Growth of Haemophilus influenzae type b in continuous culture: effect of dilution rate on outer-membrane protein and lipopolysaccharide expression.

Haemophilus influenzae type b (Hib) was grown in continuous culture under cystine-limitation between dilution rates (D) of 0.065-0.28 h-1. A similar outer-membrane protein profile, as adjudged by SDS-PAGE, was found at all dilution rates. However, a shift to a lipopolysaccharide structure with a greater electrophoretic mobility on SDS-PAGE with accompanying changes in monoclonal antibody reactivity was observed at D greater than or equal to 0.15 h-1. Growth rate per se can affect the expression of outer-membrane components of Hib.