bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacteria degrading phenolic acids isolated on a polymeric phenolic pigment
Authors: Pérez J. , Ramos‐Cormenzana A. , Martínez J.
Published: March 2008

Thirty‐eight bacterial strains were isolated from waste water of olive oil mills, olives and soil in chemically defined media containing the pigment of these wastes as sole carbon source. Most of the organisms were Pseudomonas spp. Four of the six phenolic acids associated with polymeric pigments in olive oil waste degradation were used by three strains. Only one Pseudomonas strain was able to use five acids.
Validation of flow cytometry for rapid enumeration of bacterial concentrations in pure cultures
Authors: Pinder A. C. , Purdy P. W. , Poulter S. A. G. , Clark D. C.
Published: March 2008

Flow cytometry was investigated as a rapid detection and counting method for bacteria in pure cultures. A simple two‐parameter detection scheme was employed: particle size was measured by forward angle light scatter and nucleic acid content by fluorescence of the DNA/RNA‐binding dye ethidium bromide. The technique gave results that correlated exceptionally well with conventional plate counting for four species of bacteria, and concentrations in the range 102 to 107 cfu/ml. Cyto‐metric counts were obtained in a few minutes, as compared with 2 d required for the plate counts. Under ideal conditions, each bacterial species examined exhibited a characteristic ‘signature’ on the cytometer, which could be explained by its known properties and morphology.
High‐performance liquid chromatographic analysis of α‐keto acids produced from amino acid metabolism in oral Bacteroides
Authors: Tsuchiya H. , Sato M. , Yamamoto K. , Yamauchi M. , Tani H. , Namikawa I. , Takagi N.
Published: March 2008

Profiles of metabolic α‐keto acids were determined by a high‐performance liquid chromatographic method and applied to characterization of oral black‐pigmented Bacteroides. Each bacterial strain was incubated with amino acids in a chemically defined medium. After production α‐keto acids were purified by hydrazide gel column treatment and converted to u.v.‐absorbing derivatives. They were analysed by reversed‐phase ion‐pair chromatography. Black‐pigmented Bacteroides species were differentiated into two groups according to production of aromatic α‐keto acids. Bacteroides gingivalis, B. endodontalis and B. loescheii produced both ρ‐hydroxyphenylpyruvic and phenylpyruvic acids. However, no such α‐keto acids were produced by B. levii, B. intermedius and B. denticola. In addition, production profiles of several aliphatic α‐keto acids (α‐ketoglutaric, pyruvic, α‐ketobutyric, α‐ketoisovaleric, α‐ketoisocaproic, and α‐keto‐β‐methylvaleric acids) separated each individual species in such groups. The present study offers useful chemotaxonomic information on amino acid metabolic activity of oral black‐pigmented Bacteroides species.
The incidence of Bdellovibrio spp. in man‐made water systems: coexistence with legionellas
Authors: Richardson I. R.
Published: March 2008

Bdellovibrios have been isolated from surface waters but there are no reports of its occurrence in mains water supplies. One hundred and thirty five water samples from 81 sources were examined for the presence of Bdellovibrio bacteriovorus and Legion‐ella spp. Bdellovibrics were isolated by a double‐layer agar technique with two strains of Legionella pneumophila serogroup 1 as the host organisms. Bdellovibrio spp. were isolated from 57·8% and Legionella spp. from 9·5% of the samples. The two species occurred together in 4·4% of samples. The incidence of Bdellovibrio spp. and its occurrence with legionellas in man‐made water systems is discussed.
Tetrodotoxin production of actinomycetes isolated from marine sediment
Authors: Do H.K. , Kogure K. , Imada C. , Noguchi T. , Ohwada K. , Simidu U.
Published: March 2008

Ten actinomycetes isolated from various marine sediments were investigated for the production of tetrodotoxin (TTX). Tissue culture assay, high performance liquid chromatography and gas chromatography‐mass spectrometry confirmed that the nine strains produced TTX. Actinomycetes may be responsible for TTX accumulation in marine environments.
Establishment in the piglet gut of lactobacilli capable of degrading mixed‐linked β‐glucans
Authors: Jonsson Eva , Hemmingsson Susanne
Published: March 2008

The establishment in piglets of lactobacilli with ability to degrade mixed‐linked (1 → 3), (1 → 4) β‐D‐glucans was studied in faeces from 15 animals. The piglets had free access to creep feed with an estimated content of 2%β‐d‐glucans from 5 days of age. On days 3 and 35, ca log 8 cfu/g of β‐glucan‐degrading lactobacilli were found in a majority of the samples. On days 7, 14 and 21 such bacteria were only found occasionally.

During establishment of the microflora in the neonate, the faecal lactobacilli of the piglet seemed related to those of the sow. Later, the metabolic activity of the lactobacilli in piglet faeces showed a connection to the composition of the diet. The possible relation of these bacteria to occurrence of β‐glucanases attributed to be endogenous in the pig is discussed.
Menaquinone composition of some micrococci determined by high performance liquid chromatography
Authors: Amadi E.N. , Alderson Grace
Published: March 2008

The menaquinone composition of some species of the genus Micrococcus was analysed by high performance liquid chromatography. Both unsaturated and hydrogenated menaquinones were detected. Micrococcus kristinae, M. lylae and M. nishinomiyaensis contained hydrogenated menaquinones while M. sedentarius contained unsaturated menaquinone. The predominant menaquinone isoprenologues of these species are MK‐7 (H2), MK‐8 (H2), MK‐8 (H2) and MK‐8, respectively. These observations confirm further the heterogeneity of the genus.
Antimicrobial effect of fermented Ghanaian maize dough
Authors: Mensah Patience , Tomkins A.M. , Drasar B.S. , Harrison T.J.
Published: March 2008

