Differential Media - Thioglycollate Medium

Differential Media:
Thioglycollate Medium
for the determination of the "oxygen relationship" designations
of chemoheterotrophic bacteria able to grow in this medium

This page was originally a handout for a couple of our microbiology lab courses.
Adapted from our oxygen relationship page at http://www.jlindquist.net/generalmicro/dfthiognf.html.

Some things to consider about Thioglycollate Medium:
- The medium will support the growth of common, easily-grown chemoheterotrophic bacteria, and the pattern of growth of an inoculated organism will indicate whether it can respire (using O₂) and/or ferment. The amino acids and glucose in the medium can be respired, and glucose is the only fermentable energy source in the medium (except to those exceptional organisms such as certain species of Clostridium which can ferment amino acids). Secondarily, the oxygen relationship designations derived from the growth observations (strict aerobe, facultative anaerobe, etc.) can be helpful in comparative studies of the physiologies of these organisms.
- Many organisms (including a lot of chemoheterotrophs) cannot grow in this medium for one reason or another.
- No allowance is given in the medium or method for anaerobic growth (1) with alternate electron acceptors (such as nitrate) or (2) in light (such as what is seen with the anoxygenic photosynthetic bacteria). Thus, an organism which may be termed a "strict anaerobe" in the more general sense – i.e., one which cannot tolerate oxygen and can only obtain energy by reactions which do not involve O₂ – would only show anaerobic growth in this test if it were capable of fermentation of the glucose in this medium.
With Thioglycollate Medium, we are able to differentiate two distinct patterns of growth for those classified in the Bergey's Manual definitions as "facultative anaerobes":
- Those which are indifferent to oxygen and have a strictly fermentative type of metabolism grow evenly throughout the medium.
- Those left in the facultative anaerobe category show greater concentration of growth at the top of the medium where oxygen is present and aerobic respiration is then possible.
The results we see in Thioglycollate Medium are shown below. The accompanying table gives related information.

Corresponding tube no. above	1	2	3	4
Oxygen relationship designation ––»	STRICT (OBLIGATE) AEROBE	FACULTATIVE ANAEROBE	AEROTOLERANT ANAEROBE	STRICT (OBLIGATE) ANAEROBE
AEROBIC RESPIRATION	+	+	–	–
FERMENTATION	–	+	+	+
Ability to grow aerobically (oxygen tolerance)	+	+	+	–
Ability to grow anaerobically	–	+	+	+
Catalase reaction	+	+	–	–
Reaction in Glucose O/F Medium (for those able to grow well in medium)	O or –	F
Response to sodium azide in a growth medium	SENSITIVE	SENSITIVE (under aerobic conditions)	RESISTANT	RESISTANT

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Page last modified on 2/13/06 at 9:30 PM, CST.
John Lindquist: new homepage, complete site outline.
Department of Bacteriology, U.W.-Madison

Differential Media: Thioglycollate Medium for the determination of the "oxygen relationship" designations of chemoheterotrophic bacteria able to grow in this medium

Differential Media:
Thioglycollate Medium
for the determination of the "oxygen relationship" designations
of chemoheterotrophic bacteria able to grow in this medium