bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence, biotypes, plasmid profile and antimicrobial resistance of Campylobacter isolated from wild and domestic animals from Northeast Portugal
Authors: Cabrita J. , Rodrigues J. , Bragança F. , Morgado C. , Pires I. , Gonçalves A. Penha
Published: March 2008

The incidence of Campylobacter jejuni and Campylobacter coli in wild and producing animals has been studied to evaluate their importance as potential reservoirs of campylobacter infection. These organisms were isolated from: 59 chicken (60.2%), 65 swine (59.1%), 31 black rats (57.4%), 61 sparrows (45.5%), 21 ducks (40.5%), 32 cows (19.5%) and 27 sheep (15.3%). Biotypes, plasmid and resistance profiles were studied in order to characterize the isolates. Biotypes I and II of C. jejuni were predominant in all reservoirs except swine, where C. coli I was more frequent. Plasmid prevalence was higher in strains isolated from swine (53.8%) and rats (45.5%). The size of the plasmids ranged from 1.3 to 82 MDa. A 2.3 MDa plasmid was the most frequent, detected in all the reservoirs except ducks. Antimicrobial susceptibility testing revealed that 5.5% of the strains were resistant to ampicillin, 5.5% to tetracycline, 12.6% to erythromycin and 23.5% to streptomycin. Resistance to erythromycin (26.2%) and to streptomycin (58.4%) was particularly high in isolates from swine. Tetracycline resistance was encoded by a 33 or a 41 MDa plasmid and transferred by conjugation.
A comparison of factors affecting the production of two bacteriocins from lactic acid bacteria
Authors: Parente E. , Hill C.
Published: March 2008

The effect of tryptone, yeast extract, Tween 80 and initial pH on the production of enterocin 1146 and lactocin D, two bacteriocins produced by lactic acid bacteria, was studied in a basal buffered medium (tryptone‐yeast extract‐tween, TYT) using factorial experiments and empirical modelling. Production of enterocin 1146 was affected by pH, yeast extract and Tween 80 and to a lesser degree, by the initial pH of the medium. On the basis of the predictions of the models developed, three TYT media (TYT10, TYT11 and TYT30) were designed to maximize bacteriocin production while minimizing the amount of peptides in the medium. Growth and bacteriocin production by Enterococcus faecium DPC 1146 (enterocin 1146), Lactococcus lactis subsp. lactis biovar diacetylactis DPC 3286 (lactocin D) and Lact. lactis subsp. cremoris LMG2130 (lactococcin A) was compared in TYT media and seven other culture media (Elliker lactic broth, M17, M17 dialysate, MRS, tryptose phosphate, tryptone yeast extract broth, yeast glucose Lemco broth). Bacteriocin production in TYT media was comparable with that in M17 and MRS, which had a higher peptide content. TYT30 allowed good production of enterocin 1146 and lactocin D while TYT11 proved acceptable for all the strains tested.
Identification and characterization of helveticin V‐1829, a bacteriocin produced by Lactobacillus helveticus 1829
Authors: Vaughan Elaine E. , Daly C. , Fitzgerald G.F.
Published: March 2008

Lactobacillus helveticus 1829 produced an antimicrobial agent, designated helveticin V‐1829, that demonstrated antagonistic activity against closely‐related species. The agent was excreted into MRS agar, and was present in the supernatant fluids from both overnight broth and clotted milk cultures. It was heat labile (inactivated by 50°C for 30 min) and was stable over the pH range 2.5 to 6.5. Production of the substance was pH‐dependent and maximum yields were obtained in MRS broth cultures maintained at pH 5.5. Helveticin V‐1829 was partially purified following growth of the producing strain in a semi‐defined MRS medium and precipitating the cell‐free filtrate with ammonium sulphate to 30% saturation. The cleared supernatant fluid was then brought to 60% saturation and the resulting precipitate pelleted and dialysed in 0.3 mol/l phosphate buffer. The partially purified inhibitor was sensitive to several proteolytic enzymes, and it was bactericidal in its mode of action against indicator cells of Lact. helveticus 1844 and Lact. delbrueckii subsp. bulgaricus 1489, indicating that it was a bacteriocin. A DNA probe specific for the helveticin J structural gene failed to hybridize to total genomic DNA of Lact. helveticus 1829, indicating that helveticin V‐1829 is not significantly related to helveticin J.
Species of Pseudomonas obtained at 7°C and 30°C during aerobic storage of lamb carcasses
Authors: Prieto M. , García‐Armesto M.R. , García‐López M.L. , Alonso C. , Otero A.
Published: March 2008

A total of 268 strains of Pseudomonas isolated during storage life of lamb carcasses was identified to species level. One‐hundred and thirteen strains obtained at 30°C were Ps.fragi (51), Ps. lundensis (17), Ps. fluorescens biovars I (10), III (9) and VI (1), Ps. putida biovar A (8 strains) and unidentified (17 strains). Species and biovars isolated at 7°C (155) were Ps. fragi (101), Ps. lundensis (32), Ps. fluorescens biovar I (6), Ps. putida biovar A (8) and unidentified (8). Numerical analysis (82%SSM, UPGMA) of ‘psychrotrophic’ and ‘mesophilic’ strains resulted in the formation of nine and eight clusters respectively. The dendrograms obtained exhibited similar structures. Most of the strains of Ps. lundensis and Ps. fragi clustered together. Strains of this latter species also joined the type strain of Ps. testosteroni and appeared included with phenons containing the Ps. putida strains. There were clusters made up exclusively of strains assigned to one biovar or group (Ps. fluorescens biovars I and II and unidentified). A high level of similarity was observed between clusters of Ps. fluorescens biovar I and those containing the Ps. fragi‐Ps. lundensis complex (>74%SSM) and Ps. lundensis (>80%). The recovery of pseudomonads seemed to be affected by the sampling day.
M13 DNA fingerprinting, a new tool for classification and identification of Lactobacillus spp.
Authors: Miteva V.I. , Abadjieva A.N. , Stefanova Tz. T.
Published: March 2008

