Development of Plant Hemoglobin-Based Blood Substitute: Fed-Batch Fermentation Optimization and Stability Characterization
Abstract
The need for alternative blood substitutes is undoubtedly very enormous. Therefore, it is important to evaluate and develop different sources of starting material for this product. Focus has been on use of hemoglobin (Hb) from different sources, including human, whale etc. Following recent availability of genome sequence of sugar beet (Beta vulgaris ssp. vulgaris) effort is now put on studying three of its hb genes (BvHb1.1, BvHb1.2, and BvHb2) for their potentials in developing of hemoglobin-based oxygen carrier (HBOC). Unfortunately, these proteins are expressed in low amounts in plant. Consequently, use of recombinant biotechnology is an alternative way to obtain high amounts of these proteins. In this study, a fed-batch fermentation method was used in the production of recombinant Beta vulgaris Hbs (BvHbs). Five critical fermentation parameters were monitored while varying glucose feeding profile and aeration rate. Additionally, we characterized the autoxidation properties of one of these proteins, BvHb1.2, at different temperatures to examine its level of stability. Our result revealed that different conditions are favourable for cell growth and recombinant protein expression. A similar expression pattern of these proteins in plant was observed under fermentation. On the autoxidation assay, we could observe that high temperature facilitates autoxidation process. This implies that this protein can be preserved in its active form by maintaining it at low temperatures.
Finally, we conclude that different conditions are favourable for high yield fermentation of each of these proteins. In addition, appropriate culture glucose concentration and sufficient oxygen (O2) level will reduce toxic by-product accumulation and provide high-cell density growth.
Description
Master's thesis in Biological chemistry