Abstract
BackgroundThe increasing emission of flue gas from industrial plants contributes to environmental pollution, global warming, and climate change. Microalgae have been considered excellent biological materials for flue gas removal, particularly CO2 mitigation. However, tolerance to high temperatures is also critical for outdoor microalgal mass cultivation. Therefore, flue gas- and thermo-tolerant mutants of Chlorella vulgaris ESP-31 were generated and characterized for their ability to grow under various conditions.ResultsIn this study, we obtained two CO2- and thermo-tolerant mutants of Chlorella vulgaris ESP-31, namely, 283 and 359, with enhanced CO2 tolerance and thermo-tolerance by using N-methyl-N-nitro-N-nitrosoguanidine (NTG) mutagenesis followed by screening at high temperature and under high CO2 conditions with the w-zipper pouch selection method. The two mutants exhibited higher photosynthetic activity and biomass productivity than that of the ESP-31 wild type. More importantly, the mutants were able to grow at high temperature (40 °C) and a high concentration of simulated flue gas (25% CO2, 80–90 ppm SO2, 90–100 ppm NO) and showed higher carbohydrate and lipid contents than did the ESP-31 wild type.ConclusionsThe two thermo- and flue gas-tolerant mutants of Chlorella vulgaris ESP-31 were useful for CO2 mitigation from flue gas under heated conditions and for the production of carbohydrates and biodiesel directly using CO2 from flue gas.
Highlights
The increasing emission of flue gas from industrial plants contributes to environmental pollution, global warming, and climate change
Typical flue gas emitted from combustion sources contains 10–15% CO2, and coupling microalgae cultivation with C O2 generated by industrial plants has the potential to reduce the cost of flue gas pretreatment of industrial plants and industrial-scale microalgae production [10, 11]
Isolation of Chlorella vulgaris ESP‐31 mutants under the conditions of high temperature and high C O2 concentration Over 500 potential mutants of C. vulgaris ESP-31 were obtained after NTG mutagenesis, all of which were screened for the tolerance of high temperature (40 °C) and high CO2 concentration (15% C O2/air) using the w-zipper pouch selection method
Summary
The increasing emission of flue gas from industrial plants contributes to environmental pollution, global warming, and climate change. Flue gases emitted from industrial plants containing high concentrations of CO2, NOX and SOX are mostly responsible for global CO2 emissions [2, 3]. Chou et al Biotechnol Biofuels (2019) 12:251 of CO2, NOX, SOX, and other impurities of industrial flue gases inhibits the growth of most microalgae [12, 13]. The generation and selection of fast-growing microalgal strains or mutants with high C O2 fixation efficiency and the ability to tolerate high concentrations of CO2, NOX, and SOX in flue gases will improve the efficiency and cost-effectiveness of microalgal flue gas CO2 mitigation processes [12, 14, 15]. The optimal growth temperature for most algae is approximately 20–30 °C [12, 16], and the high temperatures during outdoor cultivation suppress the growth of most microalgae
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