Application of Chlorine Dioxide in Cell Surface Modification to Enhance Its Mechanical Stability and Metal Ion...

There has been a trend toward the use of microorganisms as the biomaterial for removing dyes and metals from wastewater. However, native microorganism cells have low mechanical stability, which limit their further application in industries. In this study, chlorine dioxide (ClO₂), a high-efficiency, low-toxicity, and environmentally benign disinfectant, was used for microorganism surface modification to enhance the mechanical stability and metal ion adsorption of the cell. ClO₂ can either modify cell walls to improve their metal adsorption capacity or modify cell membranes to improve their mechanical stability. Fourier-transform infrared spectroscopy analysis indicated that several cell surface groups were involved in the cell wall modification of Bacillus sp. Microscopic observation indicated that ClO₂ treatment could deter cell membranes from forming vesicles in sodium hydroxide (NaOH) aqueous solution, and freeze-etching showed that ClO₂ treatment could alter the erythrocyte membrane proteins which might also contribute to improving the cell stability. The experimental results on Bacillus sp., Pseudomonas aeruginosa, and Mucor rouxii show that ClO₂ treatment may increase, or at least not reduce, the ability of microbial cells to adsorb heavy metals, but it can significantly improve the resistance of these cells to NaOH cleavage. It seems ClO₂ is a promising auxiliary for biosorption of heavy-metal ions.