- Volume 14, Issue 3, 1956

SUMMARY: Morphological and physiological studies were made of 12 strains of the genus Pullularia. Although inability to ferment carbohydrates has been reported characteristic of this genus, 10 of the strains produced acid from one or more carbohydrates. It is proposed that the genus be emended to include the new species P. fermentans.

SUMMARY: All the somatic antigens of ‘ smooth ’ type of some Escherichia and paracolon strains studied are not extracted by trichloroacetic acid (TCA), though they may be by boiling or by mechanical disruption of the cell.

SUMMARY: Ultraviolet irradiation and the radiomimetic antibiotic substance L-azaserine have similar effects in promoting the formation of radially enlarged cells and elongated filaments, and in the accumulation of metaphosphate in metachromatic granules, with a strain of Corynebacterium diphtheriae. Dosages effective for the formation of enlarged cells and filaments are lower than for stimulation of metaphosphate accumulation.

SUMMARY: Mutations were induced by storing non-dividing asexual spores of a Streptomyces sp. at 4° for varying periods of time. Certain stages among spores germinated at 27° were more ‘ sensitive ’ than others to this mutagenic action. This high sensitivity was not correlated with particular nuclear stages or with nuclear number. The increased frequency of mutants cannot be attributed to selection (either decreased survival of the wild type or selective growth of previously existing mutants), to increased background (gamma) radiation or to temperature shock. The data indicate that mutation rate is a function of the physiological condition of the spore and that mutations may occur in the absence of nuclear division.

SUMMARY: Suspensions of various mesophilic strains of Desulphovibrio desulphuricans show absorption bands attributable to a cytochrome and a green protein; there are small differences in the position of absorption maxima depending on the strain and culture medium. Both pigments have been extracted, together with flavins rich in flavinadenine dinucleotide; an electrophoretically and chromatographically pure preparation of the cytochrome has been obtained and is designated c 3. The green protein has been termed ‘desulphoviridin’.

Cytochrome c 3 is a soluble autoxidizible thermostable haemoprotein (reduced bands at 553, 525 and 419 mμ.) of low redox potential ( − 205 mV.), high iso-electric point (pH >10) and containing 0·9 %Fe. Degradation studies indicate that it is a bifunctional haemato-haematin with the thio-ether haem-apoprotein links also found in cytochromes c and f; its m.w. is approx. 13,000 (S20,w = 1·93 × 10−13). Spectroscopic data for various derivatives including haemin c 3 and a porphyrin derivative are recorded. Material purified to at least 94 % by cellulose and ion-exchange chromatography acts as carrier in the reduction in hydrogen of sulphite, thiosulphate, tetra-thionate or dithionite by detergent-treated bacterial preparations; a similar role has been demonstrated with cell-free systems which reduce sulphite, thiosulphate and tetrathionate. Benzylviologen would replace cytochrome c 3. No preparation has been obtained showing c 3-linked sulphate reduction; the evidence for this depends on difference spectra and competition by known sulphate antagonists.

Oxidation of H2 or organic compounds with O2 has been demonstrated with these bacteria; the H2/O2 reaction takes place fastest in an atmosphere containing 4 % O2, when oxygen is frequently reduced faster than sulphate. The reaction requires the mediation of cytochrome c 3 and is probably a consequence of the autoxidizibility of c 3.

Desulphoviridin is a thermolabile, soluble, acidic porphyroprotein absorbing at 630, 585 and 411 mμ.; no metabolic function has been detected. It is stable over a limited pH range and decomposes readily, yielding a chromophoric group which fluoresces red in ultraviolet light, absorbs at 595 mμ. in neutral and alkaline solution (solution red) and at 612 mμ. in acid solution (solution blue-green). This material can be purified by chromatography on ‘Florisil’ or paper. It is very photo-sensitive and water-soluble. Its character is obscure; it may be a highly carboxylated chlorin. Spectroscopic data are recorded.

SUMMARY: The infective transfer of defective lambda lysogeny from a defective prophage to sensitive Escherichia coli has been observed. The agent of transfer appears to be lambda phage in which has been incorporated the hereditary defective element. It is concluded that the existence of the phage genes responsible for defective lysogeny is not limited to the prophage condition.

SUMMARY: Hydrolysates of cell-wall preparations of more than 60 strains of corynebacteria, lactobacilli, streptococci, staphylococci and other Gram-positive cocci have been examined by paper chromatography. A very high proportion of the amino acid moiety of the cell-wall complex could in each case be accounted for in terms of 3 or 4 of the amino acids alanine, glutamic acid, lysine, diaminopimelic acid, aspartic acid and glycine. These were associated with varying combinations of sugars and amino sugars. In general, each bacterial genus appears to have a characteristic pattern of cell-wall components, particularly in regard to the amino acids present. Variations in the relative proportions of the sugars appear to differentiate the individual species within a genus. The possible value of cell-wall composition as a taxonomic character is discussed.

SUMMARY: A theoretical treatment of continuous culture is given, which allows quantitative prediction of the steady-state concentrations of bacteria and substrate in the culture, and how these may be expected to vary with change of medium, concentration and flow-rate. The layout and operation of a small pilot plant for the continuous culture of bacteria are described. This plant has been operated continuously for periods of up to 4 months without breakdown or contamination of the culture. No alterations in the properties of the organisms studied have occurred during such periods of continuous culture. Results are given of a series of experiments on the continuous culture of Aerobacter cloacae in a chemically defined medium, designed to allow quantitative comparison with the results predicted by the theory. The relative advantages of batch and continuous culture as production processes are discussed, and it is concluded that continuous culture may usually be expected to show a five to tenfold increase in output as compared with a batch process.

