bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrotransformation of gellan‐gum producing and non‐producing Pseudomonas elodea strains
Authors: Monteiro G.A. , Fialho A.M. , Ripley S.J. , Sá‐Correia I.
Published: March 2008

G.A. MONTEIRO, A.M. FIALHO, S.J. RIPLEY AND I.SÁ ‐CORREIA. 1992. The electrotransformation of gellan‐gum producing or non‐producing strains of Pseudomonas elodea (Gel+ or Gel‐) was optimized with respect to growth stage, cell and DNA concentrations and pulse parameters. This technique proved to be a valuable alternative to conjugal mating to search for complementation of gellan mutations for cloning the gellan genes. The electrotransformation efficiency of Gel+ or Gel‐ strains was similar. The transformation of smaller plasmids was more efficient than that of larger plasmids, and recombinant plasmids with sizes larger than 35 kb, when extracted from Escherichia coli DH1, were not transformable at detectable frequency. This was partially related to the modification/restriction system active in the recipient cells.
A one‐minute oxidase test to detect Vibrio strains isolated from cultures on thiosulphate‐citrate‐bile salts‐sucrose (TCBS) medium
Authors: Vila J. , Abdalla S. , Gonzalez J. , Garcia C. , Bombi J.A. , de Anta M.T. Jimenez
Published: March 2008

J. VILA, S. ABDALLA, J. GONZALEZ, C. GARCIA, J. A. BOMBI AND M.T. JIMENEZ. 1992. Vibrio cholerae is oxidase positive, a primary characteristic used to differentiate it from Enterobacteriaceae. But false negative oxidase test results have been obtained with colonies from thiosulphate‐citrate‐bile salts‐sucrose (TCBS) agar medium. A rapid oxidase test procedure is described here. This takes 1 min, avoids false negative results and the necessity to grow the bacteria in a general‐purpose medium. The bacteria may be recovered after the test and used for further investigations.
Myceloid cell formation in Arthrobacter globiformis during osmotic stress
Authors: Deutch C.E. , Perera G.S.
Published: March 2008

C.E. DEUTCH AND G.S. PERERA. 1992. Arthrobacter globiformis was grown in a semi‐defined liquid medium containing added solutes to determine the effects of osmotic stress on its reproduction and cell morphology. There was a progressive reduction in the specific growth rate during exponential phase as the concentration of NaCl was increased, although the final yields of the cultures during stationary phase were not affected. Clusters of branching myceloid cells rather than the typical bacillary forms predominated during exponential phase. These myceloids did not undergo complete septation and persisted into stationary phase. Similar responses were observed with potassium sulphate as the exogenous solute but less dramatic morphological effects were found with added polyethylene glycol or sucrose. The myceloids formed in response to osmotic stress could not be disrupted mechanically but were more sensitive than normal cells to lysozyme, particularly during stationary phase. Addition of osmoprotective compounds such as proline, glutamate, glycine betaine, or trehalose to the growth medium did not significantly relieve the effects of osmotic stress on growth rate or morphology. A. simplex also formed myceloid cells during osmotic stress but A. crystallopoietes did not. These results indicate that arthrobacters exhibit characteristic responses to osmotic stress and suggest these bacteria may contain novel osmoprotective compounds.
Coliform bacteria from aquatic sources in Fiji
Authors: Roberts S.
Published: March 2008

Coliform bacteria were abundant in water and bivalve molluscs in the rivers and present to a lesser extent in the coastal areas of Fiji. The rivers fed by treated sewage were highly polluted. There was a noticeable increase in concentration of coliforms in bivalve molluscs. It was also found that these bacteria could survive and grow in river water and seawater over a 5‐d period, and had a rapid growth rate in nutrient broth under ideal laboratory conditions. They were characterized by the API 20E identification system.
Bacillus anthracis but not always anthrax
Authors: Turnbull P.C.B. , Hutson R.A. , Ward Mandy J. , Jones Marie N. , Quinn C.P. , Finnie N.J. , Duggleby C.J. , Kramer J.M. , Melling J.
Published: March 2008

Gram‐positive bacilli isolated during epidemiological investigations which, on the basis of conventional tests, resemble Bacillus anthracis but which fail to produce the capsule or to induce anthrax in test animals have long been dismissed in clinical and veterinary laboratories as B. cereus or simply as unidentified Bacillus spp. and thereupon discarded as inconsequential. In this study, the application of newly available DNA probe, polymerase chain reaction and specific toxin antigen detection technology has revealed that a proportion of such strains are B. anthracis which lack the plasmid carrying the capsule gene (pXO2). While these techniques cannot, of course, be used to confirm the identities of strains resembling B. anthracis but which also lack the plasmid carrying the toxin genes (pXO1), the likelihood that these also are bonajide B. anthracis becomes more acceptable. (As yet no naturally occurring pXOl‐/2+ strains have been found.) At this point, the significance of the presence of such avirulent forms of B. anthracis in specimens can only be a subject for speculation, but the possibility that they may be indicators of virulent parents somewhere in the system being examined must be considered.
Optimization of an amplified system for the detection of Clostridium tyrobutyricum on nitrocellulose filters by use of monoclonal antibody in a gelified medium
Authors: Nedellec M. , Cleret J.J. , Robreau G. , Talbot F. , Malcoste R.
Published: March 2008

A method of immunological detection by an amplified system has been applied to detect Clostridium tyrobutyricum on nitrocellulose membranes. This method, adapted from an amplification technique, was used in a gelified medium with a monoclonal antibody raised against Cl. tyrobutyricum and an alkaline phosphatase‐conjugated antibody to mouse IgM. The technique permits the detection of about 30 bacteria per spot on membranes.
Co‐existence of β‐lactamase and penicillin acylase in bacteria; detection and quantitative determination of enzyme activities
Authors: Baker W.L.
Published: March 2008

