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United States Department of Agriculture

Agricultural Research Service

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Location: Plant Genetics Research

2012 Annual Report

1a. Objectives (from AD-416):
To advance technologies required to make the algae biofuels industry cost-effective.

1b. Approach (from AD-416):
Investigate the elemental requirements for algae growth and oil production, the relationship between them and the genes responsible for it. We will conduct nutrient growth screens in collaboration with the Sayre lab at the Danforth Center. We will then conduct genetic screens for strains that use elements more efficiently while producing oils. We will also test strains with known ionomic genes deleted for their effect on the single cell ionome of a photosynthesizing organism.

3. Progress Report:
Potential Algae biofuel production sites vary greatly in the composition of their waters, from fresh, to brackish to sea water levels of sodium and above. They may also vary in the levels and forms of the essential elements, nitrogen, phosphorus and potassium as well as micronutrients and toxic elements, and amendments can be used to alter any of these concentrations. All of these components can vary independently, so one way to think about the available conditions for growing algae is as a large, multi-dimensional ion space. For example, if you are interested in nine components of the media, you need to explore a nine dimensional space. In order to determine the growth landscape of algae strains across the space of available waters and fertilizers, we previously completed a screen of a matrix of variation of nine of the components of growth media: phosphate, potassium, ammonia, nitrate, sodium, chloride, acetate, sulphate and a buffer for the model algae Chlamydomonas Reinhardii. This year, we conducted a follow up screen exploring the spaces defined in the original screen in more detail. From this data, we determined that two strains of Chlamydomonas have drastically different growth responses to the nutrient potassium. In addition to monitoring growth of the algae, we also measured the elemental and lipid content of the algae in each media where it grew. This allowed the identification of economical medias that support algal biofuel production. We have also constructed experimental segregating populations of Chlamydomonas for use in selection and quantitative genetics experiments. Using an earlier version of these populations, we performed a selection designed to identify strains with improved growth characteristics in medias with low levels of the essential nutrients Nitrogen and Phosphate. We used these experiments to identify genes important for improved growth in economical medias. These studies complement the in-house research project by providing a window on how the biomass and oil composition of a single cell model of photosynthetic organisms are affected by changes in the nutrient environment.

4. Accomplishments

Last Modified: 06/21/2017
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