Research Publication Title

Impact of pH on Sorption Capacities of Kaolinite Products Towards Biofilm Forming Bacteria

Major

Biology

Faculty Mentor(s)

Dr. Andrei L. Barkovskii

Keywords

Kaolin, Biofilms, Biotechnology

Abstract

Biofilm forming bacteria pose a serious problem for medical, food, water treatment as well as other industries. Kaolin, a clay mineral, possesses good abrasive and sorption capabilities suitable for removal of biofilm-composing microorganisms. Microbial sorption to kaolin occurs via interaction of heterogeneously charged kaolin surfaces with charges on outer microbial wall. Kaolin charges vary with pH. Impact of pH on the sorption efficacy of kaolin products towards biofilm forming bacteria was investigated. Four kaolin products varied in their structures have been tested for sorption of gram-negative (Escherichia coli, Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus and Bacillus megaterium) bacteria in the 5-8 pH range. The above products have been incubated in triplicates with the microbial targets in 0.1M potassium phosphate and potassium hydrogen phthalate buffers for 30 min at 37○C. The bacteria have been plated on LB agar before and after incubation, colony forming units (CFU) were counted, and the removal of bacteria from a liquid medium was calculated. In general, decrease of pH resulted in better sorption of the targets to all four products rising the removal from 56 ±0.1% to 92±0.1%. The best sorption capacities have been observed for two products, Diatomaceous Earth and Calcined Kaolin at pH 5.

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Impact of pH on Sorption Capacities of Kaolinite Products Towards Biofilm Forming Bacteria

Biofilm forming bacteria pose a serious problem for medical, food, water treatment as well as other industries. Kaolin, a clay mineral, possesses good abrasive and sorption capabilities suitable for removal of biofilm-composing microorganisms. Microbial sorption to kaolin occurs via interaction of heterogeneously charged kaolin surfaces with charges on outer microbial wall. Kaolin charges vary with pH. Impact of pH on the sorption efficacy of kaolin products towards biofilm forming bacteria was investigated. Four kaolin products varied in their structures have been tested for sorption of gram-negative (Escherichia coli, Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus and Bacillus megaterium) bacteria in the 5-8 pH range. The above products have been incubated in triplicates with the microbial targets in 0.1M potassium phosphate and potassium hydrogen phthalate buffers for 30 min at 37○C. The bacteria have been plated on LB agar before and after incubation, colony forming units (CFU) were counted, and the removal of bacteria from a liquid medium was calculated. In general, decrease of pH resulted in better sorption of the targets to all four products rising the removal from 56 ±0.1% to 92±0.1%. The best sorption capacities have been observed for two products, Diatomaceous Earth and Calcined Kaolin at pH 5.