bluuebunny/crossref_metadata_2025 huggingface dataset:
Glucose Fermentation Endproducts of Erwinia spp. and other Enterobacteria
Authors: White J. N. , Starr M. P.
Published: March 2008

The endproducts formed by Erwinia spp. and other enterobacteria from the anaerobic fermentation of glucose were determined by thin‐layer chromatography and other micromethods. The 71 strains examined fell into 15 mixed acid fermentation end‐product patterns of the sort which are considered to be characteristic of the Enterobacteriaceae. The patterns ranged from the detectable formation by 6 strains of all 7 of the products which were determined (carbon dioxide, succinate, lactate, formate, acetate, 2,3‐butanediol, and ethanol) to the detectable formation by one strain of only two (carbon dioxide and lactate); 32 strains formed 6 of the products; 21 strains formed 5 of the products; 9 strains formed 4 of the products; two strains formed 3 of the products. Each of the named species (nomenspecies) of the genus Erwinia does not, in general, have a characteristic pattern of fermentation endproducts; the nonphytopathogenic enterobacteria share many of the patterns shown by Erwinia spp.
A Rapid Test for Biodegradability of PVC Film by Pseudomonads
Authors: Sharpe A. N. , Woodrow M. N.
Published: March 2008

Biodegradability of plasticized PVC film by a Pseudomouas fluorescens strain was assessed quickly by determination of ammonia produced during endogenous respiration of the organism. Values for ammonia production from 52 PVC samples after 48 h showed an excellent inverse correlation with weight loss of the film as determined after 14 days, and can form the basis of a rapid method for assessing biodegradability.
Extracellular Enzymic Activity of Poultry Spoilage Bacteria
Authors: Barnes Ella M. , Melton Wendy
Published: March 2008

The extracellular enzymic activity has been studied of 224 strains of bacteria isolated mainly at 1° from spoiling chickens and turkeys and from poultry processing plants. The isolates comprised 44 strains of pigmented Pseudomonas, 57 strains of nonpigmented Pseudomonas, 29 strains of Ps. putrefaciens, 50 strains of oxidase positive Acinetobacter and 44 strains of oxidase negative Acinetobacter. None of the strains showed any significant activity against dextrin, starch, glycogen, inulin, dextran, xylan or pectin. Proteolytic activity was found mainly amongst 2 groups of pigmented pseudo‐monads, and Ps. putrefaciens. Nuclease activity was found particularly amongst strains of Ps. putrefaciens and the oxidase negative Acinetobacter strains isolated from spoiling poultry. Almost all of the strains showed lipolytic activity when tested with tributyrin and a proportion of strains could also attack chicken fat. This latter property was particularly evident amongst the nonpigmented Pseudomonas strains.
The Automatic Spreading of Bacterial Culture over a Solid Agar Plate
Authors: Trotman R. E.
Published: March 2008

Inoculated culture plates are automatically transported from a holder, into which they are placed manually, to a unit in which the culture is spread, by means of an electrically sterilizable loop drawn along a radius, and subsequently to another holder.
Variation of Aflatoxin Content of Cultures of Aspergillus flavus with Duration of Incubation and its Relation to Studies on Aflatoxin Production
Authors: Arseculeratne S. N. , Bandunatha C. H. S. R.
Published: March 2008

Summary: Strains of Aspergillus flavus recently isolated from coconut products were cultured on grated coconut. The aflatoxin content of serial cultures was found to vary significantly with duration of incubation and for some strains to show more than one phase of increase of aflatoxin content. The occurrence of these variations indicates that the study of aflatoxigenic capacity of strains or of the capacity of a medium to support toxin production, should be based upon a knowledge of the pattern of variation of toxin content with duration of incubation of the cultures under the experimental conditions used. Assay of toxin level in a culture after one period of incubation could lead to erroneous conclusions about the identity or quantities of toxin components which the strain is able to produce.
Effect of pH on the Heat Resistance of Clostridium sporogenes Spores in Minced Meat
Authors: Löwik J. A. M. , Anema P. J.
Published: March 2008

Summary: The effect of the pH value of minced meat on the heat resistance of Clostridium sporogenes spores inoculated in it was examined. A drop in pH from 6·0 to 4·8 decreased the decimal reduction time by 40%, irrespective of the heating temperature. In other words, the z value is independent of pH.
Spore Formation and Germination of Clostridium perfringens in the Digestive Tract of Holoxenic and Axenic Mice*
Authors: Raibaud P. , Ducluzeau R. , Dubos Françoise , Sacquet E.
Published: March 2008

Summary: Vegetative cells of Clostridium perfringens were rapidly eliminated from the digestive tract of holoxenic mice when they were inoculated per os. A small number of spores was sometimes found in the faeces a few hours after the vegetative cells had been ingested, but they were eliminated even more rapidly than the vegetative cells. When spores of Cl. perfringens were inoculated, they were eliminated as vegetative cells. When either vegetative cells or spores of Cl. perfringens were introduced per os into axenic mice, the strain became established and formed spores in the various segments of the digestive tract.
Effect of Glutaraldehyde on the Outer Layers of Escherichia coli
Authors: Munton T. J. , Russell A. D.
Published: March 2008

