bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid estimation of Escherichia coli in live marine bivalve shellfish using automated conductance measurement
Authors: Dupont J. , Ménard D. , Hervé C. , Chevalier F. , Bèliaeff B. , Minier B.
Published: March 2008

Conductance measurement for quantitative estimations of Escherichia coli in live bivalve shellfish was evaluated as an alternative to the conventional most probable number (MPN) method used in France. The sensitivity of the two techniques was comparable. A single regression line (r=‐0·968, P < 10‐6) between log10 MPN and detection time (DT) was used to estimate E. coli concentrations for all shellfish examined. Estimation accuracy was ± 0·92 log unit. Repeatability was better for DT than the log10 of MPN estimations (average coefficients of variation 2·7 and 9·3%, respectively). The conductance signal was attributable to E. coli in 96% of cases, and only 0·7% of E. coli cultures failed to exhibit a signal within 20 h. The conductance method reduces analysis handling time and is much easier to use than the MPN method. Moreover, results can be obtained within 5–9 h compared to 3 d for the MPN method.
Production of brevicin 286 by Lactobacillus brevis VB286 and partial characterization
Authors: Coventry M.J. , Wan J. , Gordon J.B. , Mawson R.F. , Hickey M.W.
Published: March 2008

Brevicin 286 was produced by Lactobacillus brevis VB286 isolated from vacuum‐packaged meat and was partially purified by ammonium sulphate precipitation, gel filtration and dialysis. The bacteriocin was susceptible to proteolytic enzymes, stable to heating at 100°C particularly under acidic pH conditions, and showed a relatively narrow spectrum of activity with notable activity against Listeria sp. Production of brevicin 286 was optimal during exponential growth at 20°C. Higher rates of cell growth occurred between 30 and 37°C but with little or no expression of brevicin 286. A food‐grade formulation consisting of 4% yeast extract and 1% glucose was found to be adequate for optimal brevicin 286 production and the bacteriocin‐containing culture supernate was successfully spray dried with full recovery of antibacterial activity in the resultant powder.
A modified chemostat system to study the ecology of oral biofilms
Authors: Bradshaw D.J. , Marsh P.D. , Schilling K.M. , Cummins D.
Published: March 2008

Previously, we developed a chemostat system to study the behaviour and properties of a community of up to 10 species of oral bacteria. The present study describes modification of this system to incorporate removable and replaceable hydroxyapatite (the major mineral in human dental enamel) disks on which biofilms could develop. Hydroxyapatite disks were immersed in the chemostat for known time periods, and the bacterial content of biofilms determined by viable counting. Initial deposition rates were rapid, with all 10 species detected after 1 h, and the numbers of bacteria in biofilms continued to increase for 21 d. The species composition of biofilms reflected that of the surrounding fluid phase, and showed only limited signs of the type of ‘species succession’ which is observed in developing dental plaque in vivo, although anaerobic species increased in proportion in older biofilms. Four‐day biofilms showed the least variability and were chosen as the ‘standard biofilm’ for more detailed study. Variability in the bacterial composition of 4‐d biofilms was comparable both within a single chemostat run and between independent chemostat runs. Glucose pulsing in the absence of pH control resulted in the selection of cariogenic species; the disruption of the biofilm community was less marked than that of the equivalent planktonic culture. The model system has considerable potential in studying the effects of a variety of factors on biofilm development, as well as in comparing the efficacy of antimicrobial systems against biofilms.
Characterization of rhizobia isolated from Carob tree (Ceratonia siliqua)
Authors: El Idrissi M. Missbah , Aujjar N. , Belabed A. , Dessaux Y. , Filali‐Maltouf A.
Published: March 2008

Bacteria were isolated from root nodules of Carob tree (Ceratonia siliqua). We studied their cultural, physiological and biochemical characteristics. Strains showed some variability concerning tolerance to NaCl and KCl, and none grew at pHs below 7. The mean temperature for growth was 30°C and some strains could grow at 45°C. These isolates could use a great variety of carbohydrates as a sole carbon source (hexoses, pentos, disaccharides, trisaccharides, polysaccharides and organic acids). According to their cultural and physiological features and their in vitro infectivity on their original host, we suggest that these isolates may belong to the genus Rhizobium. Moreover, with regard to their average generation time, carbohydrate utilization, antibiotic resistance and other biochemical properties, they may be related to fast‐growing rhizobia until further characterization.
α‐Galactosidase from the yeast Torulaspora delbrueckii IFO 1255
Authors: Oda Y. , Tonomura K.
Published: March 2008

The yeast Torulaspora delbrueckii IFO 1255 was selected as the strain fermenting melibiose from 35 strains of Torulaspora species. The strain IFO 1255 produced extracellular and cell‐associated forms of α‐galactosidase when grown on either melibiose or galactose as the sole carbon source. Most of the enzyme was located outside of the cell membrane: the periplasmic space, or cell walls, or both. α‐Galactosidase was purified to homogeneity from the cell‐free extract of the strain IFO 1255 by acid treatment and column chromatography on DEAE‐Toyopearl 650M and Butyl‐Toyopearl 650M. The molecular weight of the purified enzyme was estimated to be 88 000 by SDS‐polyacrylamide gel electrophoresis and 530 000 by gel filtration. The enzyme contained 50% of its molecular weight as carbohydrate. Optimum pH and temperature were 4.5–5.5 and 55°C, respectively. The enzyme was inhibited strongly by Ag2+, Hg2+ and Cu2+ each at 1 mmol 1‐1. The Km (μmol 1‐1) for p‐, o‐, m‐nitrophenyl α‐D‐galactopyranoside, melibiose, raffinose and stachyose were 2.8, 1.3, 2.8, 4.2, 170 and 230, respectively, and Vmax (μmol min‐1 mg protein‐1) for those substrates were 310, 140, 21, 22, 30 and 44, respectively. The properties of α‐galactosidase from T. delbrueckii IFO 1255 were similar to those from the related species, Saccharomyces cerevisiae.
Detection of Salmonella typhi by polymerase chain reaction
Authors: Zhu Q. , Lim C.K. , Chan Y.N.
Published: March 2008

