I have screened hundreds of actinomycetes strains with antibacterial activity against bacterial pathogens. The strains were stored at 4 deg C. After 4-6 months of storage I have lost the activity of more than 30 strains even though it grows well in the medium. Now these strains are not showing inhibitory activity against the same pathogens. What is the reason behind this and I would like to know how to overcome this problem?
Dear Muthamil,
to store bacteria at 4°C for such a long period is never a good idea. I am not an expert on actinomycetes, but I am working with staphylococci. And when we store them in the fridge, they start autolysis. I would always recommend you working with fresh cultures. Also because of the chenged gen expression that could or should occur at these temperatures. Maybe you could "reactivate" this antimicrobial behaviour by recultivate them over some days or weeks. But I wouldn't work with these cultures anymore.
For long term storage, Always store cultures in Glycerol at -80°C. Regarding antimicrobial activity, source of isolation is important. Few organisms can show antimicrobial activity only for 2 to 3 generations and they lose their activity in laboratory cultured medium. To maintain the activity, store the first generation cultures at -80°C. Regarding actinomycetes storage, please refer to http://link.springer.com/content/pdf/10.1134/S0026261707040194.pdf
All the Best!
One request!
Please publish your observations of storage and list out the different species of Actinomyces which lost its activity at 4°C. This may help others to be careful of storing the Actinomyces in future.
I am facing same problem with Streptomyces erythreus, it has produced reduced fermented product day by day. And i'm completely agreed with Mr. Venkatesh Kumaresan
Dear Iniyan,
Few of my friends working on Marine Actinomycetes are facing the same problem. It seems storing them in fridge does have a effect on their secondary metabolites. Its always good to maintain a glycerol stock of the active microbe.
i agree with venkatesh kumaresan.Same problem i also faced when i sub cultured bacterial pathogens regulerly they lost the pathogenisity i got the false result with antibacterial sensitivity test by plant extracts.so Mr.Muthamil carefull about your bacterial pathogens also.
Dear Muthamil if you have good time and intrest you can do the comparision study between first generation organisms which are saved -80 degrees in glycerol and regular subcultured oraganisms by Antibacterial activity.you can publish your work better.
all the best.
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