Summary: Sodium lauryl sulphate (SLS) at pH 3 and 8 lysed cell walls of Escherichia coli. Pretreatment with glutaraldehyde at pH 3 and at pH 8 prevented this lysis. SLS induced maximum lysis of E. coli cells at 40°; pretreatment of cells with glutaraldehyde prevented this lysis also. Electrophoretic studies indicated that glutaraldehyde accumu lated on the surface of E. coli cells more rapidly in acid than in alkaline conditions, and that it blocked amino groups on the surface layer of Bacillus subtilis spores. The relationship of these findings to the bactericidal efficiency of glutaraldehyde in acid and alkaline solution is discussed.
The Semi Large‐scale Production, Extraction, Purification and Properties of an Antibiotic Produced by Pseudomonas fluorescens Strain 175
Authors: Woolford M. K.
Published: March 2008

Summary: Production, extraction, purification and properties of an antibiotic produced by Pseudomonas fluorescens, strain 175, are described. Extraction efficiency was c. 57% with 3–5 g of product/350 1 batch culture, the product having an activity of 7900 units/mg (0· 12 μg/ml) against Staphylococcus aureus Paler. The antibiotic had the properties, of a weak acid and was active against both Gram positive and Gram negative bacteria; it was stable over a wide pH range, was bactericidal, inactivated by serum, had low toxicity and was haemolytic at relatively high concentrations.
Separation of Colicins by Polyacrylamide Gel Electrophoresis
Authors: Hardy K. G. , Neimark H. C.
Published: March 2008

Summary: Colicins can be separated by polyacrylamide gel electrophoresis, so allowing multiple colicinogeny to be detected with a universal indicator strain.
A New Medium for Bacillus thuringiensis Berliner
Authors: Nagamma M. V. , Ragunathan A. N. , Majumder S. K.
Published: March 2008

Summary: A new solid medium for culturing Bacillus thuringiensis consists of groundnut cake, 10%; tamarind kernel powder, 1·5% and agar, 0·5%. The quantity of agar in the medium could be decreased from 1·5 to 0·5% by adding tamarind kernel powder. A spore yield (85% sporulation) of 3·2 g/l was obtained. Bacterial spores produced on the new solid medium were pathogenic to the larvae of the almond moth, Cadra cautella.
Influence of Various Factors on the Survival of Lactobacillus leichmannii during Freezing and Thawing
Authors: Johannsen Elzbieta
Published: March 2008

Summary: The influence of the age and activity of bacteria, their concentration in the protective medium, the pH value of the medium, the temperature of thawing, and the time of storage on the survival of L. leichmannii during freezing and thawing has been investigated.
The Disinfecting Activity of Methyl Bromide on Various Microbes and Infected Materials under Controlled Conditions
Authors: Harry E. G. , Brown W. Burns , Goodship Gwen
Published: March 2008

Summary: Various micro‐organisms were exposed to methyl bromide (MeBr) gas at concentrations of 20–40 mg/l for 20 h at 25°. A significant reduction was obtained in the number of viable bacteria and Aspergillus fumigatus spores, both in the dry form and in semifluid faeces, but no reduction was detected either in dried Bacillus subtilis spores or in one of the bacteriophages tested. The investigation indicates that MeBr is less effective against certain viruses, bacteria and fungi than against coccidial oocysts. The results suggest that fumigation of commercial poultry houses with these concentrations of MeBr may not, in all circumstances, provide the overall reduction of poultry pathogens desired.
Isolation of Pectolytic clostridia from Potatoes
Authors: Lund Barbara M.
Published: March 2008

Summary: A method for selective counting and isolation of pectolytic clostridia in the presence of Erwinia carotovora is described; using this method pectolytic clostridia have been found in numbers of 8 × 105–1 × 108/g of rotting potato tissue in the presence of 1–4 × 108E. carotovora/g.
Variability of Pyocine Type and Pyocine Sensitivity in Some Strains of Pseudomonas aeruginosa
Authors: Merrikin D. J. , Terry C. S.
Published: March 2008

Summary: In a study of pyocine typing of 274 strains of Pseudomonas aeruginosa isolated from the same hospital, evidence of instability in 2 pyocine indicator strains and in the pyocine type of 19% of the isolates was found. An alternative approach to pyocine typing, using purified pyocine preparation, is suggested.
Structure of Micrococcus denitrificans and M. halodenitrificans Revealed by Freeze‐etching
Authors: Sleytr U. , Kocur M.
Published: March 2008

Summary. After freeze‐etching, cells of Micrococcus denitrificans and M. halodenitrificans revealed structures similar to those observed in ultrathin sections. Both organisms had a similar cell wall structure. The cell wall was double layered, the smooth surface of which had a delicate granular structure. The cytoplasmic membrane was in 2 parts, both covered with spherical particles 8–12 nm diam. The cytoplasmic membrane possessed rod‐shaped invaginations (100–300 × 30–50 nm). The cytoplasm of both species contained inclusions of poly‐β‐hydroxybutyric acid.
The Influence of Sporulation and Germination Media on the Development of Spores of Bacillus megaterium and their Inhibition by Chlorocresol
Authors: Purves J. , Parker M. S.
Published: March 2008

Summary. Spores of 2 strains of Bacillus megaterium produced on a complex medium showed absorption of their coats on germination whereas those produced on a chemically defined medium emerged by rupture of the coat. Spores produced on a complex medium were the more resistant to chlorocresol.
The Use of Scanning Electron Microscopy to Show Confluent Growth of a Saccharomyces and a Leuconostoc Species
Authors: Passmore Susan M. , Haggett Barbara
Published: March 2008