A rapid and sensitive method for detection of Salmonella typhi would help in preventing the spread of outbreaks and in clinical diagnosis. In order to develop unique PCR primers to detect Salm. typhi, ribosomal RNA genes from Salm. typhi (Rawlings) were cloned in pUC18. The resulting clone was confirmed by sequencing. The cloned DNA fragment contained the 5S, part of the 23S rRNA genes and the 5S‐23S spacer region (EMBL/GenBank accession No. U04734).

It was expected that the 5S‐23S spacer region is divergent unlike the highly conserved 23S+5S genes. This was confirmed by comparison with the rRNA gene sequences in the EMBL/GenBank database. A pair of PCR primers specific for Salm. typhi was obtained, based on this spacer region sequence. The specificity of this pair of primers was tested with 54 Salm. typhi strains (of 27 different phage types). All these Salm. typhi strains showed the positive 300 bp PCR product with this pair of primers. Six other Salmonella species as well as six other non‐Salmonella bacteria were tested and none showed the 300 bp PCR product. The sensitivity of the detection level was 0·1 pg of pure Salm. typhi genomic DNA, or approximately 40 Salm. typhi cells in a spiked food sample. This pair of primers therefore has the potential for development into a diagnostic tool for the rapid diagnosis of typhoid fever.
Pulsed‐field gel electrophoresis as an epidemiological tool for clonal identification of Aeromonas hydrophila
Authors: Talon D. , Dupont M.J. , Lesne J. , Thouverez M. , Michel‐Briand Y.
Published: March 2008

Pulsedfield gel electrophoresis (PFGE) was used to characterize Aeromonas hydrophila strains isolated from a cluster of hospital‐acquired infections that occurred over approximately 1 month in a French hospital. Five isolates from patients and 10 isolates from the water supply were characterized by biotyping and antibiotic susceptibility patterns and compared with 10 epidemiologically unrelated strains isolated from patients and rivers, by PFGE of digests of chromosomal DNA. Five environmental and four clinical isolates belonged to the same biotype and antibiotic susceptibility pattern type. The endonucleases XbaI, SpeI and SwaI gave satisfactory profiles whereas DraI did not. The profiles were stable, reproducible and discriminatory. The 10 epidemiologically unrelated strains exhibited 10 different patterns after digestion with XbaI, the least expensive, suitable endonuclease. PFGE is a rapid and discriminatory technique for the typing of Aeromonas hydrophila where a common origin of infection is suspected.
The application of a log‐logistic model to describe the thermal inactivation of Clostridium botulinum 213B at temperatures below 121.1°C
Authors: Anderson W.A. , McClure P.J. , Baird‐Parker A.C. , Cole M.B.
Published: March 2008

In this work, the death of Clostridium botulinum 213B was measured at temperatures between 101°C and 121°C. It was found that at all temperatures tested, survivor curves deviated from log‐linearity which prevented their description using traditional first order kinetics. The survivor curves were better described using a vitalistic approach and the log‐logistic transformation proposed by Cole et al. (1993). A single equation was derived to describe all survivor curves over the temperature range tested and a comparison of predicted and measured data showed good correlation. The implications of the use of the vitalistic approach to the validity of the ‘minimum botulinum cook’ is discussed.
The effect of biocides on proteins of Pseudomonas aeruginosa PAO bacteriophage F116
Authors: Maillard J.‐Y. , Beggs T.S. , Day M.J. , Hudson R.A. , Russell A.D.
Published: March 2008

SDS‐polyacrylamide gel electrophoresis (SDS‐PAGE) was used to study the effect of several biocides on the protein content of Pseudomonas aeruginosa PAO phage F116. Eight major protein bands were identified and used as controls. The test biocides altered the control band pattern in different ways. Similarities were noticed between closely related biocides. Moreover, the alteration in the protein band pattern did not always correlate with phage inactivation.
Detection of pathogenic Yersinia enterocolitica in environmental waters by PCR
Authors: Sandery M. , Stinear T. , Kaucner C.
Published: March 2008

The isolation of pathogenic strains of Yersinia enterocolitica from food and water samples by culture is time‐consuming and unreliable. A two‐step PCR procedure has been developed which, after a period of bacterial enrichment, can detect and confirm the presence of pathogenic Y. enterocolitica within a single day. This PCR method works effectively for a range of environmental water types, including reticulated waters, reservoirs and creeks. A survey of environmental waters in Victoria, Australia, showed that the PCR method detected pathogenic Y. enterocolitica in water sampled from four separate sites (two creeks and two reservoirs). Repeat samplings of the two reservoirs yielded PCR‐positive results on all but one occasion. Culture analysis of the same samples detected pathogenic Y. entrocolitica in only one sample, indicating that the PCR can detect pathogenic Y. enterocolitica which are undetectable by culture. Results from this study confirm that potentially pathogenic strains of Y. enterocolitica can exist in environmental waters.
Uptake and utilization of n‐octacosane and n‐nonacosane by Arthrobacter nicotianae KCC B35
Authors: Radwan S.S. , Sorkhoh N.A. , Felzmann H. , El‐Desouky A.F.
Published: March 2008

