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Submitted to: American Society for Microbiology
Publication Type: Abstract Only Publication Acceptance Date: 5/23/2001 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The MIDI system (Microbial ID, Inc., Newark, Delaware) for fatty acid methyl ester analysis is widely used for identification of bacteria. However, the system is not very sensitive, requiring approximately 40 mg (wet weight), or one quadrant of a well-grown plate, and therefore cannot be used for single colonies. The sensitivity was increased at least 500-fold by concentrating the extracts down to 100 ul and using splitless injection. The splitless injection required the gas chromatograph to operate at a lower initial oven temperature and with an initial delay time, so the retention times were different. The system readily calibrated on the MIDI calibration mix diluted 1:100 once the corrected retention times were entered. Single colonies of various bacteria, including Bacillus cereus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia, were correctly identified with the environmental and clinical MIDI libraries. The high sensitivity of the method resulted in increased difficulty with contamination, so great care in choosing and cleaning glass and plasticware was necessary. |
