title: In situ analysis of heterogeneity in the lipid content of single green microalgae in alginate hydrogel microcapsules.
abstract: Microalgae, a group of microorganisms that grow using sunlight as the sole energy source and carbon dioxide as an only carbon source, have been considered as a feedstock of choice for the production of biofuels such as biodiesel. To explore the economic feasibility of such application, however, many technical hurdles must first be overcome; the selection and/or screening of competent species are some of the most important and yet challenging tasks. To greatly accelerate this rather slow and laborious step, we developed a droplet-based microfluidic system that uses alginate hydrogel microcapsules with a mean diameter of 26 μm, each of which is able to encapsulate a single microalgal cell. This novel device was successfully demonstrated using three microalgae species, namely, Chlorella vulgaris , Chlamydomonas sp., and Botryococcus braunii . In situ analysis of the lipid content of individual microalgal cells by nondestructive fluorescence staining using BODIPY (4,4-difluoro-1,3,5,7,-tetramethyl-4-bora-3a,4a-diaza-s-indacene) was possible. In all cases, we confirmed that the lipid content of microalgal species in alginate hydrogel microcapsules was comparable to that of free-living cells. Stochastic heterogeneity in the lipid content was verified under a highly viable physiological condition, implying that other analyses were possible after the determination of lipid content. Furthermore, the designed microwell arrays enabled us to distinguish the BODIPY fluorescence response of a single live alga within the microcapsules.
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology , 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea.
authors.forename: Do-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Chae Yun
authors.initials: CY
authors.lastname: Bae
authors.forename: Jong-In
authors.initials: JI
authors.lastname: Han
authors.forename: Je-Kyun
authors.initials: JK
authors.lastname: Park