bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid detection of staphylococcal enterotoxins in foods with a modification of the reversed passive latex agglutination assay
Authors: Bankes Pamela , Rose Sally A.
Published: March 2008

A modification of the reversed passive latex agglutination kit assay for detection of staphylococcal enterotoxins by centrifugation of microtitration plates reduces the incubation time of the assay from 20–24 h to 4 h. Enterotoxins can therefore be detected in foods within the working day.
A predictive model for combined temperature and water activity on microbial growth during the growth phase
Authors: Davey K. R.
Published: March 2008

An empirical and generalized model is presented, based on a modified Arrhenius equation, for predicting the combined effect of temperature and water activity on the growth rate of bacteria. When it was applied to seven separate sets of wide ranging published results, spanning some 50 years and including a spore‐former and a silage micro‐organism, predictions explained between 92.9 and 99.0% of the variation in the results with an overall mean of 96.6%. Advantages over existing models are that it is relatively easy to fit to data using least squares regression and requires only five coefficients. These, together with its simplicity and demonstrated wide application, will facilitate its practical use.
Distribution of the four flagellar (H) antigenic subserotypes of Bacillus thuringiensis H serotype 3 in Japan
Authors: Ohba Michio , Aizawa Keio
Published: March 2008

A total of 302 strains of Bacillus thuringiensis flagellar (H) serotype 3, collected from sericultural environments and soils of the three main islands (Honshu, Shikoku and Kyushu) of Japan, were examined for their H antigenic subserotypes. Of these strains, 259 (85.8%) were identified as the H subserotype 3a : 3c (subsp. alesti), 16 (5.3%) were referable to the subserotype 3a : 3b : 3c (subsp. kurstaki), 26 (8.6%) belonged to the subserotype 3a : 3d : 3e (subsp. fukuokaensis) and one strain (0.3%) was the subserotype 3a : 3d (subsp. sumiyoshiensis). The subserotypes 3a : 3c and 3a : 3b : 3c were present in sericultural environments only; the former was distributed in Honshu and Shikoku Islands but not in Kyushu Island, and the latter was distributed in Honshu and Kyushu Islands but not in Shikoku Island. The subserotype 3a : 3d : 3e, mainly found in soils but occasionally in sericultural environments, was distributed in the three main islands. It also appeared that the subserotype 3a : 3d : 3e, a recently described subserotype, was distributed in Japan more widely than the globally disseminated subserotype 3a : 3b : 3c. The results clearly showed geographical and ecological differences in the distribution of subserotypes.
Influence of retention time on degradation of pancreatic enzymes by human colonic bacteria grown in a 3‐stage continuous culture system
Authors: Macfarlane G.T. , Cummings J.H. , Macfarlane S. , Gibson G.R.
Published: March 2008

Hydrolytic enzymes were measured in gut contents from four sudden death victims. Pancreatic amylase and total protease activities decreased distally from the small bowel to the sigmoid/rectum region of the large intestine, showing that considerable breakdown or inactivation of the enzymes occurred during gut transit. To determine whether pancreatic enzymes were substrates for the gut microflora, mixed populations of bacteria were grown in a 3‐stage continuous culture system on a medium that contained pancreatic extract as the sole nitrogen source. The multichamber system (MCS) was designed to reproduce in vitro, the low pH, high nutrient, fast growth conditions of the caecum and right colon and the neutral pH, low nutrient, slow growth conditions of the left colon. Results showed that pancreatic amylase was resistant to breakdown by intestinal bacteria compared with the peptide hydrolases in pancreatic secretions. Leucine aminopeptidase, trypsin and to a lesser degree, chymotrypsin, were easily degraded by gut bacteria, but pancreatic elastase was comparatively resistant to breakdown. Protein degradation in the MCS, as determined by enzyme activities, protein concentration and ammonia and phenol production, increased concomitantly with system retention time over the range 24–69 h. These results suggest that intestinal bacteria play an important role in the breakdown of hydrolytic enzymes secreted by the pancreas and that this process and protein fermentation in general, is likely to occur maximally in individuals with extended colonic retention times.
Heat resistance of Campylobacter and Yersinia strains by three methods
Authors: Sörqvist S.
Published: March 2008

Two methods of determining the heat resistance of bacteria, a glass cup and a test tube method, were compared with a method using capillary tubes. Three strains of Yersinia enterocolitica, one of Campylobacter jejuni and two of C. coli were tested in physiological saline. The differences between the results obtained by the glass cup method and the reference method were not statistically significant for five strains and were small also for the other, a Yersinia strain. D values obtained by the glass cup method at 58, 60 and 62°C were 1.4–1.8, 0.40–0.51 and 0.15–0.19 min (z values 4.00–4.52°C) for the Yersinia strains, and 0.42, 0.13 and 0.07 min (z value 5.07°C) for one C. coli strain. For the other Campylobacter strains, D values of 0.71–0.78, 0.24–0.28 and 0.12–0.14 min (z values 4.94 and 5.60°C) were recorded at 56, 58 and 60°C. D values obtained at 60°C by the test tube method were 2.7–5.0 min and were considered to be unrealistic.
A two‐year study of the distribution of ‘thermophilic’ campylobacters in human, environmental and food samples from the Reading area with particular reference to toxin production and heat‐stable serotype
Authors: FRICKER C. R. , PARK R. W. A.
Published: March 2008

