bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Film Permeability on the Storage Life and Microbiology of Vacuum‐packed meat
Authors: NEWTON K. G. , RIGG W. J.
Published: March 2008

Joints of beef were stored in packaging films with oxygen permeabilities ranging from 0–920 ml/m224 h/atm at 25 °C and 100% r.h. The storage life of the ‘vacuum‐packaged’ meat, as assessed by discolouration and the development of putrefactive odours, was inversely related to film permeability; the best results were obtained with meat which received ‘zero oxygen’ treatment. The growth rates and final counts of Pseudomonas spp. increased with increasing film permeability; the storage life of the meat corresponded with the time taken for the counts of the organism to reach ca. 106/cm2 for putrefactive odours to be produced. Although their growth rate was unaffected, the final counts of Brochothrix thermosphacta also increased with increasing film permeability. These results are discussed in terms of the influence of film permeability on the inhibitory effects of Lactobacillus spp., whose numbers were unaffected by the permeability of the film used, and the substrates in the meat available to the bacteria.
Effect of Ammonia Concentration on the Composition, Hydrolytic Activity and Nitrogen Metabolism of the Microbial Flora of the Rumen
Authors: WALLACE R. J.
Published: March 2008

The mean NH3 concentration in the rumen of sheep fed whole barley (0d̀8 kg/d) by continuous feeders was increased from 6d̀1 to 13d̀4 HIM by supplementing the feed with urea (30 g/kg). This change caused a 90% increase in the rate of degradation of rolled barley, and smaller increases in the rates of degradation of protein and plant fibre in the rumen. The total viable count and numbers of pectinolytic bacteria in rumen fluid increased with the urea supplement. Enzyme studies indicated that NAD‐linked glutamate dehydrogenase was the main pathway of NH3 assimilation by rumen bacteria at both NH3 concentrations. Glutamate was the main free amino acid found in the rumen at low NH3 but, despite the low activity of alanine dehydrogenase and glutamate‐pyruvate aminotransferase, alanine was the principal amino acid at high NH3 concentrations. Hydrolytic rumen bacteria may require the higher NH3 concentration either for effective NH3 assimilation by an unknown mechanism involving alanine or for full expression of enzyme activity.
The Growth of Microbacterium thermosphactum on Beef
Authors: CAMPBELL R. J. , EGAN A. F. , GRAU F. H. , SHAY B. J.
Published: March 2008

Microbacterium thermosphactum grew aerobically at 5°C on beef when the pH was as low as 5.4. It did not grow anaerobically if the pH of the meat was below 5.8, but grew readily at pH 6.0 or higher. On vacuum‐packaged beef of pH 5.8 or lower, growth was dependent not only on pH but also on the oxygen permeability of the packaging film. Above pH 5.9 growth occurred with all the films tested.
A Note on Actinomycetes on a Museum Specimen of Eggshell
Authors: BOARD R. G. , PERROTT H. R.
Published: March 2008

The mycelium and spores of actinomycetes were present in and on minute black spots that had disfigured the white eggshell of a non‐parasitic cuckoo during museum storage.
The Combined Effect of Hydrogen Peroxide and Ultraviolet Irradiation on Bacterial Spores
Authors: BAYLISS CATHERINE E. , WAITES W. M.
Published: March 2008

Ultra‐violet (u.v.) light irradiation of spores of Bacillus subtilis in the presence of hydrogen peroxide produced a rapid kill which was up to 2000‐fold greater than that produced by irradiation alone. A kill of 99–99% was produced by 30s u.v. irradiation of spores of 6 strains of Bacillus and Clostridium in the presence of hydrogen peroxide 1.0 g/100 ml but with the more resistant spores of 9 further strains, irradiation in the presence of hydrogen peroxide 2–5 g/100 ml followed by mild heating was required.
The Bacterial Flora of the Rumen of Healthy and Bloating Calves
Authors: JAYNE‐WILLIAMS D. J.
Published: March 2008

Rumen samples from five healthy milk‐fed calves and one healthy calf given a milk‐replacer diet containing yeast protein had pH values of 6.5–8.0, total counts of ca. 1010/ml and viable counts of 108‐1010/ml. The facultatively and strictly anaerobic, and obligately aerobic, components of the floras were enumerated and identified. Similar tests performed on samples from two calves bloating on the yeast diet had pH values of 4.8 and 5.3, and although total and viable counts were of the same order as those from healthy calves, obligately aerobic bacteria were not detected and counts of lactobacilli were elevated. Infusion of the rumen of a calf with yeast diet caused a reduction in pH from 7.3–5.1 and an increase of at least 100‐fold in the numbers of organisms capable of forming copious gas from yeast diet. Results suggest that milk or milk‐replacer diet normally does not enter the rumen to any extent but when it does, due perhaps to poor palatability, bloat may ensue.
Fluorigenic Glycosidase Substrates: Their Use in the Identification of some slow growing Mycobacteria
Authors: GRANGE J. M. , McINTYRE G.
Published: March 2008

Glycosidase activity in slow growing mycobacteria was rapidly detected by the use of 4‐methylumbelliferone‐linked glycoside substrates. The species Mycobacterium nonchromogenicum, M. szulgai and M. marinum showed characteristic enzyme activities which distinguished them from the other species. M. marinum is unique among the mycobacteria so far examined in its possession of a very marked α‐L‐fucosidase activity. These fluorigenic glycosidase substrates should be of value in the identification of slow growing mycobacteria.
A Note on the Growth of Thiobacillus ferrooxidans on Solid Medium
Authors: MISHRA AJIT K. , ROY PRADOSH
Published: March 2008

