coliforms testing

JEDilworth bactitech at nospamhortonsbay.com
Thu Jun 20 15:22:31 EST 2002


Pseudomonads are non-glucose fermenters. Coliforms ferment glucose. Ps.
stuzeri and putida can be yellowish. 

In a clinical laboratory we plate specimens on MacConkey agar, which
shows lactose fermentation. There are non-lactose fermenters, though,
that are coliforms.

Good luck. I'm in clinical micro, not in the area that you are in, i.e.
non-clinical.

Judy Dilworth, M.T. (ASCP)
Microbiology

nicolas_pomies at hotmail.com wrote:
> 
> Hello there,
> 
> 
> 
> I am working actually on coliforms testing...
> 
> 
> 
> I am dealing with concentrated bacterial blends : pseudomonas: NCIMB11358 (stutzeri), NCIMB9494 (putida), NCIMB10643 (spp.) and NCIMB11712(fluorescens).
> 
> Concentration around 1e+09 to 1e+10 CFU/ml.
> 
> 
> 
> I need to find out a test technique specific enough to give me a response when a contamination by coliforms appears.
> 
> 
> 
> I am actually using the RVBA "double layer" method @ 30oC / 24h...
> 
> 
> 
> Anyway since I am dealing with a high concentration in Gram neg. bacteria I have colorless colonies growing on my RVBA plate with the media going "yellowish", maybe hiding a coliform contamination...
> 
> Sometimes I had no growth at all ... suspicious with Gram neg. strains ?
> 
> 
> 
> In another hand, I made trials on media and test kits using ONPG response (ex: COLILERT) for determining Total Colifoms Response... the trouble is I don't know if those pseudomonas strains present a beta-galactosidase activity (I couldn't find it in the Bergeys) ... looks like NCIMB10643 present one anyway...
> 
> 
> 
> Thanks for helping....
> 
> 
> 
> nicolas
> 
> http://www.biowww.net/index.php/forum/forumlist/1/




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