Augmented CO2 tolerance by expressing a single H+-pump enables microalgal valorization of industrial flue gas
Hong Il Choi, Sung‐Won Hwang, Jongrae Kim, Byeonghyeok Park, EonSeon Jin, In‐Geol Choi, Sang Jun Sim
Abstract
Abstract Microalgae can accumulate various carbon-neutral products, but their real-world applications are hindered by their CO 2 susceptibility. Herein, the transcriptomic changes in a model microalga, Chlamydomonas reinhardtii , in a high-CO 2 milieu (20%) are evaluated. The primary toxicity mechanism consists of aberrantly low expression of plasma membrane H + -ATPases (PMAs) accompanied by intracellular acidification. Our results demonstrate that the expression of a universally expressible PMA in wild-type strains makes them capable of not only thriving in acidity levels that they usually cannot survive but also exhibiting 3.2-fold increased photoautotrophic production against high CO 2 via maintenance of a higher cytoplasmic pH. A proof-of-concept experiment involving cultivation with toxic flue gas (13 vol% CO 2 , 20 ppm NO X , and 32 ppm SO X ) shows that the production of CO 2 -based bioproducts by the strain is doubled compared with that by the wild-type, implying that this strategy potentially enables the microalgal valorization of CO 2 in industrial exhaust.