bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of Aeromonas strains on the growth of Legionella
Authors: Toze S. , Cahill Marion , Sly L.I. , Fuerst J.A.
Published: March 2008

Thirty‐one environmental and two type strains of Aeromonas were tested for their ability to inhibit the growth of strains of several Legionella species. Of 10 Legionella spp. tested, only Legionella pneumophila and Leg. longbeachae were able to resist the inhibitory effects of some of the Aeromonas strains. Selected Aeromonas strains were also tested for their ability to inhibit the growth of several non‐legionella strains. None of the non‐legionella strains were inhibited by any of the selected Aeromonas strains. Attempts were made to isolate Aeromonas strains from cooling towers and Aeromonas hydrophila was isolated from one of the cooling towers tested. The results suggest that many strains of Aeromonas can inhibit the growth of Legionella strains on solid media and could affect the isolation of legionellas from water sources.
Evaluation of determinative tests for pathovars of Pseudomonas syringae van Hall 1902
Authors: Young J.M. , Triggs C.M.
Published: March 2008

The utility of 36 presumptive determinative tests for 32 pathovars of Pseudomonas syringae was investigated. A total of 395 strains was examined. Most strains of 12 of these pathovars (Ps. syringae pv. cannabina, Ps. syr. delphinii, Ps. syr. glycinea, Ps. syr. helianthi, Ps. syr. lachrymans, Ps. syr. mori, Ps. syr. morsprunorum, Ps. syr. phaseolicola, Ps. syr. ‘porri’, Ps. syr. papulans, Ps. syr. savastanoi and Ps. syr. tabaci) formed clusters when test data were compared by centroid analysis. Pseudomonas syr. syringae, Ps. syr. aptata, Ps. syr. atrofaciens, Ps. syr. dysoxyli and Ps. syr. japonica formed a single cluster, indicating their possible synonymy. Strains of Ps. syr. antirrhini and Ps. syr. tomato were indistinguishable, as were those of Ps. syr. garcae and Ps. syr. oryzae. Strains of Ps. syr. berberidis, Ps. syr. coronafaciens, Ps. syr. eriobotryae, Ps. syr. maculicola, Ps. syr. passiflorae, Ps. syr. pisi and Ps. syr. striafaciens and Ps. syr. tagetis did not form distinguishable clusters.

The tests which reliably differentiated pathovars are recorded in a determinative scheme.
Studies on the Bacillus flora of milk and milk products
Authors: Crielly E.M. , Logan N.A. , Anderton A.
Published: March 2008

Bacillus licheniformis and B. cereus were the most commonly isolated species of Bacillus found in milk at all stages of processing. Bacillus licheniformis was ubiquitous in the farm environment and counts in raw milks heat‐treated in the laboratory were higher during the winter months, whilst B. cereus was associated with cattle feed throughout the year, and tended to be more common in raw milks during the summer months. Although B. licheniformis was usually isolated in larger numbers than B. cereus, this pattern changed after raw and pasteurized milks and reconstituted milk powders were pre‐incubated at ambient temperatures, and B. cereus came to dominate the Bacillus population, reaching levels associated with enterotoxin production. Investigation of the growth kinetics of strains of both species showed that B. cereus grew faster than B. licheniformis at ambient temperatures. It is suggested that post‐pasteurization contamination, which is commonly blamed for spoilage of milk and milk products by B. cereus, is not necessarily the most important source of this organism.
Analytical procedure for use of conductance measurement to estimate Escherichia coli in shellfish
Authors: Dupont J. , Ménard D. , Hervé C. , Minier B.
Published: March 2008

Assays were performed with a Malthus AT Microbiological Analyzer to define an analytical procedure to estimate Escherichia coli counts in live bivalve shellfish by conductance measurement. The growth conditions used (Malthus Coliform Broth at 44°C) were selective for E. coli, and interference was noted only when Klebsiella pneumoniae were at least 100 times as numerous as E. coli. Different sample preparation procedures and seeding conditions were tested to obtain good quality conductance curves. The best results were observed when: (a) meat and shell liquor were diluted 1 : 3 with tryptone salt water and homogenized in a Waring blender for 1 min at 15 000 rev min‐1; and (b) the inoculum was taken from the liquid phase of the homogenate 20 min after blending and mixed immediately with the culture medium. Detection parameter threshold values were adjusted (first difference 1.5 μS for the baseline and 3.5 μS for detection, second difference 0.2 μS to improve detection time reliability. The repeatability of conductance measurements was very good (S.D. as % response mean ranged from 1.9 to 3.3) with the protocol used.
Effects of starvation and osmotic stress on viability and heat resistance of Pseudomonas fluorescens AH9
Authors: Jørgensen F. , Nybroe O. , Knøchel S.
Published: March 2008

This study addresses the responses to starvation and osmotic stress of Pseudomonas fluorescens isolated from spoiled fish. Culturability and viability of stressed cells were determined. Cells maintaining an active electron transport system were considered to be viable and this activity was assessed by the ability of the cells to reduce the 5‐cyano‐2,4‐ditolyl tetrazolium chloride (CTC) to fluorescent CTC‐formazan. Cells starved of carbon maintained high culturability and a high proportion of the cells were capable of reducing CTC during short‐time (up to 5 d) experiments. ATP concentrations were lower in carbon‐starved than in log‐phase cells but the measured levels suggested that metabolic activity was retained. Carbon‐starved cells developed an increased heat resistance and prolonged starvation resulted in further protection. Viable, but non‐culturable cells were found during heat challenge implying that culture methods underestimate the recovery potential of these cells. Osmotically‐stressed Ps. fluorescens maintained a high viability, whereas culturability was rapidly lost. In contrast to starved cells, no protection against a subsequent heat challenge was found in osmotically‐stressed (4 or 18 h) cells, but an increased salinity of the heating menstruum alone resulted in elevated heat resistance.
Influence of culture conditions on growth and protective antigenicity of Clostridium chauvoei
Authors: Cortiñas Teresa Inés , Micalizzi Blas , de Guzman Ana María S.
Published: March 2008

