bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of oxygen concentration on dinitrogen fixation and volatile fatty acid production by Clostridium butyricum growing in association with fungi on cellulose and on wheat straw
Authors: Chapman S.J. , Veal D.A. , Lynch J.M.
Published: March 2008

Clostridium butyricum was grown with cellulolytic fungi on the substrates wheat straw and cellulose at a range of oxygen concentrations. The straw was not sterile and was inoculated with Sodaria alcina while the cellulose was sterile and was inoculated with Trichoderma harzianum as examples of cellulolytic organisms. The straw subsequently developed a mixed fungal population. Dinitrogen fixation was only significant at a reduced oxygen concentration: optima being 9.3 and 2.3% O2 for the straw and cellulose experiments, respectively. The efficiencies of N, fixation were 6 mg N per g straw decomposed and 2.3 mg N per g cellulose decomposed and N, fixation occurred only in the presence of significant cellulolysis. Both acetate and butyrate formation increased as the oxygen concentration decreased. With cellulose as a substrate, their formation correlated with a decrease in pH and an increase in final numbers of Cl. butyricum. The thickness of the anaerobic zone at the aerobic/anaerobic interface was linearly related to the square root of the oxygen concentration at the surface of the interface.
Effect of acidic pH and salt on acid end‐products by Lactobacillus plantarum in aerated, glucose‐limited continuous culture
Authors: Bobillo Mercedes , Marshall Valerie M.
Published: March 2008

In aerated, glucose‐limited continuous culture, Lactobacillus plantarum altered its metabolic pathways of acid production in response to changes in environmental pH. Under acidic conditions, acetate and L‐lactate production decreased with decreasing pH, whereas levels of D‐lactate increased. In the presence of 6% NaCl, acetate and lactate production continued, but no acetate was detected at pH 4.5.
Cellulase production and activity by Trichoderma sp. A‐001
Authors: Gashe B.A.
Published: March 2008

Trichoderma species A‐001 was grown on various carbon and nitrogen sources supplemented with surfactants on shake cultures. Although the degree of growth was variable, the organism grew on all carbon substrates. Large amounts of the cellulase enzyme components were released into the growth medium during growth on filter paper. In the filter paper containing medium, the organism produced 167 U/ml of carboxymethylcellulase (CMCase), 18 U/ml of filter paper activity (FPase) and 49 U/ml of beta‐glucosidase activity (BGDase). Wheat straw and grass were better carbon sources than cotton or barley husks. Nitrogen in the form of KNO3 was better than NH4Cl or urea in facilitating the production of cellulase. Of the surfactants used, Tween‐80 at 0.2% concentration in the medium increased the production of cellulase several‐fold. All the cellulase components were optimally active in the assay at pH 5.5 and 60°C. CMCase and FPase lost 20–33% of their activities when kept at 60°C for 4 h before assaying. On the other hand, BGDase was moderately stable; it lost only 37% of its activity when maintained at 70°C for 4 h.
A multiple logistic model for predicting the occurrence of Campylobacter jejuni and Campylobacter coli in water
Authors: Skjerve E. , Brennhovd O.
Published: March 2008

A multiple logistic regression model was established to predict the occurrence of Campylobacter jejuni/coli, related to index bacteria such as faecal coliforms, faecal streptococci, and sulphite‐reducing clostridia, in a water source in southern Norway. The fitted model indicated that faecal coliforms were strong predictors for C. jejuni/coli, although the water temperature also had a strong influence on results. Sulphite‐reducing clostridia, faecal streptococci, and season of the year had no significant influence on the results, in spite of their apparent predictor value as separate variables. The model employed offers a new approach to the relationship between index bacteria and the occurrence of pathogenic bacteria in water. Similar models can also be established in general food microbiology.
Synthesis of lipopolysaccharide by Escherichia coli cells recovering from sublethal heat stress
Authors: Tsuchido T. , Takeuchi A. , Takano M.
Published: March 2008

Escherichia coli cells exposed to a sublethal heat treatment at 55°C for 15s synthesized lipopolysaccharide during their recovery period after heat stress. As chloramphenicol at least partly inhibited the synthesis of lipopolysaccharide, it is suggested that its synthesis might be in part due to the lipopolysaccharide‐synthesizing enzymes produced de novo. The results obtained coincided with our previous finding that the permeability barrier function was repaired by heat‐stressed cells.
Fibrobacter succinogenes S85 has multiple xylanase genes
Authors: Malburg L.M. , Smith D.C. , Schellhorn H.E. , Forsberg C.W.
Published: March 2008

