bluuebunny/crossref_metadata_2025 huggingface dataset:
Chararacteristics of Vagococcus salmoninarum isolated from diseased salmonid fish
Authors: Schmidtke L.M. , Carson J.
Published: March 2008

Isolates of the salmonid pathogen Vagococcus salmoninarum were recovered from Atlantic salmon, rainbow trout and brown trout with peritonitis. The phenotypes of these isolates and the type strain of Vag. salmoninarum NCFB 2777 were determined by morphological, biochemical and physiological tests and whole cell protein profiles by SDS‐PAGE. There was a high level of phenetic similarity between the salmonid isolates and the type strain. The species forms short Gram‐positive rods, hydrolyses L‐pyrrolidonyl‐β‐naphthylamide, is α‐haemolytic on sheep's blood agar, grows at pH 9·6 and 10°C but not at 40°C or in 6·5% NaCl and is catalase‐negative; a Lancefield group N antigen is not present. Vagococcus salmoninarum can be distinguished phenetically from similar fish pathogens including Carnobacterium piscicola, Enterococcus seriolicida and Lactococcus piscium.
Protease production by Streptomyces thermovulgaris grown on rapemeal‐derived media
Authors: Yeoman K.H. , Edwards C.
Published: March 2008

A range of actinomycete species was tested for their ability to grow on particulate and particle‐free rapeseed meal‐derived media. Streptomycetes grew on both types of medium and produced a number of extracellular enzymes. Highest activities of protease were produced by Streptomyces thermovulgaris and reflected the high available protein content of rapemeal. Enzyme production and growth were analysed in fermentor‐grown batch cultures of S. thermovulgaris using the particle‐free rapemeal broth termed medium B. Growth was biphasic and the majority of the protease was produced during the second slower phase. Analysis of the protease as azocaseinase activity revealed a high degree of thermostability in the presence of calcium such that approximately 20% of the activity remained after incubation at 70°C for 24 h. Gel filtration suggested that S. thermovulgaris synthesized more than one kind of protease and this was confirmed by using specific peptide substrates and inhibitors which revealed the presence of distinct serine and metallo‐type enzymes.
Resistance of bacterial strains to dry conditions: use of anhydrous silica gel in a desiccation model system
Authors: Janning Birgit , Veld P.H. in't , Notermans S. , Krämer J.
Published: March 2008

The Viability of 18 bacterial strains desiccated on anhydrous silica gel and stored at a temperature of 22°C for at least 3 months was determined. According to their stability in the dried state, these strains could be classified into three typical groups. Group 1, containing Gram‐positive strains and Salmonella serotypes, was marked by a very slow decrease of the concentration of culturable cells from day 14 on (respectively day 21 for Salmonella thompson. The rate of decrease expressed as regression coefficient (b) ranged from —0.000389 to —0.00521 log (cfp ml‐1) per d. The Group 2 strains Enterobacter cloacae and Escherichia coli did not reach a comparable slow decrease in the dry material within the indicated time period. Regression coefficients were respectively —0.04406 and —0.03412 log (cfp ml‐1) per d. The reciprocal values —(1/b) were respectively 23 d per log (cfp ml‐1) and 29 d per log (cfp ml‐1), indicating the time periods in which a reduction of 1 log unit of culturable cells occurred. Group 3 strains Pseudomonas aeruginosa, Aeromonas hydrophila and Aer. sobria were marked by a significant susceptibility to cell damage caused during desiccation and reconstitution. A high initial decrease (ID) of the concentration of culturable organisms seems to be a characteristic property of these bacterial strains: culturable organisms could not be detected after storage for 1 d (Aer. hydrophila, Aer. sobria) or 7 d (Ps. aeruginosa). The wide range of resistance of the different bacterial strains tested indicated that the silica gel model system is a suitable tool for microbiological challenge tests to investigate the survival of micro‐organisms exposed to desiccation and their stability in dry materials.
Comparison of the fluorescent redox dye 5‐cyano‐2,3‐ditolyltetrazolium chloride with p‐iodonitrotetrazolium violet to detect metabolic activity in heat‐stressed Listeria monocytogenes cells
Authors: Bovill R.A. , Shallcross J.A. , Mackey B.M.
Published: March 2008

The fluorogenic redox indicator 5‐cyano‐2,3‐ditolyltetrazolium chloride (CTC) was compared with the chromogenic p‐iodonitrotetrazolium violet (INT) and conventional methods to assess cellular viability. Mild heat treatment was used as a well‐controlled method for producing non‐viable and sub‐lethally injured cells. CTC gave an underestimation of the viability of Listeria monocytogenes cells when compared with classical plating methods whereas INT gave an overestimation. However, CTC proved to be a sensitive indicator of uninjured cells. The difference between the total count and the CTC count was equivalent to the injured cell population. The fluorescent formazan formed on reduction ofCTC was readily detected with a charge coupled device and cells enumerated automatically using image analysis.
Thermotolerant varieties of Bacillus licheniformis isolated from desert environments
Authors: Horani Hala Khiyami , Priest F.G.
Published: March 2008

One hundred and nineteen thermotolerant and thermophilic Bacillus strains isolated from solar‐heated and non‐heated environments in Jordan were classified by numerical techniques. Some strains were classified into thermophilic taxa which did not equate with established species. However, most of the isolates were identified phenotypically as Bacillus licheniformis, a conclusion supported by the high DNA hybridization which was detected between these strains and a reference strain of this species (gt64% at optimal renaturation temperature). Several of the B. licheniformis isolates had a higher ratio of iso‐C15 and iso‐C17 fatty acids to the anteiso equivalents in their membranes than the reference strain of B. licheniformis and they grew more strongly at high temperature than the reference strain. This suggests that the B. licheniformis isolates represent thermotolerant variants of this species.
Regulatory effects of bifidobacteria on the growth of other colonic bacteria
Authors: Gibson G.R. , Wang X.
Published: March 2008