. The effect of culture conditions on growth and immunogenicity of Clostridium chauvoei were examined. The pH control and partial feeding of the carbon source at high concentrations were beneficial for growth. The biomass yield was significatively improved, however the butanol concentration reached toxic levels hampering further growth. For each experimental condition the immunogenicity of cells was tested. No differences were found with cells obtained at different temperatures, but it decreased significatively with the partial supply of the carbon source and pH control.
Characterization of the catalase of the genus Porphyromonas isolated from cats
Authors: Love Daria N. , Redwin Judith
Published: March 2008

Crude cell extracts from members of the genus Porphyromonas isolated from catswere examined in SDS‐PAGE and nondenaturing PAGE. In eachof the species catalase activitywas detected as a single band with characteristics of typical bacterial catalases, i.e. each catalase functioned over a broad pH range (pH 5—10), was not inhibited by chloroform‐ethanol, did not possess detectable peroxidase activity, and was irreversibly inhibited by3‐amino‐1,2,4 triazole. The catalase enzyme of P. gingivalis VPB 3492, P. circumdentaria NCTC 12469T, P. salivosa VPB 3313 and VPB 3444 was inactivated at 71, 66·5, 63·5 and 57°C respectively. The molecular weights of the enzymes from P. gingivalis VPB 3492, P. circumdentaria NCTC 12469T, P. salivosa NCTC 11632T and P. salivosa VPB 3444 were 200000, 216000, 209000 and 200000 Da respectively.
Detection of low levels of specific Salmonella species by fluorescent antibodies and flow cytometry
Authors: McClelland Rosemary G. , Pinder A.C.
Published: March 2008

The use of fluorescently‐labelled monoclonal antibodies, with detection by multi‐parameter flow cytometry, was investigated for the rapid detection of salmonellas in pure cultures. Accurate detection of specific Salmonella serotypes was demonstrated down to levels of below 104 cells ml‐1 (within 30 min) and 1 cell ml‐1 (after 6 h non‐selective pre‐enrichment). This level of sensitivity was attainedeven in the presence of high levels of other bacterial species that would otherwise have interfered with the results. With combinations of different antibodies, each with a unique fluorescent label, simultaneous analysis for two species was possible.
Efficacy of four semi‐selective media for recovery of Xanthomonas campestris pv. campestris from tropical soils
Authors: Fukui Ryo , Arias R. , Alvarez R.
Published: March 2008

R. FUKUI, R. ARIAS AND R. ALVAREZ. 1994. Four semi‐selective media, CS20 ABN, aesculin—trehalose (ET), Fieldhouse—Sasser (FS), and starch—methionine (SM), were compared for efficacy in recovering Xanthomonas campestris pv. campestris from artificially and naturally infested soils. Recoveries of X. c. campestris from soils infested with relatively large populations were similar on the four media. The FS and ET media exhibited higher selectivity against background saprophytes, whereas enumeration of X. c. campestris on CS20 ABN or SM was often hampered by the overgrowth of background saprophytes. Among three starch‐containing media (CS20 ABN, ET and FS media), the zones of starch hydrolysis, characteristic of colonies of X. c. campestris, were most distinctive for FS medium. This allowed easier identification of the target colonies among numerous non‐target colonies in tests with soil containing smaller numbers of X. c. campestris. Although the starch zone was also distinctive on CS20 ABN, this medium was not as effective as FS because the starch zones were so large that neighbouring zones fused with each other and many saprophytes formed colonies within the zones. Overall, FS was most suitable for soil studies in terms of the consistent recovery of the pathogen, the selectivity against saprophytes, and the differentiation from non‐target organisms.
Purification and characterization of mitomycin C‐induced pectin lyase of Erwinia carotovora subsp. atroseptica strain SCRI 1043
Authors: Godfrey V. , Hyman L.J. , McMillan G.P. , Old D.C. , Pérombelon M.C.M.
Published: March 2008

Erwinia carotovora supsp. atroseptica strain SCRI 1043 produces pectin lyase (PNL) which degrades highly methyl‐esterified pectin by trans‐elimination when induced by DNA damaging agents such as mitomycin C. Purification of the enzyme (66.5‐fold) to homogeneity with 42.3% recovery was achieved by cation exchange chromatography on an S‐Sepharose fast flow column equilibrated to pH 8.5 with 20 mmol 1‐1 Tris buffer, followed by elution of the bound proteins with a 1 mol‐1 NaCl gradient. SDS‐PAGE and IEF‐activity staining analyses showed that the mol. wt and pI of the enzymes were 31 kDa and 9.4 respectively and only one isomer was present. The optimum pH and temperature were 8.0 and 35°C respectively, and divalent cations, 1.37 mmol 1‐1 Ca2+ and 1.37 mmol 1‐1 Mg2+, although not essential, stimulated enzyme activity by about four and six times respectively. The endo mode of action of PNL was determined by viscometry. PNL induction by mitomycin C was determined spectrophotometrically and by ELISA, and was concomitant with bacteriocin production and bacterial cell lysis. The purified enzyme caused rapid maceration of potato tuber discs and IEF‐activity staining of PNL in extracts of rotting tuber discs inoculated with strain SCRI 1043 showed that two isoenzymes were present, one corresponding to the enzyme produced in vitro and the other with a slightly higher pI.
An in‐vitro meat model for the immediate bactericidal effect of lactic acid decontamination on meat surfaces
Authors: van Netten P. , int Veld J. Huis , Mossel D.A.A.
Published: March 2008

