Storage effects on bacterial concentration: determination of impinger and filter samples

Area of Science:

• Environmental microbiology
• Aerosol science
• Analytical chemistry

Background:

• Accurate quantification of airborne bacteria is crucial for public health and environmental monitoring.
• Understanding the impact of post-collection storage on bacterial viability is essential for reliable bioaerosol sampling.

Purpose of the Study:

• To evaluate the effects of storage time and temperature on the colony recovery of airborne bacterial samples.
• To compare the performance of different bioaerosol sampling methods under various storage conditions.

Main Methods:

• Laboratory test chamber experiments using Escherichia coli and Bacillus subtilis.
• Bioaerosol sampling via AGI-30 impingers, Nuclepore filtration, and gelatin filters.
• Analysis of colony-forming unit (CFU) concentrations to determine storage effects (Ct/C0 ratio).

Main Results:

• Impinger samples showed increased bacterial culturability at room temperature and inhibition upon refrigeration.
• Storage time had an insignificant effect on Bacillus subtilis spore recovery using filtration.
• Escherichia coli recovery from filters decreased with increased storage time.

Conclusions:

• Refrigeration and prompt processing of impingement samples are advised to prevent artificial increases in bacterial counts.
• Filtration methods are suitable for Bacillus subtilis spores with minimal storage impact.
• Optimal sampling method selection is critical for maintaining bioefficiency during storage, with filters effective for spores and impingers for cells.