Influence of extracellular polymeric substances (EPS) on Cd adsorption by bacteria

• Published in: Environmental pollution (1987) Vol. 159; no. 5; pp. 1369 - 1374
• Main Authors: Wei, Xing, Fang, Linchuan, Cai, Peng, Huang, Qiaoyun, Chen, Hao, Liang, Wei, Rong, Xinming
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2011; Elsevier
• Subjects: Adsorption; Applied sciences; Bacillus subtilis; Bacillus subtilis - chemistry; Bacteria; Bacterial Proteins; Bacterial Proteins - chemistry; biofilm; Cadmium; Cadmium - chemistry; chemistry; EPS; Exact sciences and technology; Fourier transform infrared spectroscopy; heavy metals; Hydrogen-Ion Concentration; Phosphates; Pollution; Polymers; Polymers - chemistry; Polysaccharides, Bacterial; Polysaccharides, Bacterial - chemistry; Potentiometry; Pseudomonas putida; Pseudomonas putida - chemistry; Spectra; Spectroscopy, Fourier Transform Infrared; Surface chemistry; Titration; Cd; EPS; Adsorption; Bacillus subtilis; Pseudomonas putida; Pseudomonadales; Phosphates; Cadmium; Adsorption capacity; Surface complexation model; Bacillaceae; Extracellular; Heavy metal; Trace element; Bacillales; Batchwise; Biopolymer; Biofilm; Pseudomonadaceae; Bacteria; Phosphorus compound; Fourier-transformed infrared spectrometry; Functional group
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2011.01.006

The role of extracellular polymeric substances (EPS) in Cd adsorption by Bacillus subtilis and Pseudomonas putida was investigated using a combination of batch adsorption experiments, potentiometric titrations, Fourier transform infrared spectroscopy (FTIR). An increased adsorption capacity of Cd was observed for untreated bacteria relative to that for EPS-free bacteria. Surface complexation modeling of titration data showed the similar p K a values of functional groups (carboxyl, phosphate and hydroxyl) between untreated and EPS-free bacteria. However, site concentrations on the untreated bacteria were found to be higher than those on the EPS-free bacteria. FTIR spectra also showed that no significant difference in peak positions was observed between untreated and EPS-free bacteria and carboxyl and phosphate groups were responsible for Cd adsorption on bacterial cells. The information obtained in this study is of fundamental significance for understanding the interaction mechanisms between heavy metals and biofilms in natural environments. ► The presence of EPS on bacterial surfaces facilitates the adsorption of Cd. ► The promoting effects on Cd adsorption are more remarkable on Gram-positive B. subtilis cells than that on Gram-negative P. putida cells. ► Carboxyl and phosphate groups are mostly responsible for Cd binding on untreated and EPS-free cells. ► Intact bacterial cells and EPS-free cells have similar binding mechanisms for Cd. Intact bacterial cells and EPS-free cells have similar binding mechanisms for Cd.