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Vibrio cholerae detections from environmental samples - (Apr/12/2012 )

Hello all, trying to detect Vibrio cholerae from an environmental sample and the protocol I have suggest Incubating the sample in Alkaline Peptone Water at 22 degree Celsius for 6 hours and then transferring into a new Alkaline Peptone Water at 42 degrees overnight.
If I may ask, what is the principle behind that? I really have to know before I go face my PI. Any help out there.

-Kenzibit-

Vibrio cholerae can survive/grow under alkaline conditions, unlike most enterics and pseudomonads one might expect from such an environment. So alkaline peptone (assume you're using the original formula with NaCl) enriches for Vibrio. I'm most familiar with 37C incubation - but the bug grows well enough at 42C so that can be an additonal selective means.

All this is prepratory to culture and isolation on solid medium - which do you propose to use?

Here's original ref
P. Shread, T.J. Donovan, J.V. Lee, Soc. Gen. Microbiol., Q. 8, 184 (1991)

and FDA's BAM http://www.fda.gov/Food/ScienceResearch/LaboratoryMethods/BacteriologicalAnalyticalManualBAM/ucm070830.htm

-Phil Geis-

Thanks for our informative reply. But just wanted to know if this rapid increase in temperature from 22 to 42 degrees is some sort of heat shock. I wish I knew what goes on in the cells at the molecular level.

-Kenzibit-

Can't say - suggest you search the literaure. Perhpas ask the source of the protocol.

-Phil Geis-

Trying that now, thanks

-Kenzibit-