An iron oxidizing strain of Thiobacillus ferrooxidans has been grown on solid medium using purified agar, carrageenan (Type 1) and agarose. This strain produces isolated and transferable colonies after 7 d incubation. Growth (increase in viable cells) by the direct plating method has been followed in relation to iron oxidation. Acidity, agar concentration and phosphate influenced colony development on solid medium.
Isoprenoid Quinone Composition as a Guide to the Classification of Sporolactobacillus and Possibly Related Bacteria
Authors: COLLINS M. D. , JONES DOROTHY
Published: March 2008

Menaquinones with seven isoprene units were the major isoprenoid quinones detected in the chloroform‐methanol extracts of representative strains of the genera Bacillus and Sporolactobacillus. Neither menaquinones nor ubiquinones were detected in similar extracts of strains of the genus Lactobacillus.
Isolation of an Encapsulated Strain of Staphylococcus epidermidis
Authors: YOSHIDA K. , MINEGISHI Y.
Published: March 2008

An encapsulated strain of Staphylococcus epidermidis isolated from a human clinical specimen was demonstrated by electron microscopy. The outermost layer of the cell wall of these organisms probably consists mostly of polysaccharide.
Value of Coliform Tests for Assessing Meat Quality
Authors: NEWTON K. G.
Published: March 2008

The reactions of 171 psychrotrophic coliforms and Aeromonas spp. isolated from meat and the meatworks environment were determined in media used for coliform tests in food. From 22–68% of strains, depending on the medium, gave positive presumptive and confirmed tests at 35°C. As positive reactions in these tests may be due to psychrotrophic and other non‐faecal coliforms, and Aeromonas spp., they have no value as indicators of potentially harmful contamination and it is suggested that these tests should not be applied to fresh meat and meat products.
Growth Factors for Mycoplasma pneumoniae in Yeast and Tissue Extracts
Authors: RYLANCE H. J. , MARR W. , MALCOLM MARGARET G. , STEWART SHEILA M. , MARMION B. P.
Published: March 2008

1. Many tissue extracts have been shown to have growth factor activity towards M. pneumoniae notably bovine lung. Yeast extract is therefore not unique in this respect. The materials in lung digest and in yeast extract are very similar in properties and could be identical.

2. The growth factor is a low molecular weight water soluble material. Despite its stability to heat it decomposes on storage, presumably by oxidation.

3. Chromatographic procedures, on both Dowex 50W columns and on paper, indicated the presence of two active components.
Synthesis of Polygalacturonate Trans‐eliminase and Polygalacturonase by a Strain of Enterobacter cloacae Isolated from Ponded Sitka Spruce
Authors: MACKEN JEAN , PICKAVER A. H.
Published: March 2008

During the ponding of Sitka spruce in lake water there was a change from a diverse, aerobic flora (16 species) to a restricted, facultatively anaerobic flora (1 or 2 species). This change corresponded with a marked increase in the degradation of pectin and a concomitant increase in the permeability of the wood to preservatives. A strain of Enterobacter cloacae (NCPPB 2909) isolated during ponding, synthesized an extracellular and intracellular polygalacturonase (PG) and an intracellular polygalacturonate trans‐eliminase (PGTE). Both PG and PGTE were growth–linked; extracellular PG was produced initially and then replaced by intracellular PG and PGTE. A change in the pH value of the medium did not alter the relative synthesis of enzyme. Reduced oxygen tension retarded growth but had no effect on enzyme activities. PG and PGTE of E. cloacae were shown to have specific ion requirements and when tap‐water was used in the preparation of a medium growth did not occur. The results are discussed in relation to an artificial system of sprinkling water, seeded with known species of bacteria, on to spruce wood in order to control the rate of pectin degradation and thus the permeability of the wood to preservatives.
Induction of l‐Serine Dehydratase in Aeromonas punctata
Authors: NELSON G. E. N.
Published: March 2008

l‐Serine dehydratase (SD) was produced to the extent of only 0·04 international unit (iu) per mg dry weight by Aeromonos punctata NRRL B‐928 when grown on a chemically defined medium. Addition of 2% (w/v) l‐serine to this medium increased SD ten‐fold or more, indicating a significant inductive effect. d‐Serine was toxic to the organism, making weights and enzyme titres uncertain, but dl‐serine induced a specific activity of SD at least equal to that from the l enantiomorph. With complex media containing beef extract, the toxic effect of d‐serine was partially overcome, and sufficient growth was obtained to permit reliable analytical figures; d‐serine induced slightly better specific activities than the l isomer. dl‐Serine at 2% concentration induced a specific activity of 1·2 iu/mg, twice that of l‐serine at that level.
Production of Bacterial Proteins from Cellulosic Materials
Authors: RAMASAMY K. , PRAKASAM K. , BEVERS J. , VERACHTERT H.
Published: March 2008

An aerobic mesophilic Pseudomonas sp. isolated from activated sludge degraded different cellulosic materials to varying‐degrees. The degradability was mostly influenced by the lignin content and the crystalline nature of the substrate. Filter paper and cotton fibres, containing little lignin, were degraded maximally. Lignin‐rich Pinus and Larix needles were digested to a lesser extent. There was a difference between natural substrates and substrates that had undergone industrial treatment. At maximal protein production, the isolate converted 11–40% (w/w) of cellulosic substrates into proteins. Alkali treatment of the substrates had only little effect. Cellulose contained in pig‐waste was also degraded by the isolate. At first there was a period of protein production, but after long incubation, the efficiency of conversion of cellulose to protein decreased.
Effects of Sulphate, Iron and Hydrogen on the Microbiological Conversion of Acetic Acid to Methane*
Authors: VAN DEN BERG L. , LAMB K. A. , MURRAY W. D. , ARMSTRONG D. W.
Published: March 2008