In the human large intestine bifidobacteria are a numerically important group of micro‐organisms which are considered to exert a range of biological activities related to host health. One aspect is the inhibitory effect of these bacteria on other species, possibly excluding long term colonization by invasive pathogens. It has been suggested that the mechanism of inhibition carried out by bifidobacteria is related to the fermentative production of acids such as acetate and lactate. Experiments reported in this paper attemptedto address this theory. Co‐culture experiments whereby Bifidobacterium infantis was incubated with Escherichia coli and Clostridium perfringens, in a varietyof fermentation systems, indicated that the bifidobacterium was able to exert an inhibitory effect not necessarily related to acid production. Further studies showed that eight species of bifidobacteria could variously excrete an anti‐microbial substance with a broadspectrum of activity. Species belonging to the genera Salmonella, Listeria, Campylobacter and Shigella, as well as Vibrio cholerae, were all affected. These results show that bifidobacteria are able to exert more than one mechanism of inhibition, which may be of some importance with regard to protection against gastroenteritis.
Characterization of an antibiotic produced by Alteromonas luteoviolacea Gauthier 1982,85 isolated from Kinko Bay, Japan
Authors: McCarthy S.A. , Johnson R.M. , Kakimoto D.
Published: March 2008

An antibiotic produced by Alteromonas luteoviolacea strain 9K‐V10 was recovered after cold acetone precipitation of culture supernatant fluids or lysates that had beenfrozen and thawed. The precipitate obtained from cell‐free lysates was fractionated by DEAE ion‐exchange chromatography. Further purification by gel‐filtration chromatography yielded a single peak of antibiotic activity that corresponded to a protein peak with a molecular mass of approximately 100 kDa. After non‐denaturing polyacrylamide gel electrophoresis, antibiotic activity co‐migrated with a protein band. The isoelectric point of the antibiotic was estimated to be 7·7. Treatment of the concentrated active fraction with proteinase K or heating at 70°C for 10 min resulted in total loss of antibiotic activity. These results show that the antibiotic produced by Alt. luteoviolacea 9K‐V10 is of a proteinaceous nature.
Growth, pectate lyase production and solute accumulation by Erwinia chrysanthemi under osmotic stress: effect of osmoprotectants
Authors: Prior B.A. , Hewitt E. , Brandt E.V. , Clarke A. , Mildenhall J.P.
Published: March 2008

Glycine betaine strongly stimulated the growth rate of five strains of Erwinia chrysanthemi when grown in a synthetic medium at 0·986, 0·983 and 0·980 aw (NaCl) whereas in four strains, little effect was observed compared with the control. Proline, dimethyl glycine, carnitine and pipecolic acid also actedas osmoprotectants. Glutamate and trehalose, commonly accumulated by enteric bacteria in response to osmotic stress, failed to act as osmoprotectants when supplied exogenously. Glycine betaine and pipecolic acid partially overcame the inhibition of pectate lyase release by NaCl in strain ECC. 13C NMR spectroscopy of two osmotically‐stressed strains showed that glycine betaine was accumulated intracellularly from synthetic media containing the exogenous osmoprotectant. However, both strains also synthesized and accumulated trehalose in addition to glycine betaine in response to osmotic stress in complex media containing glycine betaine.
Growth of legionella and other heterotrophic bacteria in a circulating cooling water system exposed to ultraviolet irradiation
Authors: Kusnetsov Jaana M. , Keskitalo P.J. , Ahonen H.E. , Tulkki A.I. , Miettinen I.T. , Martikainen P.J.
Published: March 2008

The effect of ultraviolet irradiation on the growth and occurrence of legionella and other heterotrophic bacteria in a circulating cooling water system was studied. Water of the reservoir was circulated once in 28 h through a side‐stream open channel u.v. radiator consisting of two lamps. Viable counts of legionellas and heterotrophic bacteria in water immediately after the u.v. treatment were 0—12 and 0·7—1·2% of those in the reservoir, respectively. U.v. irradiation increased the concentration of easily assimilable organic carbon. In the u.v. irradiated water samples incubated in the laboratory the viable counts of heterotrophic bacteria reached the counts in reservoir water within 5 d. The increase in viable counts was mainly due to reactivation of bacterialcells damaged by u.v. light, not because of bacterial multiplication. Despite u.v. irradiation the bacterial numbers in the reservoir water, including legionellas, did not decrease during the experimental period of 33 d. The main growth of bacteria in the reservoir occurred in biofilm and sediment, which were never exposed to u.v. irradiation.
Rapid degradation of the triazinone herbicide metamitron by a Rhodococcus sp. isolated from treated soil
Authors: Parekh N.R. , Walker A. , Roberts S.J. , Welch S.J.
Published: March 2008

N.R. PAREKH, A. WALKER, S.J. ROBERTS AND S.J. WELCH. 1994. Seven bacterial isolates which degraded the herbicide metamitron (3‐methyl‐4‐amino‐6‐phenyl‐1,2,4‐triazin‐5‐one) were obtained from field‐enhanced soil by liquid enrichment culture. All isolates appeared to be identical and a representative, 0246b, was identified as a Rhodococcus sp. by cell wall and fatty acid analyses. This isolate degraded metamitron as the sole source of carbon within 24 h at 25d̀C and this is the first report of a bacterium capable of growing with metamitron as the sole source of carbon. Metamitron was degraded less rapidly when it was the sole source of both carbon and nitrogen. The rate and extent of degradation was affected by the presence and type of additional sources of carbon and nitrogen in the culture medium. In studies with [14C]‐phenyl‐labelled metamitron Rhodococcus sp. 0246b partly mineralized the phenyl ring.
The immediate bactericidal effect of lactic acid on meat‐borne pathogens
Authors: Netten P. Van , Veld J.H.J. Huis in t , Mossel D.A.A.
Published: March 2008

