- Volume 132, Issue 11, 1986

SUMMARY: In six liquid culture media, all of which stimulated Candida albicans to grow in the hyphal form, the rates of hyphal extension and increase in cellular ATP concentration, hyphal diameters, times of evagination of hyphae, times of septum formation and positions of septa in the hyphae appeared to vary independently. There were no discernible associations between properties such as length or volume of hyphal compartments at the time of septation and temporal parameters of hyphal growth. The results suggest that growth environment influences many of the processes contributing to hyphal development, but that these processes are not necessarily interrelated.

SUMMARY: The wax esters of Acinetobacter calcoaceticus strains NCIB 8250 and NCIB 10487 harvested at stationary phase from N-limited batch cultures were extracted and shown to consist of C14 to C18 saturated and mono-unsaturated alkan-l-ols randomly esterified with C14 to C18 saturated and mono-unsaturated fatty acids. The mono-unsaturated components contained a cis Δ9 double bond. Wax ester content of strain NCIB 8250 increased under conditions of low growth rate in N-limited continuous culture with carbon and energy source in excess. The high content of wax ester in N-limited cultures of strain NCIB 8250 was lowered by incubation in the absence of a carbon and energy source and the wax ester was converted to water-soluble materials and CO2. It is proposed that in A. calcoaceticus NCIB 8250 the endogenous wax ester present in N-limited cells can serve as an energy reserve. All 19 strains of A. calcoaceticus tested contained some wax ester and as 16 of these strains had increased wax ester contents when harvested from stationary phase N-limited batch cultures, it appears that wax esters are widespread, but not universal, energy storage components in the genus Acinetobacter.

SUMMARY: In cell-free extracts of Thiobacillus versutus, an organism which has been reported to be isocitrate lyase negative, an isocitrate lyase activity of 52 ± 18 nmol min−1 (mg protein)−1 was observed after anaerobic growth in a chemostat on acetate plus nitrate, i.e. during denitrification. Following growth on succinate plus nitrate, isocitrate lyase activity was only 1 ± 2 nmol min−1 (mg protein)−1. In cell-free extracts derived from aerobic chemostat cultures isocitrate lyase activity was always nil. The identity of the enzyme was analysed using a number of different methods, namely (a) three different enzyme assays, (b) 13C-NMR spectroscopy of the reaction products, (c) HPLC analysis of the reaction products, (d) mass spectrometry of derivatized glyoxylate enzymically produced from isocitrate and (e) radiography of derivatized glyoxylate enzymically produced from [14C]citrate. All these methods gave results consistent with the enzyme-catalysed conversion of isocitrate to glyoxylate and succinate.

SUMMARY: The extent of accumulation of methyltriphenylphosphonium ion by Escherichia coli was shown to be dependent on the permeability of the outer membrane and the activity of an efflux system for this compound. Evidence consistent with the operation of a single efflux system for compounds such as phosphonium ions, phenanthridiniums and flavines is presented. Studies on the energy coupling mechanism for this efflux system indicated that it was driven by the transmembrane proton electrochemical gradient.

SUMMARY: The effect of transcriptional and translational inhibitors on growth and on the light acclimation of the photosynthesis antennae of Anacystis nidulans was examined after a shift from white incandescent light (300 μE s−1 m−2) to red light (15 μE s−1 m−2). Addition of antibiotics that inhibit transcription (rifampicin) or translation (streptomycin, chloramphenicol and kanamycin) immediately blocked cell growth, and RNA and protein synthesis, when added either early or later after the light shift. The ratio of phycocyanin to chlorophyll a stayed constant. Addition of the antibiotics shortly after the shift also immediately blocked the increase in the ratios of phycocyanin and chlorophyll a to cell mass, whereas later addition resulted in decreases of about 50% and 12 to 30% in these ratios with rifampicin and streptomycin, respectively. No changes in pigment content were found when the antibiotics were added during steady state conditions with white or red light. The results show that both phycocyanin and chlorophyll a light acclimations are immediately and completely blocked by the addition of both transcriptional and translational inhibitors. We also propose that the light antennae may exist in an unstable form in the course of the acclimation process.

SUMMARY: L(---)Sorbose enhanced the extracellular levels of endoglucanase and filter paper unit activity in culture filtrates of Trichoderma reesei QM9414 cultivated on cellobiose or Avicel cellulose. Addition of sorbose to the culture medium retarded the uptake of cellobiose by the organism; this uptake appeared to be dependent on the surface-bound β-glucosidase. A biochemical mechanism to explain the effect of sorbose on cellulase induction, through its effect on surface-bound β-glucosidase and cellobiose uptake, is proposed.

SUMMARY: Nutritional tests were carried out on 62 strains of Escherichia coli as part of a study on the genetic basis of natural nutritional variation. The ability of these strains to utilize 84 compounds as carbon, nitrogen and carbon plus nitrogen sources was tested using an auxanographic method. The tests revealed polymorphic characters which are suitable for genetic analysis. Very few of these strains grew on the amino acids classified as “essential” for humans.

SUMMARY: A numerical taxonomic study of 64 strains of anaerobic Gram-negative bacilli isolated from men with non-gonococcal urethritis, two unclassified laboratory strains of "corroding bacilli”, and 12 other strains of anaerobic Gram-negative bacilli, including nine received as anaerobic curved rods and three as "Bacteroides corrodens” (B. ureolyticus), isolated from women with bacterial vaginosis, was undertaken. Seventeen reference anaerobic strains belonging to the genera Bacteroides, Fusobacterium, Mobiluncus, Mitsuokella and Wolinella were included. Morphological, biochemical and physiological characteristics were examined in 103 tests. The resemblance between the 95 strains was calculated using the SSM, SJ and DP coefficients for cluster analyses based on the UPGMA method. All three approaches gave similar groupings, and the estimated average probability of test error was 2.46%. The strains fell into 10 phenons. The unclassified strains from men and three from women with lower genital-tract infections, and the laboratory strains of "corroding bacilli” clustered in one phenon with the reference strains of B. ureolyticus, indicating that they correspond to B. ureolyticus. The other unclassified strains of anaerobic curved rods clustered as a distinct phenon. They correspond to species of the newly described genus Mobiluncus. The taxonomic data and the compilation of diagnostic tables serve as a useful guide for the laboratory identification of clinical isolates regarded as B. ureolyticus.