Sulphate stimulated the rate of conversion of acetic acid to methane in enriched cultures as well as in liquid from anaerobic fermenters fed with wastes, but the effect depended on the soluble iron content of the culture. At low soluble iron contents, i.e. 0–02–0–05 mM, sulphate had little or no immediate (after 7–10 d) effect, but at 0–5 mM or higher soluble iron content, sulphate (0–6 mM or more) significantly increased the rate of acetic acid conversion over that obtained with 0–5 mM soluble iron without sulphate. Long‐term continuous culture tests (100–160 d) showed that 0–6 mM or more sulphate increased the maximum growth rate of the culture from 0–07–0–08 d without sulphate to 0–14–0–16/d, even at iron levels of 0–02–0–05 mM. Hydrogen was inhibitory to the conversion of acetic acid to methane under all conditions tested, but stimulated the reduction of sulphate when present.
A Medium for Detecting β‐(1 →3) Glucanase Activity in Bacteria
Authors: MAHASNEH A. M. , STEWART D. J.
Published: March 2008

A plate medium for detecting β‐(1→3) glucanase activity in bacteria is described.
Lipids in the Classification and Identification of Coryneform Bacteria Containing Peptidoglycans Based on 2, 4‐diaminobutyric Acid
Authors: COLLINS M. D. , JONES DOROTHY
Published: March 2008

Strains of 2, 4‐diaminobutyric acid‐containing coryneform bacteria were degraded by acid methanolysis and the non‐hydroxylated fatty acid esters released examined by thin‐layer and gas chromatography. The major fatty acid structural types were straight‐chain, anteiso‐ and iso‐methyl branched‐chain acids. Polar lipids of the test strains were examined by two‐dimensional thin‐layer chromatography. All strains possessed very characteristic polar lipid patterns consisting of diphosphatidylglycerol, phosphatidylglycerol and a number of uncharacterized glycolipids. Menaquinones (vitamin K) were the sole isoprenoid quinones detected in the test strains. Corynebacterium insidiosum, Cor. michiganense, Cor. nebraskense and Cor. sepedonicum contained unsaturated menaquinones with nine isoprene units, whereas unsaturated menaquinones with 10 isoprene units predominated in strains of Cor. iranicum and Cor. tritici and a strain labelled Arthrobacter sp. The single strain of Cor. aquaticum examined contained comparable amounts of menaquinones with 10 and 11 isoprene units whereas strains of Cor. mediolanum and Flavobacterium dehydrogenans contained major amounts of menaquinones with 11 and 12 isoprene units. The results of the present study indicate that lipid markers may be of considerable value in the classification and identification of 2, 4‐diaminobutyric acid‐containing phytopathogenic and saprophytic coryneform bacteria.
Relationship Between the Increased Sensitivity of Heat Injured Clostridium perfringens Spores to Surface Active Antibiotics and to Sodium Chloride and Sodium Nitrite
Authors: CHUMNEY R. K. , ADAMS D. M.
Published: March 2008

Spores of Clostridium perfringens NCTC 8798 became increasingly sensitive to inhibition by sodium chloride, sodium nitrite and a mixture of polymyxin and neomycin when heated at 70–100°C. That the increased sensitivity to each agent was caused by the same cellular damage was suggested by: (1) the temperature coefficients for induction of cellular damage leading to increased sensitivity to all three agents were the same; (2) in the absence of the agents, the spores regained resistance to all three at about the same time and in each case in the presence of cell wall‐, protein‐ and DNA‐synthesis inhibitors; (3) combinations of the agents were generally no more inhibitory to the heated spores than were the individual agents.
A Note on a Highly Sensitive Modified ELISA Technique for Rhizobium Strain Identification
Authors: MORLEY SUSAN J. , JONES D. GARETH
Published: March 2008

A modification of the ELISA technique using a fluorescent substrate is described and comparisons are made between this highly sensitive technique and the conventional ELISA method for investigations of the Rhizobium/legume symbiosis. The technique can be used to detect Rhizobium spp. both from pure culture and from nodules on Trifolium repens, at a concentration of 104 cells/ml. Tests for cross‐reactivity indicated that the technique will facilitate a wide range of experiments which require the identification of Rhizobium strains.
Antibacterial Activity of a New Cephalosporin, Cefotaxime
Authors: RUSSELL A. D. , ROGERS D. T.
Published: March 2008

The antibacterial activity of a new cephalosporin derivative, cefotaxime (HR 756), was determined. The antibiotic was active at low concentrations against R+ and R‐ strains of Gram negative bacteria, including two out of three strains of Serratia marcescens. In general higher concentrations were needed to inhibit growth of Pseudomonas aeruginosa. Low concentrations induced elongation of cells in circumstances conducive to active growth; higher concentrations caused lysis in some strains. Cefotaxime was more stable than cephaloridine, cephalothin, cephalexin, cefoxitin and cefuroxime to various β‐lactamases.
The Potential for Nitrogen Fixation in a Lake Receiving Sewage Effluent (Grasmere, English Lake District)
Authors: JONES K. L. , ROSCOE JOSE V. , JONES J. G.
Published: March 2008

The potential for nitrogen fixation in the water column and sediment of Grasmere (English Lake District) was investigated using the acetylene reduction technique, with reference to seasonal changes and concentrations of dissolved oxygen and inorganic nitrogen in the epilimnion and hypolimnion. Potential rates of nitrogen fixation and MPN counts of nitrogen‐fixing bacteria correlated with each other and with decreases in dissolved oxygen concentration. The results suggested that selective changes in the nitrogen‐fixing microflora took place during the period of thermal stratification. Neither light‐dependent fixation, nor cyanobacteria could be detected in water column samples, and acetylene reduction was detected, for most of the season, only in samples of water and sediment to which a source of carbon and phosphorus had been added. The possible role of the sewage effluent in suppressing nitrogen fixation is discussed.
Interactive Growth of Staphylococcus aureus Strains with a Poultry Skin Microflora in a Diffusion Apparatus
Authors: GIBBS P. A. , PATTERSON J. T. , HARVEY J.
Published: March 2008

