- Volume 129, Issue 5, 1983

Streptococcus agalactiae (group B) was grown in Todd-Hewitt broth (36·4 g 1−1, pH 7·8) in a Braun Fermenter (type B20) to investigate the conditions of optimal bacterial growth and maximal production of CAMP factor. The influence of different gas atmospheres (air, N2, CO2, and gas mixtures) on growth, CAMP production and chain length of S. agalactiae was studied. The organisms grew best in the presence of 2% (w/v) glucose, at pH 6·2, with a constant flow of CO2. The number of diplococci and monococci under these conditions reached almost 80% of the total population.

The function(s) of the peptide antibiotic, gramicidin S, in its producer, Bacillus brevis Nagano, was investigated. Particular attention was paid to the possible role of gramicidin S in sporulation and spore properties. Sporulation was similar in both the gramicidin S-producing parental strain and a gramicidin S-negative mutant of this strain. Mature parental and mutant spores were equally resistant to UV irradiation, solvents (reported previously) and heat. Thus, the lack of gramicidin S synthesis impairs none of these properties. Contrary to results reported by others, we also found no difference in heat resistance between spores of B. brevis ATCC 8185 and its linear gramicidin-negative mutant, Ml.

The SHAM-sensitive alternative oxidase has been studied in Tetrahymena pyriformis strain ST as a function both of growth state and of chloramphenicol treatment. In low density cultures the total alternative oxidase activity, as revealed by SHAM titration in the presence of CN−, is equivalent to 17% of total respiration and is slightly utilized at all times. Stationary phase cells have somewhat less of the oxidase and it is not utilized even in CCCP-uncoupled cells. Respiration in chloramphenicol-treated cells is 100% CN−-resistant. Alternative oxidase activity is equivalent to 30-40% of this total and one third of it is active. The remaining 60% residual respiration is due to unknown oxidases. Following CCCP-uncoupling, a CN−-sensitive pathway is demonstrable and the alternative oxidase is fully utilized. The higher proportion of alternative oxidase in chloramphenicol-treated cells is brought about by its conservation at a time when the cytochrome chain is becoming non-functional. There is no large scale induction of the alternative oxidase.

A study has been made of the uptake of radioactively-labelled solutes by starved myxamoebae of the cellular slime mould Dictyostelium discoideum. Inulin uptake was energy-dependent, inhibited by cycloheximide, and the rate was proportional to extracellular inulin concentration. The ability of the cells to take up inulin did not change during starvation. Uptake of four other solutes, β-alanine, glucose, protein hydrolysate and uracil occurred at a similar rate to inulin uptake when expressed as an endocytic index (μl medium taken up h−1 per 106 cells). All the results were consistent with uptake occurring by fluid-phase pinocytosis. Pinocytic activity thus occurred in starving cells and was found to be affected by some agents that act as developmental inhibitors. Uptake of inulin and putrescine (previously shown to be taken up by adsorptive pinocytosis) was inhibited by chloroquine, KCl and NH4Cl, although ammonium ions also blocked developmental changes in the ability of myxamoebae to take up putrescine. Sodium ions were less inhibitory. ε-Aminocaproic acid inhibited solute uptake in a temperature-dependent, reversible manner.

Millipore filters placed underneath agar block cultures of Phytophthora parasitica were able to adsorb hormones α1 and α2 produced by A1 and A2 mating types of the fungus, respectively. Both hormones were released from moistened Millipore filters by extraction with ether, which on evaporation resulted in aqueous hormone extracts. Isolated hormones α1 and α2 stimulated oospore formation by A2 and A1 mating types of P. parasitica, respectively, when they were adsorbed on small pieces of Millipore filter, but not when they were added directly to agar cultures. Hormones α1 and α2 were removed from aqueous solutions by both cation and anion exchange resins, and could be eluted from the resins by ether. Both hormones α1 and α2 were able to pass through membranes with a molecular weight cut-off of 1000 and 500, but not 100 and 50.