An in‐vitro model of the lactic acid decontamination (LAD) of meat is described. As LAD is a disinfection rather than a preservation process the model is based on the inactivation kinetics of bacteria in a suspension of pork skin. The model takes account of interfering factors present in nature, such as microbial interactions, leaching of organic material from the meat surfaces and buffering activity.
Serological characterization of potato isolates of Erwinia carotovora subsp. atroseptica and subsp. carotovora using polyclonal and monoclonal antibodies
Authors: Alarcón B. , Gorris M.T. , Cambra M. , López M.M.
Published: March 2008

Serological, biochemical and physiological characteristics of 81 strains of Erwinia carotovora subsp. atroseptica (Eca) and 67 strains of subsp. carotovora (Ecc) from potato, isolated in Spain and from several international collections, have been studied. Ouchterlony double diffusion (ODD), indirect immunofluorescence (IIF) and indirect enzyme‐linked immunosorbent assay (ELISA) were the methods used. The antibodies were polyclonals from eight antisera prepared with Eca serogroup I and Ecc serogroup III and two monoclonal antibodies (MAbs), 4G4 from Spain and 4F6 from Canada, both prepared with Eca strains of serogroup I. Serogroup I for Eca and several serogroups for Ecc were the most commonly found in the collection studied. Serological relationships between Eca and Ecc independently of the serogroups were observed by IIF and ELISA using polyclonal antibodies. Common epitopes between all Eca and Ecc studied were detected. Both MAbs recognized epitopes in Eca strains of serogroups I and XXII in IIF and ELISA but they did not react with strains of other serogroups nor Ecc strains. The pattern of reaction against the strains assayed was rather similar but not identical indicating that they represent two different and well conserved epitopes. This study confirms the serological complexity of Ecc and Eca and gives information about the serological probes for detection of both subspecies.
Influence of pH and lactic acid concentration on Clostridium tyrobutyricum during continuous growth in a pH‐auxostat
Authors: Thylin I. , Schuisky P , Lindgren S. , Gottschal J. C.
Published: March 2008

The aim of this project was to establish the minimal inhibitory concentration (MIC) of lactic acid for growth of Clostridium tyrobutyricum. A pH‐auxostat was used to maintain a constant pH and to allow continuous growth at the highest possible rates at fixed, but adjustable concentrations of lactate. By raising the concentration of lactic acid and keeping the pH constant, the growth rate was shown to decrease linearly with increasing lactic acid concentration. The pKa of lactic acid, measured in the actual growth medium at 37°C, was 3.40 (±0.03). Based on this value, the MICundiss values for each pH were estimated. The MIC of total lactic acid (MICtot) ranged from 150 mmol l−1 to 1510 mmol l−1 at pH 4.6–6.25, respectively. The corresponding MIC values of undissociated lactic acid (MICundiss) ranged from 8.9 to 2.1 mmol l−1 at the same pH values. These results emphasize the importance of a rapid pH decrease and an equally rapid initial lactic acid fermentation of the ensilage, in order to sufficiently suppress clostridial growth.
The effect of sewage sludge treatment processes on oocysts of Cryptosporidium parvum
Authors: Whitmore T.N , Robertson L.J
Published: March 2008

T.N. WHITMORE AND L.J. ROBERTSON. 1995. The effect of common sewage sludge treatment processes on oocysts of the coccidian protozoan Cryptosporidium was evaluated in laboratory simulations. The ability of primary sewage sedimentation to remove Cryptosporidium oocysts was found to be poor. Thermophilic (55°C) aerobic digestion and sludge pasteurization at the same temperature were found to be effective treatments to inactivate Cryptosporidium oocysts. Approximately 10% of the oocyst population were found to be viable after 18 d exposure to mesophilic (35°C) anaerobically digesting sludge. The viability of Cryptosporidium oocysts decreased within the range 20–40% in sludge‐treated soil mesocosms over 30 d. The survival results obtained, however, indicated that oocysts would survive well beyond this period.
A numerical taxonomic study of fluorescent Pseudomonas strains isolated from natural mineral waters
Authors: Elomari M. , Coroler L. , Izard D. , Leclerc H.
Published: March 2008

M. ELOMARI, L. COROLER, D. IZARD AND H. LECLERC. 1995. Forty‐six strains of fluorescent pseudomonads, isolated from natural mineral waters, together with 12 strains from clinical material and 44 reference strains, were phenotypically classified by 281 characteristics. The data were processed by the Dice similarity coefficient and unweighted pair group algorithm with arithmetic averages. Eight clusters were defined at the 62% similarity level. Clusters I, II and IV were further divided into nine subclusters. Virtually all the mineral water strains fall into three groups: Ib (eight strains), Ha (14 strains) and V (16 strains). Subclusters Ib and IIa included natural mineral water strains only. Cluster V contained 13 mineral water strains and three culture collection strains of Pseudomonas fluorescens biovar III. DNA/DNA hybridization studies are needed to define the taxonomic status of these three groups within the genus Pseudomonas.
Differences in production of several extracellular virulence factors in clinical and food Aeromonas spp. strains
Authors: Pin Carmen , Marín M. Luisa , Selgas Dolores , García M. Luisa , Tormo J. , Casas Carmen
Published: March 2008

