bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF SATURATED FATTY ACIDS ON OXYGEN UPTAKE BY PENICILLIUM CHRYSOGENUM
Authors: ROLINSON G. N. 
Published: March 2008

Summary:The respiration of washed mycelium of Penicillium chrysogenum suspended in phosphate buffer solutions in the presence of the sodium salts of n‐fatty acids containing even numbers of carbon atoms was examined, using mycelium which had been grown in a lactose‐corn steep liquor‐salts medium in submerged culture. At pH 6.4 and at a concentration of 1.0% (w/v), acids of short (C2–C4) and long (C16–C18) chain length were readily oxidized, but acids of intermediate chain length (C8–C10) were toxic and completely inhibited even the endogenous respiration. The two latter acids were however oxidized at lower concentrations at pH 6.4. The toxicity of sodium caprate (C10) also depended on the pH of the system. At pH 7.0 and above, 0.02% caprate was readily oxidized; but below pH 6.0 that concentration became increasingly toxic and at pH 4.5 all respiration was inhibited. However, even at pH 4.5 very low concentrations of sodium caprate were oxidized. At pH 6.3, 0.025% sodium caprate completely inhibited the oxidation of glucose, peptone and sodium acetate but the oxidation of oleic acid was only partially suppressed. A concentration of 0.05% was required to inhibit completely the oxidation of oleic acid.
A FACTORIAL INVESTIGATION OF SOME TEST CONDITIONS IN THE EVALUATION OF THE DISINFECTANT PROPERTIES OF QUATERNARY AMMONIUM COMPOUNDS USING A DRIED FILM OF BACTERIUM COLI TYPE I
Authors: CLARKE PAMELA M. , GARVIE ELLEN I. 
Published: March 2008

SUMMARY: In a series of experiments in which a suspension of Bacterium coli strain 28.D.10, dried on a metal surface, was treated with alkyldimethylbenzylammonium chloride (BC) and cetyltrimethylammonium bromide (CTAB), the variability of the results compared favourably with that observed by other workers in the same field of disinfection, but using different methods.Quantitative estimates were obtained for the effects and interactions, on the bactericidal activity of the quaternary ammonium compound, of time and temperature of exposure, and of concentration of the compound. Increases in each of these factors reduced the percentage of surviving organisms. CTAB was less active than BC. Changes in pH between 5 and 9 did not affect the estimated activity of BC or CTAB, but in the presence either of phosphate or of borate buffers the bactericidal activity of both compounds was decreased.
SOME OBSERVATIONS ON THE BACTERIAL CONTENT OF WATER IN WATERCRESS BEDS
Authors: JONES G. ELIS , BAKER LILY A. E. 
Published: March 2008

SUMMARY: Samples of water flowing into watercress beds had higher bacterial contents during the summer months although this was less marked among samples from deep underground sources. Outlet samples showed higher contents than inlet samples and the bacterial content varied markedly with season, being highest in summer.The presumptive coli‐aerogenes contents at 30°, 37° and 44° also showed a similar seasonal variation among samples from the outlets but the marked inferiority of samples other than from bores was no longer apparent after the water had flowed through the beds. The dominant types were Bact. aerogenes type I, pectate liquefiers, Bact. coli type I, and Intermediate type I.The importance of the pectate liquefiers was confirmed by plating on pectate gel and by their isolation from these plates and from MacConkey's broth.
A SIMPLE PROCEDURE TO DETECT NISIN IN CHEESE
Authors: MOCQUOT G. , LEFEBVRE ELISABETH 
Published: March 2008

SUMMARY: A suitable amount of agar medium inoculated with a test organism sensitive to nisin (Lactobacillus lactis or Streptococcus cremoris) is poured on a cheese cylinder placed in a Petri dish. After a convenient incubation time the presence of a clear zone around the cheese cylinder will indicate the presence of nisin.The method is applicable both to natural and processed cheese and can also be used for other antibiotics that may be present in cheese.
ADVISORY MICROBIOLOGICAL STANDARDS AND TOLERANCES FOR RAW MILK
Authors: GRIFFITHS D. G. , DRUCE R. G. , THOMAS S. B. 
Published: March 2008

