Effect of Some Environmental Factors on Mercury(II) Reduction by Suspended Particulate Matter-Associated Kluvera cryocrescens Biofilms in Waterbodies

Author： Wang Wenhua Huang Yabing Liu Junhua Peng An

Publisher： Water Environment Federation

ISSN： 1061-4303

Source： Water Environment Research, Vol.74, Iss.1, 2002-01, pp. : 77-81

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Abstract

To resist the invasion of harmful external substances, microorganisms tend to attach to submerged surfaces in aquatic systems. The current study focused on the influence of environmental factors (e. g., pH value of the culture, oxidation–reduction condition, light, and cultured age of bacteria on the reduction of mercury(II) to elemental mercury (Hg⁰) that occurred on the surfaces of suspended particulate matter. A simulated biofilm system consisting of bacterium Kluvera cryocrescens separated from suspended particulate matter in the Yangtze River (China), its exopolysaccharide, and kaolinite (BEK) was used to study the transformation of mercury(II) in an aquatic system. The results showed that the reduction of mercury from mercury(II) to elemental mercury was favored in a neutral pH, light, and aerobic surrounding while a low pH, dark, and anaerobic condition inhibited the reaction. Moreover, the reduction capacity of both biofilms and free bacteria decreased with the increase of cultured age. Under all experimental conditions, the reduction capacity of biofilms was lower than that of the free bacteria, suggesting that biofilm, as a microecosystem, might function as a buffer to protect the effect of mercury(II) and the surrounding change on microorganisms.