4. Conclusion

In this study, we investigated adaptation at the single-cell level and showed that an isogenic, recombinant S. cerevisiae strain differentiated into three subpopulations: (1) cells that drastically reduced insulin production (23 %), (2) cells with reduced enzymatic capacity of the central carbon metabolism (46 %), (3) cells that exhibited pseudohyphal growth (31 %). This indicates that the bulk adaptive outcome is a mixed response composed of at least three apparent subpopulations emerged as a response to the selective pressure of the chemostat and the burden of the heterologous insulin production.