In the biotechnology sector, a main processing
goal is the production of high cell (and hence product)
yields. Therefore, little consideration is traditionally given
to the potential environmental impacts of excess culture
media ingredients. This study investigated the scope for
reducing the quantities of phosphorus (P) present in both a
complex terrific broth (TB) and semi-defined minimal
media 9/yeast extract (M9/YE) fermentation media used to
culture a model
Escherichia coli
strain engineered to produce
a recombinant β-galactosidase. Reductions of up to
70 % did not adversely affect biomass yields attained;
however, further P minimization leads to a drop in dry cell
weight obtained, particularly in the case of semi-defined
media. P concentration in TB media had little effect upon
total recombinant protein expression levels achieved. In the
case of M9/YE media, reductions >70 % P negatively
affected product expression levels. Protein functionality,
assessed by
km and
Vmax, was not influenced by the type of
media nor the P concentration present. Overall, the results
indicate that P can be reduced by a minimum of 70 %
without adversely affecting the biomass yield, the recombinant
protein yield or functionality. Such reductions
should lead to significant P savings in the large-scale
manufacturing of proteins produced by genetic engineering
in
E. coli.