P. VAN NETTEN, J.H.J. HUIS IN'T VELD AND D.A.A. MOSSEL. 1994. The kinetics of the bactericidal effect of lactic acid decontamination (LAD) on meat‐borne pathogens (Salmonella spp., Campylobacter jejuni and Listeria monocytogenes) was studied in an in‐vitro model. The bactericidal effect was greatest on organisms in the lactic acid film that replaced the natural fluid on the meat surface during LAD. A stepwise increase in pH from 2.6 to 3.5 and 4.0 progressively reduced the bactericidal effect of decontamination. For treatment with 2% lactic acid for 30–90 s at 21d̀C, the immediate death of Salmonella spp. decreased from about 0.5–2 log10 cfu at pH 2.6 to an insignificant level at pH 4.0. The immediate death for Camp. jejuni decreased from 2.6 to >5.3 at pH 2.6 to 0.3–1.0 at pH 4.0. The decrease in bactericidal effect with increasing pH could, however, be countered by an increase in the temperature from 21d̀C to 37d̀C. It is suggested that 2% LAD at 37d̀C for 30–90 s is suitable for elimination of salmonellas on meat but not for L. monocytogenes. Decontamination with 1% lactic acid at pH 3.0 and 21d̀C for at least 30 s was effective for Camp. jejuni. Mesophilic Enterobacteriaceae were reliable indicators of the LAD‐induced bactericidal effect on Salmonella spp. and Camp. jejuni.
An investigation of enumeration and DNA partitioning in Bacillus subtilis L‐form bacteria
Authors: Waterhouse Rosemary N. , Allan Eunice J. , Amijee Firoz , Undrill Valerie J. , Glover L. Anne
Published: March 2008

R.N. WATERHOUSE, E.J. ALLAN, F. AMIJEE, V.J. UNDRILL AND L.A. GLOVER. 1994. Cell numbers of two morphogenic forms of Bacillus subtilis (the cell‐walled parental and the derived stable cell wall‐deficient L‐form) have been compared by two methods: DNA hybridization (i.e. deduced genome numbers) and viable cell counts (i.e. number of colony‐forming units (cfu)). The DNA hybridization method was shown to be a reliable and reproducible method for estimating genome numbers. Comparison of different L‐form populations showed that the two methods of enumeration gave different values, with the deduced genome numbers much higher (by several orders of magnitude) than cell numbers deduced from viable cell counts. In contrast, when a culture of the cell‐walled form was enumerated, the discrepancy between the two methods was low (by a factor of about 6) The combination of a high number of L‐form genomes detected by DNA hybridization and a relatively low number of cfu was thought to be a consequence of a diminished co‐ordination between the DNA replication and cell division processes in L‐form bacteria. This suggestion was further substantiated by assessing the stability of plasmid pPL608 in a transformed B. subtilis L‐form cell line, where even in the presence of continued kanamycin selection, 25% of the population lost kanamycin resistance. The results are discussed with particular reference to cell division in cell wall‐deficient, stable L‐form bacteria.
Mechanisms of inhibition of Erwinia amylovora by Erw. herbicola in vitro and in vivo
Authors: Wodzinski R.S. , Umholtz T.E. , Rundle J.R. , Beer S.V.
Published: March 2008

The mechanisms by which Erwinia herbicola inhibits Erwinia amylovora, the fire blight pathogen, were investigated. The optimum pH for growth of Erw. amylovora strain Ea273 in nutrient‐yeast extract‐glucose broth (NYGB) was 7.0 and growth was markedly reduced at pH values below 6.0. In contrast, the growth rates of Erw. herbicola strains Eh141 and Eh112Y were only slightly reduced at pH levels as low as 4.5, relative to pH 6‐8. When Ea273 was grown in NYGB in the presence of Eh141 or Eh112Y, the media became acidic and lower populations of Ea273 were recovered, compared with populations from buffered NYGB. Acidification of plant tissue as a consequence of growth of Erw. herbicola did not occur, however, and thus acid‐based inhibition of growth in planta is unlikely. The growth rates of nine strains of Erw. herbicola and their abilities to reduce the pH of NYGB did not correlate with their different abilities to prevent development of fire blight incited by Ea273 in a research apple orchard. When grown in mixed culture, Eh114 and Eh112Y grew to higher populations than Ea273 due to depletion of a nitrogen source needed by Ea273. The ability of 12 strains of Erw. herbicola to produce antibiotics inhibitory to Ea273 on a glucose‐asparagine medium correlated with the effectiveness of the strains in suppressing fire blight. A crude preparation of the Eh318 antibiotic delayed development of disease in immature pear fruits incited by Ea273 but not by strain Ea273R318, which is resistant in vitro to the Eh318 antibiotic. Cells of Eh318 protected immature pear fruits more effectively from infection by Ea273 than from the resistant strain Ea273R318.
Competition between reductive acetogenesis and methanogenesis in the pig large‐intestinal flora
Authors: De Graeve K.G. , Grivet J.P. , Durand M. , Beaumatin P. , Cordelet C. , Hannequart G. , Demeyer D.
Published: March 2008

