Flow cytometry: a tool for understanding the behaviour of polyhydroxyalkanoate accumulators

Area of Science:

• Microbiology
• Biotechnology
• Bioprocess Engineering

Background:

• Mixed microbial cultures (MMCs) offer a promising avenue for polyhydroxyalkanoate (PHA) production.
• Optimizing MMC-PHA production necessitates understanding the physiological status of PHA-accumulating microorganisms.
• Current methods may not fully capture the dynamic metabolic state influencing PHA storage within MMCs.

Purpose of the Study:

• To investigate the utility of flow cytometry for analyzing the metabolic state and polyhydroxybutyrate (PHB) content in MMCs.
• To correlate microbial physiological status with PHB accumulation levels.
• To establish flow cytometry as a tool for optimizing MMC-PHA production.

Main Methods:

• Enrichment of an MMC with PHB-storing microorganisms using a sequencing batch reactor under feast and famine conditions.
• Application of flow cytometry to monitor microbial metabolic activity and intracellular PHB content over time.
• Analysis of the relationship between metabolic activity, PHB content, and microbial consortium composition.

Main Results:

• Flow cytometry effectively measures both PHB content and metabolic activity in microorganisms within an MMC.
• A strong positive correlation was observed between high PHB content and high metabolic activity.
• Conversely, microorganisms exhibiting low metabolic activity demonstrated low PHB content.

Conclusions:

• Flow cytometry is a valuable tool for understanding the physiological drivers of PHA storage in MMCs.
• Microbial metabolic state is a critical determinant of PHA accumulation, alongside consortium composition.
• The findings support the use of flow cytometry for real-time monitoring and optimization of PHA bioproduction processes.