Abstract: 1 Partly purified DNA and the corresponding highly purified DNA was obtained from 25 strains of Gram negative, rod-shaped bacteria. 2 The DNAs were examined by the thermal denaturation method and the melting temperatures of both partly and highly purified DNA samples from the same strain were in close agreement. 3 For all strains, the mean difference in G+C contents estimated from the melting temperatures of each partly and highly purified DNA was 0.4% G+C. 4 The presence of residual RNA and protein in the partly purified DNA samples contributed to variations in the total hyperchromism but did not significantly affect the accuracy of the melting temperature determination.

Abstract: Heat resistance at 65· of Saccharomyces rouxii and Schizosaccharomyces pombe was enhanced in solutions of sugars and polyols, containing 0·1 M-phosphate buffer, pH 6·5, at a water activity of 0·95. Resistance was maximum in solutions of sucrose, less in sorbitol and least in solutions of glucose, fructose and glycerol. Examination of the yeast cells by phase contrast microscopy showed shrinkage of cells in all solutions. Electron microscopy of freeze-etched preparations of Sacch. rouxii indicated plasmolysis of cells in sucrose and sorbitol solutions only.

Abstract: A simple method for the isolation of Bacteroides nodosus from foot-rot lesions in sheep is described together with observations on the colony morphology of freshly isolated strains and variant colonies arising on subculture in the laboratory. Serological results from a study of English isolates demonstrate a multiplicity of types based on the K antigens as well as additional antigens common to all strains.

Abstract: A comparison of four methods of estimating the microflora of mouldy hay showed that more micro-organisms were removed by washing samples than by blowing in a small wind tunnel. By contrast, actinomycete spores were estimated more efficiently from air using an Anderson Sampler than by plating diluted washings because fewer bacteria were blown than washed off the hay. Estimates of fungal spores were larger from counts in haemocytometer cells than by dilution plating but counts of actinomycetes and bacteria were higher by dilution plating. Fungi grew equally well from air or water suspensions and with the Cascade Impactor and Anderson Sampler their numbers were estimated with less variation than for the numbers of ‘actinomycetes and bacteria’even on improved media and after correcting for viability, clumping and interference between colonies.

Abstract: One hundred and sixty-five reference strains and laboratory isolates of Gram negative, non-sporing, anaerobic bacilli were subjected to a series of simple laboratory tests that were initially selected for their discriminatory value. Conventional biochemical tests, tests of resistance to antibiotics, and tolerance to dyes and bile salts were included. These tests allowed a clear separation of strains into three main groups: Bacteroides fragilis, B. melaninogenicus and Fusobacterium spp. Certain tests were found useful for identifying recognized subspecies of B. fragilis and B. melaninogenicus. A scheme for the identification of unknown laboratory isolates of Gram negative anaerobic bacilli is presented.

Abstract: Taurolin, bis-(1,1-dioxo-perhydro-1,2,4-thiadiazinyl-4)-methan, is a novel, broad spectrum, non-systemic chemotherapeutic agent. It is effective in vivo against a wide range of pathogenic organisms including Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, and Salmonella typhimurium, and would be of particular use against antibiotic-resistant organisms. It is based on an endogenous substance, taurine, which acts as a non-toxic formaldehyde carrier donating methylol groups to bacterial protein and endotoxin thus causing denaturation and polycondensation of the pathogens and their pyrogens. It is anticipated that Taurolin will be of value in the treatment of faecal peritonitis.

Abstract: All of 20 different ground spices and three mixtures purchased locally were significantly contaminated by bacteria, and only cloves were free of moulds, but thermophilic actinomycetes were isolated from only six spices. In general, the mould floras were dominated by Aspergillus spp.: A. glaucus (group) and A. niger being the most common. A. flavus was found in 14 spices and seven of 24 strains examined produced aflatoxins in vitro. Whole ginger and Jamaica, red and white peppers supported growth of A. flavus strains and production of aflatoxins.

Abstract: Lactobacillus bulgaricus NCDO 1489 produced a single, cell-bound proteinase during growth on nutrient medium at 45°C. Proteinase activity was optimal at 45–50°C and pH 5.2–5.8. and was inhibited by chelating agents. The enzyme was mainly associated with the cell envelope but could be liberated from cells under conditions favouring autolysis or by treatment of the cells with lysozyme. Its relation to the growth of the organism in milk and possible role in formation of fermented milk products are discussed.

Abstract: Miniaturized methods for the characterization of streptococci, lactobacilli and aerobic Gram negative rods are described and the results obtained with 461 cultures from the calf rumen and quail gut tabulated. The methods afford a considerable saving in time and materials without concomitant loss of accuracy.

