in my recent work I need to sterilize a chicken drumsticks samples to inoculate them later with specific E coli strain then treat them with chemicals and recover them after treatment, and the later step I will study the effect of my treatments to the strain I used. the tricky part is how can I be sure that I'm recovering the same isolate if the samples were not sterile 100% ?.
In fact I already tested some methods for sterilization I used dipping in alcohol up to 3 minutes and still have some E Coli appear in the plates, then I sent some chicken drumsticks for Gamma radiation. the issue with the radiation is I still have a high microorganisms populations around log 5-6 growing in TSA media at 30 C for 72 hours. but in the other hand there is no E coli can be detected in VRBA-MUG media at 37 C for 24 hours.
the question is should I be satisfied with the fact that Radiation possibly eliminate all the E coli background in the samples ? or the presence of other microorganisms which they can be mold yeast and other Enterobacteriaceae in TSA is problematic ?. people here think this load will affect the attachment of the E coli strain I want to use.
is radiation suppose to eradicate all microorganisms because in my reading I find it doesn't in fact it eliminate bacteria while spore forming and mold reduced only and there is temperature , time and dose factors can interfere with the results. also the radiation dose I used was 10 kGy for 17 hours which is higher than what really recommended and found in references.
Finally , is it really possible to sterilize chicken samples for experimental purpose? and if it is possible is there any better method rather that radiation?
Thanks in advance
I would think that bacteria are only on the surface of the meat/food. So if you find a way to slice of the upper layer without further contamination you should be good. Maybe you should get a whole dead chicken from a farmer (I am not kidding) and dissect it under sterile conditions instead of buying the meat at a supermarket.
Also, the US allows treatment of chicken meat with chlorine bleach for sanitation purposes. Something worth trying?
You can cook the meat so that all the bacteria are dead and ensure its sterile. Then go for doping with your Ecoli and use chemicals as you suggest as preservative.
Thank you very much Cornelia Virus for you answer, yes I know what you mean, chicken directly from the farmer may be less contaminated than meat comes from the production line. but the problem is my project focus is reducing the bacterial contamination on chicken skin surface. chlorine bleach could be more interesting, but also my group worry from this because it might change the physical property of the skin and may interfere with bacterial attachment
Thank you very much Anjali Nair for your answer. yea also I thought about using hot water but, the problem is my attention is fresh chicken meat not cooked
The only sure ways in which you can eliminate all background microflora are by a sterilizing dose of irradiation or by high temperature cooking, neither of which are really suitable if your work is concerned with raw chicken microflora. Organisms will not just be on the surface of the chicken but also in the pores of the skin. Rather than using drumsticks you might do better to use chicken breast portions with the skin still attached; or even to use skin stripped from the chicken meat. Ideally you should avoid using a chemical treatment because residues from that treatment might conflict your chosen treatment and/or inhibit your test organism.
A problem with sterilizing the surface skin is that you no longer have any natural competitors so your results may be misleading. Even in the presence of natural microbial contaminants it should be possible for inoculated cells to attach to the skin.
Why not use an organism that is resistant to a specific antibiotic (e.g. rifampicin)? You could then do your recovery experiments using a medium containing that antibiotic. A differential agar containing an appropriate concentration of the chosen antibiotic will enable you to isolate surviving organisms after you have applied your chosen chemical or other treatments. You would, of course, need to ensure that your test strain did not differ in its sensitivity to your chosen chemicals compared to wild strains but that is easy to assess in vivo.
Yes , Yes . I do agree completely with Basil. Thank you Basil and good luck Ahmed.
Thank you Basil Jarvis and Moustafa El-Shenawy for answering my question.
Kinds Regards
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