Microbiology - Volume 136, Issue 4, 1990

Summary: A new family, the Halomonadaceae, has recently been proposed for members of the genera Deleya and Halomonas. The three strains investigated, Deleya halophila, Halomonas elongata and Flavobacterium halmephilum (reclassified as H. halmophila), are aerobic heterotrophic micro-organisms exhibiting an extreme salt tolerance. The major organic osmoregulatory solutes of these organisms were examined using 13C-nuclear magnetic resonance spectroscopy. The relative proportions of the solutes varied with respect to salt concentration, temperature and carbon source. The recently described amino acid ectoine was found to be a dominant solute. For the first time it could be shown for halophilic eubacteria that the intracellular concentration of solutes is sufficient to balance the osmotic pressure of the medium. Thus, there is no need to postulate a hypo-osmotic cytoplasm.

Summary: A transitory cessation of growth was recorded in Streptomyces coelicolor A3(2) at the end of vegetative mycelium formation on solid medium. In the same phase a striking reduction in protein and nucleic acid synthesis was detected. Growth and macromolecular synthesis resumed, nearly reaching the original values, when morphological differentiation occurred. It is concluded that a physiological stress occurs within the bacterial population just before the onset of the morphological differentiation.

Summary: Monoclonal antibodies (mAbs) were raised against Penicillium islandicum, a fungus commonly isolated from stored rice grains in South-East Asia. Mice were immunized by a direct, simple method; fresh cell-free surface washings from a solid agar slant culture were injected directly into the peritoneum without prior concentration. Hybridoma supernatants were screened by ELISA. Most of the mAbs raised cross-reacted with other storage fungi and/or uninfected rice grains but three were species-specific. One of these, PI01, was used to develop ELISA and DIP-STICK assays for the detection of P. islandicum in individual grains. All inoculated grains and approximately 90% of grains in natural infected samples from Indonesia tested positively, by ELISA, for P. islandicum. This result and those obtained for discoloured grains from both Indonesia and the Philippines, 32% and 14% respectively, are higher than those obtained by direct plating of surface-sterilized grains. Heat and periodate treatment of the PI01 antigen and binding on Western blots indicate that it is a glycoprotein of M r > 90000. Hyphae of all ages stained uniformly by immunofluorescence using the PI01 antibody but mature conidia stained only weakly.

Summary: A numerical taxonomic analysis was performed on 79 phenotypic characters of 147 imperfect yeast species currently assigned to the genus Candida. The characters used were drawn from two monographs on yeast taxonomy. The analysis revealed 10 clusters of three or more species that were similar at the level of 75% or more, and seven clusters containing only one or two species. None of the 10 major clusters contained exclusively species that were traditionally assigned to the genus Torulopsis, while the 12 Candida species of basidiomycetous affinity fell into three clusters with only one species of ascomycetous affinity included. Statistical determination of the five most important differential characters for each cluster failed to show the property of pseudomycelium/mycelium formation as significant for any cluster. The study provides no evidence to support a distinction between taxa that were formerly divided between the genera Candida and Torulopsis and supports previous proposals that these genera should be fused.