Abstract: 1 The behaviour of five salmonella serotypes in minced chicken breast (pH 5.8) and leg muscle (pH 6.4) held at 1 °C, -2 °C, -5 °C and -20 °C was studied with and without the addition of 0.35% polyphosphate (Puron 604). 2 In the absence of polyphosphate, survival of the test organisms was greater in breast than in leg muscle at all four temperatures, but was greatest at -20 °C in both types of muscle and least at -2 °C and -5 °C, just above and below the freezing point of the muscle. 3 Addition of polyphosphate increased the death rate of the salmonellae in breast muscle held at -2 °C and to a lesser extent at -20 °C but had little or no effect in leg muscle or in breast held at 1 °C or -5 °C.

Abstract: Azotobacter paspali grows in the rhizospheres of Paspalum notatum where it is thought to fix nitrogen actively and hence improve pasture growth. In the experiments described here A. paspali improved growth primarily by producing growth regulating substances. Nitrogenase activity was not detected in rhizospheres of young plants. Its occurrence in older plants was not necessarily associated with the presence of A. paspali and was greater in the rhizopheres of control than of inoculated plants.

Abstract: Of nine antihistamines screened for in vitro antibacterial activity, ambodryl (bromodiphenhydramine hydrochloride) and benadryl (diphenhydramine hydrochloride) were the most active. At 50 to 100 μ/ml concentrations these inhibited a large number of Gram negative and Gram positive bacteria in vitro, with ambodryl having a broader spectrum. In vivo tests showed that the compounds at single doses of 3 and 1.5 μg/g body weight protected mice against a challenge with a virulent strain (LD50) of Salmonella typhimurium, and also significantly reduced the multiplication of this organism in the liver, spleen and blood of the protected animals in comparison with the unprotected controls.

Abstract: A medium containing tributyrin stabilized with polyvinyl alcohol was used to demonstrate the lipase activity of bacteria in foods. A modification of this new medium enables a search to be made for lipolytic bacteria in soil.

Abstract: The use of antibiotics and drugs in fish farming has prompted an investigation into the elimination of these residues from fish muscle. Young rainbow trout were given intraperitoneal injections of either chloramphenicol, framycetin, oxytetracycline or sulphadiazine/ trimethoprim and muscle tissue was examined by microbiological assay over a period of weeks for the presence of active residues. The effect of the method of administration of two of the drugs was also investigated and the results discussed.

Abstract: A simple procedure for the freezing of large batches of yeast inocula (up to 150 samples) for storage at liquid nitrogen temperatures with the retention of high viability after thawing is described. The recovered frozen cells were examined using a flow microcalorimetric procedure which enables a rapid determination of viability. The application of such inocula to antibiotic assays and growth studies is discussed.

Abstract: The oxygen uptake of an Alcaligenes sp., isolated from activated sludge, was inhibited by small amounts of nitric oxide. The occurrence of this inhibition was dependent on the growth conditions and the pretreatment of the cells. Anaerobically grown cells, which had subsequently been aerated in a nitrogen-free medium, accumulated nitric oxide, after the addition of nitrate or nitrite. When the oxygen uptake was inhibited by nitric oxide, dissimilatory reduction of nitrate and nitrite proceeded under aerobic conditions at the same rate as in the absence of oxygen. Activated sludge removed nitric oxide actively under aerobic conditions and as a consequence the oxygen uptake of the sludge was not inhibited in the presence of nitrite. The rate of nitrate reduction under aerobic conditions was about 20% of that in the absence of oxygen.

Abstract: 1 Actinomycetes and fungi causing farmers’lung and infections in man and animals were isolated preferentially using an Andersen sampler after shaking spores from mouldy hay in a sedimentation chamber. 2 Actinomycetes were isolated after 2 h sedimentation and Aspergillus fumigatus and Absidia spp. after 30 min.

Abstract: The distribution of O-antigen types of Escherichia coli in calves over a ten-month period has been determined. A total of 400 calves from separate farms located over a wide area of England and Wales have been surveyed. Of the 148 O-types recognized, 93 were found in calves, compared with 107 in a previous survey in man; 42 of these were common to both hosts. In calves 60% of isolates were resistant to at least one antibiotic. Of these, 71% belonged to ten O-types, 9 of which were found in man. It is concluded that calves form a potential reservoir of R plasmid carrying E. coli.

Abstract: The recovery of vibrios, in particular Vibrio cholerae, non-cholera vibrios and V. parahaemolyticus, on four brands of TCBS has been compared. The selectivity of the media was also compared. Eiken TCBS performed best in our tests but was closely followed by Oxoid TCBS.

