Microbial 2,3-butanediol production: A state-of-the-art review

Batch cultures of Escherichia coli were grown in minimal media supplemented with various carbon sources which supported growth at specific growth rates from 0.2 to 1.3/h. The respiration rates of the cultures were measured continuously. With few exceptions, the specific rate of oxygen consumption was about 20 mmol of O2/h per g (dry weight), suggesting that the respiratory capacity was limited at this value. The adenosine triphosphate (ATP) required for the production of cell material from the different carbon sources was calculated on the basis of known ATP requirements in the biochemical pathways and routes of macromolecular synthesis. The calculated ATP requirements, together with the measured growth rates and growth yields on the different carbon sources, were used to calculate the rate of ATP synthesis by oxidative phosphorylation. This rate was closely related to the respiration rate. We suggest that aerobic growth of E. coli in batch cultures is limited by the rate of respiration and the concomitant rate of ATP generation through oxidative phosphorylation.

Are growth rates of Escherichia coli in batch cultures limited by respiration

Chemical Engineering Use of Catalyzed Sulfite Oxidation Kinetics for the Determination of Mass Transfer Characteristics of Gas-Liquid Contactors

Publisher Summary This chapter presents a detailed description of the design and construction of a one litre “Porton-type” chemostat. The chapter also discusses in brief those considerations influencing the choice of individual components, or systems, and indicates possible alternative arrangements. The apparatus is described to meet the varied demands of research workers for an operationally versatile apparatus that is nevertheless easy to operate and service, reliable, and not too demanding of space, medium supply, and manpower. The chapter states the six basic conditions that fulfill all continuous-culture devices. The chemostat is constructed in two separable parts, the “fermenter unit” and the “control unit”, which are connected by a multi-core cable through multi-point plugs and sockets. The framework of the fermenter unit is constructed of slotted steel angle and panelled with “peg-board.” Agitation of the culture must be sufficient to promote near-perfect mixing and, in the case of aerobic cultures, to allow oxygen to dissolve in the culture at a rate greater than the maximum at which it is used by the growing organisms. To achieve steady-state conditions in a chemostat, fresh sterile medium must be added continuously to the culture at a pre-set, unvarying, rate. The culture volume must be maintained constant by removing liquid from the growth vessel at a rate equal to the sum of the rates of addition of medium, titrant, and so on.

Chapter XIII The Continuous Cultivation of Micro-organisms: 2. Construction of a Chemostat

The ATP pool in Escherichia coli. I. Measurement of the pool using a modified luciferase assay

SUMMARY: A quantitative study of the growth and carbohydrate metabolism of Aerobacter aerogenes in continuous culture with particular reference to 2:3-butanediol production is described. The effects of varying dilution rate, oxygen uptake rate, pH value, temperature and CO2 pressure were studied.

The optimum pH value was 5·0°6·0. The optimum temperature was 35–37° with a dilution rate of 0·2 hr−1. The rate of sugar metabolism was decreased by raising the CO2 pressure.

In continuous culture the maximum diol output rate/1. of working volume exceeded the greatest rate reported for batch culture by a factor of three. The maximum diol concentration and yield as a percentage of the theoretical maximum were lower in continuous culture than in batch culture. Reasons for this are given.

Some variants of the parent organism were found in continuous cultures but they caused no change in the yield of butanediol. There was no sign of loss of butanediol-producing ability by any of the cultures, some of which were maintained for 2,000 hr. For the first few generations the rate of production of butanediol actually increased.

Exocellular product formation by microorganisms in continuous culture. i. production of 2:3‐butanediol by aerobacter aerogenes in a single stage process

A two litre scale continuous culture apparatus for micro‐organisms

SUMMARY: The maximum possible oxygen solution rates in bacterial cultures with different aeration conditions were appreciably less (0·5°0·7 times) than those in a sodium sulphite solution containing a copper catalyst under the same aeration conditions. Knowledge of the relationship between the maximum oxygen solution rates in a culture and the sulphite solution enables one to predict from the sulphite measurements the aeration conditions required to satisfy the oxygen demand of a culture.

The relationship between maximum oxygen solution rates in a bacterial culture and in a sodium sulphite solution under comparable aeration conditions

SUMMARY: Inhibition of foaming in a continuous culture of bacteria has been studied. At first, foaming was inhibited by the addition of antifoam to the culture only when a foam layer was present. When the antifoam was added in this way foaming often became intense and antifoam additions had to be more and more frequent. In a preferred method the antifoam was added at regular intervals which were sufficiently short to inhibit foaming completely throughout the intervening periods. This method required less antifoam than the other. The effects of foaming in cultures, its causes, and allied problems are discussed.

S. J. Pirt

Papers

Exocellular product formation by microorganisms in continuous culture. i. production of 2:3‐butanediol by aerobacter aerogenes in a single stage process

A two litre scale continuous culture apparatus for micro‐organisms

The relationship between maximum oxygen solution rates in a bacterial culture and in a sodium sulphite solution under comparable aeration conditions

Observations on foaming and its inhibition in a bacterial culture