The optimal conditions for the application of M13 DNA fingerprinting to the genus Lactobacillus were determined. Comparative fingerprint analysis of representative strains of Lactobacillus delbrueckii subsp. delbrueckii, Lact. delbrueckii subsp. lactis, Lact. delbrueckii subsp. bulgaricus, Lact. helveticus and Lact. casei permitted the differentiation of species, subspecies and individual strains and the quantitative determination of their genetic relatedness. The results confirm the high specificity of M13 DNA fingerprinting and indicate that it might be used in the classification of Lactobacillus spp.
Epiphytic lactic acid bacteria succession during the pre‐ensiling and ensiling periods of alfalfa and maize
Authors: Lin Chunjian , Bolsen K.K. , Brent B.E. , Fung D.Y.C.
Published: March 2008

Epiphytic lactic acid bacteria (LAB) succession during the pre‐ensiling and ensiling periods were studied in 1989 for two cuttings of alfalfa (Medicago sativa L.), each harvested at three stages of maturity, and three whole‐plant maize (Zea mays L.) hybrids. Twenty‐three species and 306 strains were found. Epiphytic LAB counts were low and variable on the standing crops, particularly on alfalfa. Wilting increased LAB numbers slightly for alfalfa, but the chopping process increased the counts dramatically. Population shifts in LAB also took place during the pre‐ensiling period. Lactobacillus plantarum, Pediococcus pentosaceus, Enterococcus faecium, and Ent. faecalis were predominant on both standing crops. Lactobacillus brevis dominated alfalfa at the second cutting, 10% bloom, but Lact. viridescens was predominant after chopping. The changes in LAB caused by wilting or chopping were reflected mainly in proportional changes of Lact. plantarum, Ped. pentosaceus, Ent. faecium and Ent. faecalis. Once the crops were ensiled, total LAB counts increased rapidly, reached a maximum within 1 d, and then declined after 7 d of fermentation. Enterococcus species decreased sharply or disappeared entirely after the early stages of the ensiling period, and the species most involved in microbial succession through day 7 were Lact. plantarum and Ped. pentosaceus. After 7 d, more species, e.g. Lact. homohiochii, Lact. brevis and Lact. gasseri, joined the succession and became prevalent, depending on the crop. Only two of the six alfalfa silages were well preserved, whereas all three maize hybrids underwent typical fermentations for this crop. No relationship was found between adequacy of silage fermentation and epiphytic LAB numbers or species on the pre‐ensiled crops. Neither were pH changes during the fermentation explained by the epiphytic LAB count or population succession. Rather, the well fermented alfalfa silages were those ensiled at a high dry matter (DM) content (> 360 g/kg) and low buffering capacity (<450 meq/kg of DM). Only a few of the LAB strains were shown to be the same among the crops, thus indicating the specificity of LAB strains to an ecological niche.
Inhibition of Shigella sonnei by Lactobacillus casei and Lact. acidophilus
Authors: de Macías María E. Nader , Apella María C. , Romero Nora C. , González Silvia N. , Oliver G.
Published: March 2008

The protective effect of feeding milk fermented with a mixture of Lactobacillus casei and Lact. acidophilus against Shigella sonnei was studied. There was a 100% survival rate in mice fed for 8 d with fermented milk and then dosed orally with Sh. sonnei. The survival rate in control mice was approximately 60% after 21 d. Colonization of the liver and spleen with Sh. sonnei was markedly inhibited by pretreatment with fermented milk. Differences in cell counts of 2–3 log units between treated and control mice were always obtained, shigellas were not detected in these organs by the 10th day in treated mice, while high levels were maintained in the controls. Higher levels of anti‐shigella antibodies were found both in sera and in small intestinal fluid of mice treated with fermented milk, suggesting that the protective immunity could be mediated by the mucosal tissue. These results suggest that milk fermented with Lact. casei and Lact. acidophilus could be used as a prophylactic against gastrointestinal infections by shigellas.
In vitro studies on the inhibition of the growth of Shigella sonnei by Lactobacillus casei and Lact. acidophilus
Authors: Apella Marìa C. , González Silvia N. , de Macìas Marìa E. Nader , Romero Nora , Oliver G.
Published: March 2008

The inhibitory effect of lactobacilli on growth of Shigella sonnei was studied. The effect was not due to pH alone, as addition of hydrochloric, lactic or acetic acids to culture media did not inhibit the normal growth of the shigellas. The degree of inhibition was measured by disc assay and showed that the inhibitory substance(s) can be extracellular and diffusible, varying the degrees of inhibition depending on the media tested.

When broth was inoculated with mixed cultures of Lactobacillus and Shigella strains, the inhibition began at 6 h and the death phase at 9 h. The higher inhibition was produced by the mixture of lactobacilli (35.5 ± 2.5% at 6 h culture, 57.4 ± 1.9% at 9 h and 91.2 ± 1.2% at 14 h). The degree of inhibition was higher when the relationship pathogen: lactobacilli was 1: 103. The specific growth rate of lactobacilli and shigella was different in pure or mixed cultures. When the lactobacillus alone was grown for 12 h and the shigellas then added, the numbers of shigellas began to decrease immediately at 37°C. This work shows that the Lactobacillus strains employed in fermented milk can be used to inhibit the growth of Sh. sonnei.
General properties of extracellular bacterial inulinase
Authors: Elyachioui M. , Hornez J.P. , Tailliez R.
Published: March 2008

The extracellular inulinase system of a strain of Arthrobacter sp. consists of a β‐fructofuranosidase active on inulin raffinose and sucrose with a relative rate inulin/sucrose (I/S) of 0.2.

