Characterization of Rhodopseudomonas Palustrus Strains for the Production of Fixed Nitrogen Fertilizer for Mars

The purpose of this project was to characterize the potential of various strains of purple non-sulfur bacteria for the production of fixed nitrogen fertilizers for the manned Mars missions. Six strains of Rhodopseudomonas palustris (CGA009, CGA010, TIE-1, NifA*, and PB23) were all investigated. Through initial growth trial experiments, R. palustris NifA* and PB23 were selected for their engineered nitrogen fixation and rapid growth respectively. Growth curves and ammonium concentrations were collected over time in pilot scale batch photobioreactors (200 mL). Biomass production was then scaled up to benchtop photobioreactors (1.5 L) and then 14 L total volume for both NifA* and PB23. Cells were harvested via centrifugation, and nitrogen degradation was characterized using both volatile ammonia and soluble nitrogen arrays. While PB23 was found to grow more rapidly at small scale, NifA* performed better in scale up. Further studies will quantify rates of nitrogen degradation using the arrays developed in this Senior Design Project

Compost Nutrient Optimization Using Algal Biomass Amendment

Wastewater treatment plants worldwide are a necessary and important function of society. Contaminated water from sewer systems is brought in, filtered, purified, and released back into our rivers and lakes in enormous quantities. The biosolids removed during the many filtration steps are digested anaerobically to produce bio-methane, and then composted with woodchips to be used as a soil amendment, capable of supplying nitrogen, phosphorus, potassium, and other nutrients to plants for agricultural use. Although a value product, analysis of this compost has shown that the nutrient content is low compared to commercial fertilizers. This experiment will show that the addition of an algal biomass grown on a stream of the wastewater can be included in the compost to increase concentration of nitrogen, phosphorus, and potassium while decreasing the toxic concentrations found in the wastewater, and that this inclusion will directly correlate to increased plant growth upon application. Two species of Lactuca Sativa (lettuce plants) grown in the amended compost were used to quantify growth and were compared against a negative control of nutrient-bare soil, and a positive control of the original compost product mixed with soil. Wet mass, dry mass, leaf count, chlorophyll content, root length, and root density were used as growth parameters to quantify differences in the plants