Modeling hexavalent chromium reduction in Escherichia coli 33456

Area of Science:

• Environmental microbiology
• Biochemical engineering
• Toxicology

Background:

• Hexavalent chromium (Cr(VI)) poses significant environmental and health risks.
• Microbial reduction is a key process for Cr(VI) remediation.
• Existing models often do not fully account for Cr(VI) toxicity effects on microbial activity.

Purpose of the Study:

• To develop and validate an enzymatic model for microbial Cr(VI) reduction.
• To incorporate cellular reduction capacity (R(c)) to address Cr(VI) toxicity.
• To predict Cr(VI) reduction under both anaerobic and aerobic conditions.

Main Methods:

• Enzymatic reaction mechanism analysis.
• Nonlinear least-square analysis of experimental anaerobic culture data.
• Incorporation of a finite reduction capacity (R(c)) parameter.
• Modification for aerobic conditions including uncompetitive inhibition by molecular oxygen.

Main Results:

• The developed model accurately predicted Cr(VI) reduction in Escherichia coli 33456 under anaerobic conditions.
• Model parameters were successfully determined using experimental data.
• Predictions for aerobic conditions, including oxygen inhibition, showed excellent agreement with batch study results.
• Sensitivity analysis confirmed the uniqueness and robustness of the determined model parameters.

Conclusions:

• The enzymatic model with R(c) effectively characterizes microbial Cr(VI) reduction.
• The model provides a valuable tool for predicting Cr(VI) remediation by Escherichia coli.
• The study demonstrates the importance of considering toxicity and oxygen effects in microbial metal reduction modeling.