Arthrobacter nicotianae KCC B35 isolated from blue‐green mats densely covering oil sediments along the Arabian Gulf coast grew well on C10 to C40n‐alkanes as sole sources of carbon and energy. Growth on C20 to C40 alkanes was even better than on C10 to C18 alkanes. Biomass samples incubated for 6 h with n‐octacosane (C28) or n‐nonacosane (C29) accumulated these compounds as the predominant constituent alkanes of the cell hydrocarbon fractions. The even chain hexadecane C16 and the odd chain pentadecane C15 were the second dominant constituent alkanes in C28 and C29 incubated cells, respectively. n‐Hexadecane‐incubated cells accumulated in their lipids higher proportions of C16‐fatty acids than control cells not incubated with hydrocarbons. On the other hand, C28 and C29‐incubated cells did not contain any fatty acids with the equivalent chain lengths, but the fatty acid patterns of the cell lipids suggest that there should have been mid‐chain oxidation of these very long chain alkanes. This activity qualifies A. nicotianae KCC B35 to be used in cocktails for bioremediating environments polluted with heavy oil sediments.
Development of a simplified polymerase chain reactionenzyme immunoassay for the detection of Chlamydia pneumoniae
Authors: Wilson P.A. , Phipps J. , Samuel D. , Saunders N.A.
Published: March 2008

The 16S rRNA genes of two Chlamydia pneumoniae and two C. psittaci strains of different serovars were sequenced then compared to previously reported Chlamydia 16S rRNA gene sequences. Chlamydia pneumoniae‐specific regions were identified and specific primers for nested PCR were synthesized. Nested PCR reactions were performed, in a single tube, by varying the annealing temperature of the amplification cycles. The initial thermal cycles were selected to allow annealing and extension of only the outer primer pair, whilst in later cycles a temperature that allowed inner primer annealing was employed. The inner primers were labelled, one with biotin and the other with fluorescein and consequently the dual labelled amplicon could be immobilized onto antibiotin‐coated microtitre plates and detected colorimetrically via an antifluorescein‐enzyme conjugate. The assay was found to be sensitive and specific. No cross reactions were observed with C. trachomatis, C. psittaci or other common respiratory pathogens.
Improved method for quantification of the bacteriocin nisin
Authors: Wolf C.E. , Gibbons W.R.
Published: March 2008

Nisin, a bacteriocin produced by Lactococcus lactis subsp. lactis, is used in some types of food preservation due to its inhibitory action on Grampositive bacteria and their spores. A commonly used agar diffusion bioassay technique for quantification of nisin in food samples was modified to increase its sensitivity, accuracy and precision. Several variables were evaluated. Results showed Micrococcus luteus as the most sensitive organism tested, a lower agar concentration (0·75% compared 1·5%) increased the sensitivity of the assay (21% improvement over standard method), and incorporation of 1% Na2HPO4 buffer into the bioassay agar made it possible to prevent false inhibitory zones from developing due to the low pH of the test solutions. This resulted in a 57% improvement in accuracy and a 12% improvement in precision compared to the standard method
The certification of a reference material for the evaluation of the ISO method for the detection of Salmonella
Authors: Veld P.H. in't , Van Strijp‐Lockefeer N.G.W.M. , Havelaar A.H. , Maier E.A.
Published: March 2008

A reference material (RM) containing Salmonella typhimurium was certified as CRM 507 by the Standards, Measurements and Testing Programme of the European Commission. The material consists of a gelatin capsule filled with artificially contaminated milk powder. The material is certified for the evaluation of presence/absence methods based on the ISO 6579 procedure for the detection of Salmonella. In the certification study 11 laboratories determined the presence/absence of Salmonella from each of 50 capsules. They also determined the mean number of colony‐forming particles (cfp) and the homogeneity of the batch of RM according to an enumeration procedure. Certified values were calculated for both procedures separately. Based on the presence/absence procedure a fraction of capsules in which no Salmonella could be detected of 2·7% (one‐sided 95% confidence upper limit 4·4%) was certified, for the enumeration procedure this fraction was 0·61% (one‐sided 95% confidence upper limit 1·6%). The certified mean number of Salmonella cfp in one capsale is 5·9 (two‐sided 95% confidence interval 5·3—6·4). Data on the preparation, identification, stability (at storage and higher temperatures) and homogeneity of the material are presented.
Rapid detection of Mycoplasma bovis in milk samples and nasal swabs using the polymerase chain reaction
Authors: Hotzel H. , Sachase K. , Pfützner H.
Published: March 2008

Two methods are suggested that allow direct detection of Mycoplasma bovis from clinical samples, i.e. milk and nasal swabs, respectively. Milk samples were trypsinized in the presence of Triton X‐100 and passed through a DNA‐binding filter membrane, from which DNA was extracted and subjected to PCR. The detection limit was 500 cfu ml−1 on agarose gels and 50 cfu ml−1 after Southern hybridization so that the method can be used to monitor low‐titre samples from animals at the subclinical stage. Results became available within 24 h, thus rendering the procedure more rapid than ELISA and culture techniques. Six other methods designed for milk or other complex samples were tested in this study, but found unsatisfactory. Rapid and specific detection of the pathogen by PCR from nasal mucus treated with lysis buffer and proteinase K was demonstrated for swabs taken from experimentally infected calves. Both methods represent useful tools for effective livestock monitoring and single‐animal diagnosis.
Effect of the pre‐treatments for milk samples filtration on direct viable cell counts
Authors: Fernández‐Astorga A. , Hijarrubia M.J. , Lázaro B. , Barcina I.
Published: March 2008