Crude enzyme preparations were obtained by fractionation of the liquid culture at stationary phase of growth with ammonium sulphate. Purification was carried out by DEAE cellulose chromatography and ultrogel ACA 34. Only one protein band was observed by electrophoresis. The enzyme was stable at high temperatures and was active at neutral or slightly alkali pH. Fructose is liberated as the sole reaction product of inulin hydrolysis, suggesting that the enzyme was an exoinulinase. The Michaelis constant (calculated at 40°C and pH 6) was 0.25 × 10‐2 mol/l for the inulin and 0.12 × 10‐2 mol/l for sucrose.

The enzyme was suitable for fructose production from root extracts of plants rich in polyfructosans or sucrose.
Extracellular isoamylase produced by Bacillus circulans MIR‐137
Authors: Castro G.R. , Garcia G.F. , Siñeriz F.
Published: March 2008

A strain designated MIR‐137 was selected after a screening programme for amylolytic enzymes and was characterized as Bacillus circulans. Batch cultures showed the highest amylolytic activities in the stationary phase. Extracellular isoamylase activity exhibited an optical temperature of 60°C at pH 5.0. These properties would allow its use in normal saccharification processes in the starch industries.
Interactive effects of solutes, potassium sorbate and incubation temperature on growth, heat resistance and tolerance to freezing of Zygosaccharomyces rouxii
Authors: Golden D.A. , Beuchat L.R.
Published: March 2008

The interactive effects of solutes, potassium sorbate and incubation temperature on growth, heat resistance and tolerance to freezing of Zygosaccharomyces rouxii were investigated. Growth rates in media supplemented with glucose, sucrose or NaCl to aw 0.93 were more rapid than in unsupplemented media (aw 0.99). Although growth in unsupplemented medium was lower at 35°C, incubation at 21°C or 35°C had little effect on growth in media supplemented with glucose and sucrose. The addition of 300 μg potassium sorbate/ml to media resulted in reduced growth rates, particularly at 35°C. Heat resistance of Z. rouxii was substantially greater in cultures previously incubated at 35°C than in cultures incubated at 21° in media both with and without 300 μg potassium sorbate/ml. Zygosaccharomyces rouxii was tolerant to freezing at ‐ 18°C for up to 120 d in all test media supplemented with glucose, sucrose or NaCl. The addition of 300 μg potassium sorbate/ml to sucrose‐supplemented media resulted in increased resistance to freezing in cultures previously incubated at 21°C. Sensitivity to freezing increased when cultures were incubated at 21°C in media not supplemented with solutes. Glucose and sucrose provided the best protection against inactivation by heating and freezing, regardless of the presence of potassium sorbate in growth media.
The effect of applying lactic acid bacteria at ensiling on the aerobic stability of silages
Authors: Weinberg Z.G. , Ashbell G. , Hen Yaira , Azrieli A.
Published: March 2008

The effect of applying commercial lactic acid bacteria inoculants at ensiling on the aerobic stability of silages was studied under laboratory conditions. The silages used were wheat, hedysarum, corn and various sorghum cultivars at various stages of maturity. Three inoculants were used, two containing Lactobacillus plantarum, Enterococcus faecium and Pediococcus acidilactici (H/M F, Medipharm, USA and Sil‐All, Alltech, UK) and one containing Ent. faecium (Lacticil, M74, Medipharm, Sweden). The inoculants were applied at 0.5 times 106 cfu g‐1. Silages with no additives served as controls. After treatment, the chopped forages were ensiled in 1.5 1 anaerobic jars; there were six jars per treatment. After ensiling for 45 d, the silages were tested for aerobic stability in a test in which CO2 production was measured along with chemical and microbiological parameters.

The inoculated silages that spoiled upon aerobic exposure faster than the controls were those of wheat and of the sorghum cultivar FS5 at the milk stage of maturity. This was evident from intensive CO2 production and development of yeasts and moulds. Regression analysis indicated that aerobic deterioration of inoculated silages was associated with high levels of residual water‐soluble carbohydrates and lactic acid and lack of volatile fatty acids. Aerobic spoilage of inoculated silages was attributed mainly to yeast activity.
The influence of pH and growth rate on production of the bacteriocin, bavaricin MN, in batch and continuous fermentations
Authors: Kaiser A.L. , Montville T.J.
Published: March 2008

Bavaricin MN, a bacteriocin produced by Lactobacillus bavaricus MN, reached titres of 2000 AU ml‐1 in APT broth maintained at pH 6.0, 30°C in a batch fermenter. Levels of bavaricin MN at pH 5.5 and 6.5 were lower despite comparable levels of producer cells. The addition of 3.0 g l‐1 beef extract to APT broth resulted in increases in both the growth rate of the culture and the production of bavaracin MN. The titre of bavaricin MN in batch fermenters controlled at pH 6.0 in APT broth plus 3 g l‐1 beef extract reached 3200 AU ml‐1 at 30°C. This level was reduced to 800 AU ml‐1 by 76 h. Glucose‐limited continuous culture of Lact. bavaricus MN under the same conditions resulted in an increase in the titre of bavaricin MN to 6400 AU ml‐1. This level was maintained, independent of growth rate, for 345 h. Growth rates of 0.205, 0.118, 0.169 and 0.058 h‐1 were examined.
Comparison of conductimetric and traditional plating techniques for detecting yeasts in fruit juices
Authors: Deak T. , Beuchat L. R.
Published: March 2008

