The relationship between cell dry weight concentration and culture turbidity for a recombinant e. Coli k12 strain producing high levels of human alpha interferon analogue.

A recombinant E. Coli K12 strain carrying a runaway-type plasmid with the gene for human alpha interferon analogue and capable of producing high levels of recombinant product [1], was grown in rich medium and compared to the host strain without plasmid, and to the strain with the plasmid, but lacking the interferon gene insert. At a non-inducing temperature, gross cell morphology and the correlation between dry weight and culture turbidity was comparable for the three cultures. Following induction by temperature elevation, both plasmid-bearing strains displayed significant cell size change, but only the interferon producing strain underwent a decrease in the ratio of cell concentration measured by dry weight to culture turbidity.