Abstract Title

Determining Limiting Growth Factors in Struvite Based Media for C.reinhardtii and N.oculata

Additional Funding Sources

Support for this work is provided by the Idaho State Board of Education, Higher Education Research Council IGEM program (IGEM project No. IGEM19-001), and the USDA (Award No. 2018-67022-27894).

Abstract

Large scale algae cultivation can be used for biofuels or biproducts, but is often limited due to low cost nutrient availability that does not compete with agricultural production. One method to resolve this limitation is coupling algae biomass production with nutrient recovery from wastewater treatment. Struvite [NH4MgPO4•6H2O] is a phosphate mineral crystal that can be produced as part of the nutrient capture process associated with wastewater treatment. Struvite can also be a potential source of vital renewable nutrients (N, Mg, P, etc.) for high-value algal biomass production. However, preliminary data suggests that algae strains C.reinhardtii and N.oculata, two strains known to produce high value lipids, experience a significant decrease in algal biomass production; in a struvite based growth medium without micronutrient supplementation. Our project will determine which specific micronutrients, or combinations of nutrients, are limiting C.reinhardtii and N.oculata production in struvite-based media. Prior work indicates that chelated iron, EDTA [1,2], calcium [3] and potassium [4,5], or a combination of these elements can be crucial micronutrients for algal growth. The addition of one or a combination of FeNaEDTA, CaCl2•2H2O, and KCl can potentially increase algae biomass production. We designed an experiment that utilizes eight different media combinations of municipal struvite amended with a suite of micronutrient limiting factors (FeNaEDTA, CaCl2•2H2O, and KCl), to determine which individual or combinations of micronutrients maximize production of C.reinhardtii and N.oculata. Growth responses to our treatments are being measured over a 14-day incubation period. Treatment effects on algal production are being determined by absorbance (680nm), cell counts, and ash free dry weight analyses. Understanding which micronutrients maximize algal biomass production in struvite-based media can help optimize biomass production, while minimizing potentially costly inputs to algal cultivation systems. The increase in algal biomass production can serve to form clean renewable biofuels.

Citations

[1] Barghbani, R, et al. “Investigating the Effects of Several Parameters on the Growth of Chlorella Vulgaris Using Taguchi's Experimental Approach.” International Journal of Biotechnology for Wellness Industries, vol. 1, no. 2, 18 June 2012, pp. 128–133., doi:10.6000/28.

[2] Xiao Dou, Xiang-Hong Lu, Mei-Zhen Lu, Li-Sheng Yu, Rong Xue, Jian-Bing Ji, "The Effects of Trace Elements on the Lipid Productivity and Fatty Acid Composition of Nannochloropis oculata", Journal of Renewable Energy, vol. 2013, Article ID 671545,6 pages, 2013.

[3] Pittman, Jon K., et al. “A Cation-Regulated and Proton Gradient-Dependent Cation Transporter from Chlamydomonas Reinhardtii Has a Role in Calcium and Sodium Homeostasis.” Journal of Biological Chemistry, vol. 284, no. 1, 2009, pp. 525–533., doi:10.1074/jbc.m807173200.

[4] Xu, F., Pan, J. Potassium channel KCN11 is required for maintaining cellular osmolarity during nitrogen starvation to control proper cell physiology and TAG accumulation in Chlamydomonas reinhardtii. Biotechnol Biofuels 13, 129 (2020). https://doi.org/10.1186/s13068-020-01769-x

[5] Mtaki, K., Kyewalyanga, M.S. & Mtolera, M.S.P. Supplementing wastewater with NPK fertilizer as a cheap source of nutrients in cultivating live food (Chlorella vulgaris). Ann Microbiol 71, 7 (2021). https://doi.org/10.1186/s13213-020-01618-0

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Determining Limiting Growth Factors in Struvite Based Media for C.reinhardtii and N.oculata

Large scale algae cultivation can be used for biofuels or biproducts, but is often limited due to low cost nutrient availability that does not compete with agricultural production. One method to resolve this limitation is coupling algae biomass production with nutrient recovery from wastewater treatment. Struvite [NH4MgPO4•6H2O] is a phosphate mineral crystal that can be produced as part of the nutrient capture process associated with wastewater treatment. Struvite can also be a potential source of vital renewable nutrients (N, Mg, P, etc.) for high-value algal biomass production. However, preliminary data suggests that algae strains C.reinhardtii and N.oculata, two strains known to produce high value lipids, experience a significant decrease in algal biomass production; in a struvite based growth medium without micronutrient supplementation. Our project will determine which specific micronutrients, or combinations of nutrients, are limiting C.reinhardtii and N.oculata production in struvite-based media. Prior work indicates that chelated iron, EDTA [1,2], calcium [3] and potassium [4,5], or a combination of these elements can be crucial micronutrients for algal growth. The addition of one or a combination of FeNaEDTA, CaCl2•2H2O, and KCl can potentially increase algae biomass production. We designed an experiment that utilizes eight different media combinations of municipal struvite amended with a suite of micronutrient limiting factors (FeNaEDTA, CaCl2•2H2O, and KCl), to determine which individual or combinations of micronutrients maximize production of C.reinhardtii and N.oculata. Growth responses to our treatments are being measured over a 14-day incubation period. Treatment effects on algal production are being determined by absorbance (680nm), cell counts, and ash free dry weight analyses. Understanding which micronutrients maximize algal biomass production in struvite-based media can help optimize biomass production, while minimizing potentially costly inputs to algal cultivation systems. The increase in algal biomass production can serve to form clean renewable biofuels.

Citations

[1] Barghbani, R, et al. “Investigating the Effects of Several Parameters on the Growth of Chlorella Vulgaris Using Taguchi's Experimental Approach.” International Journal of Biotechnology for Wellness Industries, vol. 1, no. 2, 18 June 2012, pp. 128–133., doi:10.6000/28.

[2] Xiao Dou, Xiang-Hong Lu, Mei-Zhen Lu, Li-Sheng Yu, Rong Xue, Jian-Bing Ji, "The Effects of Trace Elements on the Lipid Productivity and Fatty Acid Composition of Nannochloropis oculata", Journal of Renewable Energy, vol. 2013, Article ID 671545,6 pages, 2013.

[3] Pittman, Jon K., et al. “A Cation-Regulated and Proton Gradient-Dependent Cation Transporter from Chlamydomonas Reinhardtii Has a Role in Calcium and Sodium Homeostasis.” Journal of Biological Chemistry, vol. 284, no. 1, 2009, pp. 525–533., doi:10.1074/jbc.m807173200.

[4] Xu, F., Pan, J. Potassium channel KCN11 is required for maintaining cellular osmolarity during nitrogen starvation to control proper cell physiology and TAG accumulation in Chlamydomonas reinhardtii. Biotechnol Biofuels 13, 129 (2020). https://doi.org/10.1186/s13068-020-01769-x

[5] Mtaki, K., Kyewalyanga, M.S. & Mtolera, M.S.P. Supplementing wastewater with NPK fertilizer as a cheap source of nutrients in cultivating live food (Chlorella vulgaris). Ann Microbiol 71, 7 (2021). https://doi.org/10.1186/s13213-020-01618-0