The incidence of ‘thermophilic’ campylobacters in foods and environmental samples has been studied over a two‐year period. Of 781 environmental samples, 529 (67%) were found to contain campylobacters, and campylobacters were isolated from 835 (39%) of 2116 food samples. Sewage was almost always contaminated with campylobacters (96·6% of samples) and of the food samples both poultry (55·5%) and offal (47·0%) were commonly contaminated. Determination of the heat‐stable serotypes of all strains isolated from these sources and of 921 strains isolated from human faeces showed that there was a wide distribution of serotypes in most types of sample. Serotype Pen 2 was the commonest type found in human faeces (18·9%) and it was also commonest in offal (21·3%), beef (40·0%), sewage (17·7%) and was the third commonest type in poultry. A comparison of culture media and conditions for optimal production of both cytotoxic and cytotonic enterotoxins showed that Brucella Broth incubated under microaerobic conditions for 24 h at 42°C was suitable for both toxins. Detection of cytotoxic activity was most sensitive using HeLa cells. The sensitivities of two ELISA systems and a Chinese Hamster Ovary tissue culture assay for detection of cytotonic enterotoxin were comparable. Not all strains isolated from cases of enteritis in human beings produced toxin; 23·1% produced cytotonic enterotoxin and 17·5% produced cytotoxin. There was no correlation between serotype and toxin production. The wide distribution of campylobacters, indistinguishable from those isolated from cases of enteritis in human beings, leads us to conclude that simplistic statements suggesting that one particular type of food is primarily responsible for cases of human disease should not be made.
Response of enteric luminous bacteria to environmental conditions in the gut of the fish
Authors: RAMESH A. , VENUGOPALAN V. K.
Published: March 2008

The response of luminous bacterial cultures to conditions encountered in the fish gut such as neutral pH, the presence of bile salts, gastric juice and lysozyme was examined. The organisms preferred neutral pH. Bile salts did not inhibit their growth. Neither lysozyme nor gastric juice affected their growth and viability to any extent. In the light of these findings, the adaptability of luminous bacteria to conditions existing in the gut of fish was discussed.
Comparison of properties of collected cells and cells from the culture vessel during continuous culture of Streptococcus mutans Ingbritt
Authors: MAYO JOHN A. , McDERMID ANN S. , MARSH PHILIP D. , ELLWOOD DEREK C.
Published: March 2008

In continuous‐culture studies chemostat effluents are usually collected into a receiving flask in an ice bath to obtain enough cells for an experiment. It is assumed that the properties of these are not significantly different from those of the culture in the chemostat vessel. This assumption has been tested for the dental pathogen Streptococcus mutans Ingbritt. Collected supernatant fluid and cells were compared with supernatant fluid and cells taken directly from the culture vessel, for four major groups of culture properties: viability and biomcss, concentrations of metabolites and nutrients, activities of selected enzymes, and glycolytic rates. The assumption held true except for glycolytic rate during endogenous metabolism. It is suggested that comparison of collected and culture vessel cells is an important control which should be done in all continuous culture studies of microbial physiology and biochemistry, but that the properties of Strep, mutans cells collected on ice up to 16 h do reflect those of cells actively growing in the chemostat.
The effects of nutrients on the survival of Escherichia coli in lake water
Authors: LIM C.‐H. , FLINT K. P.
Published: March 2008

Escherichia coli was shown to survive without decline in viable counts for at least 12 d in filtered‐autoclaved lake water. In unfiltered lake water there was a rapid decline in the viable count of E. coli. The addition of synthetic sewage to filtered‐autoclaved lake water led to an increase in the viable count of E. coli at 15°C and 37°C and to an increase in the survival time of the E. coli in unfiltered water. The addition of phosphate and carbon sources (glucose, glycerol, succinate, acetate and lactose) did not significantly increase the survival time of E. coli in unfiltered water over the controls. The addition of ammonium sulphate and some amino acids (as nitrogen sources) to the unfiltered lake water did lead to an increase in the survival times for E. coli and this increase was proportional to the concentration of the added nitrogen source.
Properties and attempted culture of Pasteuria penetrans, a bacterial parasite of root‐knot nematode (Meloidogyne javanica)
Authors: Williams Anita B. , Stirling G.R. , Hayward A.C. , Perry J.
Published: March 2008

When they were subjected to a range of physical and chemical treatments, spores of Pasteuria penetrans showed properties similar to those of other endospore‐forming bacteria. The spores did not take up some stains, were resistant to desiccation and sonication and showed extrusion of spore contents (‘spore popping’) on prolonged exposure to 0.1% KMnO4 in 0.3 n HNO3. Calcium and dipicolinic acid (DPA) were present at concentrations of 0.28% and 0.96% of the spore dry weight respectively, giving a Ca: DPA molar ratio of 1.2. The infectivity of P. penetrans spores was reduced to a low level after heating at 100°C for 5 min, but spore attachment was not markedly affected by heating at 100°C for 15 min. Evidence for the presence of catalase in P. penetrans spores was equivocal because the low levels of catalase activity observed in spore suspensions may have been due to contamination from catalase‐positive nematode tissue. When P. penetrans spores were exposed to a range of substances known to act as germinants for spores of Bacillus spp., germination or loss of refractility was not observed by phase microscopy. In vitro culture of P. penetrans was attempted by inoculating either spores or vegetative mycelial bodies onto a diverse range of simple and complex media and incubating them in aerobic, reduced oxygen, anaerobic and increased CO2 environments. Signs of spore germination or growth of vegetative stages were never observed.
Characterization of some previously unclassified Pasteurellaceae isolated from hamsters
Authors: Krause T. , KunstýŘ I. , Mutters R.
Published: March 2008