Washed bacterial suspensions obtained from the pig hindgut were incubated under 13CO2 in a buffer containing NaH13CO3 and carbohydrates. Incorporation of 13C into short chain fatty acids was assayed by quantitative nuclear magnetic resonance. The effects of different levels of H2 added to the gas phase (0, 20 and 80% v/v) and of the specific methanogenesis inhibitor 2‐bromoethane‐sulphonic acid (BES) were determined. In control incubations increasing the concentration of H2 markedly increased methane production. Single‐ and double‐labelled acetate and butyrate were formed in all incubations. In the absence of BES, increasing H2 significantly increased the incorporation of 13CO2 into butyrate and the proportion of double‐labelled acetate in total labelled acetate. The addition of BES proved to be very successful as a methane inhibitor and greatly enhanced the amount of mono‐ and double‐labelled acetate, especially at the highest H2 partial pressure. The results suggest that methanogenesis inhibited both routes of reductive acetogenesis, i.e. the homoacetate fermentation of hexose (represented for the most part by single labelling) and the synthesis of acetate from external CO2 and H2 (represented mostly by double labelling). A highly significant interaction between BES and H2 concentration was observed. At the highest pH2 BES increased the proportion of labelled acetate in total acetate from 17.1% for the control to 50.9%. It was concluded that although acetogenesis and methanogenesis can occur simultaneously in the pig hindgut, reductive acetogenesis may become a significant pathway of acetate formation in the absence of methanogenesis.
The use of impedance for preservative efficacy testing of pharmaceuticals and cosmetic products
Authors: Connolly P. , Bloomfield Sally F. , Denyer S.P.
Published: March 2008

Impedance was investigated for its applicability to preservative efficacy testing of pharmaceuticals and cosmetics. A good correlation between impedance detection time (Td) and total colony counts (colony‐forming units (cfu) was obtained for untreated suspensions of Staphylococcus aureus, Candida albicans, Aspergillus niger and Pseudomonas aeruginosa in phosphate‐buffered saline (PBS). A good correlation between Td and the number of cfu was also obtained for suspensions of test organisms treated for varying contact periods with selected concentrations of chlorhexidine, methyl paraben and phenoxyethanol in PBS, and methyl paraben in cetomacrogol cream, but these correlations were significantly different from those for untreated suspensions. It was found that for any given number of cfu the Td for preservative treated cells was extended. It is concluded that impedance represents a valid method for preservative efficacy testing of pharmaceuticals and cosmetics which could be used to achieve more comprehensive but economic screening of formulations against a wider range of preservative systems and concentrations than is the current approach where only a limited range of systems are tested because of the workload involved.
Immobilization of β‐amylase from Bacillus megaterium B6 into gelatin film by cross‐linking
Authors: Ray R.R. , Jana S.C. , Nanda G.
Published: March 2008

β‐Amylase (EC 3.2.1.2) from Bacillus megaterium B6 was immobilized in gelatin by covalent cross‐linking with organic hardeners, formaldehyde and gluteraldehyde, of which gluteraldehyde was proved to be better. The effect of temperature, pH, incubation time, substrate concentration, different surfactants and thiol inhibitors on immobilized β‐amylase had been investigated. Reuse efficiency and cross‐linker concentration was also studied. The data indicated that enhanced resistance to thermal and chemical denaturation, increased temperature optima (from 60° to 65°C) and rapid rate of substrate saturation were achieved after immobilization. The gelatin‐bound enzyme could also be reutilized for repeated batch experiments.
Expanded response surface model for predicting the effects of temperatures, pH, sodium chloride contents and sodium nitrite concentrations on the growth rate of Yersinia enterocolitica
Authors: Bhaduri S. , Buchanan R.L. , Phillips J.G.
Published: March 2008

The previously reported data set for the low temperature (5, 12 and 19°C) of Yersinia enterocolitica was expanded to include higher abusive temperature (28, 37 and 42°C). In addition to temperature, the data set included the effects and interactions of pH (4.5–8.5), sodium chloride (0.5‐5%) and sodium nitrite (0‐200 μg ml‐1) on the aerobic growth of Y. enterocolitica in brain heart infusion broth. Growth curves were modeled by fitting viable count data to the Gompertz equation. Quadratic models of natural logarithm transformations of the Gompertz B and M values and the derived values for lag phase durations and generation times were obtained using response surface analyses. Predictions based on the models for B and M values were comparable to predictions based on the derived values. These revised models provide an expanded means for rapidly estimating how the bacterium is likely to respond to any combination of the four variables within the specified ranges.
Isolation of a bacterium that causes anaaki disease of the red algae Porphyra yezoensis
Authors: Sunairi M. , Tsuchiya H. , Tsuchiya T. , Omura Y. , Koyanagi Y. , Ozawa M. , Iwabuchi N. , Murooka H. , Nakajima M.
Published: March 2008

Anaaki disease causes severe damage to the red algae Porphyra yezoensis from which the Japanese traditional food ‘nori’is produced. The causative agent of anaaki disease was isolated by several repeats of single‐colony isolation and infection experiments, and was identified as Flavobacterium sp. LAD‐1. The bacterium showed hydrolytic activity toward porphyran but not toward other polysaccharides composing the thallus of Porphyra, such as β‐1,3‐xylan or β‐1,4‐mannan. The bacterium also showed β‐D‐galactosidase activity.
Continuous production of bacteriocins, brevicin, nisin and pediocin, using calcium alginate‐immobilized bacteria
Authors: Wan J. , Hickey M. W. , Coventry M. J.
Published: March 2008

Bacteriocins including brevicin 286, nisin and pediocin PO2 have been produced successfully with immobilized cells of Lactobacillus brevis VB286, Lactococcus lactis subsp. lactis and Pediococcus acidilactici PO2 respectively encapsulated in calcium alginate beads. The beads encapsulating the bacteriocin‐producing cells were loaded into a column, and continuously supplied with fresh medium at a flow rate of 1 bed volume per 20 min. The concentrations of the three bacteriocins produced in the eluents were at least as high as those obtained from conventional free‐cell batch fermentations.
Efflux of ions and ATP depletion induced by pediocin PA‐1 are concomitant with cell death in Listeria monocytogenes Scott A
Authors: Chen Y. , Montville T. J.
Published: March 2008

