Related Experiment Videos
Effect of various growth media upon survival during storage of freeze-dried Enterococcus faecalis and Enterococcus
1Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Porto, Portugal.
Aims:
The effects of three different growth media (MRS, M17 and Lee's) on survival during freeze-drying and subsequent storage of six strains of Enterococcus faecalis and two strains of E. durans were investigated.
Methods And Results:
Distinct Enterococcus spp. strains were grown on M17, MRS and Lee's broth, freeze-dried and stored at 20 degrees C in air under darkness. At regular intervals throughout storage, freeze-dried samples were rehydrated and then plated on M17 agar.
Conclusions:
A higher survival rate during storage of dried E. durans was obtained when growth occurred in MRS. The same effect was not observed, however, for the majority of E. faecalis strains, which clearly survived better in the dried state when this organism had been grown in M17 or Lee's medium.
Significance And Impact Of Study:
The survival of the dried Enterococcus spp. tested during storage was shown to be strain-specific and dependent on the growth medium.
Insights
Growth medium significantly impacts the survival of freeze-dried Enterococcus species during storage. Optimal media selection is crucial for preserving E. durans and E. faecalis strains.
Area of Science:
- Microbiology
- Food Science
- Biotechnology
Background:
- Enterococcus species are important in food fermentation and can be used as probiotics.
- Freeze-drying is a common method for preserving microorganisms, but survival rates can vary.
- The choice of growth medium can influence microbial resistance to stress factors like freeze-drying.
Purpose of the Study:
- To investigate the effect of three different growth media (MRS, M17, and Lee's) on the survival of Enterococcus faecalis and Enterococcus durans strains after freeze-drying and during storage.
- To determine if growth medium composition influences the strain-specific survival rates of Enterococcus species.
Main Methods:
- Six strains of E. faecalis and two strains of E. durans were cultured in MRS, M17, or Lee's broth.
- Cultures were freeze-dried and stored at 20°C in air in darkness.
- Survival was assessed by rehydrating samples at regular intervals and plating on M17 agar.
Main Results:
- Enterococcus durans showed higher survival rates when grown in MRS medium prior to freeze-drying.
- Most Enterococcus faecalis strains exhibited better survival when grown in M17 or Lee's medium.
- Survival rates varied significantly among different strains within the same species.
Conclusions:
- The survival of freeze-dried Enterococcus species during storage is strain-specific.
- The selection of an appropriate growth medium is a critical factor influencing the post-freeze-drying viability of Enterococcus strains.
- Optimizing growth media can enhance the stability and shelf-life of freeze-dried Enterococcus preparations.