Process development in Hansenula polymorpha and Arxula adeninivorans, a re-assessment

Area of Science:

• Biotechnology and Industrial Microbiology
• Yeast Genetics and Physiology
• Metabolic Engineering

Background:

• Established industrial processes for pharmaceutical production often utilize Hansenula polymorpha (H. polymorpha).
• These processes commonly employ promoters from MOX and FMD genes involved in methanol metabolism.
• Unlike other methylotrophs, H. polymorpha promoters are de-repressed by carbon source depletion (e.g., glucose, glycerol) rather than methanol induction.

Purpose of the Study:

• To define screening and fermentation strategies for H. polymorpha strains with specific expression control elements.
• To develop and adapt fermentation conditions for H. polymorpha and Arxula adeninivorans.
• To identify suitable promoter elements for heterologous gene expression in these yeasts.

Main Methods:

• Development of a synthetic minimal medium (SYN6) for H. polymorpha fermentation.
• Adaptation of SYN6 for initial fermentation condition definition in Arxula adeninivorans.
• Consideration of yeast characteristics such as osmo- and thermotolerance for culture condition optimization.

Main Results:

• Defined screening and fermentation modes for H. polymorpha based on its unique promoter de-repression characteristics.
• Established SYN6 as a suitable medium for H. polymorpha fermentation.
• Provided a basis for defining fermentation conditions for Arxula adeninivorans, addressing its specific needs.

Conclusions:

• H. polymorpha offers established industrial potential for pharmaceutical production using specific fermentation strategies.
• SYN6 medium and defined conditions support efficient fermentation for H. polymorpha.
• Further development is needed for Arxula adeninivorans, but SYN6 and consideration of its physiological traits provide a starting point for optimizing heterologous gene expression.