Twenty‐six bacteria were examined for the presence of penicillin acylase and β‐lactamase. A copper reducing assay, which was sensitive in the analytical range 2–20 μg/ml, was used for determination of penicilloates and a fluorescamine assay was used to determine 6‐aminopenicillanic acid concentrations when both substances were produced by the action of the enzymes on a single substrate. Seventeen bacteria contained β‐lactamases, six contained penicillin acylases and four contained both enzymes. Two bacteria contained a Type 1 penicillin acylase and four bacteria contained a Type II enzyme. No ampicillin acylases were detected. All β‐lactamases were constitutive enzymes in those organisms where both enzymes co‐existed. Bacillus subtilis and B. cereus produced inducible and extracellular β‐lactamases. Acinetobacter calcoaceticus ATCC 21288 produced a constitutive β‐lactamase which was detected extracellularly.
Survival of bacterial enteric pathogens in traditional fermented foods
Authors: Simango C. , Rukure Grace
Published: March 2008

The survival of strains of bacterial enteric pathogens was investigated in two traditional fermented foods (mahewu and sour porridge) and in unfermented porridge. The foods were inoculated with cell suspensions of Salmonella, Shigella, Campylobacter, Aeromonas species and pathogenic Escherichia coli which had a final concentration of 106‐107 cfu/ml of food. None of the strains of Aeromonas and Campylobacter were detected in mahewu and sour porridge 20 min after inoculation. The salmonellas were not found 4 h after inoculation in either fermented foods but the shigellas and pathogenic E. coli strains were more tolerant to the low pH of the fermented foods. Some of the shigellas and pathogenic E. coli strains survived for 24 h after inoculation but showed a sharp decrease in numbers. All the strains of the enteric pathogens survived for 24 h in the unfermented porridge and increased in the numbers except for campylobacters, the numbers of which declined. These results suggest that the traditional fermented foods have bacteriostatic and bactericidal properties and are unlikely to play a major role in the transmission of bacterial enteric pathogens.
Effectiveness of handwashing agents in eliminating Staphylococcus aureus from gloved hands
Authors: Best M. , Kennedy M.E.
Published: March 2008

The recent emphasis on gloving has resulted in accounts of healthcare workers washing gloves instead of changing them. This study evaluated the efficacy of soap and three germicidal agents in decontaminating latex and vinyl medical gloves that were experimentally contaminated with Staphylococcus aureus. Gloves were tested for perforations before and after the glovewashing procedure. Results of this study demonstrated that contamination was reduced from the glove surfaces. Although the routine washing of gloved hands cannot be recommended, it may be carried out under limited circumstances.
Evaluation of the repeatability and reproducibility of European suspension test methods for antimicrobial activity of disinfectants and antiseptics
Authors: Bloomfield Sally F. , Looney Eilesh
Published: March 2008

A collaborative study to determine the precision of the 1987 Method of test for the antimicrobial activity of disinfectants in food hygiene is described. The repeatability and reproducibility of the test was found to vary according to the nature of the test organism, the type of disinfectant product and the skill of the operator. Results indicate that significant differences in microbicidal effect (ME values) occur within test laboratories between test periods as well as between laboratories, and that much of this variability derives from apparently random variations in the resistance of test strains from day to day and test period to test period. Indications are that although the test is sufficiently reliable to be used as a standard method, adequate test replication must be specified to distinguish borderline pass from borderline fail disinfectant concentrations. The implications of the results in relation to current work on the development of unified European test methods for disinfectants is discussed.
Incidence of pathogenic bacteria in raw milk in Ireland
Authors: Rea Mary C. , Cogan T.M. , Tobin S.
Published: March 2008

Raw milk from 70 farms was sampled over 13 months for salmonellas, listerias, Escherichia coli, Staphylococcus aureus and mastitic streptococci; total bacterial counts (TBC), coliforms and somatic cells were also counted. TBC ≤30000/ml were obtained in 63% of samples. High count milks were found mainly during the winter months: 13% of samples had > 104 mastitis pathogens/ml of milk. The mean somatic cell count varied from 4.0 × 105 to 8.0 × 105/ml throughout the year with highest counts during the late lactation period. Coliforms were present in all samples, but 65–71% of samples had < 100 coliforms/ml. Up to 60% of supplies had ≤10 E. coli/ml. One of the 589 samples tested (0.1%) was positive for salmonellas. Yersinia enterocolitica and Y. enterocolitica‐like organisms were isolated from 39% of samples with up to 68% of samples positive at some sampling periods. A total of 222 strains of yersinias were isolated; Y. enterocolitica (59%) was the most common strain followed by Y. fredriksenii (35%), Y. kristensenii (1.0%), Y. intermedia (4.5%) and Y. aldovae (0.5%). Listerias were isolated from 8.3% of samples tested; 4.9% were Listeria monocytogenes and 3.4% were L. innocua. There was a significant rise in the isolation rate between December and April from a base line of 0–5% during the spring and summer to 35–37% during the winter months while the cows were indoors. Of 66 silage samples tested from the farms involved in the survey 9% of samples were positive for listerias; 3% of these were L. monocytogenes and 6% were L. innocua. Only half of the farms feeding contaminated silage produced milk containing listerias.
Effect of premix ingredients and its inoculation with lactic acid‐producing bacteria on ensiling of poultry droppings with conventional feeds
Authors: Kamra D.N. , Srivastava S.K.
Published: March 2008