Bacteria isolated from purulent processes on the jaws of European hamsters (Cricetus cricetus) and from intestinal inflammatory processes in Syrian hamsters (Mesocricetus auratus), bred as laboratory animals have been shown to be phenotypically similar but not identical with Pasteurella pneumotropica. Deoxyribonucleic acid (DNA)–DNA hybridization studies indicate that with one exception, the strains represent two new species of the family Pasteurellaceae. In the absence of a close genomic relatedness to members of the genera Actinobacillus or Pasteurella or allied organisms, however, the two new taxa are described without any formal designation. The one exception was identified as Actinobacillus capsulatus, a species not previously isolated from hamsters.
Characterization of versilin‐sensitive sites in self‐sensitive producer and sensitive non‐producer or unrelated organism
Authors: Basu S. , Jr S.K. Bose , Bose S.K.
Published: March 2008

Studies on self‐sensitivity of producer mutant vs. sensitivity of non‐producer parent and unrelated organism showed that versilin inhibited spore germination and sporulation in the self‐sensitive producer mutant, non‐producer parent Aspergillus versicolor N5 and the unrelated sensitive Trichophyton rubrum. Sporulation appeared to be more sensitive than spore germination. The inhibition of in vivo synthesis of protein was very marked, but inhibition of RNA and DNA was slight and moderate, respectively. Thus versilin was not specific in its action, but the principal sensitive site was protein synthesis, as further suggested by inhibition of polyU‐directed in vitro synthesis of polyphenylalanine. The activation of leucine was unaffected, but the formation of leucyl‐tRNA was severely inhibited in all three strains. The differences in sensitivities between the strains were the same, whether as whole cells or as cell‐free extracts. Thus the nature of the sensitive site appeared to be identical in the self‐sensitive producer and sensitive non‐producer or unrelated organism.
Production of mosquito larvicidal Bacillus thuringiensis serotype H‐14 on raw material media from Nigeria
Authors: Ejiofor A. O. , Okafor N.
Published: March 2008

Bacillus thuringiensis serotype H‐14 de Barjac, a potent larvicide of many mosquito and blackfly species, was grown on various media compounded from fermented cassava (Mannihot esculenta), ground and whole maize (Zea mays) grains and whole cowpeas (Vigna unguiculata) in shake flask fermentations. The liquors obtained from 100g/l of the whole cowpea and maize grains as well as combinations of these were used for further fermentations in 1 and 5 1 fermenters. The final whole cultures obtained were bioassayed against L11/111 of Aedes aegypti and the concentration‐effects estimated. The potency of the preparations (estimated as LC50, strength that showed 50% mortality of the mosquito larvae) ranged from 10.5 mg/l for the 1:3 combination of cowpea steep liquor:maize steep liquor to 90 mg/l for the 2:1 combination at 95% confidence limits. The LC50 of a standard nutrient broth‐yeast extract medium was 18 mg/l. The juice of Citrus aurantifolia and an extract from Elaeis guiniensis were used as acid and alkali respectively while bleached deodorized palm olein was used as antifoam.
Inhibition by antibiotics of the bacterial response to long‐term starvation of Salmonella typhimurium and the colon microbiota of mice
Authors: Stenström Thor‐Axel , Conway Patricia , Kjelleberg Staffan
Published: March 2008

The number of viable cells of two strains of Salmonella typhimurium and the number of viable cells and the cell size of the colon microbiota of mice were examined during non‐growing conditions after exposure to antibiotics with known modes of action. Salmonella typhimurium starved for 1, 2, 4, 5, 12 and 20 d in a phosphate buffer saline solution and subsequently exposed for 2 and 6 h showed the following characteristics. The protein synthesis inhibitors gentamicin and tetracycline, the RNA synthesis inhibitor rifampicin and the membrane potential inhibitor polymyxin all impaired survival of starved cells. The reduction in the number of viable cells caused by the addition of gentamicin, rifampicin and polymyxin was generally more pronounced with extended exposure to energy and nutrient deprivation. Both 2‐ and 6‐h exposure of tetracycline, however, had diminishing inhibitory effects after 20 d compared with 5 d of starvation. Control experiments to verify non‐growing conditions in the starvation regime showed that DNA and cell wall synthesis inhibitors had no inhibitory effect after 24‐h starvation. The rough mutant strain displayed a lower sensitivity to a hydrophobic rather than a hydrophilic inhibitor as compared to the smooth wild‐type strain. The cell size reduction but not viability was partly prevented by protein synthesis inhibitors as seen for both in vivo and in vitro colon microbiota studies.
Identification of Bacillus anthracis by polyclonal antibodies against extracted vegetative cell antigens
Authors: PHILLIPS A.P. , EZZELL J.W.
Published: March 2008