Frozen fruit juice concentrates containing an average microbial population of log10 1.54 cfu ml‐1 were examined by traditional plating techniques and direct and indirect conductimetry. The initial populations in diluted (1:4) concentrates increased to an average of log10 3.82 cfu ml‐1 during incubation at 25°C for 24 h. Incubation before plating and subjecting to conductimetric tests also facilitated the resuscitation of cells that may have been freeze‐injured. Yeasts were recovered in equal numbers on acidified (pH 3.5) potato dextrose agar and dichloran rose bengal chloramphenicol agar (pH 5.6). Yeasts and bacteria were recovered on orange serum agar. Detection times determined by indirect conductimetry correlated fairly well (r= ‐0.73) with populations (cfu ml‐1) detected on traditional plating media. Populations in diluted concentrates which were not incubated before examination were detected conductimetrically in an average of 48.9 h, whereas detection times for diluted concentrates incubated for 24 h at 25°C before testing were reduced to an average of 14.1 h. Examination by conventional (direct) conductimetry required an additional 10–20 h to reach changes in conductance of 5 μS h‐1.
A chemotaxonomic study of some moderately halophilic Gram‐positive isolates
Authors: Márquez M.C. , Quesada E. , Bejar V. , Ventosa A.
Published: March 2008

A chemotaxonomic study was carried out on some moderately halophilic Gram‐positive motile cocci, previously isolated from the Salar de Atacama (Chile) and grouped in two phenons (A and B) by numerical taxonomic analysis. Strains included in phenon A had a DNA base composition ranging between 42.0 and 44.0 mol%, while that of phenon B ranged from 48.0 to 48.8 mol%. The results of DNA‐DNA hybridization studies on representative strains from phenons A and B, indicated that the strains assigned to phenon A comprise a genomically homogeneous group, with a high degree of homology (80%) to the type strain of Marinococcus albus. Similarly, phenon B constituted a homogeneous group and the representative strain studied showed a DNA‐DNA homology of 70% with the type strain of Marinococcus halophilus. Representative strains studied from each phenon had meso‐diaminopimelic acid in the cell wall and menaquinone systems with seven isoprene units (MK‐7) as a major component. All these results, together with those previously reported, indicate that strains included in phenons A and B constitute additional strains of the species Marinococcus albus and Marinococcus halophilus, respectively.
A note on the primary structure and expression of an Erwinia carotovora polygalacturonase‐encoding gene (peh1) in Escherichia coli and Saccharomyces cerevisiae
Authors: Laing Elizna , Pretorius I.S.
Published: March 2008

A 1209‐base pair (bp) DNA fragment containing the endopolygalacturonase‐encoding gene (peh1) from Erwinia carotovora subsp. carotovora was amplified by the polymerase chain reaction (PCR) technique and expressed in Escherichia coli. The nucleotide sequence of the PCR product was determined and found to be highly homologous to the primary structures of other polygalacturonase‐encoding genes. The peh1 DNA fragment encoding the mature polygalacturonase was inserted between two different yeast expression‐secretion cassettes and a yeast gene terminator, generating recombinant yeast‐integrating shuttle plasmids pAMS10 and pAMS11. These YIp5‐derived plasmids were transformed and stably integrated into the genome of a laboratory strain of Saccharomyces cerevisiae. Transcription initiation signals present in these expression‐secretion cassettes were derived from the yeast alcohol dehydrogenase (ADC1P) or mating pheromone α‐factor (MFα1P) gene promoters. The transcription termination signals were derived from the yeast tryptophan synthase gene terminator (TRP5T). Secretion of polygalacturonase was directed by the signal sequence of the yeast mating pheromone α‐factor (MFα1s). Northern blot analysis revealed the presence of peh1 mRNA in the yeast transformants and a polypectate agarose test was used to monitor polygalacturonase production.
Inability of Lactobacillus plantarum and other lactic acid bacteria to grow on D‐ribose as sole source of fermentable carbohydrate
Authors: Westby A. , Nuraida L. , Owens J.D. , Gibbs P.A.
Published: March 2008

Lactobacillusplantarum NCIMB 8026, NCIMB 8026(s), NCIMB 8014, NCFB 1752, Lact. brevis NCIMB 4617, Leuconostoc mesenteroides NCIMB 8023, Streptococcus agalactiae NCFB 1348, Pediococcus acidilactici NCFB 1859 and Ped. pentosaceus NCFB 990 did not grow on D‐ribose as the sole source of fermentable carbohydrate in a chemically defined medium but grew on D‐ribose in the presence of glucose. Lactobacillus plantarum NCIMB 8026(s) also grew on D‐xylose and L‐arabinose in the presence but not in the absence of glucose. Enterococcus faecalis NCFB 581 grew with D‐ribose as the sole fermentable carbohydrate. Leuconostoc mesenteroides NCIMB 8710 and Lactococcus lactis subsp. lactis NCFB 763 did not use ribose in the presence or absence of glucose. Lactobacillus plantarum NCIMB 8026(s) utilized ribose and glucose simultaneously in the proportion of approximately 1 ribose to 1 glucose, producing approximately 3 lactate to 1 acetate and similar yields of dry biomass from glucose and ribose. Growth of Lact. plantarum 8026(s) with glucose and excess D‐ribose ceased when D‐glucose was exhausted, but metabolism of D‐ribose to lactic and acetic acids continued. The enzyme system for the metabolism of D‐ribose in Lact. plantarum was inducible, requiring D‐glucose and amino acids for adaptation.
Isolation and characterization of carboxylesterase E3 from Salmonella enteriea
Authors: Brisabois Anne , Goullet P.
Published: March 2008