Unhygienic conditions of a typical rural community in a developing country were simulated in the laboratory by inoculating fermented maize dough porridge with Shigella flexneri and enterotoxigenic Escherichia coli (ETEC). The antimicrobial effects of the different processes involved in the preparation of fermented maize dough porridge were assessed. The soaking process reduced the pH but no antimicrobial effect against shigella and ETEC was noted. Unfermented maize dough did not inhibit any of the test strains. When the fermentation process had become established, half of the strains tested were inhibited by the fermented maize dough when examined 8 h after inoculation. Cooking the fermented maize dough into porridge reduced the antimicrobial effect but there was still significant inhibition of pathogens. This suggests that the antimicrobial effect of fermented maize dough is not due to pH per se. Fermentation of maize dough appears to be a useful strategy for reducing contamination of weaning foods by Sh. flexneri and ETEC. The possible nature of the antimicrobial agent(s) produced during the fermentation of maize dough is discussed.
Expression of glycocalyx by coagulase‐negative Staphylococcus species isolated from bovine milk
Authors: Matthews K.R. , Oliver S.P. , King S.H.
Published: March 2008

Two hundred and six strains of coagulase‐negative Staphylococcus species were assessed for expression of glycocalyx on serum soft agar, india ink and adherence techniques. The organisms were maintained on trypticase soy agar plates at 4°C for 30 d (120 strains) or stored at ‐80°C in skim milk for 90 d (60 strains). Additionally, 26 milk samples from cows known to have excreted coagulase‐negative staphylococci were used to inoculate serum soft agar directly. Nine of 26 direct culture samples and 43 of 180 strains maintained for an extended period had diffuse‐type growth on serum soft agar. The proportion that exhibited an unstained halo by india ink was similar regardless of storage time. Slime production determined by in vitro adherence revealed a higher proportion of positive strains than had been predicted by serum soft agar or india ink techniques. More strains of Staphylococcus chromogenes, Staph. epidermidis, Staph. hominis, Staph. simulans and Staph. warneri expressed glycocalyx than other coagulase‐negative Staphylococcus species. These results suggest that most coagulase‐negative staphylococci produce slime rather than a capsule. However, evidence for classical encapsulation was demonstrated in several strains by india ink. The finding that Staphylococcus species other than Staph. aureus isolated from bovine milk are capable of glycocalyx production may be of importance in investigations on the relationship between staphylococci and host defence mechanisms.
The effect of a self‐regulating trace heating element on legionella within a shower
Authors: Makin T. , Hart C.A.
Published: March 2008

A self‐regulating trace heating element was assessed for its ability to maintain a temperature of 50°C in the mixer valve and dead‐legs of a shower, and for its effect on legionellas colonizing the shower. The trace heating element maintained a temperature of 50°C ± 1·5°C in dead‐legs when the circulating hot water supply remained above 45°C. Legionellas appeared in a trace heated dead‐leg when the temperature of the dead‐leg reached 45°C and the hot water supply dropped below this temperature. Legionellas were eradicated or significantly reduced in sections of the shower where a temperature of 50°C was consistently achieved. The mixer valve which was trace heated but not insulated remained colonized with Legionellas. Legionellas were found in shower water throughout the study.
Evaluation of the antimicrobial activity of methylglyoxal bis(guanylhydrazone) analogues, the inhibitors for polyamine biosynthetic pathway
Authors: Midorikawa Y. , Hibasami H. , Gasaluck P. , Yoshimura H. , Masuji A. , Nakashima K. , Imai M.
Published: March 2008

Metabolic and antiproliferative effects of methylglyoxal bis(butylamidinohydrazone) (MGBB) and methylglyoxal bis(cyclopentylamidinohydrazone) (MGBCP), inhibitors for polyamine biosynthetic pathway, on Escherichia coli, Shigella sonnei, Aeromonas sobria, Aeromonas hydrophila and Vibrio cholerae were investigated. MGBB at the concentration of 100 μmol/1 depleted intracellular putrescine and spermidine concentrations of E. coli to 25 and 20% of the controls, respectively, while MGBCP depressed their concentrations to 38 and 24%, respectively. In these polyamine‐depleted E. coli cells the syntheses of RNA, DNA and protein decreased to 13, 54 and 29% of the control, respectively, with MGBB and to 23, 71 and 55%, respectively, with MGBCP. The minimum inhibitory concentrations (MIC) of MGBB for the growth of A. sobria, E. coli, A. hydrophila, V. cholerae and Sh. sonnei were estimated to be 50, 160, 240, 285 and 320 μmol/1, respectively, whereas those of MGBCP were slightly higher for respective bacteria.
Spontaneous occurrence of heat‐stable somatic antigen variants in Bacillus thuringiensis
Authors: Mike A. , Ohba M. , Alzawa K.
Published: March 2008

Heat‐stable somatic antigen (HSSA) variants were isolated from Bacillus thuringiensis strain T84A1‐A by antiserum‐mediated selection. Substantial differences in HSSAs were clearly shown between variants and the parent strain by HSSA agglutination tests, Ouchterlony tests and precipitin‐halo‐formation (PHF) tests of extracellular HSSAs, although a ‘one way’cross‐reaction was evident. The frequency of HSSA variants in the population was < 10‐4, as determined by PHF tests on antiserum‐agar plates. Heat‐stable somatic antigen variants showed no alteration in flagellar antigenic structure and in 30 phenotypic characteristics. The insecticidal activity of HSSA variants was on the level with that of the parent strain, when tested with larvae of three lepidopterous species.
The effects of some halogen‐containing compounds on Bacillus subtilis endospores
Authors: Williams Nicola D. , Russell A.D.
Published: March 2008

Sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC) were more active against Bacillus subtilis 8236 spores in both viability and in germination and outgrowth studies than were polyvinylpyrrolidone‐iodine (PVP‐I) and Lugol's solution. Of the two chlorine compounds studied NaOCl proved to be the more active. The two iodine‐containing compounds gave contrasting results with the Lugol's solution demonstrating increased antibacterial activity with increasing available iodine concentration. The antibacterial behaviour of PVP‐I, however, reflected the more complex nature of aqueous iodine—surfactant mixtures. Initially, non‐complexed iodine concentration (the active species) increased with increasing total available iodine concentration, resulting in increasing antibacterial activity. However, due to changes in the physical properties of the mixture, a maximum concentration of non‐complexed iodine was reached so that a further increase in total available iodine resulted in a decrease in non‐complexed iodine concentration and consequently a decrease in the antibacterial activity of the solution was observed.

