lower had no effects on the biofilm formation of 1JN2, while media containing 3mM or higher Cd2+ levels inhibited biofilm formation. Interestingly, high concentration of Cd2+ (5mM) showed inhibition of B.subtilis 1JN2 cell growth. We next tested the effects of Cd2+ in the soil by supplementing artificial Cd2+ in the tomato rhizosphere in a greenhouse setting. We found that 3mM Cd2+ in the tomato rhizosphere inhibited the colonization of B.subtilis 1JN2, reducing its ability to control against Ralstonia wilt. At 3mM Cd2+ , we only detected 103 CFU/mL 1JN2 one week post treated with 107 CFU/mL but 105 CFU/mL could be detected without Cd2+ in the soil. The presence of Cd2+ had no effect on the colonization of Ralstonia solanacearum on tomato, but the biocontrol efficacy against Ralstonia wilt by 1JN2 decreased 54.2% when the soil contained 3mM Cd2+ compared to the control without Cd2+ . Taken together, we find that the failure of biofilm formation of Bacillus subtilis 1JN2 that affected by Cd2+ lead to the decrease of its biocontrol efficacy against Ralstonia wilt on tomato. [ABSTRACT FROM AUTHOR]- Published
- 2018
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