What does CTA Raffinose media test for?

Question

I'm in microbiology, and we just finished finding an unknown bacteria for lab.

One of the tests I did was CTA Raffinose. Circumstances didn't allow me a enough time to find out what raffinose is testing for, so I need to know what enzyme or end product it is testing for.

AND, I need to know what a positive and negative result looks like.

If it helps, my unknown is Streptococcus pyogenes and was negative for the raffinose test.

I've e-mailed my professor and my lab teaching assistant, and neither seem to want to respond. PLEASE HELP

Answer 1

It evaluates hydrolysis of raffinose and fermentation of one or more of its constituents (it's a trisaccharide of glucose, fructose and galactose). The "end product" is organic acid that effects a pH change - phenol red is yellow below ~ pH 7- and the enzyme you're prob looking for is a galactosidase that catalyzes hydrolysis to galactose and sucrose.