Synergy effect of organic acids from plants on mineral dissolution by siderophore-producing bacteria

It is known that cesium in clay minerals is dissolved by bacteria. Generally, plants live symbiotically with bacteria. However, little is known about synergetic effect of plants and symbiotic bacteria on cesium dissolution from soil. In this study, we first determined an organic acid produced by a model plant, clover, which was lactic acid. Next, a symbiotic bacterium isolated from clover was cultured with or without addition of lactic acid in a medium containing biotite powder. Addition of lactic acid enhanced dissolution of biotite by the bacterium. As for cesium dissolution from biotite, the cesium concentrations in the liquid phases of the bacterial culture media were lower than those in blank media with no bacterial cells. A possible reason of this lower cesium concentration could be cesium absorption by bacterial cells as magnesium was absorbed. (author)