A greater inhibitory effect was observed in subsequent germination and outgrowth studies when spores were pre‐treated with respective biocide than when untreated spores were added to germination media containing biocide at t= 0. This may reflect a combination of different contact times plus the neutralizing effect of the germination media on such halogen compounds.
Catabolite repression vs derepression, an approach to differentiation during sporulation in Bacillus subtilis
Authors: Bhaduri Saswata , Bose Sushil K.
Published: March 2008

Glutamine, like glucose, repressed sporulation and the synthesis of mycobacillin and dipicolinic acid by Bacillus subtilis, and these syntheses were derepressed by dibutyryl cyclic GMP but not by dibutyryl cyclic AMP. Neither of these dibutyryl cyclic nucleotides affected sporulation or a number of spore‐associated parameters in the strain under normal physiological conditions. Mutants insensitive to glutamine repression were indifferent to the addition of either of the dibutyryl cyclic nucleotides both in the presence and in the absence of glutamine. Sporulation resulted from the remission of repression obtained under the catabolically active state.
The characteristics of a new non‐spore‐forming cellulolytic mesophilic anaerobe strain CM126 isolated from municipal sewage sludge
Authors: Nitisinprasert Sunee , Temmes Armi
Published: March 2008

A new mesophilic anaerobic cellulolytic bacterium, CM126, was isolated from an anaerobic sewage sludge digester. The organism was non‐spore‐forming, rod‐shaped, Gram‐negative and motile with peritrichous flagella. It fermented microcrystalline Avicel cellulose, xylan, Solka floc cellulose, filter paper, L‐arabinose, D‐xylose, β‐methyl xyloside, D‐glucose, cellobiose and xylitol and produced indole. The % G + C content was 36. Acetic acid, ethanol, lactic acid, pyruvic acid, carbon dioxide and hydrogen were produced as metabolic products. This strain could grow at 20–44·5°C and at pH values 5·2–7·4 with optimal growth at 37–41·5°C and pH 7. Both endoglucanase and xylanase were detected in the supernatant fluid of a culture grown on medium containing Avicel cellulose and cellobiose. Exoglucanase could not be found in either supernatant fluid or the cell lysate. When cellulose and cellobiose fermentation were compared, the enzyme production rate in cellobiose fermentation was higher than in cellulose fermentation. The optimum pH for both enzyme activities was 5·0, the optimum temperature was 40°C for the endoglucanase and 50°C for the xylanase. Both enzyme activities were inhibited at 70°C. Co‐culture of this organism with a Methanosarcina sp. (A145) had no effect on cellulose degradation and both endoglucanase and xylanase were stable in the co‐culture.
Deoxyribonuclease activities in Myxococcus coralloides D
Authors: Martínez‐Cañamero M. Magdalena , Muñoz J. , Extremera A.L. , Arias J.M.
Published: March 2008

Myxococcus coralloides D produced cell‐bound deoxyribonucleases (DNases) during the exponential phase of growth in liquid medium. DNase activity was much higher than that detected in other myxobacterial strains and was fractionated into three different peaks by filtration through Sephadex G‐200. The DNases were named G, M and P. The optimum temperatures were 37°C, 33°C and 25°C respectively, although high activities were recorded over the temperature range 20–45°C. The pH range of high activity was between 6·0 and 9·0, with an optimum for each DNase at 8·0. DNases M and P were strongly inhibited by low concentrations of NaCl, but activity of DNase G was less affected by NaCl. The three activities required divalent metal ions as cofactors (especially Mg2+ and Mn2+); however, other metal ions (Fe2+, Ni2+, Zn2+) were inhibitors. The molecular weights were estimated by gel filtration chromatography and SDS‐PAGE as 44 kDa (DNase G), 49 kDa (DNase M) and 39 kDa (DNase P).
Relation of human serum antibody against Staphylococcus epidermidis cell surface polysaccharide detected by enzyme‐linked immunosorbent assay to passive protection in the mouse
Authors: Ichiman Y. , Suganuma M. , Takahashi M. , Yoshida K.
Published: March 2008

A specific and rapid enzyme‐linked immunosorbent assay (ELISA) has been applied for the detection of immunoglobulins to Staphylococcus epidermidis cell surface polysaccharides in human serum. Positive IgG, IgM and IgA titres of more than 1:6400, 1:1600 and 1:400 were observed with this assay against passive protective human serum. However, IgG, IgM and IgA titres of less than 1:400, 1:100 and 1:50 were shown in non‐protective serum. When the cross‐reactivity of passive protective human serum to homologous and heterologous cell surface polysaccharides was examined by inhibition test with ELISA, remarkable inhibition was shown with homologous cell surface polysaccharide, whereas no inhibition was observed with heterologous substances. According to these results, the quantitation of human serum antibody by the ELISA method against Staph. epidemidis cell surface polysaccharide was found to be significant for the demonstration of passive protective activities against Staph. epidermidis.
Fermentation characteristics of Clostridium pasteurianum LMG 3285 grown on glucose and mannitol
Authors: Heyndrickx M. , Vos P. De , Ley J. De
Published: March 2008