Summary. An in vitro association between cells of Saccharomyces cerevisiae and a Leuconostoc sp. has been demonstrated using the scanning electron microscope. These organisms are often naturally associated in fruit products and fermenting beverages such as apple juice and cider.
Relationships between Estimates of Binding of Antimicrobial Agents by Macromolecules, based on Physiochemical and Microbiological Data: Benzoic Acid and a Nonionic Surfactant
Authors: Coates D. , Richardson G.
Published: March 2008

Binding of benzoic acid to a nonionic polyoxyethylene surfactant has been investigated by equilibrium dialysis and a microbiological viable count technique. The results indicate that the antimicrobial activity of benzoic acid in this solubilized system can be equated with the free acid in solution in the aqueous phase. Potentiation by low concentrations of several nonionic macromolecules does not occur.
The Use of Semi‐automatic Pipettes in the Viable Counting of Bacteria
Authors: Bousfield I. J. , Smith G. L. , Trueman R. W.
Published: March 2008

A method of viable counting using semi‐automatic pipettes and a surface spotting method of inoculation is described. Statistical analyses of the results are presented to illustrate the precision of the method.
Thermoduric and Psychrotrophic Organisms on Poorly Cleansed Milking Plants and Farm Bulk Milk Tanks
Authors: Mackenzie Elin
Published: March 2008

Summary. Poorly cleansed pipeline milking plants gave much higher total and thermoduric colony counts than the internal surfaces of refrigerated farm bulk milk tanks, higher counts being recorded for milking plants after circulation cleaning than after cleansing by the acidified boiling water (ABW) method. Psychrotrophic counts were highest for farm milk tanks and lowest for milking plants cleansed by the ABW method. There was much variation in the proportion of thermoduric and psychrotrophic organisms in the total bacterial content of milking plants determined at 30°, thermodurics being much more prevalent in 21% of the rinses and psychrotrophs in 16%. Both groups formed about equal proportions in 9% of the pipeline rinses. The bacterial content of the farm bulk milk tanks was characterized by many psychrotrophs and few thermodurics.
Bacterial Counts and Quality of Iced Fish Retailed at a Lusaka Market, Zambia
Authors: Watanabe K. , Ulstrup Grete
Published: March 2008

Summary. The counts of total viable, coliform, streptococcal and sulphite reducing anaerobic bacteria and the presence of salmonellae were determined on 134 iced fish obtained from Luburma Market, Lusaka, Zambia, during June‐December 1970. The quality of the uncooked fish was also assessed by appearance and odour. The purpose of these determinations was to obtain a picture of the variations of the bacterial counts in relation to season, origin, fish species and market quality. Total viable and coliform counts were of the order of millions and tens of thousands/cm2 of skin surface, respectively. Higher counts were obtained in the hot season during September‐October but with little change in appearance of the fish. There was a significant correlation (P < 0·01) of both total viable and coliform bacteria with quality scores. A maximum permissible level of 107 cells/cm2 of skin surface was proposed for total viable counts and 105/cm2 for coliform bacteria, for iced fish of acceptable quality in Zambia.
Controlling the Sporulation of Clostridium sporogenes and the Heat Resistance of the Spores
Authors: Anema P. J. , Geers Joyce M.
Published: March 2008

Summary. During growth of Clostridium sporogenes in tryptone‐salt‐peptone‐glucose medium the pH value of the medium varies due to formation of acid and CO2 and to subsequent production of NH3. Glucose concentrations of 0·2, 0·5 or 1·0% result in increasing sporulation times and in spores of low, extremely high (D110c. 80 min) and negligible heat resistance, respectively. When the pH value is maintained at 7, a reproducible sporulation time of a few hours is observed and the resulting spores have a heat resistance (D110) of 13 min, regardless of the glucose concentration.
Detection of Hippurate Hydrolase among Bacillus Species by Thin Layer Chromatography and other Methods
Authors: Ottow J. C. G.
Published: March 2008

Summary. The ability of 111 isolates of 33 species of Bacillus to hydrolyze hippurate into benzoic acid and glycine was tested. All, other than the strains classified as B. badius, B. cereus var. mycoides, B. cereus var. thuringiensis, B. macquariensis, B. medusa, B. pacificus, B. psychrosaccharolyticus and some B. macerans and B. polymyxa strains, were positive by thin layer chromatography (TLC). Of the 4 methods compared (hippurate agar, the sulphuric acid method, precipitation with ferric chloride and TLC), only the TLC procedure allowed a rapid and definite detection of the hydrolytic product, benzoic acid. The use of hippurate hydrolase as an additional diagnostic aid in the differentiation of aerobic spore‐forming bacilli is discussed. Other characters were used to compare some recently described Bacillus spp. The combination B. cereus subsp. medusa n. subsp. is proposed.
Studies on the Production of Pink Pigment in Pseudomonas extorquens NClB 9399 Growing in Continuous Culture
Authors: Downs J. , Harrison D. E. F.
Published: March 2008

Summary. The pink pigment of Pseudomonas extorquens was identified tentatively as an oxo‐carotenoid similar to rhodoxanthin. The production of the pigment increased at the end of the logarithmic phase of growth of Ps. extorquens in batch cultures. It was produced during growth on a wide variety of carbon and nitrogen sources, with the exception of ethanol, but not in the presence of diphenylamine, an observation which was consistent with the identification of the pigment as a carotenoid. The organism was grown in continuous culture under conditions of oxygen and magnesium limitation which might be expected to restrict the oxidation of γ‐carotenes to pink pigments. However, such limitations caused an increase in pigmentation over that of methanol‐limited cultures. Non‐pink mutants of Ps. extorquens, obtained after the use of the mutagen, ethyl methyl sulphonate, did not have growth‐rates lower than those of the parent strain. The pigment would seem to have no central metabolic role in actively growing cells but carbon is diverted to pigment production when growth is restricted by other than carbon limitation.
Sodium Chloride as a Cause of Low Numbers of Rhizobium in Legume Inoculants
Authors: Steinborn Julia , Roughley R. J.
Published: March 2008