The extractable protein antigens EA1 and EA2 of Bacillus anthracis were prepared from electrophoresis transblots of SDS extracts of vegetative bacteria of the Sterne strain. Hyperimmune guinea‐pig antiserum against EA2 failed to react with B. anthracis cells in immunofluorescence (IF) tests. Guinea‐pig antiserum against EA1 (anti‐EA1) reacted strongly in IF tests with non‐encapsulated vegetative cell of 10 of 12 strains of B. anthracis and with cells of strains of B. cereus and B. thuringiensis. The unreactive B. anthracis strains were α‐Vollum‐1B–1 and Texas. Encapsulated cells of B. anthracis stained poorly except for small bright regions. Absorption of anti‐EA1 with cells of B. cereus NCTC 8035 and NCTC 9946 removed activity towards all B. cereus strains tested, but only partly reduced cross‐reaction with B. thuringiensis strains. Absorption of anti‐EA1 with B. thuringiensis 4041 removed activity towards this strain and B. cereus strains. Evidence is produced that B. thuringiensis cells grown on nutrient agar possess more cross‐reacting antigens than cells grown in nutrient broth. The reaction of anti‐EA1 with Bacillus spores immobilized in clumps on microscope slides was attributed to contaminating vegetative debris because well‐separated individual spores failed to react. A rapid IF test was developed allowing identification of B. anthracis sampled from overnight cultures on blood plates. When sodium dodecyl sulphate extracts of B. anthracis vegetative cells were analysed on immunoblots (Western blots) by reaction with anti‐EA1, a number of bands were visualized in addition to the expected 91 kiloDalton EA1 band. Prior absorption of anti‐EA1 with B. cereus or B. thuringiensis cells resulted in the disappearance of most or all of the brands in blots of these species, but had less effect on blots of the B. anthracis strains. All six B. anthracis strains that were blotted including α‐Vollum‐1B‐1 and Texas, could thus be distinguished from B. cereus and B. thuringiensis by their differential reaction with unabsorbed and absorbed anti‐EA1.
The influence of incubation pH on the activity of rat and human gut flora enzymes
Authors: MALLETT A.K. , BEARNE C.A. , ROWLAND I.R.
Published: March 2008

The activities of three bacterial biotransformation enzymes (β‐glucuronidase, β‐glucosidase, nitrate reductase) were determined in suspensions of rat caecal contents or human faeces over the pH range 6–8. All three enzymes were influenced by pH, as exemplified by β‐glucosidase activity which diminished as pH increased. In other instances the rat and human flora showed distinct profiles, with nitrate reductase activity undetectable in human faeces below pH 6–6, whereas the rat caecal flora displayed optimal reduction of nitrate around neutrality. The most pronounced host‐species difference was found with β‐glucuronidase, which showed maximal activity at pH 6–0 in human faecal bacteria, while the rat caecal flora expressed greatest activity at pH 8–0. All three enzyme activities were associated with that fraction of rat caecal or human faecal material sedimented by centrifugation at 5000 g for 15 min, with little or no metabolism occurring in the 11000 g supernatant fluid. The results demonstrate that pH has a pronounced effect on the enzymic activity of bacterial preparations from rat and human sources.
Synthesis and properties of a mutant type of xanthan
Authors: TAIT M.I. , SUTHERLAND I.W.
Published: March 2008

A mutant of Xanthomas campestris produces good yields of an exopolysaccharide. This material differs from the wild‐type xanthan from the parent bacteria, in its very low content of acetate and pyruvate and in its molar ratio of D‐glucose:D‐mannose of 2:1. Analysis of the products from xanthan lyase indicates that most of the side‐chains are disaccharides rather than the normal trisaccharides. The polymer has lower viscosity than normal xanthan. The consistency index was 20 mPa.s compared with 78 mPa.s for the product of the parent strain under standard conditions. The polysaccharide could be further modified by prolonged treatment with β‐glucuronidase, which removed some of the terminal β‐D‐glucuronosyl residues. This enzyme‐modified product had much higher viscosity than that from the mutant.
Antibacterial polypeptides of Lactobacillus species
Authors: Rammelsberg M. , Radler F.
Published: March 2008

Twelve of 79 strains of the genus Lactobacillus, mainly isolated from plants or fermenting material, were found to inhibit at least one of the nine indicator strains of the species Lact. brevis, Pediococcus damnosus and Leucanostoc oenos. The antimicrobial activities from Lact. brevis B 37 and Lact. casei B 80 were caused by polypeptides detectable in the culture liquids. They are bacteriocins with a narrow antimicrobial spectrum. Brevicin 37 from Lact. brevis B 37 was active against many lactic acid bacteria and Nocardia corallina, whereas caseicin 80 from Lact. casei B 80 inhibits only one other strain of Lact. casei. Brevicin 37 is stable at 121d̀C, caseicin 80 is inactivated above 60d̀C, and both are inactivated under alkaline conditions.
A model system for the study of food container leakage
Authors: McEldowney S. , Fletcher M.
Published: March 2008

A model system to study food container leakage was developed. The model system allows the independent investigation of the effect of physical factors such as vacuum and contents viscosity, and microbial factors on the leakage process. The design, construction and operation of the container leakage model system is described.
Comparison of quantitative and qualitative methods of detecting hydrogen peroxide produced by human vaginal strains of lactobacilli
Authors: Fontaine E.A. , Taylor‐Robinson D.
Published: March 2008

A quantitative method was developed for the measurement of micromolar quantities of H2O2 produced in Rogosa broth and peptonized milk broth by vaginal strains of lactobacilli isolated from women. The production of substantial amounts reproducibly was dependent on the growth of the organisms in acid media (pH ≤6.0) under anaerobic or micro‐aerophilic conditions with continuous agitation. The addition to the media of the enzyme inhibitor, 3‐amino‐l,2,4‐triazole, with or without catalase sometimes induced the production of H2O2 especially in non‐agitated cultures. However, other agents such as concanavalin and o‐dianisidine had no enhancing effect, and catalase or peroxidase alone completely inhibited H2O2 production.