The growth of different biotypes of Staphylococcus aureus strains isolated from poultry was studied using the NBS Ecologen in which the interacting mixed culture was derived from the microfiora of hen skin and separated from the Staph. aureus culture by a membrane of 0.4 μm pore size. Inhibition of growth of the Staph. aureus cultures occurred with strains from each biotype. Marked inhibition of growth was always accompanied by the production of large numbers (>109/ml) of plaque forming units (phage). In the mixed culture chamber poultry phage group C strains became the predominant Staph. aureus type. The phages produced by the mixed culture showed a wide spectrum of lytic activity for the propagating strains of the human, bovine and poultry phage sets.
A Note on the Fate of El Tor Cholera and Other Vibrios in Percolating Filters
Authors: DANIELAND R. R. , LLOYD B. J.
Published: March 2008

Sewage effluent from the anaerobic settling tanks of the Oxfam Sanitation System contained reduced populations of Enterobacteriaceae and small numbers of non‐cholera vibrios (NCVs). This effluent was passed through percolating ‘filters’ constructed either of broken honeycomb bricks or corrugated iron in a zig‐zag stack. Multiplication of NCVs occurred in both filter matrices. Laboratory experiments confirmed that NCVs were able to multiply in sewage effluent in static culture and also that Vibrio cholerae El Tor was unable to multiply in this liquor, and died rapidly.
Fatty Acid and Polar Lipid Composition in the Classification of Kurthia
Authors: GOODFELLOW M. , COLLINS M. D. , MINNIKIN D. E.
Published: March 2008

Strains of Kurthia zopfii were degraded by acid methanolysis and the non‐hydroxylated fatty acid esters so released were examined by gas liquid chromatography. The major fatty acid types were straight‐chain, anteiso‐ and iso‐methyl branched‐chain acids. Monounsaturated fatty acids were not detected. The major fatty acid in five of the six strains examined consisted of 12‐methyltetra‐decanoic (anteiso‐C15) acid. The other strain possessed major amounts of both 13‐methyltetradecanoic (iso‐C15) and anteiso‐C15 acids. Polar lipids of all the strains were examined by two‐dimensional thin‐layer chromatography. All possessed a very simple polar lipid composition consisting of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine.
A Simple and Rapid Computer‐assisted Technique for the Identification of some Selected Bacillus Species using Biochemical Tests
Authors: WILLEMSE‐COLLINET M. F. , TROMP TH. F. J. , HUIZINGA T.
Published: March 2008

A computer‐assisted probabilistic identification technique was developed to identify species of the genus Bacillus known to be potentially pathogenic and/or frequently found as contaminants in pharmaceutical preparations. An identification matrix on 18 species of the genus Bacillus was constructed. Twenty‐four biochemical tests were used. The reaction profile of each species was quantified in probability terms and called up on a computer. The computer method was used on 30 test cultures. In each case, the most likely identification, according to the computer method, was the species to which the strain had already been assigned. In 29 of the 30 cases, the identification was with a probability level of one; in seven of these, however, more than one species tied for first choice. Only one strain was identified with a lower level of probability. The technique developed is comparatively easy to use and would seem to constitute a useful diagnostic tool within the pharmaceutical field.
Mechanism of Nitrite‐Induced Germination of Clostridium perfringens Spores
Authors: ANDO YOSHIAKI
Published: March 2008

A study has been undertaken to understand the mechanism(s) of the nitrite‐induced germination of Clostridium perfringens S40 spores. An increase in germination rates of the spores in response to increasing NaNO2 concentrations was entirely dependent on both pH and temperature of incubation. Low pH and high temperature were effective in accelerating the germination rate, the maximal germination level being reached at pH 4.0 and 60°C in the presence of 0.5 M NaNO2. On the basis of germination rate, the activation energy (μ) for the nitrite‐induced germination calculated was approximately 9.9 kcal/mol. Germination was greatly stimulated after pretreatment of spores with DTT at pH 10.5 to remove the coats. Furthermore, cortical fragments prepared from spores of the same organism were lysed not only by lysozyme but also by NaNO2. Hexosamine‐containing material was also solubilized by these reagents. However, nitrite, unlike lysozyme, released a considerable amount of free hexosamine as well. These results suggest that nitrite‐induced germination may involve an interaction of sodium nitrite as nitrous acid with some component of the cortex. A possible mechanism of nitrite‐induced germination is discussed.
Effect of Dietary Nitrogen on the Rumen Microbial Population in Lactating Dairy Cattle*
Authors: TEATHER R. M. , ERFLE J. D. , BOILA R. J. , SAUER F. D.
Published: March 2008

Rumen bacteria populations were compared in four groups of six lactating Holstein cows maintained on a basal diet (9.4% crude protein) of maize silage plus concentrate, either without supplement, or supplemented to bring the crude protein content of the diet to approximately 12.5% with soybean meal, urea, or maize silage with urea added at the time of ensiling. The response to increased dietary nitrogen was dramatic, with a 33‐36% increase in total dietary nitrogen level resulting in a 90% (urea) to 230% (urea silage or soybean meal) increase in bacterial numbers. Essentially all identified bacterial species responded to the dietary supplements. The greatest increases wereobserved among those bacterial species known to require branched chain volatile fatty acids for optimum growth in vitro, which included the predominant cellulose digesting organisms (Ruminococcus spp.) and Selenomonas spp., the dominant propionate producing species.
Bacteriological Examination of Ice‐cream in The Netherlands: Comparative Studies on Methods
Authors: TAMMINGA S. K. , BEUMER R. R. , KAMPELMACHER E. H.
Published: March 2008

