The effect of exogenous energy sources on the synthesis of beta-galactosidase in resting-cell suspensions of Escherichia coli

A simple device of an improvised fermentor for production of rhizobial culture

A simple new batch fermentor, suitable for both laboratory and industrial small scale cultivation of micro-organisms, particularly rhizobia, was designed and constructed. It was found to operate as a conventional stirring tank reactor. The device reliably ensures the sterility of cultivation, irrespective of its duration. Its installation costs are relatively low, it does not show a high consumption of energy for stirring, the operation is very simple and does not require maintenance of complicated equipment. On this basis, a procedure of design for this fermentor is outlined over the more complex scale up problems of a tank fermentor.

Synthesis of Protocatechuate Oxygenase by Pseudomonas fluorescens in the Presence of Exogenous Carbon Sources

Kirkland, Jerry J. (Oklahoma State University, Stillwater), and Norman N. Durham . Synthesis of protocatechuate oxygenase by Pseudomonas fluorescens in the presence of exogenous carbon sources. J. Bacteriol. 90: 15–22. 1965.—The addition of glucose, ribose, or fructose (0.45 or 45.0 μmoles/ml) simultaneously with protocatechuic acid shortens the lag period required for synthesis of protocatechuate oxygenase by a washed-cell suspension of Pseudomonas fluorescens . Glucose is readily oxidized and supports growth of P. fluorescens , whereas neither ribose nor fructose readily supports growth. High glucose concentrations (45.0 μmoles/ml) shorten the lag period but lower the total enzyme synthesis. The p H drops during glucose oxidation, and this is accompanied by a decrease in the rate of enzyme synthesis. High glucose concentrations, with adequate buffering, permitted “normal” enzyme synthesis. A decrease in the total enzyme synthesis was not observed in the presence of high concentrations of ribose or fructose. Succinate, pyruvate, acetate, or formate (0.45 μmole/ml) were readily oxidized, but did not shorten the lag period required for synthesis of the enzyme. The data suggest that glucose, ribose, or fructose may serve as a “specific” carbon source (such as ribose-5-phosphate or a similar precursor important in ribonucleic acid synthesis) functional in the synthesis of protocatechuate oxygenase.

ENERGY OF MAINTENANCE IN ESCHERICHIA COLI

McGrew, Sarah B. (Pennsylvania State University, University Park) and M. F. Mallette. Energy of maintenance in Escherichia coli. J. Bacteriol. 83:844-850. 1962.-Relatively dense populations of Escherichia coli B in log phase were used to detect utilization of exogenous glucose for maintenance without growth. Turbidity at 400 mmu was used as the measure of growth, since it should reflect changes in either cell number or size. A threshold level of glucose was observed below which turbidity did not change during short-time experiments. Repeated additions of glucose during prolonged incubation at 37 C either increased the turbidity slowly or maintained it, depending on the amount of glucose. Plate counts to follow viability showed slow decreases for 10 days, while the unfed controls lost viability quite rapidly. From these results it was concluded that E. coli specifically utilized exogenous glucose for maintenance, without growth. The conflict of this opinion with that of earlier workers is discussed and some implications suggested.