[Microquantitative determination of glucose in solutions using microorganisms as the test system]

Area of Science:

• Biochemistry
• Microbiology
• Analytical Chemistry

Background:

• Accurate quantification of glucose is crucial in biological and medical research.
• Existing methods may face limitations in sensitivity or specificity in complex biological matrices.
• The phosphoenolpyruvate:sugar phosphotransferase system (PTS) in bacteria plays a key role in glucose uptake.

Purpose of the Study:

• To develop and validate a novel pH-metric assay for sensitive glucose determination.
• To assess the applicability of the assay in biological liquids.
• To identify limitations regarding interfering carbohydrates.

Main Methods:

• Utilizing a suspension of E. coli strain M-17 cells as a biological indicator.
• Monitoring the release of hydrogen ions (H+) via pH-metric registration as a measure of glucose consumption.
• Testing the assay's performance with varying glucose concentrations and potential interfering substances.

Main Results:

• The proposed method allows for the determination of small glucose quantities (approximately 1 microgram in 5-10 microliters).
• The assay is specific for glucose, unaffected by most other carbohydrates, excluding those transported via the E. coli PTS.
• The use of a commercial preparation (colibacterin) containing lyophilized E. coli is demonstrated as a viable test system.

Conclusions:

• A sensitive and specific pH-metric technique for glucose quantification in biological samples has been established.
• The method offers a cost-effective and accessible approach for glucose measurement.
• Further studies could explore optimization for diverse biological fluid matrices and expanded carbohydrate interference analysis.