Escherichia coli O25: H–42 was selected to study the effect of pre‐treatments on the enumeration of direct viable cells from milk samples. Before and after inducing cell elongation by cellular division inhibitors, three pre‐treatments for milk‐filtration were used. One involved a pretreatment with trypsin (1·5 min at 50°C), addition of hot Triton X‐100 after heating and filter rinses with phosphate saline buffer. The other two involved pretreatment with trypsin and Triton X‐100 (10 min at 50°C), filter rinses with hot Triton X‐100 and organic solvents. Pre‐treatments applied after inducing cell elongation had an effect on cell recovery from milk samples depending on the pre‐treatment used. The most suitable, on the basis of the number and percentage of enlarged cells obtained was the first described. The others selectively affected recovery of elongated cells. Pretreatments applied before inducing the cell elongation, negatively affected viability with enumerations in milk samples being significantly (P < 0·001) lower than those found in controls. However, the negative effects of first pre‐treatment on viability was lower than that produced by the pre‐treatments involving organic solvents.
An assessment of the Sartorius MD8 microbiological air sampler
Authors: Parks S.R. , Bennett A.M. , Speight S.E. , Benbough J.E.
Published: March 2008

Tests described in this paper show that gelatine membrane filters used in the MD8 microbiological air sampling system collected monodispersed aerosols between 0·7 and 1·0 μm containing viable Bacillus subtilis var. niger spores, with an efficiency of 99·9995%. Gelatine membrane filters linked to the MD8 control pump system were as effective as the well established Casella slit‐to‐agar device for collecting some viable bacteria, nebulized under controlled experimental conditions and naturally occurring airborne micro‐organisms in a pharmaceutical plant. By using a long flexible hose connection to the control pump, the head could be positioned where sampling was required in locations remote from the pump exhaust, making it suitable for microbiological monitoring in critical locations such as laminar flow stations and isolators.
Comparative study on the action of S‐(+)‐carvone, in situ, on the potato storage fungi Fusarium solani var. coeruleum and F. sulphureum
Authors: Oosterhaven K. , Leitao A. Chambel , Gorris L.G.M. , Smid E.J.
Published: March 2008

Growth of Fusarium sulphureum was inhibited by S‐(+)‐carvone administered via the gas phase. Under the same conditions, the related fungus F. solani var. coeruleum was not inhibited. In liquid medium, both fungi were found to convert S‐(+)‐carvone with the same rate, mainly into isodihydrocarvone, isodihydrocarveol and neoisodihydrocarveol. Only a slight difference in the relative amounts of the bioconversion products was observed. Since the bioconversion products did not inhibit the growth of the fungi to the same extent as S‐(+)‐carvone, the process can be considered as a detoxification mechanism. The bioconversion as such cannot account for the observed difference in growth inhibition.
Morphogenesis, ATP content and oxytetracycline production by Streptomyces rimosus in solid substrate cultivation
Authors: Yang S.‐S. , Wang J.‐Y.
Published: March 2008

On agar plates, mycelia of Streptomyces rimosus TM‐55 had a slender and smooth surface at 24 h, developed a shorter form and rough surface at 116 h, and lysed after 504 h incubation. Oxytetracycline potency reached a maximum at 94 h. During cultivation on solid substrate, mycelia rarely occurred on the surface at 24 h. The organism appeared as short rods at 166 h, and formed spores at 504 h. The ATP content was maximal at 166 h, while energy charge varied between 0·63 and 0·77 during cultivation. The oxytetracycline potency was maximal at 166 h and each gram of substrate produced 11 mg of antibiotic. ATP content and energy charge of mycelia showed a positive correlation with cell activity and oxytetracycline production.
Phospholipid molecular species of Bacteroides
Authors: Wardle H.M. , Drucker D.B. , Joseph L.A.
Published: March 2008

The fatty acid composition, and types of polar lipid (PL) present, have been well‐studied in Bacteroides. Nothing is known, however, of the detailed structures of individual phospholipid and molecular species. The aim of this study was to determine molecular weights and putative identities of individual phospholipid molecular species present in Bacteroides. Thirteen culture collection strains were harvested, washed and freeze‐dried. Polar lipids were extracted and separated by conventional fast atom bombardment mass spectrometry (FAB MS). For each strain, hundreds of polar lipid peaks were seen. Nineteen major anions in the range m/z 209–299 were separated. The most intense of these was consistent with the expected presence of the C15:0 anion. Other anions were attributable to saturated, mono‐unsaturated, di‐unsaturated, tri‐unsaturated and hydroxy‐carboxylate ions. Twenty‐two major anion peaks were recorded in the range m/z 505–722. These were consistent with the presence of analogues of phosphatidic acid (PA), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG). The most intense peaks included those consistent with the presence of PE(30:0), PG(29:1), PG(30:1), PG(28:1), PE(31:0), PE(OH‐30:0), PG(31:1) and PE(OH‐31:0). This combination of PL molecular species is unique to Bacteroides and has not been reported in other organisms so far examined.
HP17, a new pigment‐like antibiotic produced by a new strain of Spirillospora
Authors: Hacène H. , Lefebvre G.
Published: March 2008

Spirillospora strain 719 produces several antibiotics. On solid and liquid media, a deep red pigment is formed and diffuses throughout the culture. It was extracted with methanol from the mycelium cake and from the fermentation broth after precipitation at pH 2 and purified using TLC and HPLC. Its u.v. absorption spectrum and its physicochemical characteristics place this antibiotic in the 3.3.2.2.8 of the Berdy et al. classification. In most respects, it resembles proteinaceous pigment from Spirillospora 1655 and 1309‐b that was studied and named spirillomycin. However, HP17 differs from spirillomycin principally in molecular weight and chemical nature.
Interaction between fish spoilage bacteria Pseudomonas sp. and Shewanella putrefaciens in fish extracts and on fish tissue
Authors: Gram L. , Melchiorsen J.
Published: March 2008