The bacteriocin pediocin PA‐1 (80 AU ml−1), which is produced by Pediococcus acidilactici PAC 1.0, reduced Listeria monocytogenes Scott A viability by 4.6 log. Concomitant with the cell death, pediocin PA‐1 induced irreversible K+ and Pi efflux and ATP depletion in concentration‐dependent and time‐dependent fashions. The maximum amount of intracellular K+ and Pi loss was 520 and 44.6 nmol mg−1 CDW, respectively. Intracellular ATP levels decreased from 2.8 to 0‐029 nmol mg−1 CDW, corresponding to 98.9% depletion. Less than 0.1% ATP efflux was found with pediocin concentrations up to 200 AU ml−1. Approximately 10, 40 and 60 min were required for maximum K+ efflux, ATP depletion and Pi efflux, respectively. Moreover, pediocin PA‐1 depleted 90% of cytoplasmic ATP when only 25% Pi efflux took place. These results suggest that loss of ATP is due to attempts by the cell to maintain proton‐motive force rather than the inability of the cell to produce ATP due to the loss of Pi. Dithiothreitol‐treated PA‐1 no longer inhibited the growth of L. monocytogenes cells, and caused neither concentration‐dependent ion efflux nor ATP depletion.
Influence of growth conditions on the production of lactocin 705, a bacteriocin produced by Lactobacillus casei CRL 705
Authors: Vignolo Graciela M. , de Kairuz Martha N. , de Ruiz Holgado Aída A.P. , Oliver G.
Published: March 2008

G.M. VIGNOLO, M.N. DE KAIRUZ, A.P. DE RUIZ HOLGADO AND G. OLIVER. 1995. The effect of growth parameters on the production of lactocin 705 by Lactobacillus casei CRL 705 isolated from dry sausages was studied. The antimicrobial compound was produced during the growth cycle at temperatures between 15 and 30°C. Maximal activity in MRS broth was achieved at pH 6.5‐7.5. Investigation into the influence of supplementation and/or replacement of nutrients on lactocin 705 production demonstrated that large quantities of the bacteriocin could be obtained by addition of Tween 80 (0.5‐2.0%), glucose (2.0%), tryptone (1.0%) and yeast extract (2.0%). Bacteriocin production did not decrease in the presence of (w/v) 3% NaC1 and 0.02% NaNO2 in the culture medium. High titres of the antimicrobial compound were obtained in whey permeate supplemented with 2.0% yeast extract and 1.0% Tween 80. Lactocin 705, proved to be stable to pH and temperature at ripening conditions (pH 5.0‐6.0 and 15°C) of dry cured sausages.
Intestinal carriage of campylobacters, salmonellas, yersinias and listerias in pigeons in the city of Barcelona
Authors: Casanovas L. , de Simón M. , Ferrer M.D. , Arqués J. , Monzón G.
Published: March 2008

L. CASANOVAS, M. DE SIMÓN, M.D. FERRER, J. ARQUÉS AND G. MONZÓN. 1995. The faecal bacterial flora of pigeons, which may be the source of infectious diseases in man, was studied in the city of Barcelona. Four hundred cloacal specimens were examined for Campylobacter jejuni, Camp. coli, Salmonella spp., Yersinia spp. and Listeria spp., over a 12 month period.

Campylobacter jejuni was the most frequently isolated micro‐organism, found in 105 pigeons (26.2%), with a greater incidence in the districts of the city with a high density of pigeons and without seasonal variation. Salmonella spp. were isolated from six specimens (1.5%) and Yersinia intermedia was isolated from only one pigeon.
Properties and significance of an α‐amylase produced by Myxococcus coralloides D
Authors: Fárez‐Vidal M. Esther , Fernández‐Vivas Antonia , González F. , Arias J.M.
Published: March 2008

M.E.FÁREZ‐VIDAL, A. FERNÁNDEZ‐VIVAS, F. GONZÁLEZ AND J.M. ARIAS. 1995. The extracellular amylase activity from Myxococcus coralloides D was purified by Sephacryl S‐200 gel filtration and by ion‐exchange chromatography on DEAE‐Sephadex A‐25. The molecular weight was estimated by SDS‐PAGE and by gel filtration as 22.5 kDa. The optimum temperature was 45°C. The pH range of high activity was between 6.5 and 8.5, with an optimum at pH 8.0. Activity was strongly inhibited by Hg2+, Zn2+, Cu2+, Ag+, Pb2+, Fe2+ and Fe3+, EDTA and glutardialdehyde, but was less affected by Ni2+ and Cd2+. Li+, Mg2+, Ba2+, Ca2+, N‐ethylmaleimide, carbodiimide and phenyl methyl sulphonyl fluoride had almost no affect. The Km (45°C, pH 8) for starch hydrolysis was 2.0 times 10‐3 gl‐1. Comparison of the blue value‐reducing curves with the time of appearance of maltose identified the enzyme produced by M. coralloides D as an α‐amylase.
Nutritional factors affecting nisin production by Lactococcus lactis subsp. actis NIZO 22186 in a synthetic medium
Authors: De Vuyst L.
Published: March 2008

L. DE VUYST. 1995 A minimal synthetic medium (SM8) for nisin‐producing Lactococcus lactis subsp. lactis strains has been designed; it consists of eight growth‐stimulating amino acids (glutamic acid, methionine, valine, leucine, threonine, arginine, isoleucine and histidine), five vitamins (biotin, calcium pantothenate, nicotinic acid, pyridoxine and riboflavin) and the mineral salts dihydrogen phosphate, disodium hydrogen phosphate, sodium chloride, magnesium sulphate and trisodium citrate. Nisin biosynthesis is strongly dependent on the presence of a sulphur source, either an inorganic salt (magnesium sulphate or sodium thiosulphate) or the amino acids methionine, cysteine or cystathionine. The amino acids serine, threonine and cysteine highly stimulate nisin production without affecting the final cell yield, indicating their precursor role during nisin biosynthesis.
The antimicrobial activity of hexapeptides derived from synthetic combinatorial libraries
Authors: Blondelle Sylvie E. , Takahashi Ema , Dinh Kim Thy , Houghten R.A.
Published: March 2008