SUMMARY: To study the value of recent modifications of microbiological tests used for advisory purposes, samples of tuberculin tested milk, taken at weekly intervals over a 5 year period from the Trawscoed Experimental Husbandry Farm and selected at random during a 12 months period from farms in Wales, were examined by a temperature compensated keeping quality test at 22°, colony count on Yeastrel milk agar in 3 days at 30° and coli‐aerogenes colony count on violet red bile agar in 20–24 hr at 30°.The results show that milk produced and handled under hygienic conditions can be expected to have colony counts of less than 2 × 104/ml and coli‐aerogenes colony counts less than 10/ml when examined within 18 hr of milking.
STUDIES OF THE GROWTH OF PENICILLIUM CHRYSOGENUM IN CONTINUOUS FLOW CULTURE WITH REFERENCE TO PENICILLIN PRODUCTION
Authors: PIRT S. J. , CALLOW D. S. 
Published: March 2008

SUMMARY: A filamentous mould was cultured by the continuous flow method in which medium is supplied at a constant rate and the culture volume is kept constant. Flow rates up to 0·1 culture volumes/hr were used. The mycelial dry weight concentration and the yield of mycelium/g of carbon source used were equal to or slightly greater than the maximum obtained in batch culture. With glucose concentrations up to 80 g/1. at a flow rate of 0·05 culture volumes/hr, about 45% of the substrate carbon was converted into mycelial carbon and the remainder oxidized to CO2.With unlimited amounts of all nutrients available growth of the mould followed the exponential law, as does bacterial growth, and therefore the mould had a constant doubling time.The oxygen demand of the mould as function of growth rate was determined.Conditions were found under which the rate of penicillin production/g of mycelium remained at its maximum value for 1000 hr.
A METHOD FOR ESTIMATING LOW CONCENTRATIONS OF DIFFUSIBLE PENICILLINASE
Authors: HEDGES A. J. 
Published: March 2008

SUMMARYA method suitable for the assay of low concentrations of diffusible penicillinase has been developed and its technique is described. The concentration of soluble penicillinase in a sample is estimated by comparing its rate of diffusion in an agar gel with that of a standard preparation, the extent of diffusion being detected, after a fixed period, by a microbiological method employing ‘zones of exhibition’. The method enables four similar samples to be compared on a single large plate in the form of a randomized Latin Square. Under these conditions a concentration of penicillinase able to inactivate only 2 units of penicillin/ml/hr was measurable with an experimental error (95% confidence interval) of c.±10%.
THE EVALUATION OF SURFACE ACTIVE DISINFECTANTS FOR USE IN MILK PRODUCTION
Authors: COUSINS CHRISTINA M. , HOY W. A. , CLEGG L. F. L. 
Published: March 2008

SUMMARYDetails are given of a can test for evaluating detergent‐sterilizers intended for farm dairy use. The materials are compared with a standard hypochlorite‐detergent solution for their ability to cleanse milk‐soiled metal surfaces resembling those encountered in practice.Results from the can test have been compared with those from a suspension test. This comparison suggests that the suspension test is of value for the initial screening of QAC‐detergent mixtures, since those with poor disinfectant properties in suspension acted poorly on surfaces. However, products giving good disinfection in suspension may fail to cleanse a soiled surface if they are poor detergents.
THE PSEUDOMONAS AND ACHROMOBACTER GROUPS OF BACTERIA IN THE SPOILAGE OF MARINE WHITE FISH
Authors: SHEWAN J. M. , HOBBS G. , HODGKISS W. 
Published: March 2008

SUMMARYTotal colony counts and analyses of the bacterial flora of the skin slime of cod, carried out at 5‐day intervals during the stowage of the fish in ice, showed that organisms of the genera Pseudomonas and Achromobacter became predominant in the later stages of spoilage.
TWO TYPES OF XYLAN FERMENTING BACTERIA FROM THE SHEEP RUMEN
Authors: HOBSON P. N. , PURDOM MARY R. 
Published: March 2008

SUMMARYDifferent types of media containing xylan were used to culture bacteria from the sheep rumen. The results suggest that facultatively anaerobic bacteria are not active in the ruminal fermentation of xylans. Gram‐negative curved rods were the predominant bacteria growing in all anaerobic cultures under CO2 and those isolated were similar to Butyrivibrio fibrisolvens. The properties of two types of xylan fermenting bacteria are given.
THE SAFETY AND CLEANLINESS OF WATERS AND FOODS
Authors: McCOY J. H. 
Published: March 2008

