Maintenance energy and molar growth yields of Escherichia coli

Wallace, Robert John (1975) Maintenance energy and molar growth yields of Escherichia coli. PhD thesis, University of Glasgow.

Abstract

Maintenance is that fraction of the metabolic activity of growing cells which does not result in the net synthesis of new cell material. The maintenance coefficient (m) is assumed to be constant, and independent of specific growth rate (mu). It can be measured by, examining the distribution of carbon to new cells and to energy production at various mu. In the arithmetic growth systems employed in this work mu changes in a predictable way and at the slow growth rates attained (mu = 0.01 - 0.1 h-1) m is a large fraction of the total energy utilisation. These factors made more simple the accurate measurement of m in comparison with methods employed by other workers. Both the maximum molar growth yield (YG) and m were readily measured using arithmetic-type continuous culture. Value of YG and YGO2 were similar to those obtained by other workers using different growth systems. The main conclusions were (i) anabolic and catabolic processes in carbon-limited were tightly coupled, but coupling broke down under nitrogen limitation; (ii) using the Bauchop and Elsden YATP of 10.5 g/mole, P/0 ratios for carbon-limited E. coli were 2 for growth on glucose, malate and glycerol, and 3 for growth on lactose. Addition of 0.5 M sodium chloride to a glycerol-limited culture reduced the P/0 ratio to 1. These P/0 ratios seemed reasonable, implying that the previous assumption of the value for YATP was probably valid, and hence YATP was considerably less than the theoretical maximum of ~30 g/mole. Maintenance in terms of carbon source and oxygen was measured in the same experiments. Findings were (i) carbon source used for maintenance was completely oxidised; (ii) maintenance energy is small in E. coli. mATP was 1 - 3 mmol (g dry wt)-1 h-1 at 37

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: W H Holmes
• Keywords: Microbiology
• Date of Award: 1975
• Depositing User: Enlighten Team
• Unique ID: glathesis:1975-72848
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Jun 2019 11:06
• Last Modified: 11 Jun 2019 11:06
• URI: https://theses.gla.ac.uk/id/eprint/72848