Major

Biology

Faculty Mentor(s)

Andrei Barkovskii

Keywords

Microbiology, biofilm-forming bacteria, kaolin, cations, sorption

Abstract

Biofilm-forming bacteria cause problems for industries such as medical, food, and water treatment. Due to its heterogeneous charges, kaolin is capable of sorption of these microorganisms. These charges are impacted by pH and cations, which change the electrostatic interactions between kaolin particles and microorganisms. Proper pH and cation composition may lead to enhanced sorption. The impact of Al3+ cations on kaolin sorption of Gram negative (E. coli and P. aeruginosa) and Gram positive (B. megaterium and S. aureus) was investigated. Calcined kaolin and Diatomaceous Earth kaolin, which were selected in previous studies, were incubated in triplicates with the above organisms at pH 5 for 30 min at 37 in the presence and absence of Al3+. Preliminary experiments evidenced that Al3+ (in the form of AlCl3 × 6H2O) concentration at the 1500 M warrants the presence of these ions in the liquid phase during the experiment. Highest sorption of Al3+ to kaolin was reported at pH 5 and was used in this study. Two controls composed of (1) buffer and bacteria, and of (2) kaolin, buffer, and bacteria were established. The initial concentration of bacteria ranged between 103-105 cells/mL. Sorption was determined via colony counts on LB plates before and after incubation, and Al3+ concentrations were monitored. Colonies were counted after 48 hours of incubation at 37. Concentration of E. coli in the aqueous phase of control (2) decreased to 102 cells/mL, whereas the presence of Al3+ resulted in 100 -101 cells/mL. Incubation of P. aeruginosa resulted in a 10-fold and 100-fold decrease of aqueous cell concentration in the control (2) and experimental treatment, respectively. The impact of Al3+ on sorption of Gram positive bacteria is investigated.

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Impact of Cations on the Sorption Capabilities of Kaolin Towards Biofilm-forming Bacteria

Biofilm-forming bacteria cause problems for industries such as medical, food, and water treatment. Due to its heterogeneous charges, kaolin is capable of sorption of these microorganisms. These charges are impacted by pH and cations, which change the electrostatic interactions between kaolin particles and microorganisms. Proper pH and cation composition may lead to enhanced sorption. The impact of Al3+ cations on kaolin sorption of Gram negative (E. coli and P. aeruginosa) and Gram positive (B. megaterium and S. aureus) was investigated. Calcined kaolin and Diatomaceous Earth kaolin, which were selected in previous studies, were incubated in triplicates with the above organisms at pH 5 for 30 min at 37 in the presence and absence of Al3+. Preliminary experiments evidenced that Al3+ (in the form of AlCl3 × 6H2O) concentration at the 1500 M warrants the presence of these ions in the liquid phase during the experiment. Highest sorption of Al3+ to kaolin was reported at pH 5 and was used in this study. Two controls composed of (1) buffer and bacteria, and of (2) kaolin, buffer, and bacteria were established. The initial concentration of bacteria ranged between 103-105 cells/mL. Sorption was determined via colony counts on LB plates before and after incubation, and Al3+ concentrations were monitored. Colonies were counted after 48 hours of incubation at 37. Concentration of E. coli in the aqueous phase of control (2) decreased to 102 cells/mL, whereas the presence of Al3+ resulted in 100 -101 cells/mL. Incubation of P. aeruginosa resulted in a 10-fold and 100-fold decrease of aqueous cell concentration in the control (2) and experimental treatment, respectively. The impact of Al3+ on sorption of Gram positive bacteria is investigated.