A premix of poultry droppings (25 parts) and wheat straw (65 parts) was inoculated with a mixed culture of Lactobacillus plantarum and Streptococcus faecalis in the presence or absence of sugarcane molasses. The inclusion of lactic acid‐producing bacteria and molasses in the premix resulted in reduced pH, ammonia nitrogen and total volatile fatty acids and increased production of lactic acid during a fermentation time of 20 d at 32–35°C. The sugarcane molasses and part of the wheat straw can be replaced with green maize fodder in the vegetative stage without any adverse effect on the silage characteristics. With an increasing level of green maize in the premix, there was a decrease in pH, dry matter of premix and wastelage and a significant increase in soluble sugars of premix and titrable acidity and lactic acid content of wastelage. A good wastelage can be produced when the premix consists of poultry droppings, wheat straw and green maize in the ratio of 25: 15:60, respectively, and it is inoculated with lactic acid‐producing bacteria.
Evaluation of antimicrobial interactions between chlorhexidine, quaternary ammonium compounds, preservatives and excipients
Authors: Pons J.‐L. , Bonnaveiro N. , Chevalier J. , Crémieux A.
Published: March 2008

The antimicrobial interactions of 49 combinations of chlorhexidine, quaternary ammonium compounds, preservatives and excipients were evaluated by the method of Berenbaum and the checkerboard titration method, with Staphylococcus aureus CIP 53154 and Escherichia coli CIP 54127 as test strains. MIC determinations were carried out as a preliminary step, and relative growth intensity was used to describe the bacteriostatic activity of surface‐active agents (Amonyl 380 BA®, Amonyl 671 SB®). In the study of combinations, results were interpreted with Fractional Inhibitory Concentration indexes and represented by isobolograms. A fair correlation was shown between the method of Berenbaum and the checkerboard titration method. Combinations between chlorhexidine, cetrimonium bromide and benzalkonium chloride were synergistic or additive; combinations of antiseptics and preservatives were generally not antagonistic. The methods were also well adapted to the study of interactions involving surface‐active agents, a critical problem in the formulation of topical antimicrobial agents.
Staphylococcus carnosus bacteriophages isolated from salami factories in Germany and Italy
Authors: Bruttin Anne , Marchesini Barbara , Moreton R.S. , Sozzi T.
Published: March 2008

Two phages lysing strains of Staphylococcus carnosus, an organism used as a starter culture for salami production, were isolated from factories in Germany and Italy. Morphologically they show the C1 morphotype and are unrelated to the only other known Staph. carnosus phage. The phages were physiologically and morphologically similar but showed differences in their structural proteins and DNA restriction patterns. Their genomes consisted of linear double stranded DNA with a genome size of 19 kb. The phages lysed a wide range of Staph. carnosus strains from commercial meat starter cultures as well as the DSM type strain. Despite the presence of these phages, the products were normal from the point of view of colour, texture and flavour.
Identification and composition of the tonsillar and anal enterococcal and streptococcal flora of dogs and cats
Authors: Devriese L.A. , Colque J.I. Cruz , De Herdt P. , Haesebrouck F.
Published: March 2008

Enterococcus faecalis was the most frequently isolated enterococcal species from anal swabs and tonsils of dogs and cats, although in the anal samples from dogs Ent. hirae was found almost as often as Ent. faecalis. Most Ent.faecium strains from dog tonsils differed from those associated with humans and other animals in that they fermented sorbitol. Typical Ent. avium as well as atypical Ent. avium‐like strains were seen in dogs, while the related species Ent. raffinosus was associated with cat tonsils. Enterococcus cecorum also occurred mainly in cats. Certain atypical strains, presumptively identified as Ent. cecorum, shared characteristics with Ent. columbae.

The most frequent streptococcal species in tonsils of cats and dogs were Streptococcus suis and Strep. canis. Streptococcus canis and Strep. bovis predominated in anal swabs. The canine Strep. suis differed from the common porcine strains in fermenting mannitol.

Forty‐seven of the 288 isolates examined could not be identified or related to known species. The characteristics of two groups of these bacteria, provisionally called ‘Ton 31 group’ and ‘O7 group’ are described.
Effect of polysaccharide interactions on antibiotic susceptibility of Pseudomonas aeruginosa
Authors: Allison D.G. , Matthews M.J.
Published: March 2008

The relative viscosity of Pseudomonas aeruginosa alginate was shown to increase markedly when combined with mucin, Ca2+ ions and the exopolysaccharide from Pseudomonas cepacia. The presence of such a heterodisperse polysaccharide solution significantly reduced the diffusion and hence antimicrobial activity of tobramycin and to a lesser extent ciprofloxacin against Ps. aeruginosa by factors of 90 and 2.5‐fold respectively over a 5 h incubation period. The clinical implications of these results are discussed in relation to cystic fibrosis.
Growth, D‐glucose utilization and malolactic fermentation by Leuconostoc œnos strains in 18 media deficient in one amino acid
Authors: Fourcassie P. , Makaga‐Kabinda‐Massard E. , Belarbi A. , Maujean A.
Published: March 2008

Six Leuconostoc œnos strains were used to study the effect of the deficiency of one amino acid on growth, heterofermentative pathway and malolactic fermentation. All strains had an absolute requirement for four amino acids (isoleucine, glutamic acid, tryptophan and arginine) and needed six other amino acids (valine, methionine, cysteine, leucine, aspartic acid and histidine) for optimum growth. Each deficiency in one amino acid had a particular effect on D‐glucose utilization. Overproduction and underproduction of D‐lactic acid were observed. The rate of L‐malic acid consumption in media deficient in one amino acid was lower than in the complete medium with all amino acids.