The H2O2 produced in the acid media was stable for more than a month at 5°C but not in media at pH ≥ 7.0. Of five strains of lactobacilli tested by the quantitative method and by a chromogenic qualitative method (Rogosa‐catalase or ‐peroxidase agar), three consistently produced H2O2 measurable by the former method, but none did so after growth of the organisms on Rogosa‐catalase/peroxidase agar which suggested that the qualitative method was unreliable. The fact that H2O2 was produced in substantial quantities by some strains and not at all by others enabled H2O2‐producers and non‐producers to be distinguished easily.
Production of exotoxins by Aeromonas spp. at 5°C
Authors: Majeed K.N. , Egan A.F. , Rae I.C. Mac
Published: March 2008

The ability of 60 strains of Aeromonas to produce enterotoxin and haemolysin after cultivation at 5°C for 7–10 d was investigated. The strains were isolated from lamb meat, offal, carcasses and faeces, and had previously been tested for their ability to produce these exotoxins at 37°C. The results showed that some strains of Aeromonas hydrophila and A. sobria were capable of producing enterotoxin and haemolysin at 5°C, but none of the A. caviae strains tested produced these two factors. Of the 30 A. hydrophila strains investigated 25 and 27 were enterotoxigenic and haemolytic respectively. Likewise, of the 24 A. sobria strains investigated 16 and 18 were enterotoxigenic and haemolytic respectively. The results indicate that certain strains of Aeromonas species, in particular A. hydrophila and A. sobria, are of potential public health significance in meats stored at refrigeration temperature.
Open fronted safety cabinets in ventilated laboratories
Authors: Clark R.P. , Osborne R.W. , Pressey D.C. , Grover F. , K.Eddif J.R. , Thomas C.
Published: March 2008

Open fronted Class I and II microbiological safety cabinets (MSCs) are required by the British Standard 5726 to provide similar levels of operator protection (viz. 105). In laboratories that are naturally ventilated large numbers of both types of cabinets have been shown to exceed this requirement consistently over a number of years. The designs of some mechanically ventilated laboratories, however, produce excessive turbulence and draughts that can prejudice containment at the front aperture. On‐site commissioning tests to determine operator protection factor are now well established and are recognized as being essential to the setting up of all open fronted cabinets in both ventilated and unventilated laboratories. This paper shows that where environmental conditions induce unsatisfactory cabinet containment, adjustments to air supply and exhaust systems can be made which will enable both Class I and II cabinets to produce operator protection factors in excess of 105. When compatibility is achieved between the local environment and the cabinets it is demonstrated that disturbances at the front aperture, caused by operator working procedures or by disturbances due to personnel movement within the room, have similar effects on both Class I and II cabinets. Once performance levels have been satisfactorily achieved, regular containment testing has shown that consistent performance can be maintained. These aspects of open fronted safety cabinet performance are discussed in relation to ventilated laboratories suitable for work with the human immunodeficiency virus (HIV). Of paramount importance in the future is the necessity to design laboratory air systems that will be compatible with satisfactory safety cabinet performance—a relatively new requirement in ventilation system specifications.
The influence of pH, temperature and organic acids on the initiation of growth of Yersinia enterocolitica
Authors: Brocklehurst T.F. , Lund Barbara M.
Published: March 2008

The influence of incubation temperature, and of acetic, lactic and citric acids on the minimum pH for the initiation of growth of six strains of Yersinia enterocolitica was determined. The strains included two of serotype O : 9, two of serotype O : 3, and one each of serotypes O : 8 and O : 5, 27. In a culture medium acidified with HC1 to pH values between 4.0 and 6.0 at intervals of approximately 0.1 unit the minimum pH at which growth was detected after incubation at 20°, 10°, 7° and 4°C for 21 d was in the ranges 4.18–4.36, 4.26–4.50, 4.36–4.83 and 4.42–4.80, respectively. The minimum pH for growth was also determined in media that contained 17, 33 and 50 mmol/1 acetic acid adjusted to pH values between 5.1 and 5.9 at intervals of approximately 0.2 unit, 24, 48 and 95 mmol/1 citric acid adjusted to pH values between 41 and 4.9 at intervals of approximately 0.2 unit, and 22, 44, and 111 mmol/1 lactic acid adjusted to pH values between 4.3 and 5.7 at intervals of approximately 0.4 or 0.5 unit. The effect of these concentrations of organic acids was, in most cases, to increase the minimum pH that allowed growth. The order of effectiveness of the organic acids in raising the minimum pH for growth was acetic > lactic > citric and the minimum inhibitory concentrations were greater at higher temperatures.
Effects of heat‐, CaCl2‐ and ethanol‐treatments on activation of Bacillus spores*
Authors: Kim Jungho , Foegeding Peggy M.
Published: March 2008

The effects of heat, CaCl2, and ethanol on activation of Bacillus spores were determined by monitoring the absorbance decrease during germination in inosine. Bacillus cereus T, B. subtilis A and B, megaterium QM B1551 spores were activated by heat‐ and CaCI2‐treatments. Ethanol activated B. megaterium and B. subtilis spores yet did not activate B. cereus spores. CaCl2‐ and ethanol‐activations were less effective than heat‐activation as judged by optimal germination rates and germination extents. The presence of CaCl2 during heat‐treatment inhibited heat‐activation of all three Bacillus spores without affecting viability or dipicolinic acid content of the spores. The electrophoretic patterns of coat plus outer membrane proteins extracted from Bacillus spores treated with CaCl2 and heat in the presence of CaCl2 were similar to each other and were distinctively different from the patterns of proteins from unactivated spores or the spores treated with heat and/or ethanol.
Effect of growth conditions and storage on the specific activity of β‐lactamases of Bacteroides spp.
Authors: Edwards R. , Greenwood D.
Published: March 2008