Samples (351) of ice‐cream were examined for ‘total aerobic’ colony count, Enterobacteriaceae, coliforms and Escherichia coli. Different methods for the indicator groups were compared. A number of the samples were also examined for Staphylococcus aureus, Bacillus cereus and Salmonella spp. In addition samples were tested microbiologically to detect fraudulently added inhibitory substances. A percentage (31.1) of the samples showed a total count ≤ 103/ml; 11.0% contained > 105/ml. which is the limit laid down in the Dutch Food Law. The MPN of coliforms (without pre‐enrichment) was ≤1/ml in 46.7% of the samples; 7.4% showed MPNs > 103 ml. Corresponding figures for Enterobacteriaceae (with pre‐enrichment) were 25.4% and 16.8% respectively. A percentage (33.0) did not meet the present Dutch standard for coliforms. The figures for samples that did not meet the standards of the Food Law are somewhat higher than those found by the Food Inspection Departments, probably because the latter generally investigate more samples from large factories. Staph. aureus and B. cereus were found only sporadically. None of 36 samples, selected because they contained appreciable numbers of indicator organisms, was found to contain salmonellas. Of 100 samples 86% showed inhibitory properties to one or more test micro‐organisms. There was no correlation between a positive test and microbial quality. Sometimes, however, the flavouring agent (lemon and chocolate) seemed to exert an inhibitory activity. The hygienic quality of ice‐cream prepared in large factories was better than that of the other samples. The poor quality sometimes reported for ‘soft’ ice‐cream was not confirmed in our investigations. A typically favourable influence of flavour on bacteriological quality could be demonstrated only for lemon ice‐cream. The same values for MPNs of Enterobacteriaceae were found when overnight pre‐enrichment in buffered peptone water was replaced by 2 h resuscitation in tryptone soya broth. Resuscitation for only 45 min in peptone saline yielded lower results. When followed by an Enterobacteriaceae colony count, overnight pre‐enrichment, 2 h resuscitation in tryptone soya broth or 1 h resuscitation on tryptone soya agar in Petri dishes gave almost the same results. No differences were found in favour of MPNs when compared with colony counts of Enterobacteriaceae. The method found most efficient for the detection of Esch. coli in ice‐cream relies on resuscitation followed by enrichment in brilliant green bile lactose broth at 44°C.
The Effect of Cultural Procedures on the Attachment of Bacteria to Chicken Breast Meat
Authors: NOTERMANS S. , DUFRENNE J. , SCHOTHORST M. VAN
Published: March 2008

Various bacterial strains were cultured in a laboratory medium, on chicken breast meat or derived from faeces of orally infected chicks. Suspensions of these bacterial cultures were brought in contact with chicken breast meat. The way in which the bacteria were cultured had little influence on the number of bacteria which attached to the chicken breast meat surface or on as the strength of attachment (i.e. the easiness of removal of attached bacteria). Only bacteria from the faeces of freshly infected chicks (24 h after inoculation) attached in higher numbers (more than one log10 unit) and these were less easy to remove.
Fragmentation of Some Gliding Bacteria During the Growth Cycle
Authors: HUMPHREY BEVERLEY A. , MARSHALL K. C.
Published: March 2008

As similar relative size distributions were obtained when populations of gliding bacteria were studied with the light microscope or Coulter Counter, the latter was used to quantitate the fragmentation in Flexibacter sp. BH3 and Cytophaga sp. KM57. Both organisms fragmented in the late stationary phase of growth; both shrank rapidly in 0.9% (w/v) saline, and swelled on fixation in 2.5% (v/v) glutaraldehyde. Fixation in 0.025% (v/v) glutaraldehyde gave satisfactory preparations. The glucose concentration of the growth medium had little effect on motility, growth rate or size distribution, whereas an increase in the casamino acid concentration increased the duration of the exponential phase and the yield of cells but inhibited fragmentation and motility.
Effect of Nutrients upon Streptococcus mutans BHT and Streptococcus mitior LPA‐1 Growing in Pure or Mixed Culture on Human Teeth in an Artificial Mouth
Authors: DONOGHUE HELEN D. , DIBDIN G. H. , SHELLIS R. P. , RAPSON GILLIAN , WILSON CONSTANCE M.
Published: March 2008

Streptococcus mutans and Streptococcus mitior were both capable of colonizing the surfaces of human teeth in an artificial mouth. Although fermentable carbohydrate was not essential for colonization, highest numbers were recovered after 5 d if 5–0°***0 (w/v) sucrose had been available intermittently. When grown together in mixed culture the interaction of the two species was affected profoundly by the available nutrients. In the presence of synthetic saliva alone, Strep. mitior was strongly antagonistic to Strep. mutans. When a nutrient broth containing sucrose was also provided intermittently there was slight inhibition of Strep. mutans accompanied by an increase in the proportion of Strep. mitior in the plaque, although the former was the dominant organism under these conditions. When 0–5% (w/v) glucose replaced the sucrose, mutual antagonism occurred and fewer organisms were recovered than if only synthetic saliva had been available. One reason why a high‐sucrose diet encourages colonization by Strep. mutans may be that insoluble extracellular polysaccharide confers a competitive advantage upon it in the face of antagonistic agents such as the hydrogen peroxide produced by Strep. mitior.
A Note on the Anti‐Pseudomonas Activity of Cephalosporins with Chlorhexidine
Authors: BARNHAM M. , HUSBAND P.
Published: March 2008

