A study of yeasts of marine origin

Ross, Sheena S (1963) A study of yeasts of marine origin. PhD thesis, University of Glasgow.

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The thesis is introduced by a review of the literature concerning the occurrence and composition of the yeast flora of marine fish and other parts of the marine environment. The experimental work can be divided into three sections: The first of these sections concerns the collection and maintenance of yeast cultures from various marine sources. Altogether 235 such cultures were obtained and of these, during this survey, 189 were isolated from marine fish and 11 from sea-water. The remaining 35 were isolated by other workers. Improved methods for sampling and subsequent isolation of yeasts are described. The second experimental section deals with the identification of these isolates using the system of Lodder and Kreger-van Rij (1952). The 213 isolates from marine fish were found to comprise eight genera Debaryomyces, Torulopsis, Candida, Rhodotorula, Pichia, Trichsporon, Quariocgcqus and Pullularia. D.kloeckeri comprised 45% of these isolates and Ttiqponsplcua (var) and plpaupsilopis each 11% respectively. The 22 isolates from other marine sources belonged to the same genera as the fish isolates and in addition five of the eleven strains isolated from sea-water samples in this survey were classified as Metschnikowia krissil (van Uden and Oastelo-branco)nov.comb. Although most of the isolates closely resembled the descriptions of the type species some differences wore obvious and these have been discussed in the light of possible strain variation within the species. The third section of experimental work comprises further studies of the isolates. The results obtained, from these studies and. their probable value in establishing strain variation have been discussed. Infrared spectrephotometry of whole cells, soluble and insoluble cellular material was found to be of little value for species or strain differentiation. It was conjectured that identical cellular components producing specific spectra occur in the different species and mask the effects of differences in other cellular components unlitative studies of the free amino-acid pools of certain of the marine isolates and terrestrial strains of corresponding species also indicated that strain characterisation on this basis is impracticable. No outstanding tjtalitative differences between the of the free amino pools of the marine and terrestrial strains were apparent. The maximum concentration of NaCl tolerated by the marine isolates was found to be a feature of each strain and there was a correlation regarding halo-tolerance among strains of a particular species isolated from different marine locations. Complex resources were found to stimulate halo-tolerance in the isolates. the concentration of Nall was increased in the growth medium a prolongation in the yeasts' lag phase was observed but their growth rate remained fairly constant. Strains/Strains of pekloeckevi, were found to exhibit optimal growth in media containing 1.0 to 3.0;, Nan, whereas the other species tested grew best without Na. The thesis concludes with a discussion concerning the occurrence and species distribution of the yeasts isolated during this survey. Skin samples had the highest incidence of yeast occurrence; the samples from the gills and mouth exhibited the next highest incidence, while a much lower value was recorded in those from the faeces. Strains of D.kloackeri were predominant among the isolates from every location of sampling whereas the occurrence of other species and the proportion of isolates comprising them varied. in the different geographical areas. Results also indicate that different fish species may carry their own characteristic yeast flora.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: E O Morris
Keywords: Microbiology
Date of Award: 1963
Depositing User: Enlighten Team
Unique ID: glathesis:1963-73184
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56
URI: http://theses.gla.ac.uk/id/eprint/73184

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