C. PIN, M.L. MARÍN, D. SELGAS, M.L. GARCÍA, J. TORMO AND C. CASAS. 1995. Production of several extracellular virulence factors (lipase, protease and haemolysin) was compared in 15 Aeromonas spp. isolated from faeces of patients with Aeromonas‐associated gastroenteritis and 81 strains isolated from food. Strains from food did not show differences in production of these factors when compared with strains isolated from faeces. However, if strains were considered in relation to autoagglutination (AA) character, the AA+ differed from AA‐ strains in lipase and protease production. Supernatant fluids of AA+ food and human strains showed 2·5‐fold more protease production than that observed in AA‐ strains. These two characteristics of certain Aeromonas strains could be related with the more virulent capacity.
Production and stability of pediocin N5p in grape juice medium
Authors: de Saad A.M. Strasser , Pasteris S.E. , de Nadra María C. Manca
Published: March 2008

The production and stability of pediocin N5p from Pediococcus pentosaceus, isolated from wine, were examined in grape juice medium. Maximum growth and higher titre (4000 U ml‐1) were observed at a initial pH of 7·5 and 30°C. The activity of the inhibitory substance was stable between pH values from 2·0 to 5·0 at 4° and 30°C. At pH 10·0 it was completely inactivated. When submitted to 30 min at 80°, 100° and 115°C, maximal stability was observed at pH 2·0. Ethanol up to 10% did not affect pediocin activity at acid pH, nor did 40–80 mg 1‐1 SO2, independently or combined with different ethanol concentrations, affect inhibitory activity.
New selective media for isolation of clostridia from faecal specimens
Authors: Fujisawa T. , Namba K. , Hirayama K. , Lee W.K. , Mitsuoka T.
Published: March 2008

Two selective media, novobiocin‐colistin agar (NCA) and colistin‐crystal violet agar (CCA), were developed for isolating clostridia from human and animal faeces. The basal medium was modified Eggerth‐Gagnon agar. The NCA medium contains novobiocin (8 μg ml‐1) and colistin (8 μg ml‐1) and the CCA medium contains colistin (10 μg ml‐1) and crystal violet (10 μg ml‐1). Nine faecal specimens were cultured. Clostridia isolated on these media were similar to those on non‐selective media, and higher than those isolated after heat treatment. However, more clostridial species were isolated on the new selective media compared with the non‐selective medium. These selective agars were particularly useful for enumerating and isolating clostridia from human faeces.
The effect of recovery conditions on the apparent heat resistance of Bacillus cereus spores
Authors: Gonzalez I. , Lopez M. , Mazas M. , Gonzalez J. , Bernardo A.
Published: March 2008

The effect of recovery media and incubation temperature on the apparent heat resistance of three ATCC strains (4342, 7004 and 9818) of Bacillus cereus spores were studied. Nutrient Agar (NA), Tryptic Soy Agar (TSA), Plate Count Agar (PCA) and Milk Agar (MA) as the media and temperatures in the range of 15–40°C were used to recover heated spores. Higher counts of heat injured spores were obtained on PCA and NA. The optimum subculture temperature was about 5°C below the optimum temperature for unheated spores. No significant differences in heat resistance were observed with the different recovery conditions except for strains 4342 and 9818 when MA was used as plating medium.

Large differences in D‐values were found among the strains (D100=0·28 min for 7004; D100=0·99 min for 4342; D100= 4·57 min for 9818). The 7004 strain showed a sub‐population with a greater heat resistance. The z values obtained for the three strains studied under the different recovery conditions were similar (7·64°C 0·25).
Effects of essential oil from mint (Mentha piperita) on Salmonella enteritidis and Listeria monocytogenes in model food systems at 4° and 10°C
Authors: Tassou C.C. , Drosinos E.H. , Nychas G.J.E.
Published: March 2008

The effect of mint (Mentha piperita) essential oil (0·5, 1·0, 1·5 and 2·0%, v/w) on Salmonella enteritidis and Listeria monocytogenes in a culture medium and three model foods; tzatziki (pH 4·5), taramosalata (pH 5·0) and pâté (pH 6·8), inoculated at 107 cfu g‐1, at 4° and 10°C for ca 1 week was studied. In the culture medium supplemented with the essential oil, no growth was observed over 2 d at 30°C determined by a conductance method with a Malthus 2000 growth analyser. Salmonella enteritidis died in tzatziki in all treatments and declined in the other foods except for pâté at 10°C as judged with viable counts. Listeria monocytogenes populations showed a declining trend towards the end of the storage period but was increased in pâté. Mint essential oil antibacterial action depended mainly on its concentration, food pH, composition, storage temperature and the nature of the micro‐organism.
Growth of food‐borne pathogenic bacteria in oil‐in‐water emulsions: I—Methods for investigating the form of growth
Authors: Parker Mary L. , Brocklehurst T.F. , Gunning P.A. , Coleman Heather P. , Robins Margaret M.
Published: March 2008

Methods are presented for investigating the site and form of growth of bacteria in model oil‐in‐water emulsions and in dairy cream. Following growth of the bacteria, the continuous aqueous phase is gelled using agarose and the oil phase removed using a mixture of chloroform and methanol. Using this method, the authors have found that Listeria monocytogenes, Salmonella typhimurium and Yersinia enterocolitica grow in the form of colonies in concentrated oil‐in‐water emulsions. Colonies of L. monocytogenes and Y. enterocolitica also form in artificially‐inoculated fresh and tinned dairy cream. If information about the precise site of growth is not required, the authors have discovered that intact colonies can be liberated from the model emulsions by dissolving away the oil phase with chloroform: methanol.
Bactericidal effect of bovine normal and immune serum, colostrum and milk against Helicobacter pylori
Authors: Korhonen H. , Syväoja E.‐L. , Ahola‐Luttila H. , Sivelä S. , Kopola S. , Husu J. , Kosunen T.U.
Published: March 2008