The interaction between fish spoilage bacteria, Pseudomonas sp. and Shewanella putrefaciens, was investigated using fish extract and fish tissue as model systems. Isolates of Pseudomonas that produced iron chelators, siderophores, inhibited growth of S. putrefaciens in a fish‐extract‐agar diffusion assay but no, or only weak, antagonistic activity was seen when the medium was supplemented with iron. Sterile‐filtered supernatant fluid from a siderophore‐producing Pseudomonas grown in fish extract was inhibitory to S. putrefaciens if the number of Pseudomonas was above 108 cfu ml−1. In contrast, supernatant fluids from siderophore‐negative Pseudomonas isolates did not inhibit growth of S. putrefaciens. The inhibitory effect was, except for one strain of Pseudomonas, not seen in supernatant fluids from iron‐enriched cultures of Pseudomonas sp. Finally, siderophore‐producing Pseudomonas sp. lowered the maximum cell level of S. putrefaciens 1–2 log units from 109 to 1010 cfu g−1 when the strains were grown on fish muscle blocks at 0°C but the growth rate of S. putrefaciens was not affected.
Detection of Nitrosococcus oceanus in a Mediterranean Iagoon by immunofluorescence
Authors: Zaccone R. , Caruso G. , Azzaro M.
Published: March 2008

The autotrophic ammonium‐oxidizing bacteriumNitrosococcus oceanuswas studied in the brackish lake of Ganzirri by cultural and immunofluorescent methods. The preparation of the specific antiserum in rabbits is reported. The polyclonal antiserum forNitrosococcus oceanuscross‐reacted with other ammonia oxidizing strains, but not with other marine bacteria. Temporal changes were determined by taking monthly water samples from a station 6 m deep and the distribution in sediments was investigated in four stations. Isolation of a strain ofNitrosococcussp. was obtained from a sediment sample collected in December. The abundance ofNitrosococcusspp. bacteria correlated positively with particulate organic carbon (POC), particulate organic nitrogen (PON), temperature and total bacteria, whereas there was a negative relationship with oxygen tension. No correlation was found between immunofluorescent and MPN counts ofNitrosococcusspp. bacteria.
A comparison of a new campylobacter selective medium (CAT) with membrane filtration for the isolation of thermophilic campylobacters including Campylobacter upsaliensis
Authors: Aspinall S.T. , Wareing D.R.A. , Hayward P.G. , Hutchinson D.N.
Published: March 2008

The newly developed CAT campylobacter selective medium employing the blood‐free charcoal‐based agar containing cefoperazone (8 mg I−1), amphotericin (10 mg I−1) and teicoplanin (4 mg I−1) was compared with the membrane filtration culture technique for isolation ofCampylobacterspp. includingCamp. upsaliensis.Nine hundred and fifty human, 275 dog and 65 cat faeces (in which modified CCDA medium was also compared) were tested. In addition, the recovery ofCamp. upsaliensisfrom pure cultures and from spiked human faeces was examined after membrane filtration. A 50‐fold reduction in recovery after filtration using the 0·65 μm filters and a 150‐fold reduction using the 0·45 μm filters was found. Recovery ofCamp. upsaliensisfrom spiked faeces was considerably improved using the CAT medium compared with filtration, especially with the lower concentration of organisms (approx. 104cfu ml−1).Campylobacter upsaliensiswas recovered from 91 specimens of animal faeces, with CCDA recovering 26 isolates (29%), CAT recovering 76 isolates (84%) and membrane filtration (0·65 μm) recovering 82 isolates (90%). CAT selective agar was found to be a suitable medium for the isolation of thermophilic campylobacters includingCamp. upsaliensisfrom faecal samples.
Use of two 16S DNA targeted oligonucleotides as PCR primers for the specific detection of Salmonella in foods
Authors: Lin C.K. , Tsen H.Y.
Published: March 2008

A 16S DNA targeted polymerase chain reaction (PCR) method specific for the detection of Salmonella isolates with various serotypes was developed. The primers used for such a PCR method were 16SF1 and 16SIII. 16SF1 is the reverse and complementary strand of 16SI which has been shown to be able to hybridize with Salmonella and Citrobacter spp. 16III on the other hand, is able to hybridize with Klebsiella and Serratia spp. in addition to Salmonella. Although 16SF1 and 16SIII were not specific to Salmonella only, when they were used as PCR primers, only the Salmonella isolates could be specifically detected. The interference from Citrobacter, Klebsiella and Serratia spp. could be prevented. None of the other non‐Salmonella isolates including strains of the family of Enterobacteriaceae closely related to Salmonella would generate the false‐positive reaction. When this PCR system was used for the detection of Salmonella cells artificially contaminated in food samples, results obtained were satisfactory. A detection limit of N× 100 cells per assay could be obtained.
In vitro inhibition of Helicobacter pylori by extracts of thyme
Authors: Tabak M. , Armon R. , Potasman I. , Neeman I.
Published: March 2008

Extracts of several plants were tested for inhibitory activity against Helicobacter pylori. Among these plants thyme (aqueous extract) and cinnamon (alcoholic extract) were the most effective. Since aqueous extract of thyme is easier to produce and consume, it was further investigated. Compared with several antibacterials, the thyme extract had a significant inhibitory effect on H. pylori, reducing both its growth and potent urease activity. From the results of this study, the aqueous extract of thyme possesses a therapeutic potential which merits validation by clinical studies.
Inhibitory effects of sucrose monolaurate, alone and in combination with organic acids, on Listeria monocytogenes and Staphylococcus aureus
Authors: Monk J.D. , Beuchat L.R. , Hathcox A.K.
Published: March 2008

