Characterization and Sorptivity of the Plesiomonas shigelloides Strain and Its Potential Use to Remove Cd2+ from Wastewater

In this study, the ability of adsorbing Cd2+ ions of Plesiomonas shigelloides was discovered. Herein, the method and mechanisms of adsorbing Cd2+ ions from aqueous solutions is discussed. The cadmium-resistant bacterium was collected from the sediment of Harbin section of the Songhua River in China, and then isolated, identified and characterized. The isolated strain was identified as Plesiomonas shigelloides H5 on the basis of morphological and biochemical characteristics, the sequencing of the 16SrDNA gene, and phylogeny analysis. P. shigelloides H5 was Gram-negative and bacillus. Maximum tolerance concentration (MTC) of the strain was 150 mg/L. The maximum adsorption rate and adsorption amounts was 42.71% ̆ 0.88% and 106.775 ̆ 2.325 mg/g when dried biomass was presented in a 50 mg/L Cd2+ solution. Dried biomass was in accordance with Lagergren pseudo-second-order models. A field emission scanning electron microscope (FE-SEM), an energy dispersive X-ray spectrometer (EDX), and Fourier transform infrared spectroscopy (FTIR) analyses were applied to identify the surface morphology and functional groups. Transmission electron microscope (TEM) results showed that Cd2+ was also absorbed into cells to form precipitates. The results revealed that the surface functional groups of P. shigelloides H5 can bind to heavy metal ions. To sum up, the ability of adsorbing cadmium ions of Plesiomonas shigelloides was discovered, which might be helpful in wastewater treatment in the future.