Abstract: The faecal excretion of E. coli from 6 adult cows was followed over a period of 105 days. E. coli were excreted in only 23·4% of specimens and the patterns of excretion varied between animals. All isolates of E. coli were antibiotic sensitive and fell into 6 O-antigen types; very few were non-typeable. The O-types excreted by each animal, compared with those from other cows in the same house, were traced with time. A similar but less intense study was undertaken in 8 calves. In contrast E. coli was excreted from all samples and included both antibiotic sensitive and resistant strains; 37 O-types were represented. The persistence of specific O-types within each calf and their spread to other calves in the same house were studied. A comparison of the O-types in the bovine species with those isolated from man has been made.

Abstract: 1A new technique is described for determining the fermentation reactions of non-sporing anaerobes. 2The fermentation reactions are carried out on horse blood agar plates to which fermentable substrates are added. 3The technique is simple, sensitive and yields reproducible fermentation patterns.

Abstract: This paper describes a method for testing the effect of various concentrations of SO2 on lactic acid bacteria from ciders. The media and methods were devised to minimize loss of SO2 due to oxidation or binding with carbonyl compounds. Exposure of laboratory or freshly isolated strains to various concentrations of free SO2 at pH 4·0 did not readily kill them even at high concentrations of free SO2 (c. 150 p/m or 0·97 p/m molecular SO2) yet they were suppressed at low concentrations (c. 5 p/m or 0·032 p/m molecular SO2). Reducing the pH to 3·4 reaffirmed how much more effective SO2 is against lactic acid bacteria at lower pH levels because more is present as molecular SO2. As a result of this the idea of quoting SO2 values as p/m molecular SO2 is advocated. Addition of hydrogen peroxide or acetaldehyde to a test system containing 142 p/m free SO2 showed that they had a similar effect in nullifying its antimicrobial properties and allowing the test bacteria to grow. There was no indication that acetaldehyde bisulphite was toxic to the test bacteria.

Abstract: Temperature and the composition of the medium influenced the production of proteinase by Pseudomonas fluorescens and Pseudomonas aeruginosa isolated from raw milk. Many isolates of Ps. fluorescens digested litmus milk at 10° but not at 5° or 2°. With Ps. fluorescens proteinase production per unit of growth in a Peptone–Yeast Extract broth declined progressively as the incubation temperature was reduced from 20° to 5°. At 30° there was heavy growth in the same medium but only slight proteinase production whereas enzyme production by Ps. aeruginosa was maximal at this temperature. Proteinase production by both species in semi-defined media was essentially a function of the organic nitrogen content of the medium; there was evidence of catabolite repression by glucose and, to a lesser extent, lactate. In milks seeded with these pseudomonads, the extent of proteolysis was either increased markedly or slightly decreased when glucose was included.

Abstract: The concentration of adenosine triphosphate (ATP) in rumen fluid from heifers fed high levels of nutrients continuously and after 12–24 h starvation has been determined in order to examine the influence of different physiological conditions. The conventional parameters for characterizing the rumen fermentation have been applied to control the effect of a different nutrient supply. The mean concentration of ATP, determined by the luciferin-luciferase assay, was 55.3 mg ATP/l rumen fluid in a heifer fed continuously, twice as much as found in a starved heifer. The mean ratio of biomass/ATP changed from 683 at the high level of energy intake to 1208 in the period of starvation. Consequently, the concentration of ATP in the rumen micro-organisms is markedly influenced by nutritional conditions. Finally, the applicability of ATP determinations in rumen microbiology is discussed.

Abstract: 1Lead-resistant bacteria isolated from domestic sewage showed simultaneous resistance to other inorganic metals and also antibiotics.

Abstract: Examination of the ultrastructure of strains of Bacteroides nodosus isolated from cases of ovine foot-rot shows the organism to be highly piliated on primary culture. On subculture in the laboratory two colony types characterized by a high and low degree of piliation can be demonstrated. In agglutination tests the interaction of pili with antibody is responsible for high titre homologous agglutination. Low titre heterologous agglutination appears to be due to other surface antigens. These findings are discussed in relation to the pathogenicity of the organism.

Abstract: An ineffective Rhizobium leguminosarum strain capable of forming green nodules of similar size and number as normally effective strains was tested for its ability to compete with an effective strain in nodule formation on the pea. The ineffective strain was found to be more competitive and influenced the pattern of nodulation by the effective strain on the same root system. Nodules containing both strains were pink and able to reduce acetylene.