Serum and colostrum but not post‐colostral milk from non‐immunized Friesian cows was found highly bactericidal for Helicobacter pylori NCTC 11637. This bactericidal activity was destroyed by heating at 56°C for 30 min and restroed by the addition of fetal calf serum as a source of complement, indicating that the bactericidal effect was probably dependent on an antibody‐complement system. Systemic, serial immunization of non‐lactating, pregnant cows with H. pylori resulted in high specific antibody titres in serum and colostrum. No titres were found in post‐colostral milk, even after booster‐immunization during lactation. Immunization did not enhance the bactericidal activity of serum and colostrum, but increased it in post‐colostral milk. The bactericidal activity was not correlated with titres of specific antibody or with IgG concentrations.
Thermal inactivation kinetics of Bacillus subtilis spores suspended in buffer and in oils
Authors: Ababouch L.H. , Grimit L. , Eddafry R. , Busta F.F.
Published: March 2008

The heat resistance of Bacillus subtilis 5230 and A spores freeze dried and suspended in buffer or oils was investigated. As expected, spores were more resistant to heat when suspended in oils than in buffer. This was ascribed to the low aw of oils and to their content of free fatty acids. Linear survivor curves were obtained for spores suspended in buffer at 105°C or above and for B. subtilis A spores suspended in a vegetable oil. However, the survivor curves of the spores suspended in mineral oil (strain 5230) or olive oil (both strains) were concave upward with a characteristic tailing. The tailing could not be ascribed to spore clumping or to a specific heat injury that can be circumvented by Ca‐dipicolinate. It is possibly due to another mechanism of injury or to the activation at high temperature of a normally dormant germination system.
Pseudomonas tolaasii control by kasugamycin in cultivated mushrooms (Agaricus bisporus)
Authors: Geels F.P.
Published: March 2008

Pseudomonas tolaasii, causing brown blotch disease on the edible mushroom Agaricus bisporus, was effectively controlled by kasugamycin. An artificial infection was first established in the first flush, by inoculating the button‐sized mushrooms of the first flush with a suspension of Ps. tolaasii. A 1% aqueous solution of kasugamycin supplied on the button‐sized mushrooms of the second flush drastically reduced bacterial blotch symptoms on these mushrooms at picking stage. Disease incidence in the second flush in the control treatment (inoculated with Ps. tolaasii) was composed of 18% lightly, 29% moderately and 10% heavily affected mushrooms, which totalled up to 57% affected. The 1% kasugamycin treatment significantly reduced total disease incidence to only 9% (lightly) affected. Single sodium hypochlorite treatments showed no result.
Diversity of cellulolytic bacteria in landfill
Authors: Westlake K. , Archer D.B. , Boone D.R.
Published: March 2008

Nine of 37 cellulolytic bacterial isolates obtained from landfill waste could be easily differentiated on the basis of gross morphological characteristics. Four isolates were selected for further characterization and on the basis of initial results appear to be previously unidentified cellulolytic species of bacteria. An aerotolerant anaerobic, cellulolytic Clostridium and three obligately anaerobic cellulolytic Eubacterium isolates are described. The Clostridium has an unusually high pH optimum for growth of 7.7. The optimum temperature for growth is 50°C. The pH growth optimum of each of the Eubacterium isolates is around pH 7.0 while temperature optima are 37° 45° and 50°C for LFI, LF4 and LF5 respectively. Most isolates had growth optima in the thermophilic range. The ease with which apparently previously unidentified species could be isolated is a reflection of the unique and highly variable, heterogeneous environment within landfill waste.
Purification and properties of an alcohol dehydrogenase (HUADHII) from Hanseniaspora uvarum K5
Authors: Venturin C. , Zulaika J. , Boze H. , Moulin G. , Galzy P.
Published: March 2008

An alcohol dehydrogenase HUADHII was purified 43.2‐fold from Hanseniaspora uvarum K5. The enzyme was trimeric with subunits of mol. wt 42 kDa. The N‐terminal amino acid sequence of HUADHII has between 45 and 75% identity with part of the sequence of isoenzymes related to group I from Saccharomyces cerevisiae and Kluyveromyces lactis. C2–C4 alcohols and aldehydes were the preferred substrates. The presence of an’α’double bond increased the enzyme activity both for alcohols and aldehydes. It was significantly inhibited by metal‐binding agents and thiol reagents. Kinetic studies suggested that HUADHII catalyses the oxidation of ethanol by a random sequential mechanism. It appears that HUADHII, a cytoplasmic fermentative enzyme, is structurally and functionally similar to members of the group I alcohol dehydrogenases.
A simple in vitro model for growth control of bacterial biofilms
Authors: Hodgson A.E. , Nelson S.M. , Brown M.R.W. , Gilbert P.
Published: March 2008

The perfused biofilm fermenter was found to be unsuitable for the long‐term culture and growth rate control of Staphylococcus aureus and Pseudomonas aeruginosab biofilms. In a simplified approach, biofilms of these organisms were grown within Sorbarod filter plugs which were perfused with culture medium. Pseudo‐steady states were established which were stable over several days at which the growth rate of the biofilm was reproducible, measurable and significantly slower than in broth culture. Environmental scanning electron microscopy of dissected Sorbarods demonstrated an association of cells with the surfaces of individual cellulose fibres, and growth characteristic of biofilms. Relatively high cell numbers recovered from the Sorbarod model facilitated biochemical investigations of biofilm populations and cells released spontaneously from them.

