초록
<P><B>Abstract</B></P> <P>The response of <I>Bordetella pertussis</I> to induced oxidative stress during fermentation was assessed. <I>B. pertussis</I> is the causal agent of whooping cough in humans and purified pertactin (PRN) is used as one of the components in the production of acellular pertussis vaccines. When grown in bioreactors, bacteria adapt to environmental conditions which may include high levels of reactive oxidative species (ROS) that stress cells and can have detrimental effects on growth and protein production. ROS that are commonly attributed to oxidative stress were tracked and related to PRN production. Oxidative stress was imposed using hydrogen peroxide addition in both flask and bioreactor studies. The results indicate a clear detrimental effect of oxidative stress on PRN productivity and cell growth, and also a significant correlation between oxidative stress and the level of extracellular NADPH. The results also showed long term adaptation of cells to stress whereby the growth rate increases after the cells were exposed to oxidative stress for a sufficiently long time. Furthermore, differences in this adaptation behavior between flask and bioreactor operations are identified and explained.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxidative stress has a negative impact in PRN production by <I>Bordetella pertussis</I>. </LI> <LI> Closed-loop oxygen control appears to exacerbate oxidative stress in bioreactors. </LI> <LI> NADPH and ROS levels increase after imposition of stress with H<SUB>2</SUB>O<SUB>2</SUB> in <I>B. pertussis</I>. </LI> <LI> NADPH and ROS decrease with cell adaption after imposition of stress with H<SUB>2</SUB>O<SUB>2</SUB>. </LI> <LI> Consumption of NADPH through enzymatic reactions could promote adaptation. </LI> </UL> </P>