The effects of sucrose esters of fatty acids, alone and in combination with ethylenediaminetetraacetic acid (EDTA), acetic acid, lactic acid and citric acid, on survival, growth and thermal inactivation of Listeria monocytogenes and Staphylococcus aureus were determined. The presence of sucrose monocaprate (400 μg ml−1) in tryptose phosphate broth (TPB) or tryptic soy broth (TSB) did not inhibit the growth of L. monocytogenes or Staph. aureus, respectively. However, significantly (P ≤ 0.05) lower populations of L. monocytogenes were detected in TPB containing as little as 100 μg ml−1 sucrose monolaurate (SML) during the logarithmic growth phase compared to populations detected in TPB containing no SML. At 400 μg ml−1, SML was lethal to L. monocytogenes. Less marked inhibitory effects were observed with Staph. aureus. The addition of EDTA to broth containing SML had a synergistic effect on the inhibition of both organisms. The chelator alone had no effect at 100 μg ml−1 on either pathogen but was inhibitory at 200 μg ml−1. Inhibition of L. monocytogenes was more pronounced as the incubation temperature was decreased from 30°C to 15 or 5°C. The addition of 0.1% acetic or lactic acid to TPB minimized the inhibitory effect of 100 and 200 μg ml−1 SML during the first 32 h of incubation. Staphylococcus aureus behaved similarly, but not as dramatically, to L. monocytogenes when cultured in TSB supplemented with SML alone or SML and organic acids. A synergistic inhibitory effect of SML and EDTA on heat inactivation of L. monocytogenes was evident but the reverse phenomenon was observed with Staph. aureus. The effectiveness of SML in controlling the growth of L. monocytogenes and Staph. aureus in foods most likely to be contaminated with these pathogens should be further investigated.
Purification and characterization of an extracellular cysteine proteinase produced by Micrococcus sp. INIA 528
Authors: Fernández J. , Mohedano A.F. , Polanco M.J. , Medina M. , Nuñez M.
Published: March 2008

Micrococcus sp. INIA 528, a micro‐organism isolated from raw ewe's milk Manchego cheese, produced an extracellular proteinase. This enzyme was purified to homogeneity from culture supernatant fluid in two chromatographic steps, with a 29‐fold increase of specific activity and a 28% recovery of proteinase activity. The homogeneous protein was characterized biochemically. The molecular weight of the enzyme was determined to be 19.4 kDa by mass spectrometry. The purified enzyme was inhibited by E‐64, PMSF and iodoacetamide and activated by cysteine, glutathione, dithiothreitol and β‐mercaptoethanol. These results suggest that the enzyme is a cysteine proteinase. Optimal conditions for activity on azocasein were 34°C and a pH of 7.0. The proteinase preferentially degraded β‐casein, while after a longer incubation period αs1‐casein was also extensively hydrolysed. The proteinase had a Km value of 6.12 g 1−1 for casein and 2.20 g 1−1 for azocasein.
Antimicrobial activity of lactic acid bacteria isolated from goat's milk and artisanal cheeses: characteristics of a bacteriocin produced by Lactobacillus curvatus IFPL105
Authors: Casla D. , Requena T. , Gómez R.
Published: March 2008

A total of 203 lactic acid bacteria isolated from raw goat's milk and artisanal cheese were tested for antibacterial activity. Only two strains of Lactococcus lactis, one strain of Enterococcus faecalis and one strain of Lactobacillus curvatus were shown to produce a bacteriocin‐like substance. Lactobacillus curvatus IFPL105 produced a heat‐stable bacteriocin, which was hydrolysed by α‐chymotrypsin, proteinase K and pancreatin and exhibited a broad spectrum of inhibitory activity. The bactericidal activity of the bacteriocin was more potent when sensitive strains were in the logarithmic growth phase, inducing cell lysis, as observed by decreases in optical density and release of intracellular marker enzymes. Curing experiments resulted in variants that lacked both bacteriocin activity and immunity to the bacteriocin. Plasmid profile analysis of the parental strain and the bacteriocin‐negative variants indicated that a plasmid of about 46 kbp may be involved in bacteriocin production and immunity to this antibacterial compound.
The lethal effects of biguanides on cysts and trophozoites of Acanthamoeba castellanii
Authors: Khunkitti W. , Lloyd D. , Furr J.R. , Russell A.D.
Published: March 2008

The effects of a range of biocides on trophozoite and encysted forms of Acanthamoeba castellanii were investigated. Viable acanthamoebae were enumerated by a plaque assay technique. The cyst form of Acanthamoeba castellanii was more resistant to all biocides tested than the trophozoite form. Of the biocides tested, chlorhexidine diacetate (CHA) and polyhexamethylene biguanide (PHMB) were the most effective. Their lethal effects were time‐ and concentration‐dependent. CHA was very effective when formulated in 0.1% EDTA combined with Tris buffer pH 7.8 whereas PHMB activity was reduced by 0.1% EDTA. Three per cent dimethylsulphoxide (DMSO) enhanced the activity of CHA but not of PHMB.
Isolation and characterization of moderately halophilic bacteria from fully cured salted cod (bachalao)
Authors: Vilhelmsson O. , Hafsteinsson H. , Kristjánsson J.K.
Published: March 2008

