Team:Nevada/Project/Co-Cult

Introduction

Co-culturing multiple bacterial strains is inherently complicated. The two species must co-exist while at the same time competing for resources. Over time the growth rate of two co-cultured species will establish equilibrium. However, conditions will not be optimal for either individual species. In our case, we want to grow the E. coli in a culture that is being provided with glucose from the cyanobacterium, Synechocystis PCC6803. It is clear that E. coli growth will be limited by the productivity of the cyanobacterium. Therefore, we need to develop a system that will optimize Synechocystis growth. One of the major considerations in cyanobacteria growth is the availability of sufficient light to optimize rates of photosynthesis. This is particularly important in our system since we are also depending on photosynthesis for the production of glucose to feed E. coli. While it is possible to grow E. coli and cyanobacteria in the same culture vessel (Niederholtmeyer et al., 2010) Applied and Environmental Microbiology 76: 3462-3466), the photosynthetic efficiency of the system will be limited by light blockage caused by E. coli. For this reason, we have developed an apparatus that physically partitions the two bacterial species from each other, while still allowing for the free exchange of growth medium. In this way, we can ensure high photosynthetic rates for Synechocystis and total accessibility by E. coli to the cyanobacterial produced glucose.