Summary. A rapid reduction, after manufacture, in numbers of Rhizobium trifolii in commercial legume inoculants was observed in 1971 and explained by the presence of high concentrations of sodium chloride in the peat used as carrier material. A strain of R. trifolii growing in broth proved to be more sensitive to sodium ions than did 2 strains of R. meliloti but was more tolerant of up to 0.3% of chloride. The effect of salt differed somewhat according to the source of peat used as carrier, but peat containing °0.2% of chloride (expressed as a % of dry peat) may cause considerable loss of viability of rhizobia.
Biochemical Studies on Accelerated Treatment of Thiocyanate by Activated Sludge using Growth Factors such as Pyruvate
Authors: Woodard A. J. , Stafford D. A. , Callely A. G.
Published: March 2008

Summary. Micro‐organisms in activated sludge oxidizing thiocyanate behave in a similar way to thiobacilli. Organic compounds such as pyruvate stimulate thiocyanate oxidation and in so doing become incorporated into cellular material; such metabolites are not oxidized to produce energy. The presence of thiocyanate in batch cultures accelerated pyruvate uptake. The carbon of thiocyanate is recovered mainly as CO2; carbonate becomes incorporated into cellular protein, but less so in sludges previously treated with pyruvate. TCA cycle enzymes are not altered appreciably after pyruvate is added to activated sludge.
The Flexibility of Bacterial Cell Walls
Authors: Isaac Lynn , Ware G. C.
Published: March 2008

Summary. There are considerable differences in the extensibility of the cell walls of bacteria in different genera. Gram negative spp. examined were more flexible than the Gram positive ones.
A Comparison of Seven Strains of Lactobacillus casei var. rhamnosus in Relation to their Use in the Microbiological Assay of Serum Folate
Authors: Tennant G. B. , Newberry C. H. , Davies Joy , Dziedzic Heather
Published: March 2008

Summary. A comparison was made of 7 strains of Lactobacillus casei var. rhamnosus in relation to their use in the microbiological assay of serum folate. The problem of clumping by some strains could be overcome by the addition of extra salt, or chloramphenicol, to the medium. The strains showed differences in their tolerance to added salts which was measured as the Mean Inhibitory Salt Concentration. The highest salt concentration which could be used in the assay medium without affecting the serum folate results was about one‐third of the Mean Inhibitory Salt Concentration and this could be less than the optimum concentration for growth. These differences in salt tolerance may provide a partial explanation of the variety of normal values reported from different laboratories.
The Occurence and Properties of Uric Acid Decomposing Anaerobic Bacteria in the Avian Caecum
Authors: Barnes Ella M. , Impey C. S.
Published: March 2008

Summary. Anaerobic bacteria which decompose uric acid have been found in the caeca of chickens, turkeys, ducks, pheasants and guinea‐fowl at levels between 5.4 × 108 and 1.8 × 1010/g of caecal material (wet weight). A study has been made of the properties and identity of 35 strains which were present in high numbers in the chicken caecum. The isolates included strains of Bacteroides clostridiiformis var. clostridiiformis, Fusobacterium plauti, Clostridium malenominatum, Peptostreptococcus productus and a number of types which could not be identified with known species. Of these 3 were Bacteroides spp., 3 Eubacterium spp., 2 Peptostreptococcus spp. and 1 was an anaerobic Streptococcus. None of the strains had an absolute requirement for uric acid.
Detection of a Vibrio sp. by the Bacteriophagous Nematode Pelodera chitwoodi
Authors: Joshi M. M. , Wilt G. R. , Cody R. M. , Chopra B. K.
Published: March 2008

Summary. Pelodera chitwoodi was able to distinguish between a Vibrio sp. (food bacterium) and Chromobacterium janthinum (non‐food bacterium), and between bacteria and mud. Nematodes migrated preferentially to the Vibrio sp. at various distances, temperatures, and pH values. Migration to food bacteria increased with an increase in bacterial concentration. Resting and dead bacteria failed to attract nematodes. Nematodes were able to detect a vibrio colony separated from them by a plastic barrier, and migrated to areas on agar containing exudate and dialysate from the vibrio. Both exudate and dialyzate contained 4 amino acids and 3 vitamins which attracted nematodes. However, attraction of nematodes to these compounds was not as strong as to metabolizing bacteria, indicating that additional compounds were also involved.
The Role of Clostridium perfringens in the Growth Response of Chicks to Dietary Penicillin
Authors: Powell L. W. , Coates M. E. , Fuller R. , Harrison G. F. , Jayne‐Williams D. J.
Published: March 2008

Summary. The previous observation that Clostridium perfringens is responsible for penicillin‐relieved growth depression in chicks has been reassessed. The administration of Cl. perfringens to germfree chicks, to birds harbouring a non‐growth depressing gut flora and to birds reared in an environment free from Cl. perfringens was without effect on growth rate. No correlation was observed in conventional chicks between the incidence of growth depression and the presence of Cl. perfringens in the gut of the chicks one day after food was first given.
Transfer of Micro‐organisms between Nurses and Patients in a Clean Air Environment
Authors: Lidwell O. M. , Towers A. G. , Ballard J. , Gladstone B.
Published: March 2008