Clostridium pasteurianum fermented glucose to acetate, butyrate, CO2 and H2. In batch cultures the fermentation pattern was only slightly affected by culture pH over the range 8·0 to 5·5. The acetate/butyrate ratio was always higher than or equal to one. Between 2·14 and 2·33 mol H2 was produced per mol glucose fermented. At unregulated pH, more butanol and less butyrate was formed. In a carbon‐limited chemostat, the steady‐state acetate/butyrate ratio was always lower than one. H2 production was approximately 1·70 mol per mol glucose consumed. Substantial amounts of extracellular protein were formed. With decreasing pH, acetate and formate production decreased, while H2 production was highest at pH 6.0. With increasing dilution rate (D), the product spectrum hardly changed, but more biomass was formed. Yglucosemax and YATPmax were 55·97 and 31·48 g dry weight per mol glucose or ATP respectively. With increasing glucose input the formation of fatty acids and H2 slightly decreased.

Continuous cultures fermented mannitol to acetate, butyrate, butanol, CO2 and H2. With acetate as co‐substrate, butanol production and molar growth yields, Ymannitol and YATP, markedly decreased, while the butyrate and H2 production increased. The latter reached a value of 2·21 mol H2 per mol mannitol consumed.
Survival of Escherichia coli and Campylobacter jejuni in untreated and filtered lake water
Authors: Korhonen Leena K. , Martikalnon P.J.
Published: March 2008

L.K. KORHONEN AND P.J. MARTIKAINEN. 1991. The survival of Campylobacter jejuni and Escherichia coli in lake water was studied using viable counts. Escherichia coli survived better than C. jejuni in all the test conditions studied. Both the species survived better in filtered than in untreated water. This suggests that predation and/or competition for nutrients affect the survival of both the species in an aquatic environment. Campylobacter jejuni survived less well in filtered autoclaved water and in 0.9% NaC1 than in filtered water without autoclaving. The lack of some essential nutrients, which may be degraded by autoclaving, might explain these results.
Study of substances released by ultrasonic treatment from Bacillus stearothermophilus spores
Authors: Palacios Petra , Burgos J. , Hoz L. , Sanz B. , Ordóñez J.A.
Published: March 2008

P. PALACIOS. J. BURGOS, L. HOZ, B. SANZ AND J.A. ORDÓÑEZ. 1991. Spore heat resistance is reduced when combined ultrasonic and heat treatments are applied. To explain this phenomenon the substances released from Bacillus stearothermophilus spores to the surrounding aqueous medium by the ultrasonic treatment (20 kHz, 120 W, 12°C, 30 min) were studied. Calcium, dipicolinic acid and a glycopeptide of 7 kDa molecular weight were detected in the ultrasonicated medium. Fatty acids, acyl glycerols and glycolipids (but no phospholipids) were also released. The decrease of heat resistance induced by the ultrasonic treatment was attributed to the release of low molecular weight substances from the spore protoplast with consequent modification of its hydration state.
Comparison of Arrhenius‐type and Bêlehrádek‐type models for prediction of bacterial growth in foods
Authors: Ratkowsky D.A. , Ross T. , McMeekin T.A. , Olley J.
Published: March 2008

D.A. RATKOWSKY, T. ROSS, T.A. WCMEEKIN AND J. OLLEY. 1991. The development of Arrhenius‐type (‘Schoolfield’) and Bêlehrádek‐type (square root) models that describe microbial growth rates is briefly described. Both types of model have been advocated for use in predictive microbiology. On the basis of published data sets for the growth of bacteria, the consequences of mathematical transformation of data and the use of invalid stochastic assumptions upon model predictions are demonstrated. Mean square error is shown to be an inappropriate criterion by which to compare the performance of predictive models. The data show that bacterial growth responses such as generation time and lag time become more variable as their mean magnitude increases. The practical consequences of such variability for predictive microbiology are discussed.
Bacteriological studies on Iraqi milk products
Authors: Abbar F. , Kaddar H. Kh.
Published: March 2008

F. ABBAR AND H. KH. KADDAR. 1991. Samples from different types of domestic milk products including cheese, kishfa and gaymer were assessed for bacteriological quality over a 4‐month period. A total of 400 samples were randomly selected across Mosul city and tested for faecal coliform counts, enteropathogenic Escherichia coli (EPEC) and enterotoxigenic E. coli (ETEC). Faecal coliforms were present at levels greater than 102 cfu/g in 72.5% and less than 102 cfu/g in 27.5% of samples. Of the 430 E. coli strains isolated from the 400 samples of milk products, 138 were serotypes of EPEC. These were found in 81 (40.5%) samples of cheese, 35 (23.8%) of kishfa and 22 (29.7%) of gaymer. During this period, 26 strains of ETEC were also isolated, all of which demonstrated heat‐labile or heat‐stable toxins. The high proportion of strains of three groups of E. coli showing resistance to antibiotics is discussed in relation to widespread use of antibiotics and the possible public health implication.
RecA‐independent resistance to irradiation with u.v. light in acid‐habituatedEscherichia coli
Authors: Goodson M. , Rowbury R.J.
Published: March 2008

Growth ofEscherichia coli1829 ColV, I‐K94 at pH 5.0 led to an increase in u.v. resistance compared with cells grown at pH 7.0. This was due to a phenotypic change, since organisms grown at pH 7.0 showed increased resistance after only 2.5–5.0 min incubation at the mildly acid pH. OtherE. coliK12 derivatives became more u.v.‐resistant at pH 5.0 includinguvrA, recAandpolA1mutants. Organisms grown at pH 5.0 also showed increased Weigle reactivation of u.v.‐irradiated Λ phage and this applied to the repair‐deficient mutants as well as the parent strains. Both the increased u.v. resistance of acid‐habituated cells and their increased ability to bring about Weigle reactivation appear to involve RecA‐independent processes and are presumably, therefore, independent of the SOS response.
Growth of thermophilic bacteria in rapemeal‐derived media
Authors: Yeoman K.H. , Edwards C.
Published: March 2008