A total of 128 Strains of moderately halophilic bacteria were isolated from wet, dry and desalted bachalao (salted codfish) as well as from fresh cod and curing salt. The viable count of these bacteria in fully cured wet and dry bachalao ranged from 103 to 107 per g. All strains were characterized with 40 phenotypic tests and clustered using the SSM coefficient and UPGMA linking analysis. The strains clustered into five phena at 75% similarity, with 77 strains in phenon A and 37 in phenon E. Two main colony types, smooth and rough, were observed and correspond to phena A, B and C on one hand and phenon E on the other. These two types seem to represent the dominating bacterial flora in fully cured, wet and dry bachalao, respectively. Representative strains of the smooth colony type were characterized further and found to grow well in 0.1–4.5 mol I−1 NaCl and at 15–37°C. They have not, at present, been assigned to any known bacterial species.
Volatilization of mercury by immobilized mercury‐resistant bacterial cells
Authors: Ghosh S. , Sadhukhan P.C. , Chaudhuri J. , Ghosh D.K. , Mandal A.
Published: March 2008

Highly toxic mercury compounds may come into the environment through the use of mercury compounds as disinfectants for hospital and household purposes, Hg catalyst in industries, burning of coal and petroleum products, mercury‐based pesticides and fungicides used in agriculture, and seed dressings. Toxic effects of mercury can be counteracted by microbial cells through the enzymes mercuric reductase and organomercurial lyase. Immobilized mercury‐resistant bacterial cells of Azotobacter chroococcum could effectively volatilize mercury from mercury‐containing buffer and detoxify mercury compounds. Moreover, the efficiency of mercury volatilization was much greater than with the native cells, as immobilized cells can be reused. Immobilized cells continuously volatilized mercury from mercury‐containing buffer after four consecutive 24 h cycles. The storage stability of immobilized cells was much better than that of the native cells.
Degradation of crude oil by Acinetobacter calcoaceticus and Alcaligenes odorans
Authors: Lal B. , Khanna S.
Published: March 2008

Two types of Indian crude oil (Bombay High and Gujarat) were tested for their biodegradability by Acinetobacter calcoaceticus and Alcaligenes odorans. Acinetobacter calcoaceticus S30 and Alc. odorans P20 degraded Bombay High crude oil by 50% and 45%, while only 29% and 37% of Gujarat crude oil (heavy crude oil) was degraded by these isolates, respectively. Acinetobacter calcoaceticus and Alc. odorans in combination deraded 58% and 40% of Bombay High and Gujarat crude oils, respectively, which were significantly higher than that of by individual cultures. Acinetobacter calcoaceticus S30 degraded more of the alkanes fraction than the aromatics fraction of both crude oils. GC fingerprinting of alkane fraction showed major degradation of heptadecane (C17), octadecane (C18), nonadecane (C19), eicosane (C20), docosane (C22), tricosane (C23) and tetracosane (C24) of crude oil, while the Alc. odorans P20 degraded alkanes and aromatics equally. The asphaltenic component increased in both types of crude oil after biodegradation. The two strains grew very well on n‐alkane up to C33 as well as on pristane (branched‐chain alkane) but could not grow on cycloalkanes. Acinetobacter calcoaceticus S30 could not grow on pure polycyclic aromatic hydrocarbon (PAH) compounds except naphthalene but Alc. odorans P20 could grow on anthracene, phenanthrene, dibenzothiophene, fluorene, fluoranthene, pyrene and chrysene.
Influence of nutritional factors on the protease production by Leuconostoc oenos from wine
Authors: Farías M.E. , Rollán G.C. , de Nadra M.C. Manca
Published: March 2008

Leuconostoc oenos X2L isolated from wine secretes two proteases (I and II) into the medium. Growth and protease production were found to be dependent on the composition of the medium. Both proteases were subject to control by ammonium ions and amino acids that repressed their production and the effectiveness was higher on the enzyme II synthesized at the end of bacterial growth. The enzymes were also differently affected by the inclusion of sodium phosphate in the basal medium.
Bacterial contaminants in liquid packaging boards: assessment of potential for food spoilage
Authors: Pirttijärvi T.S.M. , Graeffe T.H. , Salkinoja‐Salonen M.S.
Published: March 2008

Liquid packaging boards and blanks were examined for microbial contaminants. A total of 218 strains were identified and representatives of the most frequent species were characterized for their potential for food spoilage. Contaminants found were aerobic spore‐forming bacteria, mostly Bacillus megaterium, B. licheniformis, B. cereus group, B. pumilus, Paenibacillus macerans, P. polymyxa, P. pabuli and B. flexus. Production of amylolytic, proteolytic, lipolytic and phospholipolytic enzymes was common. Approximately 50% of the B. cereus group strains were positive in the diarrhoeal enterotoxin immunoassay test or in the enterotoxin reversed passive latex agglutination test. Strains capable of growth at 6°C were found among B. cereus group, P. pabuli, P. validus, B. megaterium and P. polymyxa. All B. licheniformis strains grew at 55°C. The spores of B. licheniformis were most resistant to hydrogen peroxide. The B. cereus group strains were recognizable by fatty acid components not present in any of the other paperboard strains, 11‐methyldodecanoic acid (13:0 iso) and trans‐9‐hexadecenoic acid (16:1 ω 7 trans), each contributing 7% or more to the total cellular fatty acids.
A novel polymerase chain reaction assay for the detection and speciation of thermophilic Campylobacter spp.
Authors: Jackson C.J. , Fox A.J. , Jones D.M.
Published: March 2008

A novel PCR amplification method is described which is specific for the thermophilic, enteropathogenic species Campylobacter jejuni, Camp. coli and Camp. upsaliensis. Rapid, accurate speciation of amplified strains is possible on the basis of restriction fragment length polymorphisms of PCR products digested with three restriction enzymes, Alu I, Dde I and Dra I. The sensitivity of detection is 25 cfu in water, and 2 x 103 cfu in full cream milk. An epidemiological application of the assay in detecting non‐culturable campylobacters from a contaminated potable water supply is described.
Effect of calcium channel blockers on the action of various antitumour agents in the yeast Saccharomyces cerevisiae
Authors: Tiligada E. , Giannakakou P. , Karavokyros I. , Delitheos A.
Published: March 2008

