Yeast Bioreactor: Network biology of stress responses and cell flocculation of Saccharomyces cerevisiae grown in a continuous bioreactor in microgravity conditions (Yeast Bioreactor)

The global project objective is the development of a dynamic proteomics platform and its use on-orbit for three specific microgravity research topics based on eukaryotic cell types: the yeasts Saccharomyces cerevisiae and Candida albicans, and human osteoblast cells. The platform is based on a microfluidic cellular microarray system. The miniturisation by using microfluidics is necessary to perform on-orbit systems biology. With this technology large data sets can be obtained to study complex networks. Additionally, various experiments can be combined during one mission since the cellular microarray for one cell type takes a very small volume, the uploaded mass/volume is limited, experiments can be fully automated, and for most experiments download is not needed. This platform is based on a spotted living cell clone collection in a microfluidic cell culture system, where in each cell clone a specific gene is linked with the gene sequence of a fluorescent protein (FP). In this project, we will focus on cell clone collections of the yeasts S. cerevisiae and the human fungal pathogen C. albicans, and an osteoblast cell line. Several genes will be selected and tagged with the FP gene. The selection of the genes will be based on results from simulated microgravity experiments, previous microgravity experiments and literature data. An array of the clone collection will be spotted in a microfluidic device where the living cells are entrapped in microwells and can grow for several generations with on-line monitoring of the cell morphology and gene expression. The design of the microfluidic cell culture system will be specific for each cell type (number and dimensions of microwells). Cell growth will be activated on-orbit by flowing growth medium through the microfluidic flow channel. The cells growing in the microwells will be monitored using fluorescence microscopy (or via a CMOS imaging chip directly). Using time-lapse imaging, fluorescence intensities of the cells in the wells will be recorded at suitable time intervals. These data will be processed and used as input for bio-informatic systems biology analyses. The comparison of the on-orbit analysis to the ground experiment analysis will deduce the differentially expressed genes and involved pathway(s).