Summary. A uni‐directional downflow (‘laminar’flow) ventilation system for a single‐bed patient‐room is described. It produced clean air at velocities as low as 0.12 m/sec (25 ft/min). Bacteriological studies on bed‐making done in the room showed that strains of Staphylococcus aureus carried on the nurses’external clothing were often transferred to the patients’bedclothes. This possible route of patient infection was almost eliminated when the nurses wore disposable plastic aprons over their dresses.
Effect of Water Activity on Heat Survival of Staphylococcus aureus, Salmonella typhimurium and Salm. senftenberg
Authors: HORNER K. J. , ANAGNOSTOPOULOS G. D.
Published: March 2008

The viability of Staphylococcus aureus heated at 55° in phosphate buffer was determined on recovery media of different water activity (aw) levels. The basal recovery medium, tryptone–soya agar (aw 0.997) was adjusted to lower aw levels by the addition of NaCl, glycerol or sucrose. Maximum survival occurred at aw 0.997. Viability was reduced to 1/10 of the maximum at aw 0.98 when aw, was controlled by sucrose or NaCl but not until aw 0.93 with glycerol. To eliminate effects such as incomplete mixing or post‐heating dilution and in order to use conditions comparable to those occurring in foods, a solid medium heating/recovery method was also used. This involved heating, by immersion, of surface‐inoculated agar plates and recovery of survivors in situ. Heat resistance studies could thus only be carried out at aw levels permitting growth on the heating/recovery medium. Staphylococcus aureus, Salmonella typhimurium and Salm. senftenberg 775W were heated at 55° and recovered in situ on tryptone‐soya agar adjusted to lower aw levels as above. Maximum survival of Staph. aureus occurred at a higher aw with glycerol (aw 0.965) than with NaCl (0.92) or sucrose (0.90). The maximum survival of both Salm. typhimurium and Staph. aureus heated at 55° occurred at the same aw (0.965) with glycerol. This maximum was not affected by the duration of heating. As a contrast, heat resistance of Salm. senftenberg 775W was virtually unaffected by reduction in the aw of the heating/recovery medium.
Identification of Bacillus subtilis from Sausage Products and Spices
Authors: PALUMBO S. A. , RIVENBURGH A. I. , SMITH J. L. , KISSINGER J. C.
Published: March 2008

Bacillus subtilis has been identified as the aerobic spore‐former present in several commercial and pilot plant produced sausage products. In our fermented sausages, e.g. Lebanon bolognas, the source of these aerobic spore‐formers was the spices, especially black and red pepper, ginger, and allspice. The predominant, if not sole, component of the flora of the spices was B. subtilis. On primary isolation from sausage products or from spices, B. subtilis formed a volcano‐like colony on APT agar. During subculture, even on APT agar, this volcano‐like appearance was lost and the typical rough, spreading colony type of B. subtilis was observed. Reculturing on sucrose or frankfurter extract agars did not revive the volcano‐like colony.
Antibiotics and the Oral Streptococci of Man
Authors: SUKCHOTIRATANA M. , LINTON A. H. , FLETCHER J. P.
Published: March 2008

The effects of 3 antibiotics, phenoxymethylpenicillin, cephalexin and clindamycin on the normal oral streptococcal flora in the region of the gingival crevice were investigated because these organisms are able to cause subacute bacterial endocarditis. Secretion of these antibiotics into the oral cavity was also examined. Penicillin and clindamycin exerted marked effects on the normal oral streptococci, whereas cephalexin did not cause any obvious change in the total flora. Following penicillin therapy, streptococci resistant to 1.5 μg/ml penicillin were observed and these organisms could be detected at least 8 weeks after the last dose of the antibiotic. They probably arose by selection from the mixed flora. Following cephalexin therapy, a much lower proportion of streptococci resistant to 15 μg/ml was found. The proportion of resistant strains fluctuated appreciably, however, probably due to their transient nature. Streptococci resistant to 1 μg/ml clindamycin were not observed in 10 out of 11 treated subjects.

Penicillin and clindamycin could be detected in the pooled saliva and gingival fluid after administering single doses of 500 mg and 300 mg, respectively. The peak levels were obtained between half and 1 h. The concentration of penicillin dropped rapidly within 3 h but clindamycin could be detected at significant levels for at least 6 h. No cephalexin could be detected in the pooled saliva or gingival fluid after a 500 mg dose. The implications of these findings in the prevention of subacute bacterial endocarditis are discussed.
Survival of Escherichia coli in Stream Water in Relation to Carbon Dioxide and Plant Photosynthesis
Authors: GRAY E. A.
Published: March 2008

During a study of the survival of Escherichia coli in a chalk stream and in the laboratory, the organism ceased to grow in filtered stream water if air free of atmospheric carbon dioxide was passed over the culture. Fewer E. coli cells grew with the alga Stichococcus bacillaris in the light than in the dark. In the stream, low numbers of the organism were associated with plant blooms (macrophytes and microphytes). It is suggested that the numbers of E. coli in natural waters may sometimes be determined by the content of dissolved carbon dioxide which itself must be affected by the volume of photosynthesizing green cells.
Studies on Sampling Methods Used in the Control of Hygiene in Poultry Processing
Authors: NOTERMANS S. , KAMPELMACHER E. H. , VAN SCHOTHORST M.
Published: March 2008