SUMMARYThere are two reasons for the bacteriological examination of water supplies and foods; first to determine whether the commodity is safe to consume, i.e. that pathogenic organisms are absent; second, to determine whether the commodity is clean, i.e. that the level of nonpathogenic organisms is such that the commodity will suffer no significant deterioration in quality during normal conditions of storage and transport between preparation and delivery to the consumer. In the examination of water supplies and of shellfish growing in polluted waters, both the safety and the cleanliness of the product are assessed by a single examination for the presence of the normal inhabitants of the intestinal tract of man and animals. In the examination of foods only the cleanliness of the product is assessed by an examination for the presence of normal intestinal inhabitants. The safety of foods can be assessed only by examination for the presence of pathogenic organisms.
AN ECOLOGICAL INVESTIGATION ON THE USEFULNESS OF TWO SPECIFIC MODIFICATIONS OF EIJKMAN'S TEST AS ONE OF THE METHODS USED FOR THE DETECTION OF FAECAL CONTAMINATION OF FOODS
Authors: MOSSEL D. A. A. 
Published: March 2008

SummaryAn investigation has been carried out on the suitability of two modifications of Eijkman's heat tolerance test which had previously been found useful for the detection of Escherichia coli strains of faecal origin in foods. These were: plating on Chapman's lactose tergitol‐triphenyltetrazolium agar incubated at 44°, and enrichment in brilliant green‐bile fluid incubated at 44°, followed by subculture in the same medium and in tryptone water to test indole formation. Two materials having quite different histories of faecal contamination were examined. These were ‘coliform positive’ ice cream samples and bulk raw human milk. The reliability of both methods was found to be very satisfactory.In spite of this, such Eijkman tests appeared to have only limited usefulness because E. coli was found to be readily outgrown by other bacteria under extraenteral conditions; E. coli was therefore absent relatively often even from 1 ml samples of human milk which contained quite high numbers (i.e. > 103/ml) of other organisms of faecal origin. It is recommended, therefore, that too much reliance should not be placed on the outcome of Eijkman tests, especially when they give a negative result. The hygienic evaluation of foods should rather be based on the results of the simultaneous enumeration of three groups of organisms, namely E. coli, faecal types of Klebsiella (i.e. those which are urease positive) and Lancefield group D streptococci.A striking result of this investigation was the occurrence in 69% of the human milk samples of 44° positive Achr. anitratus (B5W) in numbers from 10–5.6 times 103/ml. These bacteria were almost invariably found in samples which were E. coli negative; klebsiellae, many of which were Kb. oxytoca, were also found in such samples. The properties of these organisms and their ecological significance are discussed.
The Effect of Gamma Radiation on Some of the Organisms of Soil
Authors: Monib M. , Zayed M. N. 
Published: March 2008

SummaryA loam soil of pH 8.0, supplemented with 1% of glucose, was irradiated with gamma rays at doses from 0.1 to 1 Mrad. Microbial counts were made immediately after irradiation, and after 15 and 30 days of incubation. The higher the dose, the greater the damage to micro‐organisms, but even the highest dose did not completely sterilize the soil. Azotobacters were killed by 1 Mrad and very much reduced in numbers by smaller doses. Clostridial spores were unaffected by 0.1 Mrad, and more resistant than azotobacters to larger doses. Streptomycetes developing on agar plates were more affected than bacteria at first, but during incubation the number of streptomycetes in the irradiated samples increased to more than the number in nonirradiated controls. Doses of irradiation that are too small to sterilize a soil evidently upset the equilibrium between bacteria and streptomycetes.
A Short Cycle Autoclaving Procedure
Authors: Jayne‐Williams D. J. , Lawes L. F. 
Published: March 2008

SummaryModifications to an autoclave are described which permit media in flasks or tubes to be cooled rapidly after sterilization at higher temperatures for shorter times than are generally used. Short cycle autoclaving has been shown to have a greater sporicidal effect but lesser chemical effect than conventional autoclaving.
A Diagnostic Key for Identifying the Lactic Acid Bacteria of Vacuum Packed Bacon
Authors: Cavett J. J. 
Published: March 2008

Summary: The lactic acid bacteria isolated from stored vacuum packed sliced bacon cured in fresh brine were divided into nine groups according to a simple diagnostic key. The key was developed to help in recognizing genera which were often morphologically similar.The genera were Streptococcus (group D), Leuconostoc, Pediococcus and Lactobacillus (both hetero‐ and homofermentative), and all could grow at temperatures down to 10°. A ‘tetracoccus’ and a group of motile lactobacilli were also found. Some homofermentative groups were atypical and differed from species at present recognized. Intermediate forms were found among the heterofermenters.
The Effect of Freezing on the Radiation Sensitivity of Bacterial Spores
Authors: Matsuyama A. , Thornley Margaret J. , Ingram M. 
Published: March 2008