Three esterases (Est‐) hydrolysing α‐naphthyl acetate: Est‐E1, Est‐E3 and Est‐E4 produced by Salmonella enterica serovar Typhimurium, strain LT2 were separated by DEAE chromatography and gel filtration. Est‐E3, the major component of this set of enzymes, clearly differed from the two other esterases by its apparent molecular weight, titration curve, substrate specificity and inactivation. Immunoglobulins raised against Est‐E3 completely neutralized the activity of Est‐E3 but did not react with Est‐E1 or Est‐E4; it showed no cross reaction with carboxylesterase B of Escherichia coli or with carboxylesterases from other enterobacteria. Est‐E3 showed electrophoretic variants which were biochemically and immunologically detected in the seven subspecies of the genus Salmonella. These findings suggest that variants of Est‐E3 are the products of very closely related loci originating from a common ancestral gene. The esterase could be a phylogenetic marker of the genus and a suitable molecular tool for taxonomy and epidemiology.
Antimicrobial effect of chlorine on Yersinia enterocolitica
Authors: Paz Marta L. , Düaigues Maria V. Gallego , Hanashiro Alba , D'Aquino M. , Santini Pilar
Published: March 2008

The effects of chlorine at varying pH, culture media and incubation temperatures on one type and two wild type strains of Yersinia enterocolitica were studied. Exposure to 1 and 5 mg 1‐1 did not diminish viability, even after prolonged exposure. A level of 10 mg 1‐1 was required to achieve a 5‐log reduction in 120 s for the type strain and 80 s for the wild strains. There was an increase of more than 30% in the rate of disinfection with a 10°C rise, a remarkable increase in antimicrobial activity at pH 5‐log reduction in 20 s, as well as marked neutralization of the effect in the presence of 0.1% peptone. Younger cells were more susceptible than older ones, and those from liquid medium more resistant than those from solid medium. Incubation temperature of a 24‐h inoculum failed to show any influence. Lastly, there was a noteworthy demand for free chlorine by bacterial biomass, with agreement of the curve depicting the drop in free chlorine in the presence of inoculum with biphasic kinetics of survival curves.
Polymerase chain reaction for the rapid identification of Clostridium botulinum type A strains and detection in food samples
Authors: Fach P. , Hauser D. , Guillou J.P. , Popoff M.R.
Published: March 2008

A polymerase chain reaction (PCR) was developed for the detection of Clostridium botulinum type A, a cause of human botulism. A two primer set and an oligonucleotide detection probe were used to specifically detect Cl. botulinum type A neurotoxin gene (BoNT/A). After 40 cycles of amplification, detection of a 798 bp amplified DNA fragment was carried out by agarose gel electrophoresis and Southern blot hybridization. This assay was able to detect 12.5 fg of purified target DNA or five bacteria per reaction. The sensitivity in artificially contaminated food samples after an 18 h enrichment step ranges from 10 to 103 bacteria per g according to the type of food samples. No cross‐reactions were observed with the other Cl. botulinum toxinotypes and other bacteria found routinely in food. This PCR method may provide a suitable and rapid alternative to standard techniques for detection of Cl. botulinum type A in food samples.
Biological specificity of bottled natural mineral waters: characterization by ribosomal ribonucleic acid gene restriction patterns
Authors: Guillot Emmanuelle , Leclerc H.
Published: March 2008

The organisms from heterotrophic plate counts of four brands of bottled non‐carbonated mineral waters were analysed by ribosomal ribonucleic acid gene restriction patterns in addition to identification by customary techniques. Five commercialized bottles of each brand were examined once in the year 1989–90. The total bacterial flora was divided into two main groups: the pseudomonads and the unidentified strains. Whereas phenotypic results did not reveal any significant differences between the four brands, rRNA gene restriction patterns were discriminatory. Among the 73 strains studied, 45 distinct patterns were observed, with only three common to several springs. These results reveal, at one determined time, a remarkable biological specificity of each brand of water.
Kidney bean lectin‐induced Escherichia coli overgrowth in the small intestine is blocked by GNA, a mannose‐specific lectin
Authors: Pusztai A. , Grant G. , Spencer R.J. , Duguid Tracey J. , Brown D.S. , Ewen S.W.B. , Peumans W.J. , Van Damme Els J.M. , Bardocz Susan
Published: March 2008

The reversible and dose‐dependent hyperplastic growth of the small intestine and accelerated epithelial cell turnover caused by feeding rats with diets containing kidney bean lectin (PHA) increased the proportion of immature cells on the villi whose membrane and/or cytoplasm contained mainly simple, polymannosylated glycans. These new α‐linked mannosyl terminals, particularly of the damaged epithelium, facilitated the preferential adherence of opportunistic Escherichia coli with mannose‐sensitive Type 1 fimbriae, and other coliforms, to the glycocalyx. Accordingly, the growth of the gut was accompanied by a reversible and PHA dose‐dependent overgrowth with E.coli. As expected from their common carbohydrate specificity, the inclusion in the diet of the mannose‐specific agglutinin from snowdrop (Galanthus nivalis) bulbs (GNA) significantly reduced the extent of E.coli overgrowth, but abolished neither the growth nor the damage caused by PHA to the small intestine. Thus, GNA and perhaps other mannose‐specific lectins, especially when used in a preventive mode, can be used to specifically block the proliferation of Type 1 E.coli in the small intestine.
Effects of salinity on bacterioplankton: field and microcosm experiments
Authors: Bordalo A. A.
Published: March 2008