Although some deficiencies (glycine, phenylalanine, proline or tyrosine) had no influence on the growth, they noticeably limited the malolactic fermentation.
16S rrn gene copy number in Helicobacter pylori and its application to molecular typing
Authors: Linton D. , Moreno M. , Owen R.J. , Stanley J.
Published: March 2008

The copy number of the genes encoding 16S ribosomal RNA was analysed for the genomes of geographically diverse strains of Helicobacter pylori, and restriction site variation within and around the genes was characterized. A DNA probe of 550 bp was amplified by the polymerase chain reaction from genomic DNA of the type strain NCTC 11637. This probe constituted a sequence internal to the 3'end of the 16S rrn gene. Homology profiles were compared for genomic Southern blots made with four restriction enzymes cutting within and outside the probe sequence. A copy number of two was established for all 12 strains analysed. This approach yielded significantly simpler data than does conventional ‘ribotyping’ of H. pylori. It was equally discriminatory, however, and provided strain‐specific 16S rrn gene ‘signatures’. These represent both fundamental physical‐genetic information and a novel approach to typing this gastric pathogen.
The rate of uptake and metabolism of starch grains and cellulose particles by Entodinium species, Eudiplodinium maggii, some other entodiniomorphid protozoa and natural protozoal populations taken from the ovine rumen
Authors: Coleman G.S.
Published: March 2008

The rates of engulfment and breakdown of starch grains and cellulose particles and of the rate of synthesis of amylopectin from cellulose by individual species of entodiniomorphid protozoa (grown in vivo and in vitro) and incubated anaerobically in vitro were studied. Rates of starch uptake varied from 2.3 to 770 μg/mg protozoal protein/min; the lowest was found with Diploplastron affine and the highest with Entodinium spp. on initial incubation with starch grains. The rate of starch breakdown varied from 0.49 to 8.6 μg/mg protein/min; the rate was dependent on the initial starch concentration inside the protozoa. Eudiplodinium maggii engulfed cellulose particles more rapidly (2–7 times) than rice starch grains and digested the cellulose at rates of 10 to 16.5 μg/mg protein/min. In a mixture of starch grains and cellulose particles, it engulfed the latter at 1.35 to 25 times the rate of the former. Eudiplodinium maggii and Epidinium caudatum, but not Entodinium spp. or Dip. affine, synthesized an amylopectin‐like material from cellulose at rates of 0.4 to 4.75 μg/mg protein/min. If these reactions occur in the rumen in vivo, up to 9 g of amylopectin could be synthesized from cellulose each day by the entodiniomorphid protozoa.
Phenotypic and phylogenetic characterization of some Gemella‐like organisms from human infections: description of Dolosigranulum pigrum gen. nov., sp. nov.
Authors: Aguirre M. , Morrison D. , Cookson B.D. , Gay F.W. , Collins M.D.
Published: March 2008

A phylogenetic analysis was performed on two previously uncharacterized Gram‐positive, catalase‐negative bacteria from clinical sources. 16S rRNA sequencing studies revealed the isolates represent a new line of descent within the lactic acid group of bacteria. On the basis of the phylogenetic findings and phenotypic distinctiveness of the organisms, it is proposed that they be classified in a new genus Dolosigranulum, as Dolosigranulum pigrum sp. nov. The type strain of Dolosigranulum pigrum is NCFB 2975.
The effect of hydroxycinnamic acids on the growth of wine‐spoilage lactic acid bacteria
Authors: Stead D.
Published: March 2008

Hydroxycinnamic acids and their derivatives occur naturally in grape juice and wine. To assess their potential as natural preservatives the effect of caffeic, coumaric and ferulic acids on the growth of three wine‐spoilage strains of Lactobacillus collinoides and one of Lact. brevis was studied in acid tomato broth containing 5% ethanol at pH 4.8. At concentrations of 500 and 1000 mg l‐1, all three compounds markedly inhibited growth; coumaric and ferulic acids were more effective than caffeic acid. At a concentration of 100 mg l‐1, all compounds stimulated growth. In general, the strains of Lact. collinoides were more susceptible both to inhibition and stimulation by the hydroxycinnamic acids than was the strain of Lact. brevis. The possible influence of hydroxycinnamic acids on the malolactic fermentation of wine is discussed.
Bacteriocinogenic activity of lactobacilli from fermented sausages
Authors: Garriga M. , Hugas M. , Aymerich T. , Monfort J.M.
Published: March 2008

During the screening of the inhibitory activity of 254 strains of lactobacilli isolated from fermented sausages at different times of ripening, 22% of the strains showed inhibition that was not related to acid or hydrogen peroxide, towards one or more indicator strains. Not all the strains were capable of secreting the inhibitory compound in the supernatant fluid. The characterization of the inhibitory compound from three strains showed that they were bacteriocins with a bactericidal mode of action and a molecular weight exceeding 10000 Da. Lactobacillus plantarum CTC 305, CTC 306 and Lact. sake CTC 372 inhibited Listeria monocytogenes. Lactobacillus sake CTC372 was cured of two plasmids of 84.8 kbp and 41.3 kbp, losing the production and the immunity of a bacteriocin as well as the ability to ferment lactose.
A comparison of three salmonella antigen‐capture ELISAs and culture for veterinary diagnostic specimens
Authors: Kerr S. , Ball H.J. , Porter R.
Published: March 2008

