- Volume 130, Issue 3, 1984

The mycolic acid derivatives of 11 unidentified pathogenic coryneform bacteria were examined by TLC, GLC and GLC-mass spectrometry. The resulting mycolic acid profiles of the unidentified isolates were compared with those of type or reference strains of possibly related coryneform species, namely Corynebacterium bovis, C. diphtheriae, C. xerosis and Rhodococcus equi. It was apparent that most of the unidentified strains showed a distinctive mycolic acid profile, with predominant amounts of relatively high molecular weight mycolic acids (C32-C36) and a high degree of unsaturation, and could thus be distinguished from both C. bovis, which had exceptionally low molecular weight mycolic acids (C24-C30), and C. diphtheriae (C28-C34), which had large amounts of saturated mycolic acids. The mycolates of C. xerosis and R. equi (C28-C36) were generally similar to those of the unidentified coryneforms but their overall mycolic acid patterns were different from one another as well as the unidentified strains. The mycolic acid profiles exhibited by the pathogenic coryneforms examined here were very similar to one another but unlike that of any of the type or reference strains included in the study.

Cell surface hydrophobicity of group A, B, C, D and G streptococcal strains has been studied and compared in a new test based on the fact that the degree of bacterial aggregation in ammonium sulphate depends on amphiphilic surface antigens. M-positive group A strains showing good growth in normal human blood aggregated in the standard salt aggregation test at very low concentrations of ammonium sulphate, while M-negative strains, which were killed in normal human blood, usually aggregated at high salt concentrations. Agents such as 2 M-KSCN, 2 M-guanidine. HCl or 2 M-urea decreased the aggregation of the M-positive strains in the salt aggregation test while non ionic detergents such as Tween 20 (1%, w/v) and ethylene glycol (2 m) did not affect cell aggregation. Binding of fibrinogen and albumin resulted in a decrease of surface hydrophobicity of the group A M-positive strains. Group B strains possess a hydrophilic surface character and did not aggregate, while group C and G strains behaved in the salt aggregation test like M-negative strains of group A streptococci. Group D strains did not aggregate even at high ammonium salt concentrations. The results are discussed in relation to the influence of lipoteichoic acid and other surface antigens on strains of the various groups, and it is suggested that M protein and possibly also other surface proteins contribute to the high surface hydrophobicity of group A strains.

We examined bactericidal and opsonizing activity of pooled adult ‘immune’ serum against Haemophilus influenzae type b with and without the addition of phagocytes. Four type b strains from cerebrospinal fluid (CSF) and three such strains from the nasopharynx (NP) of healthy children were examined. Duplicate reaction mixtures contained organisms in exponential (E) or stationary phase (S) of growth, serum, a complement source (human agammaglobulinaemic serum), and culture medium (bactericidal assay); separate assays contained the above components and polymorphonuclear leucocytes (opsonization system). A decrease in bacterial density of ⩾ 1 log10 unit was considered significant. All four S-CSF strains, three of four E-CSF strains and one of three S-NP strains were sensitive to the bactericidal activity of pooled serum. The other E-CSF strain, two S-NP strains and all three E-NP strains were resistant to the bactericidal activity of pooled serum. Two of three E-NP strains were opsonized by pooled serum; the other strains resistant to the bactericidal activity of pooled serum were also resistant to opsonization. Bactericidal and opsonizing activity of serum from an immunized adult was greater than or equal to that of pooled serum against each strain. Assuming normal adults are immune to invasive H. influenzae type b infection, an experimental test reflecting this immunity is the bactericidal activity against CSF isolates tested in stationary phase. We conclude that protection against invasive disease due to H. influenzae type b appears more complex than the presence of bactericidal and opsonizing activity in serum.

Hyphomicrobium X grows on methylamine as sole source of carbon, energy and nitrogen. The uptake of the compound occurred via a single inducible transport system irrespective of whether methylamine was used as a carbon and energy source or a nitrogen source only. The transport system had the following properties: temperature optimum 30 °C, pH optimum 7·0, K m approx. 70–100 nm, V max 12·5 nmol min−1 (mg dry weight)−1. Methylamine uptake was inhibited by azide, cyanide, N-ethylmaleimide and carbonyl cyanide-m-chlorophenyl-hydrazone. The uptake was not inhibited by ammonium ions, was slightly inhibited by amino acids and amides but was competitively inhibited by short-chain alkylamines (K i ethylamine 200 nm). Cells grown on formate, methanol or ethanol as C-source and ammonium sulphate as N-source did not possess the transport system but this could be induced by the presence of methylamine for 45–50 min. The addition of formate, methanol or ethanol to methylamine-grown cells did not affect the rate of methylamine uptake. Bacteria pre-grown on dimethylamine or trimethylamine transported methylamine into the cells at rates of 99% and 52%, respectively, when compared to rates with cells pre-grown on methylamine.

When heat activated Phycomyces blakesleeanus spores were incubated at room temperature a rapid and transient increase in cyclic AMP content was observed. A similar increase was observed during the heat treatment itself but the cyclic AMP content had returned to the value of dormant spores at the end of the 5 min treatment. The cyclic AMP content increased only after treatments at temperatures which also induced spore germination. A more gradual rise in cyclic AMP was also found during activation at room temperature with acetate and after activation of the spores with pyrosulphite. The increase in cyclic AMP content is the earliest event known to occur after activation of the spores. It clearly preceded the increase in trehalase activity observed during and/or after all the activating treatments, suggesting that, as shown for in vitro activation, the in vivo activation of trehalase is due to a cyclic AMP-dependent phosphorylation. An increase in cyclic AMP was a common feature of all activation methods investigated and appears to be the factor triggering spore germination.

The plasmodium of Physarum polycephalum reacts to external stimuli tactically. Positive and negative taxes correspond to relaxation and contraction, respectively. Variations of intracellular cAMP and cGMP concentrations in response to chemical stimuli were examined in relation to the regulation of contractility. Concentrations of the two cyclic nucleotides oscillated, with a gradual shift, for some time after stimulation. The period of oscillation was 4-5 min, with phases being the same in response to repellents, but different when attractants were tested. Therefore, changes in the accumulation of the nucleotides summed over 15 min were taken as a quantitative measure of the external stimuli. Attractants (glucose, 2-deoxyglucose, galactose, maltose) induced decreases both in cAMP and in cGMP concentration, the latter being larger than the former. Repellents (KCl, CaCl2, MgCl2, sucrose) induced decreases both in cAMP and in cGMP concentration, the former being larger than the latter. Variations of the intracellular cAMP concentration for repellents and those of cGMP concentration for attractants, took place at similar concentrations of stimulants as variations of contraction and relaxation, respectively. Microinjection of cAMP and cGMP into the plasmodial strands induced contraction, cGMP being about 10 times as effective as cAMP. The results indicate that both cAMP and cGMP regulate the ability to contract, not antagonistically, but cooperatively, in the sensory transduction of the Physarum plasmodium.

A cationic polymer of d-galactosamine was isolated from culture filtrates of a colonial temperature-sensitive strain of Neurospora crassa. Adsorption of the polymer to the cell surface initiated immediate efflux of low molecular weight metabolites and subsequent loss of viability. The polymer appeared to bind to those sites on the cell surface that normally bind calcium ions. Chemical analysis of the polymer showed it to be partially N-acetylated. The polymer had an isoelectric point of 8·4. Thirty percent of the d-galactosamine residues contained free amino groups. A rapid assay that has potential application for monitoring the effect of a variety of other membrane-active factors on membrane permeability has been developed.