The Potential Roles of Free and Attached Microbial Community in Decreasing Cadmium Level from Cadmium-Contaminated Soils by Mixotrophic Acidophiles of Different Scale-Up Cultivation Stages

In this study, cadmium (Cd)-contaminated soils were bioremediated using the mixotrophic acidophiles in different scale-up cultivation stages. The free and attached bacterial and fungal diversities and community structures, and their effects on soil Cd removal were investigated. Percentages of dominant bacteria (Acidithiobacillus, Sulfobacillus, and Pseudomonas) and fungi (Acidomyces and Coniochaeta) between the free and attached communities exhibited the pronounced differences. The alpha-diversity of attached bacteria was higher than the free bacteria, while the distinct variations in attached and free fungi were not observed. However, the beta-diversity between the free and attached bacteria and fungi was significantly changed. Solution pH and reduced glucose level affected the abundance patterns of Acidithiobacillus in free bacteria and Acidomyces in attached fungi, which had great contributions to the soil Cd removal efficiency.