Bacterial populations in a tidal estuary were monitored with the aim of investigating (i) the relationship between planktonic bacteria and salinity and (ii) the survival of allochthonous bacteria in microcosm experiments at different salinities. With the increase in salinity, bacterial numbers decreased in a curvilinear fashion, rather than monotonically. Maximal abundance for different bacterial groups was found between 7 and 22%0 S. The salinity alone explained between 19 and 58% of bacterial variability. In microcosm experiments the adverse effect of salinity on the survival of freshwater bacteria and indicators of faecal contamination was particularly important. In freshwater and low salinity experiments grazing by protozoans had similar effects on the survival of allochthonous bacteria.
Characterization of Salmonella virchow phage types by plasmid profile and IS200 distribution
Authors: Torre E. , Threlfall E.J. , Hampton M.D. , Ward L.R. , Glbert I. , Rowe B.
Published: March 2008

The type strains of the 57 phage types of Salmonella virchow have been characterized by plasmid profile and by distribution of the insertion sequence IS200. Thirty‐two strains carried plasmids and 21 profile types were identified; 17 strains were resistant to antimicrobial agents. In contrast only six of the type strains carried IS200 elements and three patterns were identified. Within Salm. virchow phage type 31, five of 10 wild‐type isolates carried plasmids and two plasmid profiles were identified; in contrast, an IS200 element was identified in the genome of only one of these strains. It is concluded that for Salm. virchow, IS200 is unlikely to significantly extend the degree of discrimination achieved by phage typing which may be supplemented when appropriate by plasmid profile typing.
Characteristics of a plant deleterious rhizosphere pseudomonad and its inhibitory metabolite(s)
Authors: Åström Boel , Gustafsson Annika , Gerhardson B.
Published: March 2008

A cell‐free culture filtrate of the plant growth inhibitory bacterial isolate Å313, identified as Pseudomonas fluorescens, was tested for its effect on wheat root elongation in vitro, with and without various pretreatments. The filtrate showed a strongly inhibitory effect on root elongation and could be heated to 100°C for 5 min or incubated at a pH within the range of 4–10 without losing its activity. Unlike other root growth‐inhibitory bacterial metabolites the effect of the filtrate was not reversed by methionine, nor was any inhibitory activity present in the water phase after extraction with chloroform. The inhibitory agent(s) was formed when the bacterium was grown in an artificial medium as well as in root exudates from wheat. Two wheat cultivars differing in reaction to inoculation with living cells of Å313 showed the expected difference in growth reduction when exposed to culture filtrate, indicating a cultivar difference in sensitivity to the metabolite(s) formed by the bacterium. Isolate Å313 invaded intercellular spaces of the root cortex of gnotobiotically grown wheat plants, but did not produce pectolytic enzymes in vitro, nor induce a hypersensitive response in tobacco plants.
Rapid DNA extraction protocol from soil for polymerase chain reaction‐mediated amplification
Authors: Smalla K. , Cresswell N. , Mendonca‐Hagler L.C. , Wolters A. , Elsas J.D. van
Published: March 2008

A simple and rapid method of DNA extraction from soil was developed and DNA was made suitable for subsequent efficient amplification by the polymerase chain reaction (PCR). Key features of the extraction and purification were cold lysozyme‐ and SDS‐assisted lysis with either freezing‐thawing or bead beating, cold phenol extraction of the resulting soil suspension, CsCl and KAc precipitation and, finally, spermine‐HCl or glass milk purification of DNA. Crude DNA preparations contained 4–20 μg DNA per g of soil extracted, and at least 50% of this was recovered in the final purified DNA preparations. The resulting DNA was pure enough to be restricted by various enzymes, and was amplifiable at concentrations of up to 20 ng of soil‐derived DNA per 50 μl reaction mix.

Amplification of a 683 bp target sequence, pat, was performed with different Taq DNA polymerases. Application of the protocol enabled us to detect target DNA derived from roughly 103 introduced Pseudomonas fluorescens (RP4 :: pat) cfu per g of soil. The fate of an introduced population in the soil could be followed to this limit with PCR‐assisted detection of target DNA. In addition, target DNA was detected in soil 5 months after release, when the introduced organism was no longer detectable on selective agar plates.

The extraction and purification protocol applied to various different soil types resulted in DNA of sufficient purity to permit amplification by PCR.
The effect of slurry storage and anaerobic digestion on survival of pathogenic bacteria
Authors: Kearney Theresa E. , Larkin M.J. , Levett P.N.
Published: March 2008

The decline in viable numbers of Salmonella typhimurium, Yersinia enterocolitica and Listeria monocytogenes in beef cattle slurry is temperature‐dependent; they decline more rapidly at 17°C than at 4°C. Mesophilic anaerobic digestion caused an initial rapid decline in the viable numbers of Escherichia coli, Salm. typhimurium, Y. enterocolitica and L. monocytogenes. This was followed by a period in which the viable numbers were not reduced by 90%. The T90 values of E. coli, Salm. typhimurium and Y. enterocolitica ranged from 0.7 to 0.9 d during batch digestion and 1.1 to 2.5 d during semi‐continuous digestion. Listeria monocytogenes had a significantly higher mean T90 value during semi‐continuous digestion (35.7 d) than batch digestion (12.3 d). Anaerobic digestion had little effect in reducing the viable numbers of Campylobacter jejuni.
Influence of growth temperature on the production of extracellular virulence factors and pathogenicity of environmental and human strains of Aeromonas hydrophila
Authors: Mateos Diana , Anguita J. , Naharro G. , Paniagua Carmen
Published: March 2008