SDS‐PAGE demonstrated significant differences between the protein profiles of biofilm and eluted populations, which include, in Staph. aureus, the repression of a 48 kDa protein and increased expression of a 21 kDa protein relative to planktonic controls cultured at equivalent growth rates. The paper demonstrates the suitability of the approach for the culture of biofilm samples which are suitable for biochemical analysis.
Characterization of mucoid Pseudomonas aeruginosa strains isolated from technical water systems
Authors: Grobe S. , Wingender J. , Trüiper H.G.
Published: March 2008

The occurrence of mucoid Pseudomonas aeruginosa strains was investigated in water samples and surface material from non‐clinical aquatic environments. Ten of 81 environmental isolates displayed a mucoid colony type after incubation at 36°C for 24 h on Pseudomonas Isolation Agar. The mucoid strains obtained exclusively from surfaces of technical water systems were characterized in terms of medium‐dependent expression of mucoid colonial phenotype, exoenzyme profile, pigment production and O‐antigen type. The mucoid strains secreted substantially higher quantities of carbohydrate and uronic acid‐containing material compared to non‐mucoid environmental isolates. Major slime components of the mucoid strains were identified as O‐acetylated alginates that contained higher proportions of mannuronate than guluronate monomer residues and were composed of blocks of poly‐mannuronate and poly‐mannuronate/guluronate, whereas blocks of poly‐guluronate were absent. The results suggest that surfaces in aquatic environments may represent a natural habitat for mucoid (i.e. alginate‐overproducing) strains of Ps. aeruginosa with properties similar to clinical mucoid strains.
Production of extracellular polysaccharides by Lactobacillus delbrueckii ssp. bulgaricus NCFB 2772 grown in a chemically defined medium
Authors: Grobben G.J. , Sikkema J. , Smith M.R. , de Bont J.A.M.
Published: March 2008

Lactobacillus delbrueckii ssp. bulgaricus NCFB 2772 produced an extracellular polysaccharide when grown in a chemically defined medium with glucose or lactose as the substrate carbohydrate. The isolated extracellular polysaccharide had a sugar composition of glucose, galactose and rhamnose in a ratio of 1:6.8:0.7. The production of extracellular polysaccharides increased at higher temperatures, but the bacterium rapidly lost its polysaccharide producing ability at 47°C. Production of polysaccharides was growth‐related: no polysaccharide production was found after growth had ceased. An excess carbohydrate did not result in increased polysaccharide production.
A method for estimation of population densities of ice nucleating active Pseudomonas syringae in buds and leaves of mango
Authors: Cazorla F.M. , Olalla L. , Torés J.A. , Pérez‐Garcí A. , Codina J.C. , de Vicente A.
Published: March 2008

Active ice nucleation strains of Pseudomonas syringae pv. syringae have been associated with a necrotic disease in mango trees growing in Málaga (southern Spain). In this paper a simple multiple‐tube test is described to estimate the number of active ice nucleation bacteria associated with plant tissues and, also from suspensions of isolated bacterial strains. This method is based on the most probable number technique developed for microbiological analysis of water. The tube test presented a higher detection sensitivity of active ice nuclei than the traditional drop‐freezing test, because a larger amount of plant material could be analysed routinely. Both methods demonstrated a similar accuracy. A high correlation was obtained between the tube test‐estimated number of ice nuclei and populations of Ps. syringae‐like organisms enumerated on King's agar B.
Methicillin‐resistant Staphylococcus aureus subtyping: interest of combined antibiotyping and esterase electrophoretic typing
Authors: Mangeney N. , Bakkouch A. , Pons J.‐L. , Dupeyron C. , Niel P. , Leluan G.
Published: March 2008

Ninety‐four methicillin‐resistant Staphylococcus aureus isolates (MRSA) were characterized by means of two typing methods, antibiotyping and esterase electrophoretic typing. Antibiotyping, recorded on the basis of susceptibility testing of 13 antimicrobial agents, allowed the description of 18 antibiotypes, four of which comprised 30, 14, 14 and 12 strains respectively. Esterase electrophoretic typing, based on esterase activity against seven synthetic substrates after polyacrylamide‐agarose gel electrophoresis, led to the description of 12 electrophoretic types, two of which were predominant with 60 and 20 strains respectively. The combined use of both typing methods yielded 32 combinations, three of which were predominant with 21, 12 and 11 strains respectively. A good differentiation of strains was achieved, particularly when the antibiotype was correlated to the electrophoretic type. Thus, the combination of antibiotyping with esterase electrophoretic typing may be proposed as a well‐suited method for the characterization of MRSA strains.
Ribotyping and plasmid profiling of Vibrio anguillarum serovar O2 and Vibrio ordalii
Authors: Tiainen T. , Pedersen K. , Larsen J.L.
Published: March 2008

One hundred and twenty‐nine strains of Vibrio anguillarum serovar O2 and 14 strains of Vibrio ordalii were ribotyped and examined for plasmid contents. A total of 35 different ribotypes were detected. The V. anguillarum serovar O2 strains were divided into 32 different ribotypes. The V. ordalii strains showed three different ribotypes, clearly distinct from those of the V. anguillarum strains.

Ribotypes were separated into seven clusters, of which one comprised the V. ordalii strains. Clustering of the strains indicated a genetic difference between North European and South European V. anguillarum O2 strains. Sero‐subgroups O2a and O2b shared ribotypes; however, three of the clusters did not include O2a strains.

