I need only 2 types of bacteria for a toxicology study. Please help me out.
Very simple..take the stool sample and put it in peptone water and incubate for 2 -4 hours and streak in blood agar plate or in brain heart infusion agar and incubate overnight..and based upon difference in morphology and colour you may pick up the colonies ..if you want to further identify then you have to perform biochemical tests.
you can mix 1gram stool sample/15ml PBS. Shake it rigorously for 5 minutes. Make a serial dilution from supernatant in PBS. Then spread from each diluted tube on individual agar plate. You can use selective media if you know what the bacterial strain you are looking for.
About 10 gm of each fecal sample were homogenized in sterile enrichment broth and incubated at 37oc/24hrs. Aloopful of enrichment broth were plated on selective media.
You can use selective broth as Selenite or Mac Conkey broth but the choice of the nutrient media depends on the searched 2 microorganisms. Put 2-3 pieces of the feces into the chosen broth and after incubation in cultivator for 3-5 hours you can vigorously vortex the tubes and cultivate again for the rest to 24 hours. On the next day you can teak with a loop a sample from the upper part of the broth and streak it onto appropriate selective agar media. If there are no isolates on the next day the process can be repeated up to the sixth day.
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