Contamination which occurs at an early stage in the poultry processing line is estimated less accurately by the ‘skin‐dip’ method than by the ‘skin‐maceration’ method. From the results obtained during these studies it is also evident that the bacterial count determined by the method of rinsing the whole carcass cannot be related to counts determined using the skin maceration method.
The Isolation and Characterization of Strains of Lipolytic Bacteria from the Ovine Rumen
Authors: HENDERSON C.
Published: March 2008

The first anaerobic lipolytic bacterium isolated from the rumen was Anaerovibrio lipolytica. In this study strains of anaerobic lipolytic bacteria were isolated from a sheep rumen. All the new isolates were Gram negative curved rods with flagella. The bacteria, which produced propionic acid as a major fermentation product, could ferment only a small range of substrates. The new isolates are thought to belong to the same genus as Anaerovibrio lipolytica.
Variation in the Virulence of some Streptomycin Resistant Mutants of Pseudomonas phaseolicola
Authors: RUSSELL P. E.
Published: March 2008

One strain of each of the 2 races of Pseudomonas phaseolicola was tested for in vitro resistance to streptomycin. The race 1 strain showed a greater resistance to the antibiotic than the race 2 strain. Resistant mutants were isolated from each strain and used to infect plants of Phaseolus vulgaris cv. Higuerillo V 345. Variation was noted in both the range of symptoms produced and in the numbers of bacteria re‐isolated from the plants. Some mutants retained their resistance after passage through the plant while others reverted back to parental type.
An Investigation of Errors in Direct Counts of Aquatic Bacteria by Epifluorescence Microscopy, with Reference to a New Method for Dyeing Membrane Filters
Authors: JONES J. G. , SIMON B. M.
Published: March 2008

A number of methods for observing freshwater bacteria by epifluorescence (incident light fluorescence) microscopy are examined. The suitability of each method for quantitative studies using black membrane filters is assessed. In spite of inadequacies it was considered that the use of acridine‐based fluorochromes provided the best available estimate of the bacterial population. The errors which may arise when these stains are used were examined and it was noted that small changes in methodology could cause significant differences in the results obtained. The largest errors were associated with changes in volume of sample filtered and the pore size of the membrane used. A procedure for sample treatment is suggested and a new method for dyeing membrane filters is given which allows the use of 0·22‐μm pore size membranes of the cellulose ester and polycarbonate type.
Increased Antibiotic Sensitivity in Pseudomonas aeruginosa Following Passage in Carbenicillin‐containing Media
Authors: SPICER A. B.
Published: March 2008

Twelve dissimilar clinical isolates and 4 type cultures of Pseudomonas aeruginosa have been repeatedly passaged on agar containing 200 μg carbenicillin/ml. Passaged variants were compared with control organisms for their sensitivities to a range of antibiotics initially by a multodisk test and subsequently by serial dilution in agar. Two of the variants, both derived from clinical isolates, showed pronounced increases in sensitivity to several antibiotics, particularly kanamycin, neomycin, gentamicin and colistin sulphate. In some instances the minimum inhibitory concentration (MIC) for the passaged variants was 32–64 times lower than that for the control organisms. These potentiations contrast with previous results obtained by other workers for P. aeruginosa. In addition, several other of our passaged variants developed a more moderate degree of enhanced sensitivity to a limited number of antibiotics. Eight (67%) of the clinical isolates and one type culture did not become more sensitive to any of the antibiotics tested following carbenicillin passage. Onset of increased antibiotic‐sensitivity varied with the strain, particular antibiotic and medium employed for passage. Although the addition of sucrose (0·5 M) and magnesium sulphate (0·01 M) to the passage medium appeared to delay development of antibiotic‐sensitivity their presence eventually encouraged larger potentiations in antibiotic activity. The significance of the conversion of P. aeruginosa into forms with increased susceptibility to several antibiotics during chemotherapy with carbenicillin is discussed.
Differential Effects of Monovalent and Divalent Ions upon the Mode of Action of the Polyene Antibiotic Candicidin
Authors: HAMMOND S. M. , KLIGER B. N.
Published: March 2008

The polyene antibiotic candicidin is a potent membrane active agent, the action of which can be inhibited by the presence of certain ions. The destruction of the selective permeability of yeast membranes by candicidin allows small molecules to leak into the environment. Loss of intracellular potassium ions inhibits yeast glycolysis. This inhibition may be reversed by extracellular concentrations of potassium or ammonium ions. Monovalent ions did not prevent antibiotic absorption or protect yeast growth from the action of the antibiotic. Divalent ions did not protect yeast glycolysis from the action of candicidin, but were able to reduce antibiotic‐induced membrane damage and allowed yeast growth in the presence of antibiotic. It is suggested that divalent ions may interact with membrane sterols creating steric hindrance to subsequent candicidin absorption.
The Aerobic Flora of the Perivaginal Area: Its Relation to Contraception and Deodorant Sprays
Authors: NOBLE W. C.
Published: March 2008

The microbial flora of the thigh adjacent to the vaginal labia and of the mucosal surface of the labia has been examined qualitatively in a group of young women attending a family planning clinic. There were no differences in flora relating to either the type of contraceptive used or to the frequency of use of intimate hygiene deodorants.
Gas Flow Measurement in Fermentations: An Inexpensive System with Analogue Output for Recording
Authors: HOLDOM R. S. , SPIVEY M. J. , LARSEN V. F.
Published: March 2008

