Isolation and characterization of Chlorella sp. mutants with enhanced thermo- and CO2 tolerances for CO2 sequestration and utilization of flue gases

Abstract

Background The 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. Results In 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. Conclusions The 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.

Genetic engineering of microalgae for enhanced lipid production

“…Different physical and chemical mutagens have been used to induce mutations in the genome at a higher rate than naturally occurring in a particular organism. UV light, gamma radiation and X-rays as well as chemical mutagens such as N′nitro-N-nitrosoguanidine (NTG) and ethyl methanesulfonate (EMS) have been successfully applied on microalgae (Chou et al, 2019;B. Lee et al, 2014).…”

Combinatorial use of environmental stresses and genetic engineering to increase ethanol titres in cyanobacteria

“…An alternative strategy to improve cyanobacterial tolerance to high carbon loading is to screen variants generated by random mutagenesis for desirable traits, similar to the study with Chlorella vulgaris ESP-31 [ 109 ]. In this case, two carbon dioxide- and thermo-tolerant C. vulgaris variants were obtained from methyl‑ N '‑nitro‑ N ‑nitrosoguanidine random mutagenesis.…”

Use of <em>Dunaliella salina</em> in Environmental Applications <sup>†</sup>

“…as a source of biofuel. Because of these advantages, they are also used as raw material in the energy sector [49,50]. Biofuel production from microalgae consists of four steps: isolation, characterization, biomass production, and harvesting.…”