S.E. BLONDELLE, E. TAKAHASHI, K.T. DINH AND R.A. HOUGHTEN. 1995. A series of peptides identified through the use of synthetic hexapeptide combinatorial libraries (represented by the formula Ac‐RRWWCO‐NH2) were examined for their antimicrobial activity against five different micro‐organisms. Their toxicity was also evaluated in an in vitro haemolytic assay. The peptides showed activity against the five micro‐organisms, although higher activities were found against Gram‐positive bacteria. Both growth inhibition and cell viability assays were carried out to demonstrate the bactericidal activities of these peptides against two of the micro‐organisms tested. The dimeric cystine forms of these peptides were shown to have biological activities identical to the monomeric forms.
Characterization of Carnobacterium species by pyrolysis mass spectrometry
Authors: Manchester L.N. , Toole A. , Goodacre R.
Published: March 2008

L.N. MANCHESTER, A. TOOLE AND R. GOODACRE. 1995. Forty‐eight strains of Carnobacterium were examined by pyrolysis mass spectrometry (PyMS). The effects of culture age and reproducibility over a 4 week period were also examined. The results were analysed by multivariate statistical techniques and compared with those from a previous numerical taxonomic study based on morphological, physiological and biochemical characteristics and with studies which used DNA‐DNA and 16S rRNA sequence homologies. Taxonomic correlations were observed between the PyMS data and the previous studies. Culture age was observed to have little effect on the mass spectra obtained and the reproducibility study indicated that there was very little variation over the 4 week period. It was concluded that PyMS provides a reliable method for studying carnobacterial classification and provides a rapid way for clarifying and refining subgeneric relationships within the genus Carnobacterium. Further work may also show that it offers a potentially very rapid and accurate method for the identification of Carnobacterium.
Methylchloroisothiazolone‐induced growth inhibition and lethality in Escherichia coli
Authors: Chapman J. S. , Diehl Megan A.
Published: March 2008

J.S. CHAPMAN AND M.A. DIEHL. 1995. Exposure of log phase Escherichia coli cells to inhibitory levels of 5‐chloro‐2‐methyl‐isothiazolin‐3‐one (MCI) results in rapid bacteriostasis and a delayed onset of bactericidal activity. Inhibition of respiration occurs within the same time frame as bacteriostasis, and is followed by a decline in intracellular ATP levels. In vitro and in vivo experiments suggest that growth inhibition is the result of selective inhibition of particular targets, with succinate dehydrogenase being identified as a possible target. Such selectivity was not anticipated from this highly reactive molecule. MCI‐induced lethality is positively correlated with a loss of reduced protein sulphydryls (r2= 0·79). A greater than equimolar loss of reduced protein sulphydryls, compared with the number of MCI molecules added, and a reduction in killing by MCI after induction of the OxyR regulon suggest that free radical generation may have a role in the antibacterial activity of MCI. We present an examination of the in vivo effects of MCI exposure on bacterial cells, and evidence that the isothiazolones exhibit selectivity in their cellular targets and antimicrobial effects.
Enzyme production by lactobacilli and the potential link with infective endocarditis
Authors: Oakey H.J. , Harty D.W.S. , Knox K.W.
Published: March 2008

H.J. OAKEY, D.W.S. HARTY AND K.W. KNOX. 1995. Fifty‐six strains of lactobacilli were examined for the production of glycosidases and proteases (arylamidases) that could be associated with the ability to grow in vivo and/or be a factor in the pathogenesis of endocarditis. The strains were from seven species, with an emphasis on Lactobacillus rhamnosus and Lact. paracasei subsp. paracasei, both of which have been associated with endocarditis and provided 12 of the 13 strains isolated from cases of the disease. Other species were Lact. acidophilus, Lact. plantarum, Lact. salivarius, Lact. fermentum and Lact. oris.

Commonly expressed glycosidase activities were α‐D‐galactosidase and β‐N‐acetyl‐D‐glucosaminidase followed by β‐D‐glucosidase and α‐L‐fucosidase. The combined production of β‐N‐acetyl‐D‐glucosaminidase and α‐D‐galactosidase was a feature of the endocarditis isolates. In contrast, β‐D‐galactosidase was produced by very few of the strains within species implicated in endocarditis but most of the strains of Lact. salivarius, Lact. fermentum and Lact. oris.

The most commonly produced arylamidases active against substrates employed for testing human blood clotting cascade were activated protein C(Ca)‐like, activated factor X(Xa)‐like and Hageman factor‐like followed by kallikrein‐like and chymotrypsin‐like enzymes. Kallikrein‐like enzyme activity was shown more frequently by strains from species commonly isolated from cases of endocarditis (Lact. rhamnosus and Lact. paracasei subsp. paracasei) than from other oral species (Lact. plantarum, Lact. salivarius, Lact. fermentum and Lact. oris).