Three sandwich‐ELISAs, two of which are commercially available (Tecra and Locate), and one developed at the Veterinary Sciences Division, Stormont and a 3‐step culture protocol, were compared for the detection of salmonella in 1000 animal specimens. Eight hundred and fifty of these were new submissions and the remainder were frozen portions from specimens previously shown to contain salmonellas by culture. The incidence of ELISA false‐negative and false‐positive results was highest for the Stormont and Locate kits respectively although the differences in sensitivity and specificity between the three ELISAs was not statistically significant. On 16 occasions all ELISA methods indicated the presence of salmonellas when none were isolated by initial culture, eight of these specimens contained salmonellas when reinvestigated by culture.
Survival of pathogenic bacteria during mesophilic anaerobic digestion of animal waste
Authors: Kearney Theresa E. , Larkin M.J. , Frost J.P. , Levett P.N.
Published: March 2008

The survival of pathogenic bacteria was investigated during the operation of a full‐scale anaerobic digester which was fed daily and operated at 28°C. The digester had a mean hydraulic retention time of 24 d. The viable numbers of Escherichia coli, Salmonella typhimurium, Yersinia enterocolitica, Listeria monocytogenes and Campylobacter jejuni were reduced during mesophilic anaerobic digestion. Echerichia coli had the smallest mean viable numbers at each stage of the digestion process. Its mean T90 value was 76.9 d. Yersinia enterocolitica was the least resistant to the anaerobic digester environment; its mean T90 value was 18.2 d. Campylobacter jejuni was the most resistant bacterium; its mean T90 value was 438.6 d. Regression analysis showed that there were no direct relationships between the slurry input and performance of the digester and the decline of pathogen numbers during the 140 d experimental period.
Study of Enterobacteriaceae throughout the manufacturing and ripening of hard goats' cheese
Authors: Tornadijo Eugenia , Fresno J.M. , Carballo J. , Martín‐Sarmiento R.
Published: March 2008

The evolution of the counts and the species of Enterobacteriaceae as well as some physico‐chemical parameters (pH, αwand NaCl and moisture contents) during manufacturing and ripening of a hard Spanish goats' cheese of the Armada‐Sobado variety were studied. Enterobacteriaceae (mean log counts 4.45 g‐1in milk) increased 0.71–2.18 log units in curd and afterwards decreased until they disappeared after 2–4 weeks of ripening. This premature disappearance seems to be due to the decrease in αwvalues and in moisture contents. However, the low pH values, reached from the beginning of the ripening process, could also contribute to this phenomenon.

The most abundant species in milk wasSerratia liquefaciens(57.5% of isolates), followed byMorganella morganii(27.5%),Hafnia alvei(5%),Klebsiella oxytoca(5%) andYersinia enterocolitica(5%).Yersinia enterocoliticawas not subsequently isolated from either curd or in cheese.Hafnia alveinumbers increased in curd and in 1‐week‐old cheese where this micro‐organism was the most abundant (47.5% and 75% of the isolates respectively).Escherichia coli, which was not isolated from milk, curd or 1‐week‐old cheese, was the predominant organism in 2‐week‐old cheese (57.8% of isolates). This confirms the finding of other authors who have shown that it is one of the most resistant species in ripening cheeses.
Numerical classification and identification ofAcinetobactergenomic species
Authors: Kämpfer P. , Tjernberg Ingela , Ursing J.
Published: March 2008

A total of 211Acinetobacterstrains (representing all currently recognized genomic species) were tested for 329 biochemical characters. Overall similarities of all strains were determined for 145 characters by numerical taxonomic techniques, the UPGMA algorithm and theSSMand theSJcoefficients as measures of similarity. Seven clusters (two or more strains) and three unclustered strains were recovered at a similarity level of 80.0% (SSM). At this level a complete correspondence between phenotypic cluster and genomic species was found only for genomic species 12 (Ac. radioresistens). At higher similarity levels (84.0% to 84.6% (SSM)), however, several subclusters were found, each representing a single genomic species. An exception were the strains belonging to the genetically closely related species of theAcinetobacter calcoaceticus‐baumanniicomplex. These were recovered scattered in several subclusters. The degree of genomic relatedness between some DNA groups correlated with phenotypic similarities, especially for DNA group 8 (Ac. lwoffii) and 15 of Tjernberg and Ursing, and for DNA group 4 (Ac. haemolyticus) and 6.

For the majority of genomic species, two identification matrices were constructed consisting of 22 and 10 diagnostic characters, respectively. The correct identification rates for the matrices were 98.0% (22 tests) and 90.8% (10 tests) taking a Willcox probability >0.9. For unambiguous identification of some genomic species, however, additional methods (preferably DNA‐DNA hybridization or ribotyping) should be used.
Purification and characterization of an extracellular amylase from Lactobacillus plantarum strain A6
Authors: Giraud E. , Gosselin L. , Marin B. , Parada J.L. , Raimbault M.
Published: March 2008

Extracellular amylase from Lactobacillus plantarum A6 was purified by fractionated precipitation with ammonium sulphate and by anion exchange chromatography. The homogeneity of the purified fraction was tested by polyacrylamide gel electrophoresis and showed multiple amylase forms. A major form had an estimated molecular weight of 50 kDa. It was identified as an α‐amylase, with an optimum pH of 5.5, an optimum temperature of 65°C and Km value of 2.38 g l‐1 with soluble starch substrate. The enzyme was inhibited by N‐bromosuccinimide, iodine and acetic acid. The enzyme activation energy was 30.9 kJ mol‐1.
Effects of pH and temperature on heterotrophic bacteria in acidified and non‐acidified lochs
Authors: Rattray J. , Logan N.A.
Published: March 2008