All V. ordalii strains had a plasmid of 32 kb. This plasmid was not detected in any of the V. anguillarum strains. Seventeen different plasmid profiles with 17 different sized plasmids were detected among the V. anguillarum strains. Most of the plasmids were small (< 6 kb) and found in several strains. Except for one South European strain, plasmids were detected only in the North European strains of V. anguillarum O2.
Antibacterial polyphenols from olive oil mill waste waters
Authors: Capasso R. , Evidente A. , Schivo L. , Orru G. , Marcialis M.A. , Cristinzio G.
Published: March 2008

Olive oil vegetation waters (VW) were highly toxic to both phytopathogenic Pseudomonas syringae (Smith, Yung et al.) pv. savastanoi (Gram‐negative) and Corynebacterium michiganense (Gram‐positive) and showed bactericidal activity in their original concentration (in raw form). Among the main polyphenols, present in the waste waters, methylcatechol proved to be the most toxic to Ps. savastanoi at 10−4 mol 1−1, and also demonstrated bactericidal activity, while on Coryne. michiganense it was only slightly active; catechol and hydroxytyrosol were less active on Ps. savastanoi, but inactive on Coryne. michiganense; tyrosol and its synthetic isomers 1,2‐ and 1,3‐tyrosol were completely inactive on both bacteria. Among the derivatives of VW polyphenols considered, acetylcatechol and guaiacol were selectively toxic for Ps. savastanoi, while o‐quinone was strongly toxic for both bacteria. The minor carboxylic polyphenols of VW at 10−4 mol 1−1 were all inactive on the bacteria. VW, catechol, 4‐methylcatechol and the less abundant carboxylic polyphenols proved to be toxic on Hep2 human cells. Finally the possibility of using the active polyphenols in agriculture in an integrated pest management program for the protection of the olive plant is discussed.
Physiological responses of a methylotrophic bacterium after sudden shifts from C‐limited chemostat to C‐excess batch growth conditions
Authors: Gírio F.M. , Amaral‐Collaço M.T. , Attwood M.M.
Published: March 2008

The response of steady‐state continuous cultures of Methylobacterium sp. RXM to the addition of methanol pulses was studied. The increase of methanol concentration in the medium did not result in cell death under any of the conditions tested. When the growth rate of the steady‐state cultures was low (D= 0.046 h−1), the specific growth rate increased. When the concentration of methanol in the pulse was increased from 36 mmol l−1 to 280 mmol l−1, uncoupled growth occurred and the molar cell yield decreased. Conversely, steady‐state cultures at high growth rate (D= 0.2 h−1) showed a decrease in both specific growth rate and molar cell yield after the addition of the methanol pulses (32 and 164 mmol 1−1). For all conditions, formaldehyde and formate were excreted into the medium but the levels did not exceed 1.13 mmol 1−1 Slow‐growing cultures were characterized by cells with high derepressed specific activities of methanol dehydrogenase and low specific activities of formaldehyde and formate dehydrogenases, fast‐growing cells had lower specific activity for methanol dehydrogenase and higher activities of formaldehyde and formate dehydrogenases, resulting in the excretion of lower concentrations of formaldehyde and formate.

It is concluded that slow‐growing cultures are more stable than fast‐growing cultures for low methanol concentration fluctuations, and it is expected that maximum growth yields throughout the fermentation time are better achieved under the former conditions. However, for large fluctuations in the substrate concentration, the bacterial metabolic responses were identical both for slow‐growing and fast‐growing cultures.
A note on the development of a non‐aldehyde fixation technique for examining spores of Bacillus subtilis under the electron microscope
Authors: Knott A.G. , Hann A.C. , Russell A.D.
Published: March 2008

Various techniques were studied for fixing spores of Bacillus subtilis prior to examining them by transmission or scanning electron microscopy. A non‐aldehyde technique employing carbodiimide in cacodylate buffer produced excellent results and could be of value in studying the cytological changes produced in spores exposed to inimical treatments.
In vitro inhibition of Helicobacter pylori NCTC 11637 by organic acids and lactic acid bacteria
Authors: Midolo P.D. , Lambert J.R. , Hull R. , Luo F. , Grayson M.L.
Published: March 2008

In this Study the effects of both pH and organic acids on Helicobacter pylori NCTC 11637 were tested. Lactobacillus acidophilus, Lact. casei, Lact. bulgaricus, Pediococcus pentosaceus and Bifidobacterium bifidus were assayed for their lactic acid production, pH and inhibition of H. pylori growth. A standard antimicrobial plate well diffusion assay was employed to examine inhibitory effects. Lactic, acetic and hydrochloric acids demonstrated inhibition of H. pylori growth in a concentration‐dependent manner with the lactic acid demonstrating the greatest inhibition. This inhibition was due both to the pH of the solution and its concentration. Six strains of Lact. acidophilus and one strain of Lact. casei subsp. rhamnosus inhibited H. pylori growth where as Bifidobacterium bifidus, Ped. pentosaceus and Lact. bulgaricus did not. Concentrations of lactic acid produced by these strains ranged from 50 to 156 mmol 1−1 and correlated with H. pylori inhibition. The role of probiotic organisms and their metabolic by‐products in the eradication of H. pylori in vivo remains to be determined.
Characterization and species recognition of Lactobacillus plantarum strains by restriction fragment length polymorphism (RFLP) of the 16S rRNA gene
Authors: Johansson M.‐L. , Molin G. , Pettersson B. , Uhlén M. , Ahrné S.
Published: March 2008

