Capillary Gas Chromatography of Cellular Carbohydrates as a Means for the Differentiation of Fastidious, Slow-growing or Anaerobic Gram-negative Bacteria — A Review

Abstract

The phenotypic differentiation of microaerophilic or anaerobic Gram-negative bacteria of human origin is traditionally based on the analysis of metabolic characteristics. Due to outstanding growth requirements of many kinds of parasitic bacteria, e.g. of the facultatively and strictly anaerobic members of the human periodontal flora, conventional biochemical tests are time-consuming and sometimes lead to doubtful results. Commercial diagnostic test kits often produce misidentifications because of insufficient databases or inappropriate test combinations. In this situation, cytochemical methods can provide an alternative. Especially in the case of Gram-negative bacteria which contain considerable amounts of carbohydrates in their cell wall lipopolysaccharide layers, capillary gas chromatography of peracetylated carbohydrate derivatives prepared from bacterial whole cell hydrolysates proved to be useful to characterize individual species, and sometimes even subspecies. As soon as a pure culture is available, the derivatization of the cellular carbohydrates to their peracetylated aldononitriles and peracetylated O-methyloximes, respectively, needs only about four hours and the gas chromatographic spectra are easy to evaluate.