During the fermentation of North Sea Gas to single cell protein in a gas‐recycle system (Spivey 1973) there was a need to measure continuously low gas flow rates and to obtain a recorder signal proportional to the instantaneous flow rate. Commercial equipment, such as differential pressure transmitters linked to a pneumatic recorder, was expensive and not readily modified for the low flow rates of laboratory fermentations.
The Effect of Medium Composition upon the Production of Pyocin
Authors: PAU W. S. , TERRY C. S.
Published: March 2008

Cetrimide (0.03% w/v), added to a semi‐synthetic medium, raised pyocin titre tenfold over the other media tested, maintained the high level of pyocin for up to 24 h and also reduced slime production by Pseudomonas aeruginosa, thus facilitating extraction and purification of pyocin.
The Use of Analysis of Variance to Examine the Variations between Samples of Marine Bacterial Populations
Authors: ASHBY R. E. , RHODES‐ROBERTS MURIEL E.
Published: March 2008

Studies were made of the variations in the numbers of viable bacteria in Cardigan Bay seawater as estimated using the spread‐plate technique and various marine agar media, the results being examined using analysis of variance. Use of duplicated 500 ml sample bottles enabled the detection of statistically significant variations between samples both in terms of numbers of viable bacteria present and their different responses to different counting media, but an important micro‐distribution was also indicated. Further studies showed large differences between 25 ml samples taken 10 cm apart: these could not be explained in terms of cell aggregation as presently understood.
Rapid Techniques for the Examination of Bacterial Citrate Synthases
Authors: HARFORD S. , JONES DOROTHY , WEITZMAN P. D. J.
Published: March 2008

A method has been devised for evaluating easily and rapidly the effect of inhibitors on the activity of citrate synthase in situ in bacteria grown on agar plates. Additionally, considerable reduction in the size of the gel filtration column employed to estimate the molecular weight of citrate synthase enables such a determination to be made in a much shorter time. These two techniques make it much easier to exploit the properties of different bacterial citrate synthases as an additional taxonomic tool in bacteriological laboratories.
The Effect of Sugars and Polyols on the Heat Resistance and Morphology of Osmophilic Yeasts
Authors: CORRY JANET E. L.
Published: March 2008

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.
Neutralization of the Bactericidal Effect of Cocoa Powder on Salmonellae by Casein
Authors: ZAPATKA F. A. , VARNEY G. W. , SINSKEY A. J.
Published: March 2008

Four pre‐enrichment media (nutrient broth, lactose broth, reconstituted non‐fat dry milk and nutrient broth containing 5% (w/v) casein) were evaluated for the recovery of salmonellae from cocoa powder. Addition of 5% cocoa powder to nutrient broth and to lactose broth proved to be bactericidal to salmonellae. Heat‐damaged Salmonella typhimurium were more sensitive than undamaged cells to cocoa powder and agitation increased the bactericidal effect. The bactericidal effects were minimized in pre‐enrichment media that contained either 5% casein or nonfat dry milk.
A Method for the Production of Pre‐reduced Anaerobically Sterilized Culture Media
Authors: GOSDEN PAULINE E. , WARE G. C.
Published: March 2008

A simplified method for the production of pre‐reduced anaerobically sterilized media for the cultivation of strict anaerobes is described.
Simple Equipment for the Growth of Photosynthetic Bacteria
Authors: STEVENS S. E. , FOX J. L.
Published: March 2008

A simple temperature controlled growth facility for photosynthetic bacteria occupying 1 m2 of laboratory space is described.

Five types of growth vessels were compared in terms of cell doubling times and yields. The low form flask gave the best compromise for the large scale growth of photosynthetic bacteria.

Using six 3 21 low form flasks in this apparatus yielded 1 6 g dry wt 1‐1/day or 155 g dry wt cells/work week.
The Effect of Storage on Drugs Incorporated into Pelleted Fish Food
Authors: MCCRACKEN ANN , FIDGEON S.
Published: March 2008

Oxytetracycline and sulphadiazine/trimethoprim was incorporated into fish meal and could be detected at the original level a period of seven days.
Plaque Formation by Streptococci in an Artificial Mouth and Factors Influencing Colonization
Authors: RUSSELL C. , COULTER W. A.
Published: March 2008

The plaque‐producing properties of Streptococcus sanguis, Streptococcus salivarius, Streptococcus mutans, Streptococcus mitis and Streptococcus faecalis were investigated in an artificial mouth with continuous supply of nutrient. Attention was focused on the role of salivary factors and sucrose in tooth colonization. Plaque formation by single cultures depended on the ability to produce tenacious extracellular polysaccharide or to cohabit the tooth with an organism having this property. Sucrose was the only essential additive to nutrient broth necessary for plaque formation and could not be substituted by sterile natural saliva. Saliva neither facilitated colonization by Strep. mitis nor prevented colonization by Strep. salivarius as may have been supposed from previous reports.
Detection of Enterotoxin in Faeces and Anti‐enterotoxin in Serum after Clostridium perfringens Food‐poisoning
Authors: SKJELKVÅLE REIDAR , UEMURA TAKASHI
Published: March 2008

