Enhancing lipid productivity and saline tolerance of Micractinium sp. extremophiles using ultraviolet mutagenesis and adaptive laboratory evolution strategies
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Mentor Information
Dr. George Philippidis
Description
Microalgae represent a potential strategy to mitigate greenhouse gas emissions and perform wastewater treatment while concurrently generating value- added products like sustainable aviation fuel and nutraceuticals. However, large-scale cultivation is constrained by high freshwater consumption and low lipid yield. Two freshwater Micractinium sp. extremophiles (pH = 3.5 and pH = 10.0) were subjected to random mutagenesis and adaptive laboratory evolution (ALE) to elicit genetic modifications that lead to enhanced strains of high salinity tolerance and high lipid content. Both freshwater strains first underwent a progressive adaptation process to synthetic BBM media containing 1.5% NaCl, 2.5% NaCl, and eventually 70% seawater, while maintaining their respective extreme pH. The strains were successfully adapted with a lipid productivity (180.5 mg/L) that surpassed that of the wild types (166.0 mg/L), whereas the absence of increased carotenoid content indicated that they were able to grow in almost seawater conditions without experiencing stress. Subsequently, ultraviolet mutagenesis was used to generate mutants with boosted lipid productivity. Nile-red staining was utilized as initial screening to select promising mutants. Among 75 obtained mutants, two (M3 and M6) exhibited lipid contents of 23.8% and 21.4%, respectively, which were significantly higher than that of the wild type (18.3%). At the same time, mutants maintained the extremophilic traits and growth rate of the wild type. Finally, the promising mutants were cultivated in a 2-liter photobioreactor to assess their biochemical composition, biomass and lipid productivity, pigment profile, and fatty acid methyl ester (FAME) profile, and demonstrate the feasibility of reducing freshwater consumption during algae cultivation.
Enhancing lipid productivity and saline tolerance of Micractinium sp. extremophiles using ultraviolet mutagenesis and adaptive laboratory evolution strategies
Microalgae represent a potential strategy to mitigate greenhouse gas emissions and perform wastewater treatment while concurrently generating value- added products like sustainable aviation fuel and nutraceuticals. However, large-scale cultivation is constrained by high freshwater consumption and low lipid yield. Two freshwater Micractinium sp. extremophiles (pH = 3.5 and pH = 10.0) were subjected to random mutagenesis and adaptive laboratory evolution (ALE) to elicit genetic modifications that lead to enhanced strains of high salinity tolerance and high lipid content. Both freshwater strains first underwent a progressive adaptation process to synthetic BBM media containing 1.5% NaCl, 2.5% NaCl, and eventually 70% seawater, while maintaining their respective extreme pH. The strains were successfully adapted with a lipid productivity (180.5 mg/L) that surpassed that of the wild types (166.0 mg/L), whereas the absence of increased carotenoid content indicated that they were able to grow in almost seawater conditions without experiencing stress. Subsequently, ultraviolet mutagenesis was used to generate mutants with boosted lipid productivity. Nile-red staining was utilized as initial screening to select promising mutants. Among 75 obtained mutants, two (M3 and M6) exhibited lipid contents of 23.8% and 21.4%, respectively, which were significantly higher than that of the wild type (18.3%). At the same time, mutants maintained the extremophilic traits and growth rate of the wild type. Finally, the promising mutants were cultivated in a 2-liter photobioreactor to assess their biochemical composition, biomass and lipid productivity, pigment profile, and fatty acid methyl ester (FAME) profile, and demonstrate the feasibility of reducing freshwater consumption during algae cultivation.