Summary: Bacillus pumilus spores, irradiated under aerobic conditions, were inactivated exponentially at the same rate whether they were at room temperature (10–13°) in phosphate buffer or at ‐79° in phosphate buffer or in heart infusion broth.Clostridium welchii spores were irradiated in Robertson's cooked meat medium under anaerobic conditions. With unheated spores, and those subjected to a heat shock before irradiation, the inactivation rate was the same at room temperature and ‐79°. The same applied to spores heat shocked after irradiation for doses up to 450 Krads, but above this dose level the spores irradiated frozen were more sensitive.The effect of the heat shock, whether applied before or after irradiation, was to increase the number of survivors, and the proportionate increase appeared to vary with dose.
Psychrotrophic Clostridia
Authors: Beerens H. , Sugama S. , Tahon‐Castel M. 
Published: March 2008

Of 287 strains of clostridia of 23 different species 96 grew well at 6°, 77 of which were Clostridium carnofoetidum var. amylolyticum and 16 were Cl. perfringens.The water of polluted wells seems to be the normal habitat of Cl. carnofoetidum var. amylolyticum. This species is both proteolytic and saccharolytic and is not pathogenic for mice or guinea pigs. Spores survive at 80° for 40 min. Mg is essential to obtain sporulation of the strains in artificial environments.Growth temperatures vary between 6 and 37° with an optimum at 30°. At 6° strains untrained to grow at this temperature grow in about 5 days in Rosenow medium. Trained stains have a lag phase of 24 h. Growth curves show a longer logarithmic phase at 6° than at 30°. At the end of this phase the bacterial count is the same at both temperatures. Cl. carnofoetidum var. amylolyticum is, therefore, a true psychrotrophic species.Glucose and pyruvate breakdown studied by Warburg's method confirms the slowing down of metabolism at 6°. A study of amino acid degradation indicates that serine is the substance most rapidly attacked at 37°, but at 6° the activity against serine disappears completely.In Rosenow medium at the first inoculation 8 strains of Cl. perfringens out of 24 failed to grow at 6° after 30 days. They were all enterotoxic types. Among the other 16 strains none survived beyond the tenth transfer at 6° and it was not possible to train any strain to grow at this temperature. An examination of the growth curves shows that they are not truly psychrotrophic.
Comparative Studies on Coryneform Bacteria from Milk and Dairy Sources
Authors: Jayne‐Williams D. J. , Skerman T. M. 
Published: March 2008

Summary. Physiological characteristics of 133 strains of coryneform bacteria originating from milk, milk products and dairy equipment were studied. Based on the results of a number of selected tests, the majority of these strains have been classified in four groups, the first three comprising organisms derived from aseptically drawn milk. Group I strains were lipolytic, nonhaemolytic, nonproteolytic, V‐P and urease positive, grew in the presence of 9% NaCl, and had a nutritional requirement fulfilled by Tween 80. They were identified as Corynebacterium bovis.Group II strains were also urease and V‐P positive, but were nonlipolytic, haemolytic, salt sensitive, and they liquefied gelatin slowly at 22°. Marked changes in morphology were shown; cells from 6–8 h cultures were predominantly large coryneform rods, whereas those from 24–36 h (or older) cultures were almost uniformly coccoid. Evidence is presented in support of the identification of these strains as C. ulcerans. Group III comprised catalase and V‐P negative, lipolytic organisms which liquefied coagulated serum; they grew optimally on media containing blood in a CO2‐enriched atmosphere and were identified as C. pyogenes. The last group consisted of organisms isolated from market milk, milk products and dairy utensils; presumably for these the udder is not a suitable habitat. They were salt sensitive, V‐P negative, nonhaemolytic and nonlipolytic, and, although exhibiting variable heat resistance, closely resembled C. lacticum. Although heat labile, some of the strains which had pronounced caseolytic activity were otherwise similar to descriptions of C. liquefaciens; however it is held that there are insufficient grounds to justify their taxonomic separation from C. lacticum.A residue of 11 isolates originating from the same sources as Group IV strains could not be satisfactorily classified and have been placed in a Miscellaneous group.
Sporulation of Clostridium perfringens (welchii) in Four Laboratory Media
Authors: Groom Rosemary A. , Strong Dorothy H. 
Published: March 2008

