title: Engineering strategies for improving the CO2 fixation and carbohydrate productivity of Scenedesmus obliquus CNW-N used for bioethanol fermentation.
abstract: Engineering strategies were applied to improve the cell growth, CO2 fixation ability, and carbohydrate productivity of a Scenedesmus obliquus CNW-N isolate. The resulting carbohydrate-rich microalgal biomass was subsequently utilized as feedstock for ethanol fermentation. The microalga was cultivated with 2.5% CO2 in a photobioreactor on different operation modes. Semi-batch operations with 50% replacement of culture medium resulted in the highest CO2 fixation rate (1546.7 mg L(-1) d(-1)), carbohydrate productivity (467.6 mg L(-1) d(-1)), and bioethanol yield (0.202 g/g biomass). This performance is better than most reported values in the literature. The microalgal biomass can accumulate nearly 50% carbohydrates, as glucose accounted for nearly 80% of the total carbohydrate content. This glucose-predominant carbohydrate composition of the microalga is well suited for fermentative bioethanol production. Therefore, using the proposed carbohydrate-rich microalgal biomass both as the carbon sink and as the feedstock provides a feasible alternative to current carbon-reduction and bioethanol-production strategies.
authors.affiliation: Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Shih-Hsin
authors.initials: SH
authors.lastname: Ho
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Hasunuma
authors.forename: Jo-Shu
authors.initials: JS
authors.lastname: Chang
mesh_terms: D018533:Biomass; D019149:Bioreactors; D002241:Carbohydrates / Q000737:chemistry*; D002245:Carbon Dioxide / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D009584:Nitrogen / Q000378:metabolism; D055668:Photochemical Processes; D044444:Scenedesmus / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D002245:Carbon Dioxide; D000431:Ethanol; D009584:Nitrogen
keywords: Bioethanol; CO(2) fixation; Carbohydrates; Microalgae; Scenedesmus obliquus