Nutrient Feed Rate Research Articles

Open-loop control of specific growth rate in fed-batch cultures of recombinant E.coli

A computer-based algorithm was used for the open-loop control of specific growth rate in fed-batch cultures of recombinant E.coli.. The control of nutrient feed rate to an exponential trajectory resulted in growth of the culture at a constant specific growth rate. Stable specific growth rates between 0.08 and 0.4 h−1 were achieved.

Fed‐batch culture automated by uses of continuously measured cell concentration and culture volume

An automated control method of fed-batch culture in which the nutrient feed rate was determined from continuously measured cell concentration and culture broth volume was developed. Theoretical background was elucidated, from which it was found that the method is unique in that it controls specific substrate consumption rate of the microorganism. The method was experimentally applied to the fed-batch cultures of recombinant Escherichia coli HB101. It was observed that the specific substrate feed rate affects not only the specific growth rate but also the growth yield. If some conditions are satisfied, this type of automated fed-batch culture can be applied widely to any microbial systems and seems especially useful when the culture medium is composed of natural complex nutrient(s) because their concentrations are very difficult to detect and control.

A microcomputer-based instrumentation system for anaerobic wastewater treatment processes

A microcomputer-based system for monitoring and control of anaerobic wastewater treatment processes is described. Instrumentation includes a gas chromatograph that measures CH 4, CO 2, H 2 and CO concentrations in the gas phase every 2 min, a second gas chromatograph that measures volatile acids (C 1C 4) every 12 min, and sensors for continuous measurement of temperature, pH, ORP and gas production rate. The H 2 and CO detection limits are less than 1 ppm. Nutrient and substrate feed rates can be varied in a pre-programmed manner to allow automated collection of transient—response data. Data are presented for experiments in which a fluidized-bed reactor (for which the main carbon source is butyrate) is subjected to multi-frequency binary variations in feed flow rate.

The Use of Phase-plane Analysis in the Modeling and the Control of a Biomethanization Process

In this paper, deeper insight into the dynamics of a continuous biomethanization process is obtained through the use of phase plane analysis and simulation on a hybrid computer. Stable and unstable stationnary states for the anaerobic reactor are found along with conditions on the nutrient feedrate and concentration for converging towards such states. Furthermore, control schemes are described which drive quickly and safely the reactor towards such stable stationnary states. The next step is the implementation of such control schemes on a microprocessor which is connected to the real-life reactor.

Mathematical models for hollow‐fiber enzyme reactors

AbstractTwo analytically solved mathematical models are presented for a reactor ystem employing immobilized whole cells as a biocatalyst. The whole cells are entrapped or pumped through the shell side of the dialyzer reactor unit. The reactant mixture is circulated through the cialyzer tube side. Nutrient diffuses across the hollow fiber membrane from the tube side to the shell side, where it reacts to form product, which then back diffuses into the reactant mixture stream. The use of a high recirculation ratio of nutrient through the dialyzer tubes to nutrient feed rate to the entire system, allows the system to be modeled as a continuous‐flow stirred‐tank reactor. The first analysis details the development of an effectiveness‐factor correlation for first‐ and zero‐order kinetics. The second analysis presents the solution to an unsteady‐state‐system mass balance with Michaelis–menten kinetics.

The relationship between nutrient feed rate and specific growth rate in fed batch cultures

Equations are described which relate nutrient feed rate to specific microbial growth rate in fed batch culture. Fed batch cultures are classified into three types: 1) those allowing constant specific microbial growth rate, 2) those in which the rate of change of flow rate is constant and 3) those in which the nutrient flow rate is constant. The basic properties of these three types are described.