Stanley, Stephen Hall (1977) A study of the physiology and gas limited growth of Methylococcus capsulatus. PhD thesis, University of Warwick.

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Abstract

The results presented in this thesis have provided an understanding of gas limited growth, as well as an insight into the physiology of the methanotroph Methylococcus capsulatus (Bath). A theory of gas limited growth is presented which explains the experimentally observed dilution rate curves obtained during this investigation. Measurement and calculations of yield data are described and the problems encountered in these estimations are considered, particularly the transient effect of pHs additions on carbon dioxide production The maximum yield obtained was 0.65g. cells/g. of methane used.
The rate of gas utilisation by the organisms was proportional to the partial pressure of the limiting gas entering the system. Cultures of Methylococcus capsulatus (Bath) grown on air/methane mixtures were oxygen-limited above 15% methane and methane limited below 4% methane. On occasions these cultures were sensitive to sudden increases in oxygen availability and would completely oxidise methane to carbon dioxide. Antifoam additions lowered
An enclosed batch culture system was developed to enable changes in the gas and liquid phases to be monitored during growth. Nutrient-limited growth in batch cultures (linear growth) is described and typical growth curves presented, 0.1% v/v methanol did not inhibit growth of established cultures of Methylococcus capsulatus (Bath) but did inhibit methane oxidation. Methanol was used in preference to methane (demonstrated in batch and continuous culture) and was not detected in culture supernatants. Additions of 20 mM formate did not increase the yield of the organism grown on methane and nitrate mineral salts.
The problems of growth on three nitrogen sources are discussed and the comparative yields on nitrate, ammonium and dinitrogen were respectively 0.48, 0.52 and 0.45 g. cells/ g. of methane used.
Acetylene was found to be a potent specific inhibitor of methane oxidation. Ethane and ethanol inhibited methane- uptake and were oxidised to acetaldehyde which accumulated in the culture.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QR Microbiology
Library of Congress Subject Headings (LCSH):	Methylotrophic microorganisms, Methane -- Oxidation, Oxidation, Physiological
Official Date:	October 1977
Dates:	Date Event October 1977 Submitted
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Whittenbury, R.
Sponsors:	Science Research Council (Great Britain) ; British Petroleum Company
Extent:	xiii, 211 leaves : illustrations
Language:	eng

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