Twenty‐one strains, labelled Lactobacillus plantarum or Lact. plantarum‐like, and isolated from different natural sources, were characterized by restriction fragment length polymorphism (RFLP) of the 16S rRNA gene using HindIII and EcoRI cleaved chromosomal DNA, together with Lact. plantarum ATCC 14917T, Lact. pentosus ATCC 8041T, Lact. plantarum ATCC 10776 and Lact. plantarum ATCC 8014. The fermentation patterns on API 50CH were recorded at 30°C and 37°C for all strains. The phenotypes were heterogeneous, and the ability to ferment 17 of the 49 carbohydrates varied. The fermentation of some carbohydrates, for example D‐raffinose and D‐arabitol, was temperature‐dependent. Strains having identical API profiles were separated by the plasmid profile. All strains but one (affiliated to Lact. casei) had identical 16S ribosomal DNA sequences (Lact. plantarum/Lact. pentosus). The RFLP study resulted in identical ribopatterns for 17 of the strains, including the type strain of Lact. plantarum (pattern A1). Four strains had related fragment patterns to that of Lact. plantarum sensu stricto; three of these strains had more than 60% DNA: DNA homology to the type strain of Lact. plantarum, and one had less than 50% DNA: DNA homology to Lact. plantarum ATCC 14917T. Two strains had fragment patterns similar to the type strain of Lact. pentosus, and they had more than 80% DNA: DNA homology to Lact. pentosus ATCC 8041T. One of the Lact. pentosus strains shared one band with the A1 pattern. The ribopatterns of Lact. plantarum were homogeneous (identical for 85% of the strains), irrespective of phenotype and source of isolation. RFLP of the 16S rRNA genes using EcoRI and HindIII might be used for species recognition of Lact. plantarum, but seems less suitable for strain typing.
Seeds as natural matrices for immobilization of Aspergillus niger mycelium producing pectinases
Authors: Fiedurek J. , Szczodrak J. , Rogalski J.
Published: March 2008

J. FIEDUREK, J. SZCZODRAK AND J. ROGALSKI. 1995. A simple method for the immobilization of Aspergillus niger mycelium producing polygalacturonase (PG) and pectinesterase (PE) is described. Fungal conidia were immobilized on wheat, rye, barley, peas, buckwheat and mustards seeds. Spongy mycelia overgrowing the seed surfaces on mineral medium with pectin produced extracellular PG and PE; the highest production was reached on the wheat carrier. Some of the variables influencing the enzymatic activity have been optimized. After every 24 h, a culture liquid with 6˙8–7˙8 U of PG ml−1 and 7˙0–10˙1 U of PE ml−1 was obtained. This procedure also made possible repeated batch enzyme production and, as many as eight subsequent 24‐h batches could be fermented by using the same carrier without any loss of PG activity. The addition of sodium orthovanadate (1 mmol) into the medium with pectin caused a significant increase in PG and PE activity produced by free cells of A. niger (by 1˙59‐fold and 1˙67‐fold respectively), and only 0˙47‐fold of PG activity in case of the immobilized mycelium.
Production of poly‐β‐hydroxybutyrate by Azotobacter chroococcum H23 in chemically defined medium and alpechin medium
Authors: Martinez‐Toledo M.V. , Gonzalez‐Lopez J. , Rodelas B. , Pozo C. , Salmeron V.
Published: March 2008

M.V. MARTINEZ‐TOLEDO, J. GONZALEZ‐LOPEZ, B. RODELAS, C. POZO AND V. SALMERON. 1995. Azotobacter chroococcum H23 is able to produce large amounts of poly‐β‐hydroxybutyrate (PHB) during growth in chemically‐defined medium (N‐free or with NH+4) and alpechin (wastewater from olive oil mills) medium. Polymer production was not dependent of the nutrient limitation. Strain H23 was capable of accumulating PHB up to 70% of the cell dry weight after 24 h incubation in chemically‐defined media containing 1% glucose, fructose, mannitol, saccharose or starch. Azotobacter chroococcum grown on NH+4‐medium supplemented with alpechin formed PHB up to 50% of the cell dry weight after 24 h, suggesting that these wastes could be utilized by Azotobacter as a cheap substrate for producing PHB.
Partial purification and characterization of bacteriocin from Yersinia kristensenii
Authors: Toora S.
Published: March 2008

A raw milk bacterial isolate, identified as Yersinia kristensenii was found to produce a bacteriocin which was inhibitory to Yersinia enterocolitica but not to other selected species of Yersinia or Gram‐negative bacteria. Maximum production of bacteriocin was obtained when the organism was grown in shake culture at 28°C. Mitomycin C at a concentration of 0.5 μg ml‐1 induced bacteriocin production. The bacteriocin was partially purified and characterized by ammonium sulphate fractionation and gel filtration. The bacteriocin was completely inactivated when treated with proteolytic enzymes (trypsin and chymotrypsin). Bacteriocin activity was heat‐resistant and it retained some of its activity after 5 min at boiling temperature. A total of 15 bacteriocin sensitive‐suspected food isolates were further identified biochemically as Yersinia enterocolitica and a non‐sensitive isolate was identified as Yersinia intermedia.
Isolation of insect pathogenic bacteria, Providencia rettgeri, from Heterorhabditis spp.
Authors: Jackson T.J. , Wang Huayan , Nugent Miriam J. , Griffin Christine T. , Burnell Ann M. , Dowds Barbara C.A.
Published: March 2008

Nematodes of the genus Heterorhabditis carry bacteria of the genus Photorhabdus into insects including pests of horticultural crops. The bacteria kill the insect and provide conditions which allow for the growth and development of the nematodes. It is reported here that the majority of Heterorhabditis spp. strains tested contained a second bacterial species which was identified as Providencia rettgeri. Injection of the bacteria into waxmoth larvae showed that P. rettgeri was at least as pathogenic as Photorhabdus sp. K122. Both had LD50 values of less than one bacterial cell/larva, but P. rettgeri killed the insects at a considerably faster rate than K122 at both 28°C and 9°C. Since Photorhabdus kills very slowly at low temperatures, it appeared that P. rettgeri might be a better pest control agent under these conditions. However, P. rettgeri was not pathogenic when carried into insect larvae by the nematode, indicating that the nematode suppressed either its release or pathogenicity. It will be necessary to find ways of bypassing or inhibiting this suppression for P. rettgeri to fulfil its potential in pest control.