Biogeochemical cycling of metals impacting by microbial mobilization and immobilization

Microbial mobilization and immobilization processes can affect the bioavailability and mobility of metals thereby influencing their toxicity and can therefore be utilized to treat solid and liquid wastes contaminated by metals. However, the microbial mobilization and immobilization of metals depends on the microbial metabolism, the environment conditions. In this review, mobilization and immobilization of metals are discussed with regard to the presence and function of involved microorganisms and in relation to applications such as bioleaching. Furthermore, the biosorption process is evaluated as a possible approach for microbial immobilization of metal on the basis of four mechanisms: (1) physical adsorption, (2) ion exchange, (3) complexation, and (4) microprecipitation. In addition, sulfide precipitation by sulfate reducing bacteria was included as an example of an application of microbial immobilization. Based on the evaluation and recommendations in this paper, bioremediation strategies for metals can be improved thus increasing the opportunity for field applications.