The biochemical properties, virulence for mice and trout, and the extracellular virulence factors at 28° and 37°C of 11 environmental and nine human strains of Aeromonas hydrophila were compared. All the environmental isolates and four of the human group were virulent for trout at 3 x 107 cfu, but only human strains were able to cause death or lesions in mice by the intramuscular route. Extracellular virulence factors such as haemolysins, cytotoxins and proteases were also investigated in supernatant fluids of cultures grown at 28°C and 37°C. The production of haemolysins, caseinases, elastases and growth yields of environmental strains decreased sharply during cultivation at 37°C but cytotoxins were produced to the same extent, or slightly less, than at 28°C. The human strains differed from the environmental strains in response to growth temperatures: protease activity decreased at 37°C, although growth yield was not affected, but more haemolysins and cytotoxins were produced by the virulent strains at this temperature than at 28°C. Sodium caseinate SDS‐PAGE of culture supernatant fluids of selected human strains revealed that temperature selectively inhibited the production of certain proteases.
Production and characterization of antibacterial compounds produced by Pediococcus damnosus and Pediococcus pentosaceus
Authors: Skyttä Eija , Haikara Auli , Mattila‐Sandholm Tiina
Published: March 2008

The broad‐spectrum antibacterial activity exhibited by three Pediococcus strains isolated from beer was preliminarily characterized. Factors affecting the production rate of bacterial inhibitors were screened and the effects of simultaneous cultivation of Lactococcus and Pediococcus on the production of inhibitory substances were studied. The antibacterial activity against a range of Gram‐negative test organisms was not affected by catalase or proteolytic enzymes and was extremely thermotolerant. Production of the inhibitors was maximal between pH 6 and pH 7. A growth medium containing unhopped end‐fermented wort was beneficial for the production of inhibitors, particularly by the Pediococcus damnosus strain, and anaerobic growth conditions were preferable. The antagonistic activity against the Gram‐negative test organism Salmonella infantis could be demonstrated after an incubation period of only 2 d if the Pediococcus and Lactococcus strains were incubated simultaneously as a mixed population.
Detection of Aeromonas hydrophila in food with an enzyme‐linked immunosorbent assay
Authors: Merino Susana , Camprubì Silvia , Tomás J.M.
Published: March 2008

A microtitration plate, antibody capture, enzyme‐linked immunosorbent assay was developed for the detection of Aeromonas hydrophila serotype O : 11 (highly virulent strains). The assay utilizes a detector antibody which shows no cross‐reactions with Aeromonas strains other than serotype O : 11 or non‐Aeromonas competing organisms. The detector antibody is mixed with the sample and incubated for 1 h, microcentrifuged and the supernatant fluid (unadsorbed antibody) titred in a microtitre plate coated with A. hydrophila cells from serotype O : 11. All the A. hydrophila strains from serotype O : 11 tested reacted strongly with the detector antibody. Also by culturing and performing the immunoassay with the detector antibody we established and quantified the presence of A. hydrophila O : 11 in different foods.
Methods for the detection of thermotolerant campylobacters in foods: results of an inter‐laboratory study
Authors: Scotter Susan L. , Humphrey T.J. , Henley Alison
Published: March 2008

An inter‐laboratory comparison of three methods for the detection of thermotolerant campylobacters is described. One of two proposed by the International Standards Organisation was significantly better for detecting campylobacters in minced chicken skin naturally contaminated at levels of either 2 or 10 cells per 10 g, but involved extensive manipulations not likely to be well received in a busy laboratory. This method yielded 18% false negative results compared with 48–54% for the other two but also gave 8% false positive results. Pre‐enrichment of samples with a gradual addition of antibiotics to suppress competing organisms seemed to improve the recovery of campylobacters, as did a non‐selective blood agar isolation medium used in combination with a membrane filtration technique.
Determination of the collection efficiency of a microbial air sampler
Authors: Benbough J.E. , Bennett A.M. , Parks S.R.
Published: March 2008

The Biotest RCS Plus air sampler was compared with the well‐established Casella slit sampler for the quantitative analysis of the microbiological content of air. The results of the tests reported here show that the RCS Plus sampling efficiency is similar to that of the Casella sampler over the range of particles likely to be encountered in the environment. For particles less than 4 μm down to the sub‐micronic sizes the efficiency of sampling falls off only gradually so that the efficiency of sampling for 1·0 μm particles is only reduced to about 50%. The ability to pre‐select 10 different volumes (from 1 to 1000 1) enables the samplers to be used for measuring a wide range of concentrations of airborne micro‐organisms in a variety of locations.
Phenotypic identification of non‐clinical isolates of Acinetobacter species
Authors: Soddell J.A. , Beacham A.M. , Seviour R.J.
Published: March 2008

Five different phenotypic identification systems were used in attempts to place 164 Acinetobacter strains obtained from a biological nutrient removal plant and 16 reference cultures into the genospecies of Bouvet and Grimont, and Tjernberg and Ursing. Of these strains only four, including two of the reference strains, were identified at a Willcox probability level of >0·95 and a modal likelihood fraction of > 0·0001 by all five systems. These different identification schemes were compared for their usefulness with such non‐clinical isolates.
The colonization of solid PVC surfaces and the acquisition of resistance to germicides by water micro‐organisms
Authors: Vess R.W. , Anderson R.L. , Carr J.H. , Bond W.W. , Favero M.S.
Published: March 2008

