Kinetic modeling of growth and biodegradation of phenol and m-cresol using Alcaligenes faecalis

Abstract

A phenol-degrading microorganism, Alcaligenes faecalis, was used to study the substrate interactions during cell growth on phenol and m-cresol dual substrates. Both phenol and m-cresol could be utilized by the bacteria as the sole carbon and energy sources. When cells grew on the mixture of phenol and m-cresol, strong substrate interactions were observed. m-Cresol inhibited the degradation of phenol, on the other hand, phenol also inhibited the utilization of m-cresol, the overall cell growth rate was the co-action of phenol and m-cresol. In addition, the cell growth and substrate degradation kinetics of phenol, m-cresol as single and mixed substrates for A. faecalis in batch cultures were also investigated over a wide range of initial phenol concentrations (10–1400 mg L −1) and initial m-cresol concentrations (5–200 mg L −1). The single-substrate kinetics was described well using the Haldane-type kinetic models, with model constants of μ m1 = 0.15 h −1, K S1 = 2.22 mg L −1 and K i1 = 245.37 mg L −1 for cell growth on phenol and μ m2 = 0.0782 h −1, K S2 = 1.30 mg L −1 and K i2 = 71.77 mgL −1, K ′ i 2 = 5480 ( mg L − 1 ) 2 for cell growth on m-cresol. Proposed cell growth kinetic model was used to characterize the substrates interactions in the dual substrates system, the obtained parameters representing interactions between phenol and m-cresol were, K = 1.8 × 10 −6, M = 5.5 × 10 −5, Q = 6.7 × 10 −4. The results received in the experiments demonstrated that these models adequately described the dynamic behaviors of phenol and m-cresol as single and mixed substrates by the strain of A. faecalis.