A high-throughput method for quantifying metabolically active yeast cells.

Area of Science:

• Microbiology
• Cell Biology
• Biotechnology

Background:

• Traditional methods for quantifying microbial populations, such as CFU counts, are time-consuming.
• Optical density (OD) measurements do not distinguish between live and dead cells, limiting their physiological relevance.
• There is a need for efficient, high-throughput methods to assess eukaryotic cell viability and metabolic activity.

Purpose of the Study:

• To adapt and validate the methylene blue reduction test (MBRT) for quantitative physiology of eukaryotic cells.
• To establish MBRT as a cost-effective and efficient method for high-throughput applications.
• To demonstrate MBRT's superiority over traditional methods for growth rate estimation and metabolic activity assessment.

Main Methods:

• Redesigned the methylene blue reduction test for bacteria and yeast.
• Validated the MBRT in fermenters and high-throughput systems.
• Compared MBRT-derived reduction curves with CFU counts and OD measurements.

Main Results:

• MBRT demonstrated equivalent performance to traditional methods in fermenters and high-throughput systems.
• Reduction curves from MBRT directly correlated with CFU counts.
• MBRT proved superior for growth rate estimation by quantifying only metabolically active cells.
• MBRT revealed a more pronounced drop in metabolic activity during the diauxic shift in yeast compared to OD curves.

Conclusions:

• The redesigned MBRT offers a cheap, efficient, and high-throughput methodology for quantitative physiology of eukaryotic cells.
• MBRT accurately quantifies metabolically active cells, providing superior insights into growth dynamics and metabolic shifts.
• This method has broad applications, including characterizing cell death phases and drug screening with pathogenic yeasts.