bacterial isolates preserved for about 3 years ,
the antimicrobial susceptibility will change or remain the same after 3 years .
if it'll change , the changing will be toward sensitivity or resistance.
I would like to add that if you have a resistant strain of a bacteria and the phenotype is given by a specific coding gene, preserving it appropriately (at -80 °C) is the way to ensure that the susceptibility profile will remain the same, since generally changes in susceptibility and resistance are given by mutations and by horizontal transfer of genes. As long as the bacteria is kept frozen at -80°C and it is not multiplying, the resistance phenotype will not change over time. If you are going to work with the bacteria, you have to make sure that every time the strain is taken from the stock at -80 °C and not subculture repeatedly to avoid mutations.
Hello,
Some types of bacteria acquire resistance in long term preservation but it depends to type of bacteria totally. You can check the changing in antimicrobial susceptibility of your bacteria in Specified intervals.
It will depend upon the method of preservation. If there is good amount of stress, then you may find susceptibility increasing. On the other hand if you preserve by processes like lyophilization (where the mortality rate is very high) then any thing could happen depending upon the surviving population.
It depends on how long you have preserved, which bacterium and method used to preserve. I have compared the data from preserved stocks after every 6 months till 3 years and I found slight change in the susceptibility of my strain. My strain belongs to genus Pseudomonas. results can be different for different genus.
I agreed with above mentioned comments.
It is totally depend up on which method of preservation you have chosen. I want to add some comments here when you preserve (by any method) then the trend show the resistant factor against antimicrobial agents and also one thing is valued here that how many times you have resuscitate your preserved culture???
I would like to add that if you have a resistant strain of a bacteria and the phenotype is given by a specific coding gene, preserving it appropriately (at -80 °C) is the way to ensure that the susceptibility profile will remain the same, since generally changes in susceptibility and resistance are given by mutations and by horizontal transfer of genes. As long as the bacteria is kept frozen at -80°C and it is not multiplying, the resistance phenotype will not change over time. If you are going to work with the bacteria, you have to make sure that every time the strain is taken from the stock at -80 °C and not subculture repeatedly to avoid mutations.
Dear Colleagues, Most Gram-negative bacteria such as E.coli, Klebsiella and Pseudomonas maintain well their resistance markers for many years if they kept preserved at -70 to-80 C or at room temperature in nutrient agar . However, repeat subculture for many time may result in losing certain resistance marker if they present on transferable plasmid .
I am sure that preservation of any bacteria at very low temp., will keep the antibiotic sensitivity pattern as resistance is obtained by exposure to other bacterial genes or by exposure to the antibiotic itself
I agree with all above. If a young growing young culture (cells of early to mid log phase) is prserved at around -80C with 10% glycerol, and left undisturbed under the condition, the culture should be alright for years, without any change in its drug resistance or susceptibility. Good luck.
Long time preservation of microbes doesn't affect their antimicrobial or any other property, if done accurately (using the most apt techniques). If the properties of microbial cultures had been changing over preservation period, then we would have never be able to get pure and original cultures (with a set of unique characteristics) from the culture collection centres.
It all depends on the method of preservation. And lyophilization is the most common and reliable method to preserve microbial cultures.
Can long time preservation of any beneficial bacterial strain affect its antagonistic behaviour against pathogenic strain?
Yes, Storage cells at mid log in 10% glycerol put in -80 and cultures, will last for years.
Have a good day.
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