- Volume 131, Issue 11, 1985

Summary: Two-dimensional diffusion gradients (of NaCl and H+ concentrations) were established in solid growth medium containing glycerol and yeast extract as major carbon sources. These were used to investigate conditions favourable for growth and bioluminescence of three species of luminous bacteria during incubation at different temperatures. Photobacterium leiognathi, Photobacterium phosphoreum and Vibrio fischeri all grew over the entire salt range used [0.9–3% (w/v) NaCl] and at pH values < 7 at the most favourable temperatures (20 °C, 20 °C and 15 °C respectively); upper and lower temperature limits for growth over a 72 h period were 30 and 10, 25 and 5, and 30 and 5 °C respectively. Bioluminescence was observed at all temperatures that supported growth; in P. leiognathi emission at 10 °C was hardly detectable even after 72 h, but at higher temperatures it occurred at all NaCl concentrations. Low pH values and high NaCl concentrations favoured luminescence in the other two organisms; after 48 h light emission decreased from the high pH and low NaCl regions of the gels. These results are discussed with reference to the symbiotic (P. leiognathi, V. fisheri) or free-living (P. phosphoreum) origins of the organisms studied.

Summary: A description is given of the vegetative growth of Chlamydomonas eugametos in liquid cultures. When a circadian light/dark regime is applied, cell division takes place during the dark periods and the release of the daughter cells is phased round the dark/light transitions. However, as long as the cultures are agitated, only a fraction of the cells divides during any dark period. The mother cells stick firmly to the surface of the culture vessels, making it possible to separate them from the non-dividing cells. They release daughter cells that show cell cycles of 1 × 24 h, 2 × 24 h and longer. Only in static cultures do all cells divide synchronously every 24 h. To explain these results, a correlation is postulated between the chance of settling and the length of the division cycle.

Summary: Autolysis of purified Saccharomyces cerevisiae cell walls resulted in the release of several components thought to be mannoprotein in nature, since they were retained by Concanavalin A-Sepharose. The most abundant was a 29 kDal molecule which was also a major species among mannoproteins solubilized by the β-glucanase complex Zymolyase. There was a concomitant release of glucose and mannose oligosaccharides and of β-glucanase activity. Glucanase and protease inhibitory treatments considerably lowered the release of mannoproteins. The use of different protease inhibitors during autolytic incubations interfered with at least two proteases (one of them being a cysteine protease) apparently involved in the solubilization and partial degradation of mannoproteins from the walls.

Summary: Chromosomal DNA was extracted from eleven Neisseria meningitidis and seven Neisseria gonorrhoeae isolates and cleaved with the restriction enzyme HindIII. The DNA fragments were separated according to their size, using a 4% polyacrylamide gel. The band patterns obtained were digitized and statistically analysed by the SIMCA method. To develop the models for N. meningitidis (class 1) and N. gonorrhoeae (class 2), all eleven meningococci and seven gonococci were used. All strains were classified correctly and showed an extremely good class separation.

Summary: The electrophoretic mobilities of 12 enzymes from 19 Neisseria species (including 6 strains of N. perflava), Gemella haemolysans, Escherichia coli and Branhamella catarrhalis were characterized by polyacrylamide slab gel electrophoresis. All strains and species tested exhibited qualitatively different zymogram patterns. Species and strain relationships were quantified by pairwise comparisons of all 12 enzyme systems to obtain similarity indices; these data were subjected to numerical clustering methods to obtain groups and a phenogram. The electrophoretic classification compared favourably with those obtained by other criteria. In addition, the quantitative clustering data indicated that N. ovis and N. caviae are sufficiently different from the other Neisseria species to warrant their separation into a distinct group. These two species also lacked the characteristic NADPH-diaphorase zymogram pattern found in all the other Neisseria species. Intra-species similarity indices were generally greater than the inter-species index values. However, certain species such as N. meningitidis and N. gonorrhoeae had similarity index values in the range of inter-strain index values.

Summary: A new Mycoplasmatales virus, referred to as MV-O1, was isolated during cloning of Acholeplasma oculi 19L. The virus formed plaques only on strains of A. oculi, i.e. the original clone, A. oculi 19L, a subclone of A. oculi 19L (A. oculi-i), A. oculi Goat 5 and a wild isolate (K-2) of A. oculi, but not on other acholeplasmas, including strains of A. laidlawii, nor on five human mycoplasma species tested. The virus required horse serum for multiplication as well as for plaque formation and passed through a 100 nm filter. Electron microscopy revealed enveloped, spherical particles 80-130 nm in diameter. The buoyant density of purified virus was 1.23 g ml−1 in CsCl, and agarose gel electrophoresis indicated that the viral nucleic acid was DNA.

Bodies initially thought to be spirochaetes were observed in the ascites of mice injected intraperitoneally with Bacillus aneurinolyticus (KA bacillus). Electron microscopy revealed that these bodies were in fact ‘pseudospirochaetes’ originating from the flagellar bundles of the bacilli.

Summary: Six IncP plasmids were tested for their ability to generate tellurite-resistant variants by plating bacterial strains harbouring them on medium containing potassium tellurite. Four plasmids, three of subgroup IncPα and one not allocated, formed variants that could transfer tellurite-resistance at the same frequency as plasmid-determined drug resistance. This property was not shared by two examples of subgroup IncPβ.