- Volume 130, Issue 2, 1984

Spheroplasts of Candida albicans were regenerated in [14C]glucose and buffered magnesium sulphate (0·1 m-Tris/HC1; 0·5 m-MgSO4, pH 7.2) at 35C. Uptake of glucose by spheroplasts was faster than that by intact yeast cells. After 6 h, 65% of the glucose taken up by the yeast appeared as CO2 and 30% was incorporated into the cellular material. With spheroplasts, 55% of the glucose taken up was expired as CO2, 25% was excreted into the medium as other metabolites and 20% was incorporated into the cells. The regenerating spheroplasts excreted 14C-labelled carbohydrates into the medium which were fractionated on a Sephadex G-15 column. Acid hydrolysis of the low molecular-weight fraction yielded the following sugars: mannose (75·7%), fucose (3·8%), arabinose (3%), galactose (2·1%) and an unidentified monosaccharide (14%). Spheroplasts did not incorporate mannoprotein into the regenerated wall. The wall carbohydrate from regenerated spheroplasts was fractionated on the basis of solubility in sodium hydroxide. The alkali-insoluble fraction was analysed by sequential enzyme hydrolysis; 40% of the incorporated counts were associated with β(1 → 3)-linked glucan and 50% with a mixed glucan comprising β(1 → 3)- and β(1 → 6)-linkages and chitin.

Cells of the yeast Saccharomyces cerevisiae of the a mating type were arrested at the G1 phase of the cell division cycle after treatment with α factor in a culture medium containing a high concentration (2%, w/v, or higher) of a catabolite-repressing sugar. In media containing either a lower concentration of sugar or a non-fermentable carbon source, the extent of G1 arrest induced by the pheromone was reduced or became undetectable. Under catabolite-derepressing conditions α factor was inactivated by a cells at a higher rate than that found in repressing media. These results indicate the existence of a close correlation between the action of α factor on a cells and conditions of catabolite repression or derepression. A joint mechanism of action of aα factor and catabolite-repressing carbon sources on a cells is postulated.

DNA base composition, DNA-DNA homology and long-chain fatty acid studies were performed on Streptococcus thermophilus andStreptococcus salivarius. These species possess similar mol % G + C values (about 37 to 41), long-chain fatty acid profiles and belong to a single DNA homology group. On the basis of the present and earlier studies it is proposed that Streptococcus thermophilus (Orla-Jensen) be reclassified as Streptococcus salivarius subsp. thermophilus comb. nov.

Representative strains of Mycobacterium fortuitum, “Mycobacterium peregrinum” and Mycobacterium smegmatis were degraded by acid methanolysis and patterns of long-chain compounds were determined by two-dimensional thin-layer chromatography. The same general pattern of mycolic acid methyl esters was found in all 39 strains examined, the major components being so-called α-mycolates and characteristic pairs of polar mycolates. Analysis of alkaline methanolysates of selected strains confirmed that these polar mycolates were derived from epoxymycolic acids, as found previously.