Amino Acids Production for Galdieria sulphuraria Under Different Stressors

  • Author / Creator
    Fayadh, Abdullah
  • Amino acids are building blocks for protein synthesis and are essential to every metabolic process. A well-balanced diet is one in which all required amino acids are present in the food that is eaten. Unfortunately, this is not always the case and nutritional supplements can be used to make up the balance of the required amino acids. Supplements can be produced from different sources including animals, plants and microbial organisms. Animal sources such as fish and beef can generally be complete but require lengthy periods for growth and harvesting. These sources, however, are also susceptible to diseases and contaminations. Amino acids derived from individual plants do not form the basis for a complete diet and a mixture of plants is required for a healthy diet. This requirement is because individual plant proteins do not contain all nine of the essential amino acids in sufficient amounts. Microorganisms that have been used to produce amino acids include bacteria, fungus, and algae. These microorganisms can be genetically engineered to over produce specific proteins or amino acids. Algae has received much less attention than bacteria, yeast and fungi. The goal of this thesis is to establish a base case for amino acid production from non-genetically modified algae by investigating the effect of different growth parameters. The selection of the specific strain of algae is based on choosing a strain that can be cultured efficiently and economically. Algae can be divided into freshwater and saltwater environments, and both approaches have issues researchers must handle in growing and harvesting algae for protein production. For example, freshwater algae can be contaminated by a large number of microorganisms and the procedure for maintaining a monoculture free from contaminations is very difficult for mass production. On the other hand, saltwater algae have fewer contaminants than the freshwater algae but the operator must contend with control and disposal of salts in the growth media. The expanding need for natural ways to produce high amounts of amino acids is fueling the search for other strong and competitive microalgal strains. This study investigates Galdieria sulphuraria, a type of red algae that can thrive in harsh environments that not many microorganisms can tolerate. G. sulphuraria is an extremophile that requires both thermophilic and acidophilic conditions for proper growth; furthermore, G. sulphuraria can also be a halotolerant alga, which has the ability to grow in high salt concentration conditions. G. sulphuraria also has the ability to consume a wide variety of sugars and nitrogen sources. A Box-Behnken experimental design was used to investigate amino acid production in this algal strain with the manipulated parameters being sugar sources and concentrations of macronutrients (carbon, nitrogen and phosphate). The amino acids that are directly correlated to the concentration of these macronutrients are serine, histidine, arginine, valine, phenylalanine, isoleucine, leucine, and proline. A poor correlation was observed between the concentration of the manipulated macronutrients and the amino acids aspartic acid, glutamic acid, glycine, threonine, alanine, tyrosine, cysteine, methionine, and lysine. Different sugars influence amino acid productions, even with the same carbon number and molecular weight. G. sulphuraria fed with glucose has the capability to produce higher amino acid concentrations compared to the same medium with a substituted sugar type, mannitol, using equivalent molar mass. This response is strongly noticeable with a growth medium supplied with xylose, in which G. sulphuraria produces greater amino acid concentrations compared to arabinose. When G. sulphuraria is grown on xylose, after 48 hours, the culture contains more amino acids than was observed with the other three sugar types. The only exception was for the concentration of aspartic acid when compared to growth on glucose. In this case, when grown on xylose, the aspartic acid concentration decreased by 178%. The superior production of amino acids from a xylose containing medium, which has an increasing value of 70% for serine, 61% for histidine, 75% for arginine, 78% for valine, 71% for phenylalanine, 71% for isoleucine, 70% for leucine, 80% for proline, 48% for glutamic acid, 95% for glycine, 69% for threonine, 76% for alanine, 84 % for tyrosine, 74% for cysteine, 46% for methionine, and 80% for lysine, suggests that amino acid production is irrelevant to the number of carbons in sugars.

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  • Degree
    Master of Science
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    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.