The influences of growth conditions and cold storage on the specific activity of β‐lactamases of four strains of Bacteroides spp. was studied. Interbatch variation was observed in extracts prepared in an identical way on separate occasions but less variation was observed in extracts prepared from bacteria grown on Brain Heart Infusion agar supplemented with yeast extract, haemin and menadione, than in similar extracts of bacteria grown in broth or on other solid media. The loss of enzyme activity seen during the stationary phase of growth of some strains in broth was minimal during incubation for 48 h on agar. Storage of enzyme extracts at 4°C was associated with loss of enzyme activity, but activity was retained during storage at—70°C for up to 32 days. Freezing and thawing had little effect on enzyme activity.
Yeast contaminants of micropropagated plant cultures
Authors: Leifert C. , Waites W.M. , Nicholas J.R. , KEETLEY Julia W. W.
Published: March 2008

Leifert, C., Waites, W.M., Nicholas, J.R. & Keetley, J.W. 1990. Yeast contaminants of micropropagated plant cultures. Journal of Applied Bacteriology69, 471–476.

Of 36 yeast strains isolated from contaminated plant cultures 78% were Candida, 20%Rhodotorula and 2% were Cryptococcus species. Strains of Candida guilliermon‐dii represented 45% of all yeasts isolated. Yeasts grew rapidly on plant growth media with a pH of between 2.5 and 6.0 and decreased the medium pH to values of between 2.0 and 3.0. Candida yeasts growing on plant medium for 28 d metabolized about 75% of the sucrose and produced fermentation products such as ethanol and acetic acid. In contrast, Rhodotorula did not produce ethanol or acetic acid and only metabolized about 20% of the sucrose. Possible sources of contamination are discussed.
Heat resistance in Salmonella enteritidis phage type 4: the influence of storage temperatures before heating
Authors: Humphrey T.J.
Published: March 2008

Humphrey, T.J. 1990. Heat resistance in Salmonella enteritidis phage type 4: the influence of storage temperatures before heating. Journal of Applied Bacteriology69 493–497.

Storage of cultures of Salmonella enteritidis PT4 at either 4° or 8°C before heating significantly increased heat sensitivity. The differences between fresh and stored cultures, which became apparent after 4–7 h, were more pronounced with cultures stored at the lower temperature and in those heated at 60° rather than 55°C. Incubation of the stored cultures in either egg or Lemco broth for 30 min at 37°C prior to heating enabled the organisms to recover heat resistance.
Centroid search optimization of cultural conditions affecting the production of extracellular proteinase by Pseudomonas fragi ATCC 4973
Authors: Myhara R.M. , Skura B.
Published: March 2008

Myhara, R.M. & Skura, B. 1990. Centroid search optimization of cultural conditions affecting the production of extracellular proteinase by Pseudomonas fragi ATCC 4973. Journal of Applied Bacteriology69, 530–538.

The production of extracellular proteinase by Pseudomonas fragi ATCC 4973 grown in a defined citrate medium, containing glutamine as the sole nitrogen source, was determined under varying cultural conditions. Simultaneous evaluation of cultural conditions using a ‘centroid search’ optimization technique showed that the optimum cultural conditions for proteinase production by Ps. fragi were: incubation temperature, 12.5°C; incubation time, 38 h; initial pH, 6.8; organic nitrogen concentration, 314 mmol nitrogen/1 (glutamine); a gas mixture containing 16.4% oxygen flowing over the medium (7.42 ppm dissolved oxygen). Oxygen was the major factor influencing proteinase production by Ps. fragi. The results may have applications in the storage of fluid milk. Centroid search optimization was shown to be suitable for microbiological experiments.
Chemical reactivity of some isothiazolone biocides
Authors: Collier P.J. , Ramsey A. , Waigh R.D. , Douglas K.T. , Austin P. , Gilbert P.
Published: March 2008

Collier, P.J., Ramsey, A., Waigh, R.D., Douglas, K.T., Austin, P. & Gilbert, P. 1990. Chemical reactivity of some isothiazolone biocides. Journal of Applied Bacteriology69, 578–584.

Chemical reactions between the isothiazolone biocides, N‐methylisothiazol‐3‐one (MIT), benzisothiazol‐3‐one (BIT) and 5‐chloro‐N‐methylisothiazol‐3‐one (CMIT) with cysteine have been investigated by u.v. and NMR spectroscopy. At physiological pH all three agents interacted oxidatively with thiols to form disulphides. Further interaction with thiols caused the release of cystine and formation of a reduced, ring‐opened form of the biocide (mercaptoacrylamide). In an analogous fashion to the initial reaction the mercaptoacrylamide reacted with another molecule of biocide to give biocide dimers. NMR spectral studies indicated that for CMIT the mercaptoacrylamide form is capable of tautomerization to a highly reactive thio‐acyl chloride. Formation of mercaptoacrylamide was in all cases highly pH‐dependent. Alcohol dehydrogenase was insensitive to all three agents but was highly sensitive to CMIT when co‐administered with dithiothreitol. Capacity to form a thioacyl chloride from the mercaptoacrylamide is suggested to account for much of this enhanced activity. Stopped‐flow spectroscopic studies showed rates of reaction with glutathione (GSH) to directly parallel antimicrobial activity. Additionally, CMIT was able to react directly with both ionization states of GSH (pH 7–10) whilst BIT and MIT appeared only to interact when the glutamyl‐nitrogen of GSH was charged (pH 8.5).
Growth and extracellular enzyme production by strains of Bacillus species isolated from fermenting African locust bean, iru
Authors: Aderibigbe Esther Y. , Odunfa S.A.
Published: March 2008

Adeiubigbe, E.Y. & Odunfa, S.A. 1990. Growth and extracellular enzyme production by strains of Bacillus species isolated from fermenting African locust bean, iru. Journal of Applied Bacteriology69, 662–671.