Two outbreaks of Clostridium perfringens food‐poisoning involving the same person were investigated. In the first, typical symptoms with diarrhoea and abdominal pain were observed. In the second, there were no classical signs of food‐poisoning; the victim felt some flatulence and the faeces had a pasty appearance and an unpleasant smell. Counterimmunoelectrophoresis and the reversed passive haemagglutination test were rapid and reliable assay methods for enterotoxin in faeces. In the first outbreak, 13–16 μg enterotoxin/g faeces were detected, and 3–4 μg/g in the second. The detection of enterotoxin in faeces indicates the potential use of enterotoxin tests on diarrhoeal samples for diagnosing C. perfringens food‐poisoning. No enterotoxin was detected in serum during the acute stage of the illness, but the antibody titre showed a considerable rise in the first two months after the food‐poisoning outbreak.
Effects of Polyethoxyalkyl Phenols on the Leakage of Intracellular Material from Staphylococcus aureus
Authors: LAMIKANRA A. , ALLWOOD M. C.
Published: March 2008

Polyethoxyoctyl derivatives Triton X45 and Triton X100 induced leakage of cellular materials from Staphylococcus aureus. The total leakage of 260 nm‐absorbing material, potassium (K+), amino acids and protein depended on the concentrations of surfactant, with K+ loss occurring most rapidly. There appeared to be little quantitative correlation between loss of viability and leakage. It is suggested that leakage may reflect changes in membrane permeability resulting in the inability of cells to recover normal functions when placed in a growth‐supporting medium.
Effects of Polyethoxyalkyl Phenols on the Optical Density of Staphylococcus aureus
Authors: LAMIKANRA A. , ALLWOOD M. C.
Published: March 2008

Triton X45 and Triton X100 are antibacterial non‐ionic surfactants which bring about a considerable increase in the optical density (OD) of Staphylococcus aureus suspensions and isolated cell walls. Both surfactants caused rapid lysis of sphaeroplasts, Triton X100 being the more effective lytic agent. It is proposed that the increases in the OD of cell suspensions occur principally as a result of changes in the reflective properties of cell walls.
A Method for the Rapid Isolation of Listeria monocytogenes from Infected Material
Authors: MAVROTHALASSITIS P.
Published: March 2008

Two media, one for enrichment and the other for differentiation of Listeria monocytogenes, are described and a method is proposed for the selective isolation of this bacterium from material containing a mixed bacterial flora such as faeces, vaginal swabs etc. Addition of potassium dichromate, chromium trioxide, thionin, nalidixic acid and amphotericin B to Todd‐Hewitt Broth (BBL) made a satisfactory enrichment broth in which good selective growth of L. monocytogenes was obtained without notable damage to cells. The differentiation agar was Trypticase Soy Agar (BBL) supplemented with gallocyanin, pyronin and nalidixic acid. On this medium L. monocytogenes colonies, when viewed by the Henry's oblique transillumination technique, were blue in contrast to colonies of other bacterial species which were pink or red. Trials with experimentally infected materials showed that L. monocytogenes could be recovered from faeces infected with as few as 20 L. monocytogenes cells/g. All common contaminants, with the exception of a few strains of Streptococcus faecalis, were inhibited.
The Long Term Effects of Kerosine Pollution on the Microflora of a Moorland Soil
Authors: JONES J. G.
Published: March 2008

Two moorland sites were examined approximately seven years after heavy pollution by a kerosine containing acid sludge. The vegetation at both sites showed no real sign of recovery, although the soil microflora at the wetter site (B) was not inhibited to the same degree as that at Site A. The general effect of the pollution was to reduce the microbial standing crop although respirometric analyses showed that the organisms which were present were at least as active as those in the control areas. The slow recovery of the sites may be due to reduced permeability and gas‐exchange at the soil‐air interface.
Evaluation of the Spiral Plate Maker for the Enumeration of Micro‐organisms in Foods
Authors: JARVIS B. , LACH V. H. , WOOD J. M.
Published: March 2008

A statistically based comparison of five methods of enumerating bacteria in foods has been undertaken to assess the potential application of the Spiral Plate Maker (Gilchrist et al. 1973) which is claimed to reduce very significantly the costs involved in the quantitative estimation of viable micro‐organisms in foods. The performance of the Spiral Plate Maker was compared with that of three conventional methods (pour plate, surface spread plate and drop count) for the examination of four types of food by four different operators. Analysis of variance showed that there were no differences between the methods at the 5% level although some isolated interactions occurred. Regression and correlation coefficients between the various methods were all highly significant and the results obtained by the spiral plate method were within the limits of error for traditional quantitative methods. The spiral plate method, in many cases, can replace advantageously any of the other methods for the quantitative estimation of viable microorganisms in foods. Labour requirements for the enumeration of micro‐organisms by the spiral plate method were only 31% of that required for one conventional method. In addition considerable savings in materials were achieved.
Mechanism of Resistance of Saccharomyces bailii to Benzoic, Sorbic and Other Weak Acids Used as Food Preservatives
Authors: WARTH A. D.
Published: March 2008

Saccharomyces bailii grows in the presence of high concentrations of sorbic, benzoic and other short‐chain monocarboxylic acids commonly used as preservatives. Starved cells concentrate these acids intracellularly, approximately as expected from the pH of the ceil and the pKa of the acid. On addition of glucose, the intracellular content of preservative is considerably reduced. The glucose effect is sensitive to metabolic inhibitors, and anaerobic respiration is stimulated by the preservatives. The ability to maintain a low intracellular concentration of any of the preservatives tested is induced by growth in the presence of sorbic or benzoic acid and less effectively by butyric or acetic acid. Both induced and uninduced cells are permeable to benzoic and butyric acids. Benzoate and sorbate are not metabolized at a rate significant with respect to the permeation rate. Resistance to these preservatives apparently results primarily from an inducible, energy requiring system which transports preservative from the cell.