An investigation into the impact of acidification on bacterial populations in Scottish lochs revealed that in the range pH 3.8–6.5, increasing acidity had little effect on activities and diversities of aerobic heterotrophs. Only one organism, a Cytophaga species, showed reduced numbers at lower pH. Large and rapid increases in water temperature, however, resulted in decreasing diversities with the emergence of dominant populations of a few species, whilst others became undetectable. A dominant strain achieved higher numbers than a non‐dominant strain in competition studies with both slow and rapid temperature increases, but as the organisms coexisted and washout did not occur it was inferred that the organisms were not competing for substrate.
Effect of heat treatment on Listeria monocytogenes and Gram‐negative bacteria in sheep, cow and goat milks
Authors: MacDonald Fiona , Sutherland A.D.
Published: March 2008

Sheep milk, compared with cow and goat milk, had a protective effect on Gram‐negative bacteria and Listeria spp. heated at 65°C in a test‐tube method. This effect was not solely due to fat content as cow milk artificially reconstituted to 10% homologous fat was not as protective. Listeria monocytogenes in whole sheep, cow and goat milks at an inoculum level of 1 times 106 cfu ml‐1 was heated at 68°C for 15 s in the plate pasteurizer and survival was only detected in whole sheep milk after heating. Whole sheep, cow and goat milks containing high levels of L. monocytogenes (1 times 106 cfu ml‐1) could not survive the current HTST plate pasteurization protocol.
Construction and detection of bioluminescent strains of Bacillus subtilis
Authors: Cook N. , Silcock D.J. , Waterhouse R.N. , Prosser J.I. , Glover L.A. , Killham K.
Published: March 2008

Bioluminescence (lux) genes from Vibrio fischeri and V. harveyi were introduced into Bacillus subtilis on a plasmid vector and by chromosomal integration. The plasmid‐bearing strain was highly luminescent and stable under antibiotic selection, but luminescence was lost in the absence of selection and following sporulation and germination. The chromosomally marked strains emitted less light but were found to be stable without the requirement for antibiotic selection and following sporulation and germination. Individual luminescing colonies of both B. subtilis strains could be detected against a high background of non‐bioluminescent indigenous soil microbial colonies on agar plates using a charge‐coupled device camera. These bioluminescent Gram‐positive strains could be of value in studies concerning the survival and spread of genetically‐modified micro‐organisms in soil environments.
Effects of the in vitro fermentation of oligofructose and inulin by bacteria growing in the human large intestine
Authors: Wang X. , Gibson G.R.
Published: March 2008

The in vitro fermentability of oligofructose and inulin was compared with a range of reference carbohydrates by measuring bacterial end‐product formation in batch culture. Short chain fatty acid and gas formation indicated that these substrates, which occur naturally in the diet and reach the colon in a largely intact form, were utilized by mixed populations of gut bacteria. Bacterial growth data showed that oligofructose and inulin exerted a preferential stimulatory effect on numbers of the health‐promoting genus Bifidobacterium, whilst maintaining populations of potential pathogens (Escherichia coli, Clostridium) at relatively low levels. Pure culture studies confirmed the enhanced ability of bifidobacteria to utilize these substrates in comparison with glucose. Batch culture experiments demonstrated that the growth of Bifidobacterium infantis had an inhibitory effect towards E. coli and Clostridium perfringens. Potentially, an increase in the concentration of these substrates in the diet may therefore improve the composition of the large intestinal microflora and have positive effects on the quality of the Western diet.
Kinetics of lactate fermentation and citrate bioconversion by Lactococcus Iactis ssp. Iactis in batch culture
Authors: Cachon R. , Diviès C.
Published: March 2008

The growth kinetics of Lactococcus lactis ssp. lactis were studied in batch culture in conditions of non‐limiting lactose and the presence of citric acid. The control of pH modified growth and citrate metabolism but did not change the yield of acid formation. At controlled pH the growth rate was unaffected by citrate metabolism. Lactose was transformed to L‐lactate and assay of the metabolic by‐products showed some heterofermentation at the end of the growth of cultures with low growth rates. This heterofermentation was interpreted as a slowing down of glycolysis with activation of both the pyruvate formate lyase (PFL) and the pyruvate dehydrogenase complex (PDHC). Under these conditions the presence of citric acid affected the activity of both the PDHC and the alcohol dehydrogenase (ADH). L‐Lactate remains the major fermentation end‐product and the sole inhibitor of fermentation, this inhibition was greater on growth than on lactic acid production.
Formation of vitamins by pure cultures of tempe moulds and bacteria during the tempe solid substrate fermentation
Authors: Keuth Sylvia , Bisping B.
Published: March 2008

The formation of water soluble vitamins (vitamin B12, vitamin B6, riboflavin, thiamine, nicotinic acid and nicotinamide) during the tempe solid substrate fermentation was investigated. The role of several strains of Rhizopus oligosporus, R. arrhizus, and R. stolonifer and the role of several bacteria in the vitamin formation process were checked. All fungal and bacterial strains were isolated from Indonesian tempe and soaking water samples. The Rhizopus strains formed riboflavin, nicotinic acid, nicotinamide and vitamin B6. The final concentrations of these substances depended on the different strains involved and on the fermentation time. Isolates of R. oligosporus were generally the best vitamin formers. The moulds did not produce physiologically active vitamin B12. The thiamine content decreased during fermentation. The addition of bacteria, which had been selected in a screening for vitamin B12 production, resulted in an increase of physiologically active vitamin B12. Citrobacter freundii and Klebsiella pneumoniae showed the best formation capabilities. Furthermore, the bacteria produced riboflavin and vitamin B6 in addition to the moulds. The influence of Rhizopus on the vitamin B12 formation of Cit. freundii was also investigated. The vitamin content of tempe that was fermented with the mould and the bacterium was three times as high as a control fermentation with Cit. freundii only.
The development and assessment of DNA and oligonucleotide probes for the specific detection of Bacillus anthracis
Authors: Hutson R.A. , Duggleby C.J. , Lowe J.R. , Manchee R.J. , Turnbull P.C.B.
Published: March 2008