Thirty clinical isolates of Pseudomonas aeruginosa were tested for susceptibility to cephaloridine, cefuroxime, cefotaxime and cefoxitin with and without chlorhexidine in agar dilution ‘chequerboard’ titrations and antibiotic disc tests. A synergistic response (σFIC = < 0.7) in combined titration with chlorhexidine was seen in 50% of the strains with cefuroxime and cefoxitin and 13% with cefotaxime. Cephaloridine MICs mostly exceeded the tested range but a definite reduction in combination was shown with 33% of strains. Susceptibility to cephaloridine, cefuroxime and cefoxitin was not enhanced to clinically useful levels and the effect was seen only in chlorhexidine concentrations close to the MIC. Disc tests failed to show the antibacterial activity of the combinations. It is suggested that the level of the principal lesion induced by chlorhexidine in the inner membrane might be too deep to affect the penetration of β‐lactam antibiotics to their site of action.
Isolation and Enumeration of Listeria monocytogenes from Sewage, Sewage Sludge and River Water
Authors: WATKINS J. , SLEATH KAREN P.
Published: March 2008

Listeria monocytogenes in sewage, sewage sludge and river water was isolated by enrichment at 4°C with subculture and enrichment in thiocyanate, naladixic acid broth and plating on to Tryptose Agar. The results indicated that L. monocytogenes is present in sewage and sewage sludge in considerable numbers and that this organism survives longer than Salmonella spp. on land sprayed with sewage sludge.
An Egg‐yolk Agar Diffusion Assay for Monitoring Phospholipase C in Cultures of Clostridium welchii
Authors: RIGBY G. J.
Published: March 2008

An egg‐yolk agar diffusion assay of phospholipase C has been developed and investigated. The results demonstrate the necessity for strict control of the pH and volume of the egg‐yolk agar and of the temperature and duration of incubation of the assay plates. The method has been used to monitor phospholipase C production in cultures of Clostridium welchii sparged continuously with CO2 in N2 and shows that maximal concentration occurs after ca. 6‐8 h incubation at 37°C. The concentration falls slowly during subsequent anaerobic incubation supporting the opinion that Cl. welchii may elaborate a proteinase which destroys phospholipase C.
Nutritional Requirement for the Expression of Nitrogenase Activity by Rhizobium sp. in Agar Culture
Authors: PANKHURST C. E.
Published: March 2008

The effect of various carbon sources, nitrogen sources, vitamins and trace elements on the ability of three strains (32H1, CB627, CB744) of a slow‐growing Rhizobium sp. to develop nitrogenase activity in agar culture was studied. Strains 32H1 and CB627 developed nitrogenase but showed differences with respect to the nature and concentrations of carbon sources required for optimum activity. Strain 32H1 had less specific requirements than CB627 in this respect and could sustain high nitrogenase activity over a wider range of phosphate concentration (5 to 60 mmol/1) in the medium than CB627. There were only minor differences between these two strains with respect to the nitrogen source [glutamine, asparagine, histidine or (NH4SO4] required in the medium for nitrogenase induction, and nitrogenase activity in both strains was unaffected by changes in the concentration of vitamins or trace elements supplied. Strain CB744 did not develop nitrogenase activity under any of the conditions tested. Adenosine 3′, 5′‐cyclic monophosphate (1 mmol/1) was found to accelerate derepression of nitrogenase synthesis in agar cultures of strains 32H1 and CB627.
An Ecological Study of Marked Rhizobium trifolii Strains on the Host Plant Trifolium repens var. Huai in an Acidic Peat and a Neutral Mineral Soil
Authors: MCLOUGHLIN T. , DUNICAN L. K.
Published: March 2008

An ecological study of the nodulation of Trifolium repens var. grassland Huai by genetically marked Rhizobium trifolii was carried out in two Irish soils, a neutral mineral and an acidic peat. An indigenous population of 2 x 104R. trifolii/g was found in the mineral soil. In the peat soil, 4 x 101R. trifolii/g was found in the uninoculated peat. This number increased to 4.5 x 105R. trifolii/g, however, eight weeks after the peat soil was neutralized, supplemented with nutrients and sown with uninoculated clover seed. Indigenous R. trifolii strains from the mineral soil were effective whereas strains from the peat soil were ineffective on the host plant T. repens under plant room conditions. The introduced strains were inoculated on to clover seed at the rate of 1 x 105R. trifolii/seed. In the mineral soil, the introduced inoculum failed to establish at any period during the growing season. In the peat soil, the percentage establishment of the introduced inoculum varied from 40‐50% of nodules selected eight weeks after sowing to 70‐90% of nodules selected at the end of the growing season.
Effects of the Human Intestinal Flora on Germ‐free Mice
Authors: HAZENBERG M. P. , BAKKER M. , VERSCHOOR‐BURGGRAAF A.
Published: March 2008

The effects of complete human intestinal flora and of intestinal anaerobes on germ‐free mice were studied. The gross composition of the flora of mice was similar to that of the flora with which the animals had been contaminated and appeared to be stable provided that the animals were kept isolated. The complete flora and the anaerobes reduced caecal weight to normal values and induced an antagonistic effect against Escherichia coli. In contrast to the complete flora, the anaerobes were not invasive in immunosuppressed mice and induced colonization resistance and antagonism against Pseudomonas aeruginosa.
Potassium Leakage as a Lethality Index of Phenol and the Effect of Solute and Water Activity
Authors: KROLL R. G. , ANAGNOSTOPOULOS G. D.
Published: March 2008

