Batch biodegradation of para-nitrophenol using Arthrobacter chlorophenolicus A6

Area of Science:

• Environmental microbiology
• Biotechnology
• Biochemical engineering

Background:

• p-nitrophenol (PNP) is a toxic pollutant requiring effective biodegradation strategies.
• Arthrobacter chlorophenolicus A6 is a known microorganism capable of degrading phenolic compounds.

Purpose of the Study:

• To investigate the biodegradation kinetics of p-nitrophenol (PNP) by Arthrobacter chlorophenolicus A6.
• To determine the kinetic model that best describes PNP biodegradation under substrate inhibition conditions.

Main Methods:

• Batch shake flask experiments were conducted with initial PNP concentrations ranging from 25-225 mg/l.
• Biokinetic constants were estimated by fitting experimental data to various substrate inhibition kinetics models.
• The Webb model was identified as the best fit using root mean square error analysis.

Main Results:

• Arthrobacter chlorophenolicus A6 demonstrated substrate inhibition kinetics for PNP biodegradation, with a decay coefficient of 0.0132 h(-1).
• The Webb model provided the best fit to the experimental data, yielding kinetic constants: μ=0.161 h(-1), Ki=128 mg/l, Ks=60.15 mg/l, and K=100 mg/l.
• Observed and theoretical yield coefficients, maintenance energy, and specific growth rates were also determined.

Conclusions:

• The study successfully characterized the substrate inhibition kinetics of PNP biodegradation by Arthrobacter chlorophenolicus A6.
• The Webb model is suitable for describing this biodegradation process, providing valuable parameters for bioreactor design and optimization.