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coliforms testing
Posted by: nico (IP Hidden, New member, 0)
Date: June 20, 2002 07:01AM
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
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