Continuous monitoring of K+ leakage from Serratia marcescens on exposure to phenol in aqueous and solute‐containing suspensions was followed by a K+ selective electrode. At each phenol concentration, the suspension reached an equilibrium between the internal and external K+ as the result of cell leakage. The K+ concentration at equilibrium was constant for each cell suspension and independent of the phenol concentration that induced it. Phenol concentration affected only the rate of K+ release and the time ‘tKmax’to reach the equilibrium state. The cell number affected the maximum K+ concentration at equilibrium and the rate of K+ leakage in such a way that ‘tKmax’was constant at a given phenol concentration. Therefore, the ratio tKmax/D value was constant at phenol concentrations below 1.2%. When the water activity of the phenol solutions was reduced by addition of sucrose and glycerol. the kinetics of K+ leakage compared consistently with that of lethality by phenol. Consequently, the concentration coefficient ‘n’derived from the log‐log plot of tKmax. and phenol concentrations was influenced by the solutes and the resulting water activity similarly as that derived from D values. Thus, ‘n’increased in the presence of suerose and decreased in the presence of glycerol progressively with their concentration. It was concluded that tKmax could be used as a lethality parameter with predominantly membrane active antimicrobial agents.
Transmission of Salmonella typhimurium among Feedlot Cattle after Oral Inoculation
Authors: CLINTON N. A. , WEAVER R. W. , HIDALGO R. J.
Published: March 2008

Fifteen six‐eight month old steers and bulls weighing approximately 160 kg were inoculated orally with a virulent strain of Salmonella typhimurium. Three or four inoculated animals were confined in each of four pens, immediately after inoculation, with approximately 22 uninoculated cattle. The pen size in the experimental feedlot was 23 x 46 m. The 15 intentionally inoculated animals all became infected and excreted Salm. typhimurium in their faeces. Two of them died of salmonellosis and more than half the cattle penned with the inoculated animals became infected within 8 d after exposure. Twenty‐four of the animals were still excreting salmonellas 71 d after initiation of the experiment.
Rapid Enumeration of Bacteria in Heat‐treated Milk and Milk Products Using a Membrane Filtration‐Epifluorescent Microscopy Technique
Authors: PETTIPHER G. L. , RODRIGUES UBALDINA M.
Published: March 2008

A rapid direct epifluorescent filter technique (DEFT), taking ca. 20 min to complete, was used to enumerate bacteria in heat‐treated milk and milk‐products. The DEFT count could detect as few as 5750 bacteria/ml in pasteurized and skim milk, pasteurized cream, whey and sweet cream butter and was in agreement with the standard plate count. The technique was also used to determine the sterility of cartoned ultra heat‐treated milk after incubation at 37°C. The agreement between the DEFT and plate count was poor for evaporated and condensed milks, some reconstituted skim milk powders, pasteurized whey and ripened cream butter. Possible reasons for this are discussed.
Hydrolysis of Selected Organophosphorus Insecticides by Two Bacteria Isolated from Flooded Soil
Authors: ADHYA T. K. , BARIK SUDHAKAR , SETHUNATHAN N.
Published: March 2008

Flavobacterium sp. ATCC 27551 hydrolysed both diethyl (parathion and diazinon) and dimethyl (methyl parathion and fenitrothion) phosphorothioates while Pseudomonas sp. ATCC 29353 hydrolysed only diethyl (parathion and diazinon) phosphorothioates. Glucose inhibited the hydrolysis of parathion by Pseudomonas sp., but not by Flavobacterium sp. Evidently, the Flavobacterium hydrolase differs from that of Pseudomonas sp. The Pseudomonas sp. converted 4‐nitrophenol to 4‐aminophenol in the presence of glucose and to nitrite in its absence; 4‐nitrophenol was not metabolized by the Flavobacterium sp.
The Effect of Water Activity and the aw Controlling Solute on Spore Germination of Bacillus stearothermophilus
Authors: ANAGNOSTOPOULOS G. D. , SIDHU H. S.
Published: March 2008

The germination of spores of Bacillus stearothermophilus was studied in nutrient broth in relation to the water activity (aw) of the medium, the nature of the aw controlling solutes glycerol, sucrose, KCl, and NaCl, and temperature. Quantitation of germination was based on the change of the phase‐bright spore to phase‐dark. Activation of spores was by exposure to 100°C/10 min in a medium of the same composition as that used for germination.

Of the four solutes used, sucrose proved most inhibitory to germination, especially in the upper part of the temperature range 38‐75°C, glycerol was the most favourable whereas KCl and NaCl, whose effect was almost identical, occupied an intermediate place. The glycerol effect became more pronounced as the aw of the medium decreased towards 0.960, becoming inhibitory thereafter.

The solute effect on spore germination followed a pattern that related to the class of solute, i.e. electrolyte or non‐electrolyte, and its cell penetration characteristics.