K.H. YEOMAN AND C. EDWARDS. 1992. A clarified, soluble, protein‐rich medium was developed from rapemeal by boiling with 0·1 mmol/1 NaOH. The medium contained 78% of the original meal protein and supported the growth of a range of thermophilic micro‐organisms that included Bacillus, Streptomyces and fungi. Amino acid analysis of the medium showed a full range of amino acids, and that acidic ones such as glutamate predominated. Growth of a thermophilic Bacillus spp. (termed 1/15) in the medium was biphasic and significant amounts of extracellular protease were synthesized during the scond growth phase. Biphasic growth was probably due to preferential utilization of free amino acids during the first phase of growth followed by degradation of proteins during the second phase.
Developmental changes to gut microflora metabolism in mice
Authors: Brennan‐Craddock W.E. , Mallett A.K. , Rowland I.R. , Neale S.
Published: March 2008

W.E. BRENNAN‐CRADDOCK, A.K. MALLETT, I.R. ROWLAND AND S. NEALE. 1992. Developmental changes in the activities of bacterial nitrate reductase, nitroreductase and β‐glucuronidase and their response to fermentable dietary fibre, were investigated in caecal contents from suckling mice (2‐week‐old) and in mice aged 4–24 weeks fed either a purified fibre‐free diet or that diet supplemented with 5% (w/w) pectin. There was no apparent age‐related trend common to the three enzymes studied. Nitrate reductase activity in the mice fed the fibre‐free diet did not markedly alter with age. Pectin administration, however, was associated with a significant increase in nitrate reductase activity, particularly in 4‐week‐old mice. Nitroreductase activity exhibited an overall upward trend in mice from 2 to 12 weeks and thereafter decreased. Caecal β‐glucuronidase activity in mice increased sharply between 2 weeks and 4 weeks of age, thereafter not changing significantly until the 24th week. Pectin feeding had no consistent effect on activities either of nitroreductase or β‐glucuronidase. The changes in enzyme activities with age were not related to the concentration of bacteria in the caecum, which was highest in the 2‐week‐old mice.

We conclude that the weaning is a period in which marked changes in caecal bacterial enzyme activities can occur.
Acidic exopolysaccharide from Bradyrhizobium (Chamaecytisus proliferus)
Authors: León‐Barrios M. , Gutiérrez‐Navarro A.M. , Pérez‐Galdona R. , Díaz‐Siverio J. , Trujillo J. , Corzo J.
Published: March 2008

M. LEON‐BARRIOS, A.M. GUTIERREZ‐NAVARRO, R. PEREZ‐GALDONA, J. DIAZ‐SIVERIO. J. TRUJILLO AND J. CORZO. 1992. The exopolysaccharide from a strain of Bradyrhizobium isolated in the Canary Islands was studied. The polysaccharide was found to be acidic and composed of glucose, galactose, mannose and galacturonic acid in a relation 3: 1: 1: 1, respectively. Acetyl was the only acyl substituent detected. Polyacrylamide gel electrophoresis showed that it had a polymeric structure with a variable degree of polymerization. At low ionic strength it aggregated but in EDTA solutions it was resolved as a polydisperse sample by gel exclusion chromatography.
Occurrence of Listeria species in raw milk and dairy products produced in Northern Ireland
Authors: Harvey J. , Gilmour A.
Published: March 2008

J. HARVEY AND A. GILMOUR. 1992. The overall incidence of Listeria spp. in raw milk samples surveyed was found to be 25.0% (Listeria monocytogenes 15.3%), with the incidence in samples from processing centres 54.0% (L. monocytogenes 33.3%); this was higher than that in samples from dairy farms (Listeria spp. 8.8%L. monocytogenes 5.3%). The FDA enrichment procedure was much more productive than cold enrichment and Oxford agar was superior to modified McBride agar for isolation of Listeria. Listeria monocytogenes was never isolated by direct plating of raw milk samples on Oxford agar at a detection level of 1.0 cfu/ml. Listeria spp. were isolated from 1 of 95 pasteurized milk samples (L. monocytogenes) and 1 of 33 soft cheese samples (L. seeligeri). Restriction fragment length polymorphism was more useful than sero‐ or phage‐typing for typing of L. monocytogenes strains, and results suggest that specific L. monocytogenes strains may persist in both farm and processing environments.
Plasmid transfers by conjugation and electroporation in Pediococcus acidilactici
Authors: Kim W.J. , Ray B. , Johnson M.C.
Published: March 2008

W.J. KIM, B. RAY AND M.C. JOHNSON. 1992. Plasmid profiles of wild and mutant strains of Pediococcus acidilactici M showed that a 53.7 kb plasmid (pPR72) encodes the sucrose hydrolysis trait (Suc+) and an 11.1 kb plasmid encodes the bacteriocin production trait (Pap+). Neither of these plasmids encode traits involving fermentation of other carbohydrates, antibiotic resistance or resistance to bacteriocin. Broad host‐range plasmids (pAMβ1 and pIP501) from Enterococcus faecalis and plasmid pPR72 from Ped. acidilactici were conjugally transferred by filter mating into two strains of Ped. acidilactici. Four plasmids, ranging in size from 4.4 to 53.7 kb, were also transferred into Ped. acidilactici strains by electroporation. Optimum transformation of the 4.4 kb plasmid, pGK12, was obtained at a DNA concentration of 1 μg/220 μl. The same amount of DNA gave lower transformation frequencies as the plasmid size increased. Results of these studies indicated that both conjugation and electroporation can be used to transfer plasmid‐linked traits in Ped. acidilactici strains.
Starch digestion and adsorption by β‐amylase of Emericella nidulans (Aspergillus nidulans)
Authors: Chatterjee Banhisikha , Ghosh Anuradha , Das Arati
Published: March 2008

