Humans have exploited microbes for centuries to produce cheese,
beer and bread. Bacteria are not only part of the biosphere, but they
are also part of the flora in our guts and fundamental for life as we
know it. The huge potential of microbes is already harnessed today
by using their microbial cells as production facilities to produce fuels,
chemicals, enzyme for detergents and pharmaceutical proteins such
as insulin.
This study explores the potential of two bacteria commonly used in
food fermentations, namely Lactococcus lactis and Bacillus subtilis, to
produce proteins for the biotech industry. A simple and inexpensive
approach to create a growth based selection system that increases
protein production is presented. The system can pick high protein
producers out of a collection of protein producing variants, by using
a coupling device that ties expression of the gene of interest to an antibiotic
resistance gene. The coupling mechanism is further elucidated
in a patent application, which reports the development of multiple
strength levels for the coupling device and demonstrate its viability
in Gram-negative bacteria (Escherichia coli and Pseudomonas putida).
Together, the results reported in this PhD project expand the
knowledge on Gram-positive cell factories and introduce a new tool
that will likely benefit the optimization of future ones. Coming studies
will build on the established platform and provide further insight
in protein production