- Volume 115, Issue 2, 1979

Rhodococcus erythropolis DSM 43215 produced a surface-active trehalose lipid whose formation was induced by n-alkanes to a maximum of 2*1 g l−1 in a 501 batch culture on 2% (w/v) «-alkanes of chain length C12 to C18. The glycolipid was extracted from the biomass with n-hexane and was purified by repeated chromatography on silica gel. It contained a,a-trehalose as the sole non-reducing sugar. The lipid moiety was characterized by 13C nuclear magnetic resonance spectroscopy and mass spectrometry and consisted predominantly of saturated long-chain a-branched ^-hydroxy fatty acids (mycolic acids) ranging from C32H6403 to C38H7603, of which C34H6803 and C35H70O3 predominated. The molar ratio of trehalose to mycolic acids was 1:2. 13C nuclear magnetic resonance analysis of the O- hexamethyltrehalose obtained by saponification of the permethylated trehalose dimycolates revealed, with the aid of deuterium exchange, that the ester linkages of mycolic acids are to both primary alcohol groups at the C-6 and C-6' positions of the trehalose.

The specificity of adherence of various Enterobacteriaceae to different mammalian cells was studied in vitro. 3H-Labelled organisms of the same species isolated from various clinical sources differed significantly in their abilities to adhere to the same mammalian cells. Bacteria frequently adhered better to cells derived from sites other than those analogous to their original source. Bacteria did not display consistently ‘high’ or ‘low’ attachment to a variety of human and tissue-cultured cells and little selective adherence was demonstrable.

Cysteine auxotrophs of Salmonella typhimurium mutated in cysB, cysI or cysJ grew with sulphate as a sulphur source when incubated under a hydrogen/carbon dioxide atmosphere. Yields obtained under these conditions were equivalent to those characteristic of wild-type S. typhimurium. The same mutants failed to grow with sulphate as a sulphur source when incubated aerobically. Auxotrophs mutated in cysA, cysC, cysD, cysE, cysG and cysH required cysteine for growth under both incubation conditions. The results suggest that mutations in cysB (regulation of the several cys operons) and also cysI and cysJ (sulphite reductase activity) can be circumvented during anaerobic growth under hydrogen.

Cell wall-deficient forms of Mycobacterium smegmatis were produced in growth medium containing d-cycloserine and horse serum. These cells were transformed into protoplasts with EDTA and lysozyme. Subsequent lysis by nucleases followed by osmotic shock produced membrane vesicles (whole cell ghosts).

A methanol dehydrogenase containing cytochrome c which was reduced on addition of methanol was isolated from Hyphomicrobium X. Metal-chelators or oxygen blocked this electron transport. Oxygen changed the coupling irreversibly, transforming the enzyme in the complex into the already known, NH4 +-requiring enzyme form. This ‘classical’ methanol dehydrogenase differs in several respects from the more natural enzyme reported here.

The results of serological studies on six strains of Micropolyspora faeni from hay, sputum and plant debris, and five strains of Mip. rectivirgula from soil indicated no significant differences between the two species. Antisera raised in rabbits against purified antigens of the type strains were used to compare the 11 strains by immunoelectrophoresis. The detailed antigenic composition of the type strains was also determined by two-dimensional immunoelectrophoresis against specific rabbit antisera and pooled serum samples from patients suffering from farmer's lung. Cross-reacting antigens were identified by intermediate gel immunoelectrophoresis.

The close similarity of the two species was confirmed by the results of 60 morphological, physiological and biochemical tests applied to the 11 strains. We consider that the strains belong to a single species and propose that the specific epithet faeni be conserved for the taxon.