B. CHATTERJEE, A. GHOSH AND A. DAS. 1992. A mutant strain of Emericella nidulans MNU 82 was isolated by multistep mutation. The β‐amylase produced by the mutant was able to digest raw starch. It was readily and strongly adsorbed onto raw starch at pH 5.0. The enzyme to starch ratio was 1950 U/g starch. The enzyme showed no correlation between the capacity of raw starch digestion and adsorption of the enzyme.
The PhoE porin and transmission of the chemical stimulus for induction of acid resistance (acid habituation) in Escherichia coli
Authors: Rowbury R. J. , Goodson Margaret , Wallace A.D.
Published: March 2008

R. J. ROWBURY, M. GOODSON AND A.D. WALLACE. 1992. Escherichia coli K12 becomes resistant to killing by acid (habituates to acid) in a few minutes at pH 5.0. Habituation involves protein synthesis‐dependent and ‐independent stages; both must occur at an habituating pH. The habituation sensor does not detect increased ΔpH (or decreased Δψ) nor an increased difference between pHo and periplasmic pH but probably detects a fall in either external or periplasmic pH. Phosphate ions inhibit habituation, at any stage, probably by interfering with outer membrane passage of hydrogen ions. Most outer membrane components tested are not required for habituation but phoE deletion mutants habituated poorly and are acid‐resistant. Strains derepressed for phoE, in contrast, showed increased acid sensitivity. These and other results suggest that habituation involves hydrogen ions or protonated carriers crossing the outer membrane preferentially via the PhoE pore, a process inhibited by phosphate and other anions. Stimulation by phosphate of the poor growth of E. coli at pH 5.0 is in accord with the above. Acetate did not enhance acid killing of pH 5.0 cells, suggesting that their resistance does not depend on maintaining pHi near to neutrality at an acidic pHo level.
The bactericidal activity of a methyl and propyl parabens combination: isothermal and non‐isothermal studies
Authors: Gilliland D. , Wan Po A. Li , Scott E.
Published: March 2008

D. GILLILAND, A. LI WAN PO AND E. SCOTT. 1992. The effect of temperature on the kill rate of Escherichia coli by methyl and propyl parabens was studied. The kill kinetics was first order. It was shown that the Arrhenius equation provided a good model for describing the relationship between the first order rate constant and the temperature. The activation energy was found to be 274 kJ/mol for exponential phase cells and 168 kJ/mol for stationary phase cells. Exponential phase cells were much more susceptible to the lethal effects of the parabens than were the stationary phase cells. For example, at 34°C stationary phase cells, in chemically defined media, had a kill rate constant of 0.072/h while the corresponding value for exponential phase cells was 0.238/h. In water the rate of kill for exponential phase cells was even faster giving a rate constant of 5.25/h at 34°C. Non‐isothermal kinetic testing was not found to be useful for modelling bacterial kill kinetics because we could not achieve the precision required in bacterial enumeration.
Kinetic evaluation of claimed synergistic paraben combinations using a factorial design
Authors: Gilliland D. , Wan Po A. Li , Scott E.
Published: March 2008

D. GILLILAND, A. LI WAN PO AND E. SCOTT. 1992. The antimicrobial effects of methyl and propyl parabens are investigated, with Escherichia coli as test organism, with a view to determining whether the parabens act synergistically. At appropriate concentrations, the parabens killed E. coli cells according to first order kinetics and the bactericidal effects were quantified by the first order kill rate constants. Combinations of methyl or propyl parabens, at concentrations which slow down or inhibit bacterial growth when used singly, produced definite kill. In this sense, the parabens are therefore synergistic since in combination they produce an effect which is not observed when they are used singly. This effect is not true synergism as shown by the results of our experiments with a factorial design. Analysis of variance indicated no significant interaction between the two parabens.
Nucleotide sequence and structural relationships of a chloramphenicol acetyltransferase encoded by the plasmid pSCS6 from Staphylococcus aureus
Authors: Cardoso Marisa , Schwarz S.
Published: March 2008

M. CARDOSO AND S. SCHWARZ. 1992. The 4.6 kb chloramphenicol resistance (CmR) plasmid, pSCS6, isolated from a naturally occurring Staphylococcus aureus biotype C encoded an inducible chloramphenicol acetyltransferase (CAT). The respective cat gene and its regulatory region were cloned. Sequence analyses revealed two open reading frames: one for a 9‐amino acid leader peptide and the other for the 215‐amino acid CAT monomer. Comparisons of the predicted CAT amino acid sequences revealed a high degree of similarity between CAT from pSCS6 and the CAT variants encoded by CmR plasmids of the pC221 family. These close structural relationships suggested an intraspecific exchange of CmR‐determinants between Staph. aureus of human and bovine biotype.
Evaluation of coliforms as indicators of water quality in India
Authors: Ramteke P.W. , Bhattacharjee J.W. , Pathak S.P. , Kalra N.
Published: March 2008

P.W. RAMTEKE, J.W. BHATTACHARJEE, S.P. PATHAK AND N. KALRA. 1992. The total and thermotolerant coliform counts in rural drinking water derived from ground water, piped supplies and surface water are reported for a number of areas in India. To evaluate these counts as indicators of recent faecal contamination the total coliforms and thermotolerant coliforms isolated have been identified. Thermotolerant Escherichia coli formed 11.7% of the total coliforms and 75.1% of the thermotolerant coliforms. Citrobacter sp. (20.4%) and Klebsiella sp. (50.9%) were the other common total coliforms isolated and, among the thermotolerant coliforms, Klebsiella sp. (16.4%) was the only other organism frequently encountered. The total coliform counts were significantly correlated with water temperature. The applicability in tropical areas of standards developed for temperate climates is discussed.
An investigation of dye reduction by food‐borne bacteria
Authors: Learoyd Stephanie A. , Kroll R.G. , Thurston C.F.
Published: March 2008