SUMMARY: Five A strains and three B strains of influenza virus were purified and found to contain ribonucleic acid in amounts varying from 0·75 to 1·1 %. The proportion of the purine and pyrimidine derivatives in the nucleic acid of each strain was determined. When the ratio adenine + uracil : guanine + cytosine was evaluated, the following values were obtained: A strains —PR 8, 1·27 ± 0·02; MEL, 1·22 ± 0·01; WSE, 1·26 0±01; SWINE, 1·24 ± 0·04; CAM, 1·28 ± 0·01. B strains—LEE, 1·42 ± 0·04; MIL, 1·43 ± 0·05; ROB, 1·38 ± 0·01. The nucleic acid content of PR8 virus preparations of varying degrees of incompleteness was determined both by specific absorption at 260 mµ. and by estimation of phosphorus present in the nucleic acid extract. As measured by both methods, virus preparations of low infectivity were found to have a decreased nucleic acid content. The demonstration of specific differences in the nucleic acid of A and B strains and of the relationship between the infectivity and nucleic acid content of the virus affords strong evidence that the nucleic acid is an intrinsic part of the influenza virus particle.

Purified preparations of influenza virus were examined in the ultracentrifuge and electron microscope principally to assess the degree of purification achieved. As indicated in the main paper (Ada & Perry, 1956) the same purification procedure was used for each batch of virus.

SUMMARY: The sensitivity to various antibiotics of certain facultatively anaerobic bacteria when growing under aerobic or anaerobic conditions was compared. The antibiotics tested were: dihydrostreptomycin, penicillin, chloramphenicol, erythromycin, carbomycin, chlortetracycline, oxytetracycline, tetracycline. Dihydrostreptomycin was unique amongst the antibiotics tested in being less active against facultative anaerobes when they were growing anaerobically than when growing aerobically. Dihydrostreptomyein was relatively inactive against Clostridium welchii and C. novyi, and its action was governed by the inoculum size. Dihydrostreptomyein is not a useful selective agent for the isolation of C. welchii.

SUMMARY: The colour variation of a strain of Fusarium oxysporum Schlecht ex Fr. was found to depend on the production of carotenoids and naphthoquinones. The carotenoids were only produced as a result of exposure to light, whereas the production of naphthoquinones, which were pH indicators, was mainly regulated by the carbon/nitrogen ratio of the medium. The morphogenetic effects of radiation and of carbon/nitrogen ratio were also considered. A low carbon/nitrogen ratio favoured chlamydospore formation and aerial mycelium, whereas ultraviolet radiation, and to a lesser extent light, promoted macrospore and sclerotium production.

SUMMARY: The localized formation of perithecia in colonies of Chaetomium globosum growing in association with certain other micro-organisms (e.g. Aspergillus fumigatus) is associated with the presence of organic phosphates, especially phospho-glyceric acid, in the medium. These phosphates are normal metabolic products of the associated micro-organism, and only when they diffuse into the medium and locally reach a critical concentration does the fruiting response follow.

SUMMARY: Equipment for the automatic control of pH value in cultures of micro-organisms is described. The apparatus was designed for a 2 l. scale continuous culture apparatus. The equipment will continuously control pH value with an accuracy of ± 0·05 unit for periods of many hundred hours. The pH value may be changed at will by turning a knob on the controller. It is sufficient to check the pH meter standardization once every day or two. The main components of the apparatus are standard commercial products.

SUMMARY: In twelve strains, comprising three species of saprophytic Spirillum and two of Vibrio, a life cycle was observed in which small gonidia, resembling very tiny bacteria, sometimes motile by means of polar flagella, were formed within enlarged mother-cells. After a period of reproduction in this phase, the gonidia became progressively enlarged to reconstitute the original form. In one species of Spirillum, the cycle was induced by the addition of penicillin to the medium, and in this and certain other respects was reminiscent of the L-cycle.

SUMMARY: A new Vi-phage type of Salmonella typhi, T4904, is described. The homologous typing phage (phage 4904) was prepared from phage D 6, a host-range mutant of Vi-phage II. The new type belongs to the E group and consists of type E1 carrying the determining phage d6. The formula El(d6) has therefore been assigned to it. The host range of phage 4904, the homologous typing phage, is considered in relation to the structural formula of T4904. This formula fully explains the ability of the phage to lyse strains other than T4904. The general aspects of adaptation of Vi-phage II to new Vi-types of S. typhi are discussed. It is shown that the older attitudes to this subject require modification in the light of recent work. The applications of the results of study of the temperate type-determining phages to the solution of practical problems in Vi-phage typing are described.

SUMMARY: Spore suspensions were used to investigate the metabolism of p-hydroxy- benzaldehyde, ferulic acid, syringaldehyde and vanillin by Haplographium sp., Hormodendrum sp., Penicillium sp. and Spicaria sp. The intermediate products of their metabolism, p-hydroxybenzoic, syringic and vanillic acids, were found to be attacked by adaptive enzymes. The formation of these enzymes was greatly decreased by the antibiotic citrinin.

The results of experiments, based on a technique in which fungal spore suspensions were used in place of hyphae, are presented in this paper. Under investigation was the metabolism of certain phenolic compounds related to lignin, which have already been reported to be utilized by soil microfungi as sources of carbon (Henderson & Farmer, 1955).