SEROREACTIVE SPECIES-SPECIFIC LIPOOLIGOSACCHARIDES OF MYCOBACTERIUM-MUCOGENICUM SP. NOV. (FORMERLY MYCOBACTERIUM CHELONAE-LIKE ORGANISMS) -IDENTIFICATION AND CHEMICAL CHARACTERIZATION

Strains of the new species Mycobacterium mucogenicum exhibit physiolog ical and biochemical features very similar to those of the other speci es of the Mycobacterium fortuitum complex. To define taxonomic criteri a for easy identification of M. mucogenicum, the glycolipid patterns o f the reference strains and of 32 environmental and clinical isolates were examined by TLC. It was concluded that all M. mucogenicum strains of smooth colony morphology contained species-specific alkali-labile glycoconjugates. Three different patterns were observed among the stra ins of the smooth colony type. Fractionation followed by conventional chemical analyses of the purified glycolipids showed the specific glyc olipids to be lipooligosaccharides (LOS). The three LOS showed a simil ar fatty acid composition consisting of straight chain (dodeca-, tetra deca-, hexadecanoyl and hexadecenoyl) and methyl-branched (2,4-dimethy leicosanoyl and 2,4-dimethyleicosenoyl) fatty acyl substituents. The m ost commonly encountered LOS (present in 76% of the smooth strains) co ntained a tetraacylated pentasaccharide composed of four moles of gluc ose and one mole of a 2,4-di-O-methylhexose. A LOS composed of arabino se, glucose and mannose was present in 20% of the smooth strains, wher eas the newly proposed type strain of M. mucogenicum (ATCC 49650) was the only strain that contained a LOS composed of glucose and galactose . Serological studies clearly differentiated most of the strains of M. mucogenicum from those of the other members of the M. fortuitum compl ex, and demonstrated the existence of serovars within the former speci es. Altogether, these data confirm the validity of the new species but show ATCC 49651 to be the most representative strain.