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Comparative qualitative analyses of hydrolysis products of extracellular polysaccharides

University of British Columbia

The objective of the experiments was to compare qualitatively the monosaccharides in the hydrolysis products of the extracellular polysaccharides of several yeasts and yeast-like fungi. Specifically, the study was aimed at finding similarities and differences that might be useful in suggesting and supporting taxonomic relationships. Gas chromatography and paper chromatography were used as methods of analyses in an effort to find out what method is sufficient at the qualitative level for distinguishing some genera of yeasts and yeast-like fungi; and what method would be best at the quantitative level for distinguishing amongst some species of the same genus. From the analytical results it was found that paper chromatography using the solvents ethyl acetate: pyridine: water, (8:2:2) was sufficient for qualitative determination of the monosaccharides in the extracellular polysaccharide hydrolysis products. However, indications were that quantitative analyses by gas chromatography, using the trimethylsilyl derivatives of the monosaccharides would have been successful in distinguishing among species of the same genus. Two groups were formed on the bases of the qualitative results. Group I contained two subgroups. Subgroup I encompassed those yeasts and yeast-like fungi with the monosaccharides galactose, glucose, mannose, xylose present in the hydrolysis products of their extracellular polysaccharides. Included in this Subgroup I are: Cryptococcus laurentii, Tremella mesenterica, Bullera alba, Sporobolomyces odorus, Sporobolomyces singularis, and Rhodotorula glutinis. Subgroup II is Ustilago hordei only, with the monosaccharides galactose, glucose, mannose, and lacking xylose. Group II contains Taphrina populina only, with glucose and mannose present and both galactose and xylose absent. The two groups formed support some of the taxonomic relationships that have already been suggested. The Tremella - Cryptococcus taxonomic relationship that had previously been postulated on the basis of similarities in extracellular polysaccharide hydrolysis products, morphology, carbon assimilation patterns, enzymatic xylosylation reaction, and starch formation was supported. Secondly, the Cryptococcus-Bullera relationship that had been suggested on the basis of inositol assimilation, lack of pseudomycelium, and similarities in starch synthesis, was supported by the qualitative analysis of the monosaccharides present in the extracellular polysaccharide hydrolysis products. The monosaccharides found in both Cryptococcus laurentii and Bullera alba extracellular polysaccharides were the same qualitatively. Duality amongst species of Sporobolomyces might be supported with further work using quantitative gas chromatographic analyses. This duality had been postulated on account of the duality shown in antigenic analyses and percent G+C base analyses of DNA. Taphrina populina can be distinguished from Rhodotorula glutinis and Cryptococcus laurentii. Cryptococcus laurentii produces starch and assimilates inositol: Rhodotorula glutinis assimilates inositol but does not produce starch; and Taphrina populina produces starch but does not assimilate inositol. Two monosaccharides present in the extracellular polysaccharide hydrolysis products of both Cryptococcus laurentii and Rhodotorula glutinis are galactose and xylose whereas Taphrina populina lacks these two monosaccharides. Results obtained from the qualitative analyses of the extracellular polysaccharides produced by fungi may be important taxonomically. This is because the qualitative information may be used when deciding on Perfect-Imperfect fungal relationships. However, this information should be considered along with data from other fields such as morphology, cytology, and genetics before hypothesizing on a taxonomic relationship.

Text

2011-04-21

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http://hdl.handle.net/2429/33939

Botany

University of British Columbia

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