科研之友
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摘要
Soluble Mn (II) can be rapidly oxidized to form Mn (III, IV) oxide minerals via microbial activity. Most studies on microbe-mediated Mn(II) oxidation were conducted using microbe isolates in homogeneous liquid or solid media. Microbial cells in terrestrial ecosystem usually adsorb on soil particle surfaces; however, impacts of cell adsorption on Mn-oxidizing ability remain largely unknown. In this study, we examined how cell adsorption of Mn-oxidizing bacterium HN79, an isolate from Fe-Mn nodules, on montmorillonite and goethite surfaces affects Mn (II) oxidation kinetics and bacterial growth rates as well. Results showed that the maximum adsorption quantity of montmorillonite to HN79 was greater than that of goethite while the binding strength (K value) was less than that of goethite. Compared with unadsorbed system, both montmorillonite and goethite promoted the bacterial growth in the coexisting adsorption system and isometric adsorption system. In the saturated adsorption system, both clay minerals reduced bacterial biomass. In saturated adsorption and isometric adsorption systems, Mn (II) oxidization rate was lower than that of unadsorbed system, while in coexisting system, Mn (II) oxidization rate was greater than that of unadsorbed system. It suggests that the surface characteristics of clay minerals affected Mn (II) oxidization. Mn (II) oxidization capacity of the montmorillonite-bacteria complex was greater than that of the goethite-bacteria complex.
