Kaolin Products as Prospective Tools for the Sorption of Biofilm-Forming Bacteria

Hilton St. Petersburg Bayfront, FL 33701-4342

Biofilm-forming bacteria negatively affect medical, food, and water treatment industries. These bacteria produce extracellular polymeric substances (EPS), which gives the biofilm its physical and chemical properties. Kaolin, a clay mineral, was evaluated for its sorption capabilities potentially allowing for the removal of biofilm-forming bacteria from aqueous media. The kaolin products, which differed in structure and composition, were evaluated for sorption capacity. Four biofilm-forming bacteria, Escherichia coli 11775, Pseudomonas aeruginosa 27853, Staphylococcus aureus 27661 and Bacillus megaterium 14581, and ten different kaolin products were used in the study. Impacts of bacterial concentration (10²-10⁹ range), pH (5-8 range), potassium phosphate buffer molarity (0.001-1 M range), and Al³⁺ cations were evaluated using serial dilutions and the spread plate technique. In most cases, pH and 0.1M buffer concentration were found to be the optimal for sorption. While the impact of the above parameters varied between the tested products, the best results were obtained for products based on diatomaceous earth and calcined kaolin. The best results were achieved for two diatomaceous earth products at pH 5 and in the presence of Al³⁺ cations. Under the above conditions, these products have removed 98-100% of the above bacteria from aquatic solutions in the entire range of their concentrations. The obtained effect resulted from electrostatic attraction and co-sorption of Al³⁺ and bacteria to kaolin surfaces. Optimization of kaolin sorption capacities towards bacteria may lead to new approaches in water treatment and related technologies.

http://scholarcommons.usf.edu/sebasm/2017/antimicrobial_therapeutics_and_resistance_1/4