Screening of microalgal isolates of the Persian Gulf and evaluation of their potential as the promising bioethanol feedstock

Abstract

ABSTRACT The high levels of carbohydrates in some microalgae make them a promising feedstock for bioethanol production. The pretreatment of microalgal biomass is one of the most important stages to improve cell disruption for increasing the accessibility to the intracellular compounds. The isolation and identification of newly isolated microalgae that produce high biomass and carbohydrate production were done in this research. Among six isolates, Chlorella S-4 and Picochlorum D-8 showed the highest specific growth rates of 0.189 and 0.215 (µ day−1), respectively, from which the former showed a suitable self-precipitation property. A combination of cell disruption methods, including acid-thermal, acid-thermal/sonication bath, and acid-thermal/freeze & thaw pretreatment was applied to disrupt the cell wall of isolated microalgae on a laboratory scale. The effectiveness of cell disruption methods was evaluated based on total carbohydrate measurement. The maximum carbohydrate content of 22% and 27% of dry weight with the productivity of 7 and 6 mg/L/d was obtained from Chlorella S-4 and Picochlorum D-8, respectively, using acid-high thermal pretreatment (121°C for 20 min). This study is trying to demonstrate the Persian Gulf native microalgae potential for possible bioethanol production.