S.A. LEAROYD, R.G. KROLL AND C.F. THURSTON. 1992. The rates of reduction of seven redox dyes by 13 bacterial strains were measured and found to vary greatly between different bacterium/dye combinations. Phenazine ethosulphate and toluidine blue were the most rapidly reduced dyes by the majority of bacteria and resorufin and 2‐hydroxy‐1,4‐naphthoquinone were reduced slowly, if at all. There was also considerable variation in the rates of reduction with any single dye/organism combination. Glucose stimulated the rates of endogenous dye reduction in about half of the organisms. For Bacillus cereus, Pseudomonas fluorescens and Escherichia coli, dye reduction was stimulated by a range of exogenous substrates but lactose, the primary available carbon and energy source in milk, had little effect. In Lactococcus lactis, dye reduction was stimulated by sugars but not by organic acids. Oxygen successfully competed with dye reduction in organisms containing respiratory chains, but with membrane fractions, dye reduction was more rapid than oxygen consumption. All the organisms showed little cytosolic dye reduction, except L. lactis which showed substantial rates of reduction of some dyes by this fraction. With the membrane fraction of E. coli and Ps. fluorescens, cyanide inhibited NADH and succinate‐dependent dye reduction, Antimycin A inhibited lactate and succinate and rotenone had no significant effect, but inhibition was not always observed with membrane from both organisms.
The influence of temperature and organic matter on the bactericidal activity of short‐chain organic acids on salmonellas
Authors: Cherrington Christina A. , Allen Vivien , Hinton M.
Published: March 2008

CHRISTINA A. CHERRINGTON, VIVIEN ALLEN AND M. HINTON. 1992. Acetic and lactic acids and BioAdd, a commercial preparation of formic and propionic acid, were tested at a concentration of 0.1% (w/w) at 20, 30, 40 and 50°C and in the presence of organic material for bactericidal activity against Salmonella serotype Kedougou. BioAdd was the most active of the solutions at all temperatures, followed by lactic acid and acetic acid. The presence of horse blood at all four temperatures, and milk and serum at 50°C, did not greatly affect the antibacterial activity of the acids although yeast extract (50°C) provided some protection for the salmonella. Acid activity was related to low pH values although the bactericidal activity of acetic acid with blood and milk was greater than the unadulterated acid even though the pH was 0.4 units higher.
Survival strategies of plasmid‐carrier and plasmidless Escherichia coli strains under illuminated and non‐illuminated conditions, in a fresh water ecosystem
Authors: Barcina Isabel , Arana Ines , Fernandez‐Astorga Aurora , Iriberri J. , Egea L.
Published: March 2008

A Comparative study, in illuminated and non‐illuminated systems, was made to determine the survival strategies of plasmid‐carrier and plasmidless bacteria in sterile river water. Two strains of Escherichia coli from river water were selected: one plasmidless, EC1, and one antibiotic‐resistant strain, EC7, which showed plasmid bands. By matings with EC7 as donor and E. coli K12 strain J62 as recipient, transconjugants were generated, the J627 strain, which showed both antibiotic resistance and plasmid bands. Ethidium bromide curing of the EC7 strain generated the EC72 strain which showed a partial loss of resistance and a reorganization of plasmid bands. Under non‐illuminated conditions the total number of cells detected by direct count and the number of culturable cells (injured and non‐injured cells) remained practically constant throughout the period of incubation. In the illuminated systems, however, the number of cfu decreased in four of the five strains studied. The greatest decreases are those of the J62 strain, followed by those of the J627, EC1, EC72 and EC7 strains. Differences in survival strategies as a consequence of the presence or absence of plasmids are discussed.
Ageing‐related changes in Mycoplasma canadense membranes
Authors: Muñoz Gtaciela E. , Sotomayor C.P.
Published: March 2008

Fluidity and composition of cell membranes during progression of Mycoplasma canadense cultures grown in a serum‐free medium was assessed. The fluorescence anisotropy of 1,6‐diphenyl‐1,3,5‐hexatriene at 25°C of intact cells and liposomes in the exponential and stationary phases of growth was compared. A decrease in fluidity and an increase in the ratio of saturated to unsaturated fatty acids was detected in cell membranes on ageing. Nevertheless, membrane density remained unaltered although the molar ratio of cholesterol to phospholipids decreased. It is proposed that the increase in lipid order is primarily due to the increase in the ratio of saturated to unsaturated membrane fatty acids, being the diminished molar ratio of cholesterol to phospholipids involved in the reduced unsaturated fatty acid uptake.
The effect of moisture potential on growth and survival of root nodule bacteria in peat culture and on seed
Authors: Griffith G.W. , Roughley R.J.
Published: March 2008

Peat from three sources was dried, milled and packed separately in polyethylene bags and sterilized by irradiation. The carrier was impregnated with broth cultures of either Rhizobium leguminosarum bv. trifolii strain WU95, Bradyrhizobium japonicum strain CB1809 or B. lupini strain WU425 and sterile water to provide five moisture potentials in the range > ‐ 1 × 104 ‐ 1 × 106 Pa. The packets were stored at 26°C under conditions which restricted moisture loss. Numbers of root nodule bacteria were counted at intervals up to 12 weeks. No single moisture potential was optimum for all strains in all carriers because of a significant (P < 0.05) interaction between moisture potential × strain × carrier × time. Where direct comparisons could be made, all strains survived best at ‐ 1 × 104 and/or −3.2 × 104 Pa. Seeds of Trifolium subterraneum and polypropylene beads (used to avoid seed coat toxicity), were inoculated with WU95 prepared in two sources of peat and at each of the above moisture potentials and stored at 15°C. Seed coat toxicity significantly effected the log death rate (k) of WU95 on subterraneum clover seed for the period 0–0.25 d (k1.796) compared with k ‐ 0.399 for polypropylene beads. In the first 24 h moisture did not affect survival but by 28 d rhizobia grown in Badenoch peat survived best at −3.2 × 104 Pa. In Millicent peat, survival was equally as good at −3.2 × 104 and −1 × 104 Pa.
An investigation of the antibacterial effect of carrot on Listeria monocytogenes
Authors: Nguyen‐the C. , Lund Barbara M.
Published: March 2008

