Screening, characteristics and mechanism of Cd-tolerance Cunninghamella bertholletiae

An isolate, designated as ZZY, was obtained from a long-term heavy metals contaminated soil with the potential to remove Cd2+. The strain's screening, identification and biosorption characteristics including the effect of initial concentration of metal ions, pH value, biosorption temperature, biosorption time, inoculum size, mineral nutrients, and competing ions on biosorption were studied. Based on morphological observations and 18 S rRNA gene sequence identification, ZZY had affinity to Cunninghamella bertholletiae. The optimum parameters for Cd2+ biosorption by the strain were: Cd2+ tolerance of 4 mg/L, pH value of 4, biosorption time of 84 h, biosorption temperature of 35 °C, quantity of added thallus of 6% (v/v), the mineral collaborative concentration of 0.05 g/L (mass of mineral nutrition per liter of medium). In addition, the determination of biosorption sites distribution and the results of Fourier transform infrared spectroscopy (FT-IR) showed that biosorption occurred at the thallus surface, the chief active biosorption sites being OH, CO, and NH.