Solute penetration during heat activation and germination was considered as the major germination factor and was associated with the osmoregulation mechanism within the spore proposed recently as the basis of spore dormancy and resistance.
A Note on the Use of Membrane Faecal Coliform Medium for Enhancing Resolution and Accuracy when Enumerating a Small Plaquing Coliphage
Authors: PARKER W. F.
Published: March 2008

A modified membrane faecal coliform (mFC) medium was used to improve resolution and accuracy when enumerating plaques of bacteriophage MS2. The method enables an economical and rapid drop‐count technique to be used.
The Escherichia coli Content of Mytilus edulis from Analysis of Whole Tissue or Digestive Tract
Authors: AL‐JEBOURI M. M. , TROLLOPE D. R.
Published: March 2008

The dissected digestive tract of edible mussels from two sites was examined for Escherichia coli and the counts compared with those from the total tissue of parallel mussel samples. The method using 4 x 1 ml pour plates was preferred to the 1 x 4 ml pour plate or to the 2 x 0.2 ml spread plates. Counts from the digestive tract were up to sixfold higher than parallel counts using total tissue. Digestive tract inoculum also produced amplified Esch. coli detection when lightly polluted mussels were examined by the semi‐quantitative percentage‐clean technique. It was concluded that dissection of the bacteriologically rich digestive tract significantly increases the sensitivity of Esch. coli detection and has application in environmental assay procedures using mussels or other filter‐feeding molluscs. Significant differences in the frequency of Esch. coli biotypes from the two mussel locations could be related to small differences in the pollution regimes at these two sites.
Liposome‐trapped Penicillins in Growth Inhibition of Some Penicillin‐resistant Bacteria
Authors: CHOWDHURY M. K. R. , GOSWAMI R. , CHAKRABARTI P.
Published: March 2008

Liposome‐trapped penicillin causes growth inhibition of penicillin‐resistant Staphylococcus aureus (meta 18), Bacillus licheniformis (749/C) and Escherichia coli. Liposome has been prepared from the positively charged, negatively charged and polar lipids of respective organisms. Positively charged liposome containing penicillin causes 77% growth inhibition in the case of Staph. aureus (meta 18) and 61% in the case of Esch. coli. In the case of B. licheniformis (749/C), 40–43% growth inhibition has been observed with liposome‐entrapped penicillin. Homology, composition and charge of liposomes do not seem to have significant effect in percentage inhibition of this organism.
Observations on Infections Associated with South Wales Natural Waters
Authors: HARVEY R. W. S. , PRICE T. H.
Published: March 2008

Diseases associated with contaminated surface waters in South Wales are recorded. Information on these infections has been obtained from publications, records and personal experience in the Regional Public Health Laboratory, Cardiff.
Hemicellulose‐degrading Enzymes Synthesized by Rumen Bacteria
Authors: WILLIAMS A. G. , WITHERS SUSAN E.
Published: March 2008

Over 100 bacterial cultures isolated from ovine rumen contents by enrichment techniques in polysaccharide‐containing media were examined for the ability to degrade plant cell wall structural polysaccharides. Approximately two‐thirds of the isolates retained were Gram negative and amongst the coccoid isolates diplococci predominated. Many of the rods examined were piliated and/or flagellated. Thirty of the more active xylan‐ and arabinan‐degrading isolates were examined for both the production and activity of the principal polysaccharidase and glycosidase enzymes associated with plant cell wall polysaccharide hydrolysis, following culture in a hemicellulose containing growth medium. The wide range of glycosidase activities detected in these hemicellulolytic isolates was evidence for their rôle in the breakdown of dietary polysaccharides in the rumen.
A Comparison of Methods to Measure Operator Protection Factors in Open‐fronted Microbiological Safety Cabinets
Authors: CLARK R. P. , ELLIOTT C. J. , LISTER P. A.
Published: March 2008

Comparative tests to measure operator protection factors in microbiological safety cabinets in accordance with British Standard 5726 have demonstrated good agreement in the results obtained by a microbiological method using a Collison nebulizer and the technique producing an aerosol of potassium iodide. Either method is suitable for testing for operator protection factors in Class I and Class II safety cabinets.

The Collison nebulizer should be considered as the standard aerosol generator for the microbiological method; alternative nebulizers meeting the general requirements of BS 5726 should be compared in performance with this nebulizer if they are to be used for containment tests.

Any microbiological safety cabinet specified for a new installation should have been ‘type’ tested to ensure compliance with BS 5726. However, in order to ensure adequate performance, on‐site commissioning tests (and routine maintenance checks thereafter) are necessary to verify that air velocity, filtration and operator protection factor requirements are met.
Isolation and Characterization of Cellulolytic Bacteria from Activated Sludge
Authors: RAMASAMY K. , MEYERS M. , BEVERS J. , VERACHTERT H.
Published: March 2008

Cellulolytic aerobic bacteria were isolated from activated sludge systems. Of the media tested for enumeration, only filter paper media gave reliable counts. Five isolates were studied further for characterization. It was found that one strain (DK) belonged to the genus Cellulomonas. The other four strains expressed similarity to the genus Pseudomonas. The different characteristics that were studied, however, do not permit them to be identified with any recognized species. Based on certain characters we believe that they are alcaligenes‐like pseudomonads.
A Refinement in Mechanized Plating
Authors: ANAGNOSTOPOULOS G. D.
Published: March 2008

A plating instrument is described for use in the determination of viable counts of micro‐organisms in foods and other biological materials. It is based on the linear distribution of a fixed volume of inoculum on the surface of a rotating agar plate in a continuous spiral fashion. The rate of inoculation is controlled so that from the relative position and number of the emerging colonies, viable counts up to 109/ml can be obtained without the necessity to dilute the sample. Counting can be rapid and the time taken for reading the plates can be reduced considerably. The instrument includes controls for the variability in the agar thickness, uneven surface as the result of drying, multi‐plate inoculation without re‐charging and speedy de‐contamination between inoculations.
Antibiotic Production by Cutaneous Brevibacterium sp.
Authors: AL‐ADMAWY A. M. , NOBLE W. C.
Published: March 2008

Three isolates of a Brevibacterium species isolated from human skin produced an antibiotic active against Gram positive and Gram negative bacteria. The active compound is most probably a peptide with’a molecular weight in the range 1100–1400; there is chromatographic similarity to compounds such as tyrothricin. Production of such a compound in vivo could contribute to microbial interaction in, for example, tinea pedis.