On the current-voltage relationships of energy-transducing membranes: submitochondrial particles [proceedings].
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Adenosine Triphosphate↗
Biomedical subjects
D B Kell
Publications and source records attributed to D B Kell.
Quantifying heterogeneity: flow cytometry of bacterial cultures.
Flow cytometry is a technique which permits the characterisation of individual cells in populations, in terms of distributions in their properties such as DNA content, protein content, viability, enzyme activities and so on. We review the technique, and some of its recent applications to microbiological problems. It is concluded that cellular heterogeneity, in both batch and continuous axenic cultures, is far greater than is normally assumed. This has important implications for the quantitative analysis of microbial processes.
Bacteria↗
Quantitative approaches to the analysis of the control and regulation of microbial metabolism.
Recently, a number of novel ways of considering the control, regulation and thermodynamics of microbial physiology have been developed and applied. We here present an overview of the new concepts involved, of their limitations and of the most recent attempts to deal with those limitations. We conclude that there no longer exist reasons of principle for vagueness in discussions of the control of microbial physiology and energetics. Further, the novel conceptual methods serve to remove part of the discordance between holistic and reductionistic views of microbial physiology.
Adenosine Monophosphate↗
The use of dielectric permittivity for the control of the biomass level during biotransformations of toxic substrates in continuous culture.
Since the permittivity signal of a cell suspension measured using dielectric spectroscopy at radio frequencies is essentially determined only by viable (intact) cells, it can be used to monitor the concentration of viable cells in a fermentor in which a large proportion of the cells is nonviable. This could be used to select for organisms that are highly resistant to stress, for example from toxic chemicals used in biotransformations. We sought to control the concentration of viable yeast cells in a fermentor by adding small amounts of benzaldehyde, thus imposing a selection regime for cells highly resistant to benzaldehyde. However, after the addition of benzaldehyde, an increase in the permittivity is seen first followed by a decrease, thus making the control of biomass using a standard on-off controller difficult. It is shown that it is possible effectively to control the level of viable biomass in the fermentor in the presence of a large concentration of necromass using a combination of an inverse response compensator and a PID controller.
Algorithms↗