A 31P NMR study of the fungal pathogen Candida albicans was carried out. Yeast-form cells at different phases of growth, as well as germ tubes and hyphae were examined. In all cases, the NMR spectra showed well separated resonance peaks arising from phosphorus-containing metabolites, the most prominent being attributable to inorganic phosphate (Pi) polyphosphates, sugar phosphates and mononucleotides, NAD, ADP and ATP. Relevant signals were also detected in the phosphodiester region. The intensity of most signals, as measured relative to that of Pi, was clearly modulated both at the different phases of growth and during yeast-to-mycelium conversion, suggesting significant changes in the intracellular concentration of the corresponding metabolites. In particular, the intensity of the polyphosphate signal was high in exponentially growing, yeast-form cells, then progressively declined in the stationary phase, was very low in germ tubes and, finally, undetectable in hyphae.

NMR spectral analysis of the Pi region showed that from early-stationary phase, Pi was present in two different cellular compartments, probably corresponding to the cytoplasm and the vacuole. From the chemical shift of Pi, the pH values of these two compartments could be evaluated. The cytoplasmic pH was generally slightly lower than neutrality (6·7–6·8), whereas the vacuolar pH was always markedly more acidic.

In the presence of calcofluor white, budding scars and dividing cross-walls of Saccharomyces cerevisiae exhibited fluorescence, indicating that the brightener was a specific marker of fungal chitin. In addition, incubation of cells in the presence of the brightener did not stop protein and wall-polymer formation, but abnormal deposition of chitin occurred. Chitin synthesis was normal in regenerating protoplasts of Candida albicans in the presence of calcofluor, but formation of the crystalline lattice was blocked. These results suggest that crystallization of nascent subunits may occur by a self-assembly mechanism that was blocked by the stain.

Gonococci were cultured from the urethra of male patients and from the cervix and urethra of their female partners. SDS-PAGE of cell lysates from within each group of consorts showed that outer membrane protein I remained constant but considerable variations were seen in the apparent molecular weight of protein II. Pili were purified from the isolates of some groups of consorts. In each case the pili expressed by the isolates from the female cervix and urethra differed in subunit molecular weight and were usually also distinct from the pili expressed by the isolate from the male partner.

Six main groups were formed from a complete linkage dendrogram on 557 bacteria tested for 53 physiological features. The organisms were obtained from culture collections and included representatives of the following genera: Arthrobacter, Brevibacterium, Caseobacter, Cellulomonas, Corynebacterium, Curtobacterium, Micrococcus, Microbacterium, Mycobacterium, Nocardia, Oerskovia and Rhodococcus. The six groups were individually subjected to a numerical taxonomic analysis based on linkage maps, which resulted in a total of 33 subclusters. An identification key to determine the affiliation of the bacteria to the six main clusters and five group-specific schemes is presented. Reference strains are proposed for the 33 subclusters.

The present study was undertaken to examine the genetic relationships among the closely related species, Clostridium novyi types A and B, C. haemolyticum and C. botulinum type C. These species were tested for DNA-DNA homology and thermostability of DNA duplexes and sorted into three genetically related groups: I, C. novyi type A; II, C. novyi type B, C. haemolyticum and one C. botulinum type C strain (Stockholm); III, the remaining C. botulinum type C strains. A few biochemical criteria corresponding to the genetic differences were recommended to differentiate each group. These studies imply that C. haemolyticum might be considered as C. novyi type D and that there are two genetically different groups in C. botulinum type C.

Rhizobium japonicum USDA191 is a member of a new group of Rhizobium japonicum strains found in China. This strain is one of several strains shown to be salt-tolerant and fast-growing; it is unique in being the only strain of this group that effectively nodulates American soybean cultivars. For these reasons strain USDA191 was chosen for further study and comparison to the common American Rhizobium japonicum isolate USDA110. Strain USDA191 has a doubling time of 3.2 h in complex medium and grows in concentrations of up to 0·4 m-NaCl, while strain USDA110, which has a doubling time of 12 h, is severely inhibited in media containing 0·1 m-NaCl. Under salt stress conditions, intracellular levels of K+ and glutamate were shown to increase. A comparison based on carbohydrate metabolism, DNA homology and protein patterns on polyacrylamide gels reveals that strain USDA191 is more closely related to the fast-growing rhizobia than to Rhizobium japonicum. However, the strain retains capacity to nodulate American soybean and cowpea cultivars effectively.