미세조류 Chlamydomonas reinhardtii dZL 균주의 100 L 평판형광생물 반응기를 이용한 대량 배양에서의 접종 농도에 따른 바이오매스 생산 성 향상 연구

Abstract

Beside the commercialized pigments from microalgae, such as astaxanthin, beta-carotene, and c-phycocyanin, zeaxanthin is another pigment with great potential for commercialization as it can be used to prevent or cure age-related macular degeneration. However, low zeaxanthin productivity due to its low content in microalgal biomass has been the major obstacle to commercialization. With recent advances in genome editing technology, a green microalga Chlamydomonas reinhardtii dZL was engineered to accumulate zeaxanthin with growth by knocking out enzymes that convert zeaxanthin into other carotenoids. In the present study, C. reinhardtii dZL was cultivated using TAP medium in 100 L flat-panel photobioreactors (PBRs), and the effect of initial cell density (ICD) on biomass productivity in batch operation was investigated. ICD of 0.1 g/L was predicted to yield highest biomass productivity from experiments using 2 L bubble column PBRs. In 100 L flat-panel PBRs, as ICD increased from 0.005 g/L to 0.08 g/L, biomass productivity was increased from 0.03 g/L/ day to 0.16 g/L/day. However, further increasing ICD from 0.08 g/L to 0.16 g/L reduced to 0.14 g/L/day as the maximum biomass concentration was limited by the light intensity. The results showed that ICD could affect biomass productivity in positive and negative ways, and thus ICD should carefully be determined with regards to the culture conditions. Such strategy could be applied to improve productivity for other compounds of interests in other microalgae as well.