Principles and Practice of Chromatography - Chromatography Applications > Gas Chromatography Applications > The Identification of Bacteria by Their Volatile Fatty Acid Profiles. > Page 78

The Identification of Bacteria by Their Volatile Fatty Acid Profiles.

The bacteria genus clostridium are rod shaped and found largely in soil. Among these germs are those that can cause some of the most deadly diseases in man, such as tetanus (clostridium tetani) botulism, (clostridium botulinum) and gas gangrene, the deadly killer of wounded soldiers in the trench warfare of the first world war. The clostridium bacteria are particularly dangerous as they are very resistant to heat and thus all materials with which they may come in contact must be carefully sterilized.

 

Samples are prepared using the following procedure. 2 ml of the acidified culture is placed in a conical centrifuge tube and 1 ml of diethyl ether added. The tube is sealed and well mixed and then centrifuged to break up the emulsion. The ether layer is pipetted from the tube and anhydrous sodium sulfate added. The mixture then is allowed to stand for about 10 min. to remove all traces of water. An appropriate volume of the dry ether extract is injected onto the column. An example of the fatty acid profiles for three different types of bacteria are shown in figure 40, two of which are clostridium. A packed column was employed carrying a 15 % loading of a proprietary stationary phase and 1% of phosphoric acid supported on 100/120 Chromosorb W AW, a processed diatomite. The column was made of glass, 6 ft long, 4 mm I.D. and operated isothermally at 145˚C. Helium was used as the carrier gas at a flow rate if 60 ml/min. and 15 ml of the ether extract was injected onto the column. The three different types of bacteria gave quite different volatile fatty acid profiles. Furthermore it would appear that the acid profile; could be used as a means of identification.

Courtesy of Supelco Inc.

Chromatogram provided to Supelco by K.J. Hauser, Department of Pathology, Mount Sinai Medical Center, Milwaukee, WI.

Figure 40 Volatile Fatty Acid Profiles from Different Bacteria.