(501b) Microfluidics Enabled Parallel Co-Cultivation of Compartmentalized Human Microbiota: Towards Elucidation of Microbial Interactions

In nature, diverse microbial communities exist with specific cell population profiles, which affect and adapt to various environments. Among them, the human body is a representative host for microbial communities, such as oral, skin, vaginal and gut microbiota. The genes from these microbial populations greatly outnumber human genes, contribute to human metabolism, and increases genetic complexity in human. Despite their relevance, the human microbiota remain largely unknown, due to their complexity and uncultivability. Most of the previous work were based on genetic identification, while microbial intercellular networks have been hardly investigated so far.

In order to elucidate microbial interactions in human microbiota, we are constructing microfluidic devices capable of compartmentalizing subsets of the total human microbiota and cultivating them. Since the gut microbiota habours the largest population among the human microbiota, we used the fecal sample collected from gnotobiotic mice colonized with human gut microbiota. The sample was diluted and then compartmentalized in multiple droplets, which were serially generated in Parylene-coated glass devices adapting slanted T-junction geometry. Localization of each subset, in microdroplets (< 10nl) dispersed in immiscible oil, separates essential intercellular links for growth from the whole complicated network. Depending on the initial cell concentration in the droplets, different numbers of cell clusters comprising multiple species were developed in each droplet. Droplets carrying fully-grown microbial communities were retrieved from the device using microfluidic control, after their growths were monitored under the microscope. Off-chip PCR of 16S rRNA genes with universal bacterial primers from the retrieved culture shows the species profiles in subsets of the microbiota. Based on these result, we can start to elucidate the intercellular relationship in the community. This parallelized microfluidic compartmentalization and on-chip cultivation platform can also be extended for the investigation of microbial communities in other environments such as the human oral microbiota.