The data indicate that some lactobacilli can produce enzymes that would enable the breakdown of human glycoproteins and the synthesis and lysis of human fibrin clots, characteristics which aid the colonization and survival of bacteria infecting an endocarditis vegetation.
Differentiation of Lactobacillus sake and Lact. curvatus isolated from naturally fermented Greek dry salami by SDS‐PAGE of whole‐cell proteins
Authors: Samelis J. , Tsakalidou Effie , Metaxopoulos J. , Kalantzopoulos G.
Published: March 2008

J. SAMELIS, E. TSAKALIDOU, J. METAXOPOULOS AND G. KALANTZOPOULOS. 1995. To confirm the phenotypic characterization of 169 predominant sausage isolates of the Lactobacillus sake/curvatus group, SDS‐polyacrylamide gel electrophoresis (SDS‐PAGE) of whole‐cell proteins of 29 representative strains was undertaken. The results of the electrophoretic analysis indicated that each species yielded a specific protein profile, identical to the respective type strain. It was shown that all melibiose‐positive isolates belonged to Lact. sake, whether or not they were arginine‐ and maltose‐positive, whereas all melibiose‐ and arginine‐negative isolates were assigned to Lact. curvatus. A group which phenotypically appeared to lie between Lact. sake and Lact. curvatus, on the basis of arginine (+), melibiose (‐) and maltose (‐) reactions, was shown to be more closely related to Lact. sake. The SDS‐PAGE method was valuable in distinguishing between species, but did not allow further differentiation of Lact. curvatus or Lact. sake strains displaying high heterogeneity in secondary physiological and biochemical properties.
Heat resistance of Pectinatus sp., a beer spoilage anaerobic bacterium
Authors: Watier D. , Leguerinel I. , Hornez J.P. , Chowdhury I. , Dubourguier H.C.
Published: March 2008

D. WATIER, I. LEGUERINEL, J.P. HORNEZ, I. CHOWDHURY AND H.C. DUBOURGUIER. 1995. The heat resistance of three strains of Pectinatus (Pectinatus cerevisiiphilus DSM 20466, Pectinatus sp. DSM 20465 and Pectinatus frisingensis ATCC 33332) were measured at different temperatures (50–60°C), different pH (4–6·3), in two media (MRS and wort). Similar D60 values were obtained for DSM 20465 and ATCC 33332, but DSM 20466 was more resistant in MRS. Moreover the z values were higher in MRS than in wort for the three strains. Thermal destruction at different pH was variable. Results were discussed in relation to factors affecting heat resistance.
Purification and properties of three esterases from Brevibacterium sp. R312
Authors: Lambrechts Christel , Escudero J. , Galzy P.
Published: March 2008

C. LAMBRECHTS, J. ESCUDERO AND P. GALZY. 1995. The esterases of Brevibacterium sp. R312 were found to have an intracellular location. Electrophoresis of lysed cell supernatant fluids revealed seven bands of esterase activity in the presence of α‐naphthyl acetate. Eight esterases were separated by anion exchange chromatography. The three main esterases (esterase 4b, 2 and 4a) of Brevibacterium sp. R312 were purified. The molar masses, the pH optima, the temperature optima and heat stabilities were determined. Esterase 2 differed from the two others in sensitivity to inhibitors. Esterase 4b differed from esterases 2 and 4a in its substrate specificity. This enzyme hydrolyses aliphatic and nitrophenyl esters. The spectrum of activity of the two other esterases is narrower. They hydrolysed only naphthyl esters and, in the case of esterase 2, tributyrate and ethyl butyrate.
Transfer of plasmids between strains of Escherichia coli under rumen conditions
Authors: Scott Karen P. , Flint H.J.
Published: March 2008

K. P. SCOTT AND H.J. FLINT. 1995. Strains of Escherichia coli originally isolated from the rumen of sheep were shown to be capable of exchanging a 60kb plasmid, conferring resistance to tetracycline and ampicillin, at low frequencies (below 10‐6 per recipient) under anaerobic conditions in the presence of (a) autoclaved and clarified rumen fluid, (b) raw clarified rumen fluid, or (c) whole rumen fluid. Under anaerobic conditions the two rumen strains showed no inhibition of growth rate when 50 mmol 1‐1 volatile fatty acids were added to LB medium at pH 7, although significant inhibition resulted with 100 mmol 1‐1 VFA. The two rumen strains, and four strains from the pig gut, showed less inhibition of anaerobic growth by volatile fatty acids than did three laboratory strains examined for comparison. These findings indicate that plasmid transfer between certain E. coli strains can occur under conditions that closely simulate an anaerobic gut environment.
The effect of step changes in sucrose concentration on the growth of Salmonella typhimurium LT2
Authors: Brocklehurst T.F. , Mitchell G.A. , Pleass W. , Smith A.C.
Published: March 2008

Water activity is a method of preservation that can affect microbial growth in foods and that may fluctuate during their processing, distribution and storage. Sucrose has been used to change the water activity of microbiological culture media. Suspensions of Salmonella typhimurium LT2 in the exponential phase of growth have been subjected to step changes in sucrose concentration at 20°C. The changes in the numbers of viable bacteria were measured with time and the experimental growth curves compared with predictions based on growth data obtained at constant sucrose concentrations. Steps down in sucrose concentration showed some apparent loss of viability after the step followed by growth at a rate close to the expected value. Steps up in sucrose concentration resulted in a greater apparent loss of viability after the step and either growth or the inducement of lag, depending on the final concentration of sucrose. A series of small steps up in sucrose concentration to 45% (w/v) was able to sustain growth where it was not possible by inoculation directly into this concentration. Improved recovery of bacteria subject to osmotic stress was possible with a medium containing sodium chloride.
Development and evaluation of two novel oligonucleotide probes based on 16S rRNA sequence for the identification of Salmonella in foods
Authors: Lin C.‐K. , Tsen H.‐Y.
Published: March 2008

DNA sequence in the V3 to V6 region of the 16S rRNA gene of Salmonella enteritidis was determined. By comparison of this sequence with those of Escherichia coli and Proteus vulgaris obtained from GenBank/EMBL database, three oligonucleotides termed as 16S I, 16S II and 16S III were synthesized. Hybridization of these oligonucleotides with 325 Salmonella isolates and some non‐Salmonella isolates including the Salmonella closely related species of the family of Enterobacteriaceae showed that 16S II could not be used as a Salmonella specific‐probe. 16S I and 16S III hybridized with all the Salmonella isolates tested, the former also hybridizing with Citrobacter spp. and the latter hybridizing with Klebsiella pneumoniae as well as Serratia marcescens. Since enrichment of the target cells in food samples was usually required prior to the DNA hybridization assay, the interference from those non‐Salmonella isolates could be prevented by enrichment by culturing in lactose‐combined tetrathionate (CTET) broth followed by Gram‐negative (GN) broth at 37°C and/or 43°C. Such a culture step could inhibit the growth of Klebsiella spp., Ser. marcescens and/or Citrobacter spp. and allowed the specific detection of Salmonella.
Expression of novobiocin resistance genes in the novobiocin‐producing organism Streptomyces niveus
Authors: Hoggarth J.H. , Ritchie D.A.
Published: March 2008