The cytotoxic effects of a 22 h treatment with four antineoplastic agents in the yeast Saccharomyces cerevisiae ATCC 2366 were investigated. Two agents, doxorubicin and 5‐fluorouracil (5‐FU), were effective in decreasing the colony‐forming ability of yeast cells. Following examination under the light microscope, the effect of doxorubicin appeared to be, at least partially, due to killing of yeast cells whereas the effect of 5‐FU was rather due to changes in cell structure leading to abnormal bud formation. For amsacrine (AMSA) and melphalan, cytotoxicity was totally absent. In the presence of diltiazem the above described effects were not significantly changed. When verapamil was added in the culture medium the cytotoxic activity of doxorubicin and 5‐FU did not change. However, following treatment with AMSA in combination with verapamil, cell survival was significantly decreased whereas the presence of verapamil increased the yeast survival which was observed after melphalan treatment.
The influence of gamma radiation and substrate on mycotoxin production by Fusarium culmorum IMI 309344
Authors: O'Neill K. , Damoglou A.P. , Patterson M.F.
Published: March 2008

Mycotoxin production (deoxynivalenol (DON), acetyl deoxynivalenol (A DON) and zearalenone) by Fusarium culmorum inoculated on to maize (heat sterilized, irradiation sterilized and non‐sterile) and irradiated to 1 kGy or 3 kGy, or unirradiated, was investigated over a period of time. Lowest mycotoxin production was observed on non‐sterile maize which may be due to the presence of a competitive microflora on non‐sterile maize. In general, mycotoxin production was higher on heat‐sterilized grain as compared to irradiation‐sterilized maize. It was suggested that this pattern of mycotoxin production was possibly caused by changes in the grain brought about by autoclaving, which favoured mycotoxin production and possibly induced changes in irradiation‐sterilized maize which inhibited mycotoxin production. On sterile maize, there was no significant difference in DON production by unirradiated, 1 kGy and 3 kGy irradiated cultures up to 56 d of incubation; between days 56 and 77 of incubation, DON production increased rapidly with largest increases occurring in irradiated (1 kGy and 3 kGy) cultures. On non‐sterile grain, neither DON nor A DON were detected in unirradiated cultures of F. culmorum but were detected in cultures irradiated to 1 kGy and 3 kGy. In practice grain should be stored under conditions of temperature and moisture content which prevent fungal growth. However, in this study, the grain was stored under conditions that were approaching ideal for growth of the test organism. The results highlight that irradiation disinfestation of grain must be combined with good grain handling practices so that excessive mycotoxin production can be prevented during storage.
Incidence of antibiotic resistance and sex pheromone response among enterococci isolated from clinical human samples and from municipal waste water
Authors: Valdivia E. , Martin‐Sánchez I. , Quirantes R. , Martínez‐Bueno M. , Gálvez A. , Maqueda M.
Published: March 2008

The incidence of resistance to various antibiotics as well as the capacity to elicit aggregation response to sex pheromones have been investigated in strains of Enterococcus faecalis isolated from clinical and municipal waste waters (MWW). While clinical isolates showed a high incidence of antibiotic resistance (87%) and sex pheromone response (33%), these traits appeared with a much lower frequency in MWW isolates (12% and 4% respectively). The simultaneous incidence of both traits was of 52% and 0% for clinical and MWW isolates, respectively. The capacity to elicit a positive pheromone response as well as antibiotic resistance traits seemed to be strongly correlated with the presence of gelatinase activity among clinical isolates. Among MWW isolates, only sex pheromone response seemed to correlate with the presence of gelatinase activity.
Evaluation of technologically important traits in lactic acid bacteria isolated from spontaneous fermentations
Authors: Herrero M. , Mayo B. , González B. , Suárez J.E.
Published: March 2008

A set of 120 isolates of Lactobacillus (75), Lactococcus (25) and Leuconostoc (20), mainly isolated from natural starter‐free fermentation processes, has been screened for some technologically important traits, including lactose hydrolysis, extracellular polysaccharide production, fermentation of carbohydrates, antimicrobial agent susceptibility and bacteriocin production. Some of the strains exhibited important features for particular fermentations. Furthermore, the sensitivity resistance phenotype to antimicrobials showed genus‐specific patterns.
Immunological analysis of extracellular products and cell surface components of motile Aeromonas isolated from fish
Authors: Santos Y. , Bandín I. , Toranzo A.E.
Published: March 2008

The present work describes the characterization of antigens present in the extracellular products (ECP) and cell wall of strains of motile Aeromonas isolated from rainbow trout culture systems. The relationships among virulence for fish, O‐serogroup and profile of LPS were also examined. The slide agglutination test showed that most of the virulent strains of motile Aeromonas (72%) were included in the serotypes O3, O6, O11 and O19 (Guinée and Jansen System). However, there were also non‐pathogenic strains within these groups. Electrophoretic analysis of lipopolysaccharides (LPS) and proteins from cell envelope and ECP showed heterogeneity not only among the different serogroups but also within the same serotype. Immunoblot assays of cell envelope components, and of LPS present in the ECP demonstrated a close relationship among Aeromonas strains from the same serotype, while strains from different serotypes were not immunologically related. Moreover, this assay showed that motile Aeromonas belonging to distinct serotypes produced extracellular proteins immunologically related. On the other hand, antigenic cross reactivity was observed between the LPS obtained from cell envelope and those obtained from the ECP. The present results point out the need to include strains representative of each of the serotypes which predominates in a particular area and their ECPs in the formation of vaccines against motile Aeromonas septicaemia.