Overexpression of Calvin Cycle Enzyme Fructose-Bisphosphate Aldolase to Increase Algal Growth Rate

Undergraduate #49
Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology

Lian Jackson - Baltimore City Community College
Co-Author(s): Binika Chunara, Rose Gbemefu, and Stephen M. Miller, UMBC, MD

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Algae are plant-like organisms that can be used for sustainable production of biofuels and other commercially valuable products. Chlamydomonas reinhardtii, a single celled green alga, has been used as a model organism to research algal biofuel production, due to its sequenced genome, ability to be genetically manipulated and its fast growth rate. Algal biofuel production could be a cheaper, greenier alternative to fossil fuels. Carbon dioxide (CO2) is limiting factor for algal growth, so it is believed that certain enzymes that function in the Calvin cycle, which converts CO2 into carbohydrates, may be key targets for improving photosynthesis and growth. Fructose-bisphosphate aldolase (FBA) functions in the regeneration phase of the Calvin cycle, and overexpression of this enzyme in higher plants improves growth significantly. We have tested the idea that overexpressing FBA will also increase flux through the Calvin cycle in algae. Using recombinant DNA techniques, we have generated C. reinhardtii transformants that contain the coding region for C. reinhardtii FBA (myc-epitope tagged) under the control of psbD and psbA 5’ and 3’ regulatory sequences, respectively, integrated into the chloroplast genome. We used western blot analysis to determine accumulation of transgenic protein and found that transformants accumulates a myc-reactive protein near the expected size of ~44 kDa.. Next we will use an algal multicultivator to compare the growth rate of the best expressing transformants to that of a control/recipient strain. If overexpression of FBA improves C. reinhardtii growth, we will apply these methods to other algae, such as the biotechnology production organism Chlorella.

Funder Acknowledgement(s): These results were obtained as part of the Research Experience and Mentoring (REM) program in the Department of Biological Sciences at the University of Maryland Baltimore County. This program is funded by a grant (REM supplement to NSF-EFRI-1332344) from the National Foundation (NSF) Directorate for Engineering (ENG) Office of Emerging Frontiers in Research and Innovation (EFRI).

Faculty Advisor: Stephen M. Miller, stmiller@umbc.edu

Role: I was able to test for overexpression of FBA, and increase flux through the Calvin cycle by using a transformant that was introduced into the coding region using recombinant DNA technology.