Seven strains of Bacillus subtilis group, isolated from fermented African locust bean (iru), were screened for proteolytic activity. Three strains (BS2, BL2 and BP2), which were found to be highly proteolytic, were compared on the basis of growth and extracellular enzyme production in media with and without locust bean. AH had their optimum pH for growth between 7.0 and 9.0.

The three strains produced varied amounts of amylase, polygalacturonase, galac‐lanase and sucrase. The amounts of amylase and polygalacturonases produced by strain BS2 were significantly higher (at α= 0.5) than those of strains BL2 and BP2. None of the strains produced pectinmethylesterase in nutrient broth with or without African locust bean. Although the three strains were lipolytic on tributyrin agar plates, only trace amounts of lipase were detected titrimetrically in broth medium containing African locust bean. The three strains produced varying levels of sucrase and galactanases. Phytase activity was not detected in the broth culture of strain BS2. The presence of African locust bean in culture medium generally enhanced the production of extracellular enzymes significantly (at α= 0.05) in the three strains.
Sequential release of antigens from chloroform‐treated Staphylococcus epidermidis: application towards a possible vaccine
Authors: Ahmad A. , Clarke S. , Buchan A. , Skinner G.R.B.
Published: March 2008

Ahmad, A., Clarke, S., Buchan, A. & Skinner, G.R.B. 1990. Sequential release of antigens from chloroform‐treated Staphylococcus epidermidis: application towards a possible vaccine. Journal of Applied Bacteriology69, 676–685.

This study describes the properties of two potential Staphylococcus epidermidis vaccines prepared by chloroform treatment of bacteria and release of antigen from these chloroform‐treated organisms. Both vaccines were antigenic on testing with homologous hyperimmune serum and induced immune reactivity in immunized rabbits. There was protective efficacy in mice against intraperitoneal challenge by Staph, epidermidis.
The cutaneous microbiology of haired and hairless mice
Authors: Harnby D. , Gowland G. , Holland K.T. , Kearney J.N.
Published: March 2008

Harnby, D., Gowland, G., Holland, K.T. & Kearney, J.N. 1990. The cutaneous microbiology of haired and hairless mice. Journal of Applied Bacteriology69, 686–691.

The cutaneous microflora of the mid‐dorsal area of hairless and haired mice was studied by processing skin biopsies. In both C3H and CBA hairless genotype animals the prevalence of colonization and the bacterial density were significantly greater than in the haired animals. The dominant bacteria were staphylococci and aerobic coryneforms. No propionibacteria were isolated. Temporal studies with C3H mice showed that from 0 to 9 days after birth the cutaneous microflora reduced and from then on the haired genotype animals maintained a low cutaneous microflora, whilst hairless genotype animals gradually lost hair from head to tail and the microflora density increased. Reciprocal skin grafting between haired and hairless animals showed that the donor skin acquired the microflora characteristics of the recipient animal after 15 d post‐grafting even though the donor skin remained morphologically true to genotype.
Growth of Bacteraides fragilis group in agar and broth media
Authors: Brook I.
Published: March 2008

Brook, I. 1990. Growth of Bacteroides fragilis group in agar and broth media. Journal of Applied Bacteriology69, 697–700.

The rate of bacterial growth of four .Bacteroides fragilis group organisms was determined in agar and broth media. Exponential bacterial growth occurred in agar media within 4 to 8 h, while such growth was delayed in broth media and occurred within 12–24 h after inoculation. This phenomenon may explain why antimicrobials which manifest an ‘inoculum effect’ may show increased resistance to antimicrobials when tested in agar media.
Stability of solvent production by Clostridium acetobutylicum in continuous culture: strain differences
Authors: Woolley R.C. , Morris J.G.
Published: March 2008

Woolley, R.C. & Morris, J.G. 1990. Stability of solvent production by Clostridium acetobutylicum in continuous culture: strain differences. Journal of Applied Bacteriology69, 718–728.

Several strains of Clostridium acetobutylicum, including strains ATCC 824 and DSM 1731, continue to produce solvents during prolonged periods of chemostat culture. In such cultures, dominance is established by asporogenous mutant(s) that retain the ability to produce solvents. Strain NCIB 8052 (which is not identical with ATCC 824) behaved differently in that its chemostat cultures invariably became acidogenic due to ultimate selection of asporogenous mutant(s) unable to produce solvents, incapable of synthesizing granulose, and demonstrating enhanced sensitivity to environmental stresses of various types. These mutants spontaneously reverted, at a low but measurable frequency, to the parental phenotype, indicating thai their multiple loss of capacities was the pleiotropic consequence of a lesion in some global regulatory gene. Their resemblance to previously described cls mutants of strain P262 and the possible nature of the affected regulatory gene are discussed. A simple tetrazolium blue plate assay procedure is described which allows visual discrimination between solvent‐producing and non‐solventogenic colonies of Cl. ocetobutylicum.
Evaluation of rapid methods for differentiation of Bifidobacterium species
Authors: Roy D. , Ward P.
Published: March 2008

Roy, D. & Ward, P. 1990. Evaluation of rapid methods for differentiation of Bifidobacterium species. Journal of Applied Bacteriology69, 739–749.