Summary. Sporulation of 7 strains of Clostridium perfringens (welchii) was investigated in 4 laboratory media. A method to induce rapid and simultaneous sporulation was attempted which involved obtaining a purely vegetative culture to inoculate the test media. Heat resistance of spores produced in the individual media by each of 4 selected strains was investigated. The clean spores for the heating tests were obtained by a special procedure which included chilling to 6° for a minimum of 1 week immediately following the usual incubation period, then centrifuging, resuspending to volume in 0.85% NaCl solution and pasteurizing at 75° for 20 min before subjecting to the heating tests. Morphology of each strain was studied using stained microscopic preparations from the 24 h sporulating cultures.In the Ellner medium spore counts approaching 107/ml were recorded and this medium appeared to be the most efficient when judged in terms of numbers of spores produced. In other media the counts were in the range 104‐105 spores/ml. Cooked meat medium yielded slightly higher spore counts than did either SEC broth or modified Wagenaar & Dack medium, the latter contained in a dialysis sac apparatus. A period of chilling to 6° for a minimum of 1 week following incubation enhanced maturation in all cultures except those grown in SEC broth for 24 h or 15 days and those grown 15 days in the modified Wagenaar & Dack medium.Considerable heat resistance, expressed as percentage spore survival, was recorded for spores of 4 strains when heated at 80°, and heat resistance generally increased with lengthening of incubation time for the culture. Survival of spores heated at 100° for 10 min was usually less than 0.01% but spores in SEC broth after 15 days showed a somewhat greater heat resistance than the others. In no instance did total destruction of spores occur at 100°.
Use of Ferritin Labelled Antibodies in the Location of Spore and Vegetative Antigens of Bacillus subtilis
Authors: Walker P. D. , Thomson R. O. , Baillie Ann 
Published: March 2008

SUMMARYThe ferritin labelled antibody technique has been used to locate vegetative antigens in the spores of Bacillus subtilis. The results confirm those previously described for B. cereus.
Occurrence of Micrococci and Staphylococci in the Intestines of Piglets and Pigs
Authors: Wilssens A. T. E. , Vandé Casteele J. C. 
Published: March 2008

SUMMARYOver 300 Gram positive, catalase positive cocci isolated from the intestinal contents of piglets and pigs were examined and classified by the methods of Baird‐Parker (1963). Most of the subgroups of the Micrococcaceae were represented in the samples, but Staphylococcus subgroups I, III, and VI were present only in the piglets. Subgroup VI could be clearly subdivided further into VI (the original subgroup of Baird‐Parker) and VIa, according to the response in the acetoin test. The organisms belonging to subgroup VIa were quite frequently isolated. In adult pigs Micrococcus subgroups 2, 3, 4, 5, 6 and 7 were found, but in piglets only subgroups 3, 5 and 7 occurred. A high proportion of the strains isolated belonged to Micrococcus subgroups 5 and 7.
Enumeration of Coagulase Positive Staphylococci in Cheese
Authors: Rammell C. G. , Howick Jocelyn M. 
Published: March 2008

SUMMARYA method is described for the enumeration of coagulase positive staphylococci in cheese. Samples are emulsified in 1% sodium citrate solution and suitable dilutions plated out on the surface of bovine blood agar. After incubation at 37° for 18–20 h, the number of haemolytic staphylococcal colonies is counted. Less than 3% of such staphylococci were coagulase negative.
A Note on the Continuous Flow culture of Mixed Populations of Lactobacilli and Streptococci
Authors: Lewis Patricia M. 
Published: March 2008

SUMMARYPure cultures of thermophilic yogurt starter strains of Lactobacillus and of Streptococcus, and 2‐member cultures of these strains, were established in chemostat continuous cultures and maintained for periods of up to 6 and 9 days, and one month respectively. Cultures were maintained at 45° in a 100 ml chemostat vessel at flow rates varying from 0.2‐1.4 culture volumes/h, giving a yield, at the highest flow rate, equivalent to 33 batches a day. The population values obtained in 2‐member cultures were similar to those occurring in pure cultures, indicating different growth limiting factors for the two organisms. Some oscillation in population densities occurred but the system was thought to be fundamentally suitable for production of mixed starter cultures.