The Inability of Pyrolysis Gas-Liquid Chromatography to Differentiate Selected Foodborne Bacteria

Pyrolysis gas-liquid chromatography (PGLC) and stepwise discriminant analysis (SDA) were ineffective when used to differentiate selected genera, species and strains of foodborne microorganisms. Each of 18 individual bacterial strains analyzed was grown, harvested and subjected to PGLC analysis. The resulting pyrolysis products were separated on a high resolution capillary column and the elution patterns (pyrograms) were subjected to stepwise discriminant analysis of 26 (a-z) characteristic peaks. Classification with the combination of PGLC and SDA was 87% accurate for gram-negative strains of bacteria and 94% accurate for gram-positive strains of bacteria. PGLC-stepwise discriminant· analysis correctly discriminated 80% of the bacterial strains according to the known gram-stain reactions. Only 63% were correctly classified to the genus level when all samples were compared. These findings point out the weak points for this method of bacterial analysis.