Two DNA probes and a number of oligonucleotide probes were designed from the virulence factor genes of Bacillus anthracis. These probes were tested for specificity against 52 B. anthracis strains and 233 Bacillus strains encompassing 23 other species. A rapid slot blotting technique was used for screening the large numbers of isolates involved. All probes tested appeared to be specific for B. anthracis under high stringency conditions. These probes could differentiate between virulent and avirulent strains. The probes were also applied to the detection of B. anthracis in routine environmental and clinical samples. A non‐radioactive hybridization and detection system based on digoxigenin‐11‐dUTP was developed.
Inhibition of Lactobacillus plantarum by polyphenols extracted from two different kinds of olive brine
Authors: Ruiz‐Barba J.L. , Brenes‐Balbuena M. , Jiménez‐Díaz R. , García‐García P. , Garrido‐Fernández A.
Published: March 2008

The characteristic phenolic content of NaOH‐treated and untreated olive brines is reported. Detection, quantification and isolation of the phenolic compounds were carried out by HPLC. Viability of Lactobacillus plantarum in the presence of single or combined fractions of these isolated compounds was tested. When assayed at the concentrations found in brines, only the single phenolic fraction containing hydroxytyrosol strongly inhibited Lact. plantarum. However, inhibition of Lact. plantarum was also observed when double phenolic fractions (e.g. the glucosides, oleuropein and verbascoside) were used; this showed a combined effect in the inhibition. The different permeability of fruit for polyphenols and organic compounds is discussed as the primary cause of the rapid fermentation of alkaline‐treated, but not of untreated, olives.
Distribution of pathogen inhibition in the Lactobacillus isolates of a commercial probiotic consortium
Authors: Chateau N. , Castellanos I. , Deschamps A.M.
Published: March 2008

Pure strains of Lactobacillus ssp. isolated from a commercial probiotic consortium were checked in a double layer solid medium for their inhibition activities against selected pathogenic bacteria including serotypes of Listeria monocytogenes, Escherichia coli and Salmonella. The antagonistic properties of the Lactobacillus strains may be related to the production of bacteriocin‐like compounds. All the pathogens tested were inhibited by one or a few strains of Lactobacillus, the best inhibition was observed against L. monocytogenes but the inhibition was also satisfactory against E. coli, Salm. typhimurium and Salm. enteritidis.
Detection by in vitro amplification of the alpha‐toxin (phospholipase C) gene from Clostridium perfringens
Authors: Fach P. , Guillou J.P.
Published: March 2008

A polymerase chain reaction (PCR) with thermostable DNA polymerase from Thermus aquaticus is described for the specific amplification of the phospholipase C (alpha‐toxin) gene of Clostridium perfringens. A set of primers selected for their high specificity could detect Cl. perfringens in stools with a detection limit of approximately 5 x 102 bacteria, after bi‐amplification. A modified PCR without thermal steps was performed to rapidly amplify, with a yield of 60%, the DNA template. With this PCR method Cl. perfringens alpha‐toxin gene could be detected within 2 h. The PCR method detected alpha‐toxin positive Cl. perfringens but did not react with phospholipase C‐producing Bacillus cereus, Pseudomonas aeruginosa, Cl. sordellii and Cl. bifermentans.

The amplified PCR products were screened through ethidium bromide agarose gel electrophoresis or, in only 1 h, with the PhastSystem (Pharmacia). This PCR satisfies the criteria of specificity, sensitivity and rapidity required for a useful tool in epidemiology and for the diagnosis of the pathogen Cl. perfringens as it may be used directly on stool samples.
The production of antifungal volatiles by Bacillus subtilis
Authors: Fiddaman P.J. , Rossall S.
Published: March 2008

A strain of Bacillus subtilis which produces an antibiotic metabolite was also found to produce a volatile compound(s) which was antifungal to Rhizoctonia solani and Pythium ultimum.

Growth of the fungi was severely impaired in the presence of the volatiles and physiological abnormalities of the hyphae were observed, including hyphal distortion and vacuolation. A range of media were tested for volatile production and potato dextrose agar (PDA) was found to be the most active. Temperature had a considerable effect on antifungal volatile activity with the greatest inhibition occurring at 30°C. Addition of iron (III) chloride to Sabouraud's glucose agar (SGA) also enhanced the antifungal effect. The volatiles were found to be water soluble and remained active when trapped in SGA.
An ion‐exchange based extraction method for the detection of salmonellas in soil
Authors: Turpin P.E. , Maycroft K.A. , Rowlands C.L. , Wellington E.M.H.
Published: March 2008

