Microbial Preservation Efficacy of Dacron Swabs: A Study on Freeze-Drying vs. Conventional Drying for Bacterial Viability

Document Type : Short Communication

Authors

Microorganisms Bank, Iranian Biological Resource Centre (IBRC), ACECR, Tehran, Iran

Abstract

In general, microbiological and biotechnological research depend significantly on microbial preservation. Researchers and medical professionals have used swabs to transfer and preserve clinical specimens for many years. Studies have demonstrated that the synthetic fiber Dacron has a high sample release rate, which is essential for the effectiveness of bacteriological and molecular tests, including the collection of bacterial samples. This study evaluated the recovery of five commonly referenced bacteria: Lacticaseibacillus casei IBRC-M 10711, Bacillus subtilis subsp. subtilis IBRC-M 10997, Salmonella enterica subsp. enterica IBRC-M 10707, Staphylococcus aureus subsp. aureus IBRC-M 10917, and Streptococcus mutans IBRC-M 10682 after preservation on Dacron swabs using standard microbiological assays. The ability of Dacron swabs to retain viable bacteria following two drying methods, freeze-drying and conventional drying methods, and the bacteria recovery was monitored for one year. The results showed that all five bacteria maintained their viability for three months by freeze-drying and conventional drying methods, with no discernible differences between them according to comparing viability percentage. Among tested bacteria, only B. subtilis and L. casei were effectively recovered from the Dacron swabs maintained at 4 °C after one year. B. subtilis was recovered after one year when preserved by both drying methods. In contrast, L. casei sustained viability only with the freeze-drying process. So, for medium-term bacterial preservation (up to three months), conventional drying methods are a cost-effective and straightforward approach for preserving bacteria on Dacron swabs; however, for long-term preservation, one-year results indicate that the type of strain may have a major impact on how effectively bacteria can be preserved using this method.  Therefore, more strains must be assessed before an ultimate decision on the method's suitability for long-term preservation can be made.

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References

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Microbiology, Metabolites and Biotechnology
Volume 7, Issue 2
December 2024
Pages 109-115

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