Carrot slices immersed in a potassium phosphate buffer (0.1 mol/l, pH 7.0) or carrot tissue macerated in the buffer had a lethal effect on Listeria monocytogenes. This antilisterial activity was suppressed by anaerobiosis, thiol compounds (1 mmol/l) and bovine serum albumin (0.05%) but was not affected by sodium ascorbate (200 mmol/l), propyl gallate (25 mmol/l), catalase (1100 U/ml), superoxide dismutase (357 U/ml), or chelating agents (10 mmol/l). Free‐radical scavengers had no effect at 10 mmol or 50 mmol/l but histidine and diazabenzocyclooctane at 100 mmol/l reduced the antilisterial activity. The addition of Tween 20, 0.05% (v/v), to carrot macerates improved the recovery of the activity in the supernatant liquid after centrifugation at 10 000 g for 2 min. The addition of higher concentrations of the detergent to the macerate reduced the antilisterial activity.
The use of immobilized lectins in the separation of Staphylococcus aureus, Escherichia coli, Listeria and Salmonella spp. from pure cultures and foods
Authors: Payne M.J. , Campbell Shona , Patchett R.A. , Kroll R.G.
Published: March 2008

Lectins from Helix pomatia, Canavalia ensiformis, Agaricus bisporus and Triticum vulgaris agglutinated cultures of Staphylococcus aureus, Escherichia coli, Listeria and Salmonella spp. This agglutination was specific as it was inhibited (except with A. bisporus lectin) by the competing sugar substrates. The ability of three of these lectins, immobilized on a variety of supports, to separate these micro‐organisms from pure cultures was investigated. Immobilization of the lectins on magnetic microspheres was the most effective method. Immobilized T. vulgaris lectin bound 87–100% of cells from cultures of L. monocytogenes, 80–100% of Staph. aureus, 33–45% of Salmonella spp. and 42–77% of E. coli. The A. bisporus lectin bound 31–63% of cells in cultures of L. monocytogenes, 83% of Staph. aureus but only 3–5% of the salmonella cells. Similarly H. pomatia lectin bound >92% of Staph. aureus and 64% of L. monocytogenes cells but was poor at binding the Gram‐negative organisms. This preference for binding Gram‐positive organisms was confirmed when mixed cultures were studied. The T. vulgaris lectin was effective in removing L. monocytogenes (43%) and Staph. aureus (26%) from diluted milk and Salmonella (31–54%) from raw egg. Agaricus bisporus lectin removed L. monocytogenes from undiluted milk (10–47%) or ground beef (32–50%).
A combined PCR and selective enrichment method for rapid detection of Listeria monocytogenes
Authors: Fitter S. , Heuzenroeder M. , Thomas C.J.
Published: March 2008

Development of a routine detection assay for Listeria monocytogenes in foods that uses the polymerase chain reaction (PCR) and enrichment cultures was investigated. Oligonucleotide primers were chosen to amplify a 3’region of L. monocytogenes hlyA gene spanning a conserved HindIII site. PCR detection sensitivity for L. monocytogenes in dilutions of pure enrichment cultures was between 50 and 500 colony forming units. A short enrichment period before PCR amplification allowed detection of the organisms in a range of complex foods contaminated with 104 cfu/g. Detection sensitivity for the assay in the presence of chicken skin and soft cheese was determined at 10–100 cfu/g. Utilization of enrichment cultures and PCR allowed identification of the organism within 24 h or 2 days.
Identification and quantitative analysis of degradation products of chlorhexidine with chlorhexidine‐resistant bacteria with three‐dimensional high performance liquid chromatography
Authors: Ogase H. , Nagai I. , Kameda K. , Kume S. , Ono S.
Published: March 2008

The products of the degradation of chlorhexidine by two chlorhexidine‐resistant strains of Achromobacter xylosoxidans, isolated from an ultrasonic hand washer, were identified by three‐dimensional HPLC. In the degradation process a pathway forming p‐chlorophenol, probably through p‐chloroaniline, was also observed, as was a pathway forming phenol and pyrogallol. The quantitative measurement of these products at their maximum absorption spectra by two‐dimensional HPLC suggested the presence of chlorhexidine‐degrading enzymes.
Isolation and properties of a bacteriocin‐producing Carnobacterium piscicola isolated from fish
Authors: Stoffels Geesje , Nes Ingolf F. , Guomundsdóttir Agusta
Published: March 2008

A facultative psychrotrophic lactic acid bacterium isolated from fresh fish was identified as Carnobacterium piscicola on the basis of carbohydrate utilization, G + C content and 16S RNA analysis. Its bacteriocin, designated carnocin UI49, is produced during the mid‐exponential phase of growth at temperatures between 15°C and 34°C. Carnocin UI49 is active against a large number of closely‐related lactic acid bacteria including carnobacteria, lactobacilli, pediococci and lactococci. Furthermore, the bacteriocin has a bactericidic mode of action which results in lysis of sensitive cells. Maximum bactericidal activity is observed at 34°C with a decrease in activity down to 15°C where it is completely abolished.