A method that uses a cation‐exchange resin (Chelex 100) and differential centrifugation for the extraction and detection of salmonellas in soil was developed. The extraction efficiencies of a range of materials were examined and Chelex plus polyethylene glycol was identified as the best combination. Shake speeds, shake times and differential centrifugation speeds were selected to give an optimum salmonella recovery. The Chelex method accurately enumerated 1 cell per 10 g of nonsterile soil within 24 h. Addition of glycerol to soil samples enabled storage at — 70°C for 85 d without significant decreases in salmonella numbers. The Oxoid Salmonella Rapid Test (SRT) could be used to pre‐screen large numbers of soil samples for the presence of salmonellas, prior to analysis by the Chelex method. The SRT method detected Salmonella typhimurium at levels as low as 2·5 cells per 10 g of nonsterile soil.
Characterization of a variant of the polysaccharide acetan produced by a mutant of Acetobacter xylinum strain CR1/4
Authors: MacCormick C.A. , Harris J.E. , Gunning A.P. , Morris V.J.
Published: March 2008

Acetobacter xylinum NRRL B42 (NCIB 40123) produces both cellulose and a complex anionic branched heteropolysaccharide called acetan. Chemical mutagenesis was used to isolate stable cellulose‐minus Acetobacter xylinum mutants. Further chemical mutagenesis of these cellulose‐minus A. xylinum bacteria was used to select mutants which secrete polysaccharides which are variants of the acetan structure. Preparation, purification and characterization of these polysaccharides are described. Methylation analysis of the polysaccharide structure CR1/4 suggests that the polysaccharide has an acetan structure with a truncated sidechain terminating in glucuronic acid.
The effect of the olive phenolic compound, oleuropein, on growth and enterotoxin B production by Staphylococcus aureus
Authors: Tranter H.S. , Tassou Soula C. , Nychas G.J.
Published: March 2008

The presence of low concentrations (0.1% w/v) of oleuropein, a phenolic compound extracted from olives, delayed the growth of Staphylococcus aureus in NZ amine A and brain heart infusion media modified by the addition of growth factors and glucose (NZA + and BHI +), as indicated by changes in conductance, whilst higher concentrations (0.4–0.6% w/v) inhibited growth completely. Intermediate concentrations of oleuropein (0.2%) prevented growth in BHI + but allowed growth to occur in NZA + despite an extended lag phase (30 h). Concentrations of oleuropein > 0.2% inhibited growth and production of enterotoxin B in both types of media. Lower levels (0.1%) did not affect the final viable count and production of toxin in BHI + but decreased the number of viable organisms and reduced the toxin production in NZA + by eightfold. An increase in the concentration of oleuropein resulted in a decrease in the amount of glucose assimilated and consequently the amount of lactate produced. In addition, oleuropein prevented the secretion of a number of exoproteins. Addition of oleuropein during the exponential phase appeared to have no effect on the growth of Staph. aureus in NZA +.
Phylogenetic studies of the rRNA group II pseudomonads based on 16S rRNA gene sequences
Authors: Li Xiang , Dorsch M. , Dot T Del , Sly L.I. , Stackebrandt E. , Hayward A.C.
Published: March 2008

Nearly complete sequences of 16S rRNA genes were determined for eight bacterial strains representing five species of the rRNA homology group II pseudomonads that are members of the beta subclass of the class Proteobacteria. Comparative analysis with published sequence data indicated that Pseudomonas andropogonis, Ps. caryophylli, Ps. gladioli pv. gladioli and Ps. cepacia aggregate in one coherent cluster at 94·2% sequence similarity; Ps. solanacearum and Ps. pickettii shared 95·3% and 92·8% similarity with Alcaligenes eutrophus in another cluster. Both clusters joined at 87·8% similarity, which is similar to that for genera in this subclass of Proteobacteria. Based on this study and on comparison with other works we suggest that these species are separated from authentic pseudomonads and constitute a new genus or possibly two related genera accommodating Ps. andropogonis, Ps. caryophylli, Ps. gladioli, Ps. cepacia, and Ps. solanacearum, Ps. pickettii and A. eutrophus, respectively. Four strains of Ps. solanacearum representing Biovars 1, 2, 3 and 4 were subdivided into two clusters at 99·1% sequence similarity, in agreement with other published phenotypic and genotypic studies. The two clusters may be potentially regarded as subspecies.
Laboratory study of several enrichment broths for the detection of Salmonella spp. particularly in relation to water samples
Authors: Moriñigo M.A. , Muñoz M.A. , Martinez‐Manzanares E. , Sánchez J.M. , Borrego J.J.
Published: March 2008

The selectivity and efficiency of several enrichment broths used for the detection of salmonellas were comparatively evaluated under laboratory and environmental conditions. Media with selenite were less efficient in their inhibition of the growth of Gram‐positive micro‐organisms. Salmonellas grew slowly in tetrathionate broth and in media containing brilliant green. These media inhibited the growth of Salmonella typhi, which grew only in media containing selenite. The results obtained in the experiments with stressed salmonellas indicate that the media selenite F, selenite F with novobiocin, selenite cystine and Rappaport‐Vassiliadis (RV/43), in conjunction with the double agar layer technique, showed an optimal efficiency for the detection of stressed salmonellas. When natural samples (freshwater and seawater) were used to evaluate the media, however, those containing malachite green, whether or not supplemented with sodium novobiocin, enhanced the recovery of salmonellas.
Enterobacteria associated with grass and silages
Authors: Heron Shirley J.E. , Wilkinson J.F. , Duffus Carol M.
Published: March 2008

Enterobacteria were isolated from grass and silages and identified by the API 20E system. The effects of various ensiling treatments on their numbers and types were determined. The enterobacteria appear to follow a pattern of succession. Erwinia herbicola and Rahnella aquitilis dominated on fresh grass but after ensiling were rapidly superseded by Hafnia alvei, and finally Escherichia coli. Serratia fonticola may appear early on if the pH falls very rapidly.