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Bio-Transformation of Fatty Acids Open Access


Other title
Unsaturated fatty acids, biotransformation, lipoxygenase, hydroxy fatty acids
Type of item
Degree grantor
University of Alberta
Author or creator
Shahzadi, Asima
Supervisor and department
Dr. Gaenzle, Michael (Agricultural, Food and Nutritional Sciences)
Dr. Bressler, David (Agricultural, Food and Nutritional Sciences)
Examining committee member and department
Dr. Curtis, Jonathan (Agricultural, Food and Nutritional Sciences)
Department of Agricultural, Food, and Nutritional Science
Food Science and Technology
Date accepted
Graduation date
Doctor of Philosophy
Degree level
This research focused on the bioconversion of unsaturated fatty acids to hydroxy fatty acids, which are platform chemicals of biological and industrial significance. Oleic, linoleic and linolenic acid are liberated in the soap stock of plant oil refineries as free fatty acids and were used as model substrates for bioconversion. The thesis selected microorganisms, and developed methodology for the rapid and enhanced enzymatic transformation of these unsaturated fatty acids to hydroxy fatty acids. The protocols established can be extended to derive value added compounds from the by-products of plant oils. The first objective was to identify bacteria with the ability to produce hydroxy fatty acids, and to increase the product turnover. GC-MS analyses indicated the transformation of oleic acid to 10-hydroxystearic acid by Pseudomonas aeruginosa, Lactobacillus plantarum, L. sanfranciscensis, L. reuteri, L. sakei, and Bifidobacterium bifidum BB12. Linoleic and linolenic acid were converted to 10-hydroxy-12-octadecenoic acid, 13-hydroxy-9-octadecenoic acid and 10, 13-dihydroxystearic acid by lactobacilli but not by P. aeruginosa. Maximum transformation rate was observed from crude cell extract and the activity of a hydratase enzyme was indicated. The second objective was to develop a single step method for the production of coriolic acid from linoleic acid with lipoxygenase (Lox). Single step formation of coriolic acid was achieved with a 70% or higher yield from free and immobilized Lox with cysteine as reducing agent containing 2 mmol/L and 100 mmol/L initial linoleic acid. Immobilized Lox was re-used 10 times with 64% yield from 2 mmol/L linoleic acid and 3 times with 40% yield from 100 mmol/L linoleic acid. A comparable activity of free Lox was observed in reactions performed at a 5 mL and 1 L scale. The dissertation provides practical approach for the biotransformation of unsaturated fatty acids to hydroxy fatty acids by using the specific enzymes from bacterial cell extracts or by commercially available enzymes. The nature of products depends upon the substrates, source of enzyme and transformation conditions. The products thus generated hold the potential to be used as bioactive compounds for food, pharmaceutical and industrial purposes.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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