I'm writing up a practical for a BSc (Infection Control). Any info on the
following would be gratefully received:
1. Sugar broth/Durham tube tests
2. Hugh and Liefsen tests - does it test for acid production and/or
fermentation; are they the same thing?
Thanks in advance
"Sugar broth" I assume this refers to carbohydrate fermentation test medium.
The most common I'm aware of is called Purple Broth. This is a medium with a
purple acid-base indicator. Carbohydrates are added as needed. The medium has
an inverted small glass tube inserted and filled with the medium (the tube
fills up with medium after autoclaving). A fermenting organism will turn the
medium yellow by producing acid from the carbohydrate, and bubbles of gas will
get trapped in the inverted Durham tube IF the organism produces gas
(note...some bugs will ferment and not produce gas......). The broth can be
prepared with many different carbohydrates to determine the organism's
"profile" for identification purposes.
The second test you refer to must be Hugh and Leifson's formulation of a medium
called OF Basal Medium. This medium is also a basal medium to which one can
add many different carbohydrates. The medium is green and set at a pH of around
6.8-7.2. If the organism ferments a carbohydrate, the medium will turn yellow
from acid production. I believe oxidative utilization of the carbohydrate will
produce a blue color in the medium. It is used for carbohydrate utilization
tests of "non-fermentors" such as Psuedomonas.
Martin Gross
Media Laboratory
American Type Culture Collection
mgross at atcc.org
