Related Experiment Video
Updated: Aug 30, 2026
Enrichment of Native and Recombinant Extracellular Vesicles of Mycobacteria
Published on: December 8, 2023
Influence of storage on monodispersed cells of Mycobacterium terrae used for quantitative carrier test prEN 14563
Eva Woelk1, Peter Goroncy-Bermes, Wolfgang Sand
1Institute of Botany, Department of Microbiology, University of Hamburg, D-22602 Hamburg, Germany.
Abstract:
The degree of cell clumping increased with time of storage (1% cell clumps immediately after homogenization and 3 and 6.5% after 48 and 96 h of storage, respectively), and the number of living single cells decreased. Quantitative carrier tests were carried out with these cells using ortho-phthaldialdehyde (OPA) and coco fatty aminoxethylate as biocides. In contrast to OPA, with coco fatty aminoxethylate the reductions obtained with freshly homogenized mycobacteria were significantly higher (P = 0.02) than those obtained with mycobacteria kept in the refrigerator for 4 days. Therefore, it is advisable to prepare the test suspension freshly for each test.
Insights
Freshly prepared mycobacteria suspensions are crucial for accurate biocide testing. Storing cells increases clumping and reduces viability, impacting test results, especially with coco fatty aminoxethylate.
Area of Science:
- Microbiology
- Biocide Efficacy Testing
Background:
- Cell clumping and decreased viability occur during mycobacteria storage.
- Storage duration impacts the effectiveness of biocides in quantitative carrier tests.
Purpose of the Study:
- To evaluate the effect of storage time on mycobacteria cell viability and clumping.
- To compare the efficacy of ortho-phthaldialdehyde (OPA) and coco fatty aminoxethylate as biocides using stored vs. fresh mycobacteria.
Main Methods:
- Mycobacteria cell suspensions were stored for up to 96 hours.
- Quantitative carrier tests were performed using OPA and coco fatty aminoxethylate.
- Cell clumping and the number of living single cells were assessed over time.
Main Results:
- Cell clumping increased from 1% to 6.5% after 96 hours of storage.
- Viable single cell counts decreased with prolonged storage.
- Coco fatty aminoxethylate showed significantly higher reductions with fresh cells (P=0.02) compared to stored cells.
Conclusions:
- Preparing fresh mycobacteria suspensions for each test is recommended.
- Storage negatively affects mycobacteria cell integrity, impacting biocide efficacy.
- Biocide efficacy, particularly for coco fatty aminoxethylate, is dependent on the freshness of the mycobacteria test suspension.
