Kinetics of phenol oxidation by washed cells

Abstract

Summary. The uptake of phenol by pure cultures of Psc~rrdomonas prrridtr growing on phenol in continuous culture has been studied. The purpose of the experiments was to determine the kinetic parameters governing uptake of phenol by organisms growing on phenol in the highconversion range by measuring uptake rates per unit biomass per unit time at various phenol concentrations. The microorganisms used were taken from a chemostat at residence times of 8. 5.25, 3.85, 3.2, 3. and 2.7 h. The Monod-Haldane model and modifications of it were applied to the data and the best kinetic parameters were determined by nonlinear leastsquares techniques. The bsst model was a two-parameter simplification of Monod-Haldane in which I* = K I S / ( K z + S'), The value of K , was found to increase monotonically with the value of phenol concentration in the original chemostat with an apparent induction "threshold" of 0. I mg/L.

Robust control for an uncertain chemostat model

“…We suppose that s is the phenol and the biomass x is Pseudomonas putida [21], the objective is to stabilize the concentration of phenol below the level s + after a finite time T . Then, the contaminant concentration becomes upperly bounded:…”

“…SERT, 1990 This model is affected by several uncertainties: the data presented by Sokol and Howell [21], show that the function f that describes the growth of x(t) is of type:…”

“…• We can consider the chemostat as a simple wastewater plant (see for example [21], [24]), where a selected microorganism x consumes a contaminant s and is expected to make decrease its concentration toward an acceptable level given by environmental laws. This goal is considerably complicated by uncertainties of the kinetic model and the output.…”

On Nonlinear Dynamics of Predator-Prey Models with Discrete Delay

“…However, there are experiments in microbial dynamics that indicate that nonmonotonic responses occur at the microbial level: when the nutrient concentration reaches a high level an inhibitory effect on the specific growth rate may occur. This is often seen when micro-organisms are used for waste decomposition or for water purification (see Andrews [1], Sokol and Howell [78], Bush and Cook [18]). In population dynamics, nonmonotonic functional response occurs when the prey exhibits group defense (Freedman and Wolkowicz [40], Wolkowicz [87]), the phenomenon whereby predation is decreased, or even prevented altogether, due to the increased ability of the prey to better defend or disguise themselves when their numbers are large enough.…”

Catechol biodegradation kinetics using Candida parapsilopsis

“…For all the assays, the initial pH value was 7.0 and incubation at 30 °C under agitation. A number of substrate-inhibition models have been proposed for use with inhibitory substrates (Sokol and Howell, 1981;Yang and Humphrey, 1975). The simplest and most commonly used model, which is the Haldane's model, is given as:…”