Modeling of optimal antibiotics concentration in bacteria with PHREEQ tool

Abstract

PHREEQC is a computer program developed by the US Geological Survey (USGS) and has become the standard for water chemistry. In present PHREEQC is implementing in biochemistry and environment science where a computational tools are needed. This study is an attempt to model practical appliance and to compute optimal antibiotics (tetracycline, penicillin G and penicillin V) concentration at with the accumulation of antibiotics in bacteria E. coli reaches 0.5 mg per 1 g of bacteria at solution pH ≈ 5.0. This study used simplified model of extracellular water including of Na+, K+, Ca+2, Mg+2 Cl-, HPO4-2 and HCO3- ions, antibiotics (tetracycline, penicillin G, penicillin V) and data sets of thermodynamic parameters for use in PHREEQC. Uptake of antibiotics by bacteria was described and computed as adsorption of neutral species of antibiotics with their log K values 2.36 for tetracycline, 2.24 for penicillin G and 2.26 for penicillin V respectively. Using PHREEQC was modeled 0.5 mg accumulation of each antibiotic per 1 g of bacteria when concentration in solution of tetracycline was 100 mg/L, penicillin G was 300 mg/L and penicillin V was 300 mg/L. While antibiotics where added pH value of solution was changed from 5.5 at initial point to 4.97 at final point.