The fermentation patterns of 20 Bifidobacterium strains were determined by two methods: a carbohydrate utilization test, based on the production of acid from a given range of sugars in modified MRS broth (micromethod), and a gas chromato‐graphic (GC) analysis of fermented modified MRS broth. The micromethod provides a qualitative fermentation pattern whereas the GC method gives a quantitative evaluation of carbohydrate utilization. The micromethod and GC analysis can be applied for the differentiation of Bifidobacterium strains used in fermented milks.
Sterols and diacylglycerophosphocholines in the lipids of the hydrocarbon‐utilizing prokaryote Rhodococcus rhodochrous
Authors: Sorkhoh N.A. , Ghannoum M.A. , Ibrahim A.S. , Stretton R.J. , Radwan S.S.
Published: March 2008

Sorkhoh, N.A., Ghannoum, M.A., Ibrahim, A.S., Stretton, R.J. & Radwan, S.S. 1990. Sterols and diacylglycerophosphocholines in the lipids of the hydrocarbon‐utilizing prokaryote Rhodococcus rhodochrous. Journal of Applied Bacteriology69, 856–863.

Two strains of Rhodococcus rhodochrous were grown in an inorganic medium containing either glucose or dodecane as sole sources of carbon and their total lipids were extracted and analysed. Dodecane‐grown cells contained more total lipids than glucose‐grown cells. Lipid classes that increased in dodecane‐grown cells were sterols, monoacylglycerols, diacylglycerophosphocholines and an unknown glyco‐lipid. Sterols and diacylglycerophosphocholines were unequivocally identified in this species. The major acyl moieties in total lipids from glucose‐grown cells were palmitic and octadecanoic acids, in addition to small amounts of linoleic and linolenic acids and traces of tuberculostearic acid. The latter was confined to diacyl‐glycerophosphoglycerols and the unknown glycolipid. In addition to these acids, dodecane‐grown cells contained relatively large proportions of lauric and myristic acids in their total lipids, which were esterified mainly in diacylglycerophosphocholines and the unknown glycolipid.
The role of silica in Bacillus licheniformis
Authors: Mohanty B.K. , Ghosh S. , Mishra A.K.
Published: March 2008

Bacillus licheniformis, an indigenous strain from high silica‐containing magnesite ore was found to tolerate 250 μg of Si/ml (Na2SiO3.5H2O) in the medium. During growth the bacterium was capable of accumulating about 21 μg of Si/ml within 8 h. The absence of phosphate was highly inhibitory to its growth as well as silicon absorption. A relationship between growth, utilization of Si and its release from magnesite ore is discussed. A feedback inhibition of Si release from the ore has been predicted.
Purification and characterization of cellulolytic enzymes produced by Aspergillus nidulans
Authors: Bagga P.S. , Sandhu D.K. , Sharma S.
Published: March 2008

Three exo‐glucanases, two endo‐glucanases and two β‐glucosidases were separated and purified from the culture medium of Aspergillus nidulans. The optimal assay conditions for all forms of cellulase components ranged from pH 5.0 to 6.0 and 50°C and 65°C for exo‐glucanases and endo‐glucanases but 35°C and 65°C for β‐glucosidases. A close relation of enzyme stability to their optimal pH range was observed. All the cellulase components were stable for 10 min at 40–50°C. Exo‐II and Exo‐III (Km, 38.46 and 37.71 mg/ml) had greater affinity for the substrate than Exo‐I (Km, 50.00 mg/ml). The Km values of Endo‐I and Endo‐II (5.0 and 4.0 mg/ml) and their maximum reaction velocities (Vmax, 12.0 and 10.0 IU/mg protein) were comparable. β‐Glucosidases exhibited Km values of 0.24 and 0.12 mmol and Vmax values of 8.00 and 0.67 IU/mg protein. The molecular weights recorded for various enzyme forms were: Exo‐I, 29000; Exo‐II, 72500; Exo‐III, 138000; Endo‐I, 25000; Endo‐II, 32500; β‐Gluco‐I, 14000 and β‐Gluco‐II, 26000. Exo‐ and endo‐glucanases were found to require some metal ions as co‐factors for their catalytic activities whereas β‐glucosidases did not. Hg2+ inhibited the activity of all the cellulase components. The saccharification studies demonstrated a high degree of synergism among all the three cellulase components for hydrolysis of dewaxed cotton.
Effect of short‐chain organic acids on macromolecular synthesis in Escherichia coli
Authors: Cherrington Christina A. , Hinton M. , Chopra I.
Published: March 2008

Incubating cultures of Escherichia coli with propionic acid (5 mmol/l) or formic acid (10 mmol/l) at pH 5.0 produced bacteriostasis lasting 30 and 120 min respectively. During this time rates of RNA, DNA, protein, lipid and cell wall synthesis were reduced. Growth resumed after continued incubation in the presence of acid, but cells from acid‐treated cultures were larger than controls. DNA synthesis was particularly sensitive to the presence of the propionic or formic acid.
Effect of the DNA replication velocity on the response of Salmonella typhimurium to mild heating
Authors: Mirhabibollahi B. , Davies R.
Published: March 2008

Changes in the DNA replication velocity of Salmonella typhimurium following mild heat stress (52°C) were studied independently of the major physiological parameter of growth rate, using thymine‐requiring mutant strains derived from Salm. typhimurium LT2. The isolated mutant strains BM1 or BM2, grown either as batch or chemostat cultures, showed a greater sensitivity to 52°C heat stress when grown on a minimal medium containing near‐limiting concentrations of thymine, compared with growth in the presence of excess thymine. Radiolabelling experiments provided evidence for alterations in the velocity of DNA replication upon growth on different thymine concentrations, independent of the growth rate. Thus, replicating DNA was implicated as the major site of injury after mild moist heat stress. and accepted 3 June 1989