Six common water bacteria were examined for their ability to colonize polyvinyl chloride (PVC) surfaces, survive various germicidal treatment, and re‐establish themselves in sterile distilled water (SDW). For each test, two 30·4 cm PVC pipes attached to a 90° PVC elbow were filled with 600 ml of distilled water inoculated with either Pseudomonas aeruginosa, Ps. cepacia, Ps. mesophilica, Acinetobacter anitratus, Mycobacterium chelonae or M. chelonae var. abscessus. After 8 weeks contaminated water was removed and the pipes were exposed to 600 ml of 1 : 213 iodophor disinfectant (ID), 1 : 128 phenolic detergent (P), 1 : 256 quaternary ammonium compound (QA), stock iodophor antiseptic (IA), 2% formaldehyde (F), 10–15 ppm free chlorine (C), 2% glutaraldehyde (G) and 70% ethanol (E). These germicides were periodically sampled, neutralized and examined for surviving organisms. After exposure for 7 d the germicides were removed and each pipe was refilled with SDW. This was assayed at 7 d intervals to determine microbial re‐establishment. Samples were removed during microbial conditioning and examined by scanning electron microscopy (SEM). Pseudomonads were isolated directly from ID, QA, C, P and F, and mycobacteria from QA, IA, ID, P, G, C and F. Pseudomonas aeruginosa and Ps. cepacia survived in PVC pipes after 7 d of exposure to P, ID and C; Ps. mesophilica, after C and ID; and both mycobacteria, after C. SEM examination of PVC remnants revealed bacterial attachment and formation of extracellular material with embedded cells. These studies show that common water bacteria can attach and colonize the interior surface of PVC pipes and develop significant resistance to the action of certain germicides. Specific disinfection strategies are needed to control microbial populations that form in water distribution systems.
Separation of bacteria using agglutinins isolated from invertebrates
Authors: Payne M.J. , Campbell Shona , Kroll R.G.
Published: March 2008

The agglutination of a selection of Gram‐positive and Gram‐negative bacteria by the haemolymph and coelomic fluid from several invertebrates was studied. The haemolymph from Lumbricus terrestris and Limulus polyphemus caused the strongest agglutination of most of the bacteria studied. When the agglutinating fraction of Lim. Polyphemus was liganded to magnetic microspheres 53% of the cells in pure cultures of Listeria monocytogenes C200, 15% of Salmonella enteritidis 37782, 92% of Staphylococcus aureus NCDO 949, 19% of Escherichia coli E4936/76 and 65% of E. coli W2–2 were adsorbed to the beads. The immobilized haemolymph from Lumb. terrestris adsorbed 42% of Salm. enteritidis 37782, 64% of E. coli 4936/76 and 27% of Staph. aureus NCDO 1499 cells and the coelomic fluid from Haemopsis sanguisuga adsorbed 42, 48 and 50% of these cultures respectively. With immobilized Haem. sanguisuga agglutinins, 21–27% of Staph. aureus NCDO 2044 cells were recovered from full‐fat pasteurized milk and 20–51% from braising steak. Immobilized Lim. polyphemus agglutinins recovered 17–34% of Staph. aureus cells from raw egg. The potential of agglutinins isolated from invertebrates for enhancing rapid microbiological assays of foods is discussed.
Adhesion of Lactobacillus acidophilus to avian intestinal epithelial cells mediated by the crystalline bacterial cell surface layer (S‐layer)
Authors: Schneitz C. , Nuotio L. , Lounatma K.
Published: March 2008

Lactobacillus acidophilus was isolated from washed and homogenized walls of the crop and caecum of an adult fowl. A strain that adhered well in the Fuller adhesion test was subcultured until colonies on Lactobacillus Selective agar changed from rough to smooth. This coincided with a change from aggregate to planktonic growth in liquid medium and a marked loss of ability to adhere. The ultrastructure of cells from both types of culture was studied by electron microscopy. An S‐layer formed the outermost part of the cell wall in the strongly‐adherent strain, whereas this layer was covered with polymerized material or was absent in strains that lacked the ability to adhere, or those with reduced adherence.
Routine monitoring of Cryptosporidium oocysts in water using flow cytometry
Authors: Vesey G. , Slade J.S. , Byrne M. , Shepherd K. , Dennis P.J. , Fricker C.R.
Published: March 2008

A flow cytometric method for the routine analysis of environmental water samples for the presence of Cryptosporidium oocysts has been developed. It uses a Coulter Epics Elite flow cytometer to examine water samples and to separate oocysts from contaminating debris by cell sorting. The sorted particles are then rapidly screened by microscopy. The method has been evaluated and compared with direct epifluorescence microscopy on 325 river, reservoir and drinking water samples. The technique was found to be more sensitive, faster and easier to perform than conventional epifluorescent microscopy for the routine examination of water samples for Cryptosporidium.
Mesenterocin 52, a bacteriocin produced by Leuconostoc mesenteroides ssp. mesenteroides FR 52
Authors: Mathieu F. , Suwandhi I. Sudirman , Rekhif N. , Millière J.B. , Lefebvre G.
Published: March 2008

F. MATHIEU, I.S. SUWANDHI, N. REKHIF, J.B. MILLIERE AND G. LEFEBVRE. 1993. One hundred and sixty‐five isolates of Leuconostoc spp. were tested for bacteriocin production. Only one strain, Leuc. mesenteroides ssp. mesenteroides FR 52, isolated from a raw milk, produced a bacteriocin which was named Mesenterocin 52. This bacteriocin inhibited other Leuconostoc strains and several strains of Enterococcus and Listeria spp. No activity was found against lactococci and lactobacilli. The antibacterial spectrum differed from that of previously described Leuconostoc bacteriocins. Mesenterocin 52 was secreted into the medium during the growth phase. It was inactivated with protease treatments. At pH 7.0 it had a relative stability after heating at 100d̀C (15 min), but it had a greater stability at pH 4.5 than at pH 7.0 after 6 h at 80d̀C. The apparent molecular mass was estimated to be less than 10 kDa by ultrafiltration. Mesenterocin 52 showed a bactericidal effect on Leuconostoc paramesenteroides DSM 20288.