RNA isolated at intervals during fermentation from the novobiocin‐producing wild‐type strain of Streptomyces niveus and from a series of novobiocin‐non‐producing (Nov‐) mutants was hybridized to DNA probes containing sequences which specify novobiocin resistance. The probes were made from inserts contained in the clones pGL101 and pGL103 which increase the level of novobiocin resistance of S. lividans transformants from 10 μg ml‐1 to 50 μg ml‐1 and 150 μg ml‐1, respectively. No hybridization was detected with the pGL101 probe. The pGL103 probe hybridized to RNA extracted during the later stages of growth—a pattern corresponding to the transition from low to high level novobiocin resistance during growth of S. niveus wild‐type cultures. Neither probe hybridized to RNA extracted from four Nov‐ mutants. These mutants showed variable levels of novobiocin resistance but none expressed the high wild‐type levels. The authors conclude that expression of the DNA sequence in pGL103 is associated with high level novobiocin resistance.
Effect of Pediococcus pentosaceus FBB61, pediocin A producer strain, in caecal fermentations
Authors: Piva A. , Meola E. , Panciroll A.
Published: March 2008

The objective of this study was to investigate the effect of pediocin A in in vitro caecal fermentations. Pediococcus pentosaceus FBB61, pediocin A producer (bac +) and its isogenic mutant (bac—) Ped. pentosaceus FBB61‐2 were added to fermentation vessels. Pediocin A did not alter the normal activity of caecal microflora. Nevertheless, the presence of pediocin A producer strain reduced proteolysis compared to the mutant strain as indicated by ammonia concentrations (P < 0·05), and isobutyric and isovaleric molar proportions (P < 0·05).
The effect of incubation temperature and sodium chloride concentration on the growth kinetics of Vibrio anguillarum and Vibrio anguillarum‐related organisms
Authors: Guérin‐Faublée Véronique , Rosso L. , Vigneulle Martine , Flandrois J.‐P.
Published: March 2008

The effect of temperature and NaCl concentration on the growth kinetics of Vibrio anguillarum and V. anguillarum‐related (VAR) strains was studied.

For one wild VAR strain, NaCl concentration interfered with growth temperature parameters, in particular, with the maximum growth temperature but also with the optimum temperature (defined as the temperature at which μmax equals its maximal value μopt), and with μopt itself. For the same strain, optimal growth required the adding of NaCl to the medium to a final concentration of 1·5%. These results were not confirmed by tests on a V. anguillarum collection strain.

When the NaCl concentration in the culture media was 1.5%, the optmum temperature for the nine strains studied ranged from 29.7°C to 34°C whereas the maximum temperature ranged between 35.3°C and 38.5°C.

Hence, antbiotic susceptibility testing as well as biochemical identification might be carried out at 30°C in the presence of 1.5% NaCl, which corresponded to a suboptimal growth.
Factors affecting the growth of Listeria monocytogenes on minimally processed fresh endive
Authors: Carlin F. , Nguyen‐the C. , da Silva A. Abreu
Published: March 2008

The influence of various factors on the fate of Listeria monocytogenes on cut leaves of broad‐leaved endive has been studied. Factors considered were temperature, characteristics of the leaves (age, quantity and quality of the epiphytic microflora) and characteristics of the L. monocytogenes inoculum (concentration, strain). The increases in numbers of L. monocytogenes were lower than those of the aerobic mesophilic microflora at 3°, 6°, 10° and 20°C. Doubling times of the populations of L. monocytogenes were in the same order of magnitude as those of aerobic bacteria at 10° and 20°C, but longer at 3° and 6°C. There were positive significant correlations between growth of L. monocytogenes and populations of aerobic bacteria, and between growth of L. monocytogenes and extent of spoilage on the leaves.

Of 225 bacteria isolated from the leaves, 84% were identified as fluorescent pseudomonads; there was no difference in the species isolated from leaves that showed a low growth of L. monocytogenes and leaves that showed a high growth of L. monocytogenes. Populations of L. monocytogenes increased faster during the first 2 and 4 d of storage at 10°C on leaves inoculated with 10–103 cfu g‐1 than on leaves inoculated with about 105 cfu g‐1, but the population reached after 7 d was lower. The behaviour of L. monocytogenes was similar among the three strains tested.
Induction of bacteriocin in Carnobacterium piscicola LV17
Authors: Saucier L. , Poon A. , Stiles M.E.
Published: March 2008

Domination of Carnobacterium divergens LV13 by a bacteriocin‐producing (bac+) organism Carnobacterium piscicola LV17 was dependent on the level of inoculum of the producer strain and its bacteriocin production. When C. piscicola LV17 was grown in APT broth from an initial inoculum of α‐104 cfu ml‐1, bacteriocin was not produced (bac‐) although maximum population was reached. The culture remained bac‐ during subsequent inoculation at 102‐107 cfu ml‐1 unless it was first grown on solid medium or if heat‐treated supernatant fluids from a bac+ culture of C. piscicola LV17, LV17A or LV17B were added to the culture prior to the stationary phase of growth. Use of purified carnobacteriocins from C. piscicola LV17A and LV17B confirmed their role in regulation of the bac+ phenotype. The need for induction might account in part for differences in bacteriocin production by cultures in liquid and on solid growth media.