X-GAL CLEAVAGE BY V. CHOLERAE

Dr. Warren Wakarchuk wakarchu at biologysx.lan.nrc.ca
Tue Sep 1 16:24:26 EST 1992


In article <1992Sep1.152134.202619 at uctvax.uct.ac.za> coyne at uctvax.uct.ac.za writes:
>From: coyne at uctvax.uct.ac.za
>Subject: X-GAL CLEAVAGE BY V. CHOLERAE
>Date: 1 Sep 92 15:21:33 +0200

>Dear Netters,

>I am attempting to isolate transposon generated lacZ operon fusions in 
>Vibrio cholerae by cleavage of X-gal to generate blue colonies.  According to
>Bergeys, V. cholerae is lactose negative.  However, I have found that
>V. cholerae is able to cleave X-gal to generate blue colour which is a major 
>problem with respect to my strategy.  I would greatly appreciate it if anyone 
>could supply me with an answer to the following question:

>   Does V. choerae possesses a beta-galactosidase enzyme?
>   (The bacterium was scored as lac- as a function of growth on lactose).

>You may post the answer e-mail it directly to me.

>Many thanks in advance,

>Vernon Coyne
>vernon at micro.uct.ac.za
> 
Your problem is likely that another glycosidase like Beta-glucosidase is 
cleaving the X-gal.  Most gram negative strains have such enzymes and the 
specificity is rather "loose".  E. coli Beta-galactosidase does cleave other 
glucosides as well.  You might have to look for the enzyme itself, not its 
activity.

Warren Wakarchuk
IBS NRCC
wakarchu at biologysx.lan.nrc.ca



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