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Title: Studies on thermophilic fungi, with particular reference to their nitrogen nutrition and lipid composition
Author: Sumner, J. L.
Awarding Body: Keele University
Current Institution: Keele University
Date of Award: 1968
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Two aspects of the physiology of thermophilic fungi have been investigated, their nitrogen nutrition and lipid composition. The main experimental material was the phycomycete fungus Mucor pusillus. Preliminary experiments indicated that M. pusillus grew and spored well in still culture at 45-50°, on a synthetic medium containing a nitrogen source at a concentration of 250mg. N/1. and a carbon source at 20g./l. These culture conditions were used in a study of the effect of different nitrogen sources on the growth and sporulation of this fungus. Nutritionally, M. pusillus proved extremely versatile, being able to grow and spore on a wide range of inorganic and organic nitrogen sources. The fatty acid composition of the mycelial lipids of psychrophilic, mesophilic, thermotolerant and thermophilic fungi in the Mucorales was studied by gas-liquid chromatography (GLC), while the individual fatty acids were identified by combined mass spectrometry and gas chromatography. The lipids of thermophilic and thermotolerant fungi were found to be more saturated than those of psychrophilic and mesophilic fungi. The effect of various environmental factors on the fatty acid composition of the lipids of M. pusil1us were also studied by GLC. The mycelial lipids were found to be more unsaturated when the fungus was grown at a lower temperature, or when the nitrogen content of the medium was increased; increasing the carbon concentration of the medium resulted in increased synthesis of mycelial lipids. Electrometric determination of the oxygen partial pressure (p02) in the medium of cultures of M. pusillus showed that at 50 the fungus grew under almost completely anaerobic conditions, and the possibility that the oxygen concentration may limit the biosynthesis of unsaturated fatty acids was investigated. Increasing the oxygen concentration of the gas phase above growing surface cultures resulted in only small increases in the degree of lipid unsaturation, and it is considered that significant increases in lipid unsaturation would require highly aerated submerged culture conditions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QH301 Biology