Rational medium design for Bordetella pertussis: basic metabolism

Area of Science:

• Microbiology
• Biotechnology
• Metabolic Engineering

Background:

• Ammonium accumulation limits Bordetella pertussis cell density in fed-batch cultures due to substrate imbalances.
• B. pertussis exhibits partially dysfunctional glycolysis and citric-acid cycle, impacting its metabolism.

Purpose of the Study:

• To map Bordetella pertussis catabolic and anabolic capabilities.
• To design a culture medium that prevents ammonium accumulation and ensures complete substrate metabolism.
• To enhance biomass yield in B. pertussis cultures.

Main Methods:

• Utilized nuclear magnetic resonance (NMR) and electron microscopy to analyze B. pertussis metabolism.
• Investigated various carbon sources, including glutamate, lactate, and combinations thereof.
• Assessed metabolite excretion and poly-hydroxy-butyrate (PHB) globule formation.

Main Results:

• Adding various carbon sources to glutamate-containing media avoided ammonium accumulation but led to acetate and beta-hydroxy-butyrate excretion.
• Poly-hydroxy-butyrate (PHB) globules were observed, coinciding with beta-hydroxy-butyrate and acetoacetate formation.
• Using lactate with glutamate as substrates prevented metabolite excretion and ammonium accumulation, achieving a high biomass yield (8.8 g C-mol⁻¹).

Conclusions:

• A novel medium using lactate and glutamate effectively supports B. pertussis growth without ammonium accumulation or metabolite excretion.
• This optimized medium significantly improves biomass yield compared to existing literature values.
• Further optimization for pertussis toxin production is detailed in a separate study.