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Diacyl phthiodiolone A and phenolphthiodio-lone A lipids were isolated from two strains of Mycobacterium ulcerans . The diol units of the phthiodiolone A and phenolphthiodiolone A components were shown to have erythro stereochemistry by infrared spectroscopy and proton nuclear magnetic resonance of an acetal derivative. This stereochemistry is shared only by related diols from M. marinum , the diols from M. bovis, M kansasu, M leprae and M. tuberculosis having threo stereochemistry.

1. INTRODUCTION 2. MATERIALS AND METHODS Since the early work of Cummins and Harris [1] cell wall analysis has become a widely used tech- nique in both the classification and identification of Gram-positive bacteria [2]. Methods for de- termining wall amino acids include paper chro- matography, thin-layer chromatography (TLC) and ion exchange chromatography using the amino acid analyser; the latter being the method of choice where quantitative data are required [3]. Paper chromatography and TLC have been used prim- arily to provide a rapid qualitative assessment of the wall amino acid composition and to detect diagnostic diamino acids [4,5]. An established technique, applied only rarely to bacterial amino acids [6,7], is the conversion of amino acids into volatile derivatives and their analysis by gas chro- matography (GC) [8]. This approach is of poten- tial value since it provides reliable quantitative data on wall amino acids without the use of an amino acid analyser. This paper reports on the application of GC to the analysis of wall amino acids from selected defatted actinomycetes.

Preparations of Mycobacterium leprae, purified from host animal tissues, were screened by pyrolysis high-resolution gas-chromatographic analysis (Py-GC) for the presence of (myco)bacterial contaminants, which produce wax-ester mycolates. Contamination levels as low as 5% of the total number of acid-fast bacilli could be detected, based on the presence or absence of the marker compounds: a series of isomeric alkenes. The on-line pyrolysis capillary GC method provides an easy procedure for rapid quality control of preparations of purified M. leprae.

Lipids were extracted from small skin biopsies obtained from 5 lepromatous leprosy patients by employing a procedure designed to produce separate non-polar and polar fractions. The defatted tissue was subjected to alkaline hydrolysis and the total fatty acids in the hydrolysate were converted to methyl esters by a phase transfer reaction using iodomethane. The composition of free lipids and methyl esters of fatty acids was analysed by special thin-layer chromatographic systems. The presence of dimycocerosates of phthiocerol A, phthiocerol B and phthiodiolone A, phenolic glycolipid-I, two phosphatidyl inositol mannosides and 2 mycolates − alpha- and keto-mycolate − was demonstrated using reference lipid samples.

Free lipids were extracted from Mycobacterium tuberculosis H37Rv, and their antigenicity was assessed directly on thin-layer chromatograms (TLC) by an immunostaining technique. A family of glycolipids, composed of trehalose acylated with multimethyl branched long-chain fatty acids, was investigated. The most polar of these glycolipids was identified as a possible specific surface antigen. A pair of novel polar glycolipids also showed positive antigenic reactions.