Degree Type

Dissertation

Date of Award

1991

Degree Name

Doctor of Philosophy

Department

Food Science and Human Nutrition

First Advisor

Earl G. Hammond

Abstract

The oleaginous yeast Apiotrichum curvatum ATCC 20509 was grown on various lipids as carbon sources. When commercial oils were used as substrates, the yeast triglyceride had a fatty acid profile similar to that of the substrate oil, but the glyceride structure was altered. The yeast did not utilize saturated free fatty acids with less than 14 carbons. An emulsion of palmitic acid was well utilized by the yeast, however stearic and arachidic acid emulsions gave very limited and no growth, respectively. Palmitic and stearic acids were extensively desaturated before being deposited in the yeast triglyceride. Oleic acid supported very good yeast growth; eicosenoic acid supported limited growth; erucic acid gave very poor growth. The yeast grew on petroselinic acid and deposited it extensively in its triglyceride. When the medium was supplemented with 1000 ppm butylated hydroxyanisole, linoleic and linolenic acids supported excellent growth and lipid accumulation. The yeast deposited ricinoleic, eleostearic and vernolic acids in its triglyceride when the yeast was grown on triglycerides containing these fatty acids, but the yeast triglyceride contained less of these fatty acids than were found in the substrate oils. When crambe oil was used as a carbon source for the yeast, fatty acids with 20 or more carbons were concentrated in the residual substrate oil. The yeast incorporated very little of the cholesterol in the growth medium into its depot fats. Oleic-linoleic mixtures in various combinations gave good growth and yielded triglycerides with an extensive range of acyl compositions. Plots of the percentage of oleate and linoleate on the glycerol positions vs. the percentage in the whole yeast triglyceride gave linear relations over most of the range for each acyl group. A simple mathematical model of triglyceride assembly was proposed to explain this observation.

DOI

https://doi.org/10.31274/rtd-180813-9289

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Inmok Lee

Language

en

Proquest ID

AAI9212158

File Format

application/pdf

File Size

99 pages

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