Four distinct DNA fragments encoding xylanase activities, pBX1.2, pXC30.2, pX14 and LX31, were cloned from plasmid and γ libraries constructed using genomic DNA from Fibrobacter succinogenes S85. pBX1.2 contained an insert which was homologous, and mapped similarly to that previously cloned in pBX1 while the three remaining clones pX14, pXC30 in plasmids, and LX31 in lambda, represented new xylanase activities. The X14 xylanase was a 73 kDa exo‐type xylanase, which was exported to the periplasm of the Escherichia coli host, and produced large quantities of xylose and xylobiose from oat spelt xylan. The XC30 xylanase, also exported in E. coli, was a 77 kDa protein which exhibited both xylanase and endoglucanase activities, and a low cellobiosidase activity. The LX31 enzyme was a 58 kDa endoxylanase that produced a mixture of xylooligosaccharides. Zymograms of isoelectric focusing gels showed that the X14 xylanase had a neutral pI, XC30 contained acidic, neutral and basic enzymic components, while BX1 and LX31 were acidic. These results indicate that, in addition to the many other elements of its polysaccharide‐degrading repertoire, F. succinogenes S85 possesses at least four distinct xylanases.
Microflora of the aerobic preservation of directly brined green olives from Hojiblanca cultivar
Authors: Gonzalez M.J. Fernández , García P. García , Fernández A. Garrido , Quintana M.C. Durán
Published: March 2008

New procedures for the preservation stage of ripe olives from Hojiblanca cultivar were studied. An aerobic fermentative process was used with initial pH correction (0.3% acetic acid) and various NaCl concentrations: 6, 3 and 0% (w/v) in tap water. Treatments were carried out at industrial level and the spontaneous changes monitored. At initial salt concentrations of 6 and 3% (w/v) NaCl, pH rose progressively, reaching 4.3 at equilibrium maintaining during this period a constant free lactic acidity of around 0.4% (w/v). When the initial solution was tap waste, however, the pH decreased rapidly to stabilize at about 3.7, and lactic acidity increased continuously to reach values over 1% (w/v) at the end of the preservation process. In all treatments aeration effectively purged the carbon dioxide from the preservation brines, preventing shrivelling of olives. The microbial growth was strongly influenced by the initial NaCl concentration. At 6 and 3%, only yeasts grew, the most abundant being Pichia membranaefaciens, P. vini, P. fermentans and Hansenula polymorpha. However, when there was no NaCl, lactic acid bacteria colonized the solution. Lactobacillus plantarum and Pediococcus inopinatus were the only species found. In this case there was a co‐existence between yeasts and lactic acid bacteria. As the treatment that supported lactic acid bacteria achieved the best final pH and acidity for olive stability, it may help to overcome the obstacles to a lactic fermentative process during the preservation stage of ripe olives from the Hojiblanca cultivar.
Isolation and enumeration of Serratia entomophila—a bacterial pathogen of the New Zealand grass grub, Costelytra zealandica
Authors: O'Callaghan M. , Jackson T.A.
Published: March 2008

Several agar media were tested for their use in a selective isolation and identification scheme for Serratia entomophila, a bacterium causing amber disease of the New Zealand grass grub, Costelytra zealandica (White). Soil dilutions were plated on caprylate thallous agar (CTA), selective for Serratia spp. Most strains of Ser. entomophila grew well on CTA; the mean efficiency of colony formation on CTA was 94 ± 3% of that on a non‐selective medium. The identity of colonies growing on CTA was determined on the basis of their growth reactions on DNase‐toluidine blue agar, adonitol agar and itaconate agar. Serratia entomophila could be distinguished from other Serratia spp. found in New Zealand soils, in particular Ser. proteamaculans, another causal agent of amber disease of grass grub. The identification scheme allowed the selective recovery of Ser. entomophila from field soils containing a diverse microflora.
Relationship between Lactococcus lactis subsp. lactis 952, an industrial lactococcal starter culture and strains 712, ML3 and C2
Authors: Lucey Mary , Daly C. , Fitzgerald G.
Published: March 2008

Lactococcus lactis subsp. lactis 952, used as a component of a cheese starter culture, was found to be closely related to the 712/ML3/C2 group of strains. Plasmid profiles of the four isolates were very similar and factory phages isolated against strain 952 could produce plaques on all the other strains at the same titres. Treatment with mitomycin C failed to induce phage from strain 952 although homology was observed between φT712 and the chromosome of strain 952. Pulse field gel electrophoresis of the four strains revealed only minor differences in their genomic DNA. The clumping phenomenon observed during lactose transfer in strains 712 and ML3 was also evident in strain 952. The ability of strain 952 to mobilize non‐conjugative vectors such as pGB301 was also examined and analysis of pGB301 transconjugants revealed that some contained novel enlarged plasmids not present in either the donor or the recipient. Preliminary characterization of these enlarged plasmids suggested the involvement of a sex factor type element in strain 952.
Antibacterial activity of Lactobacillus strains isolated from dry fermented sausages
Authors: Vignolo Graciela M. , Suriani F. , Holgado Aida Pesce de Ruiz , Oliver G.
Published: March 2008

One hundred strains of lactic acid bacteria isolated from dry cured sausages were tested for antagonistic activity against a set of test strains. Nine of 52 strains of Lactobacilus casei and three of 48 strains of Lact. plantarun produced inhibition zones against the indicator species. The substance excreted by Lact. casei CRL 705 was active against Lact. plantarum, Listeria monocytogenes, Staphylococcus aureus and a wide range of Gram‐negative bacteria. The activity of the antibacterial compound from Lact. casei CRL 705 was destroyed by papain, trypsin and pepsin, but was resistant to heat (100°C for 20 min), lysozyme and catalase. The agent was produced during the growth cycle and when the concentrated and neutralized supernatant fluid was added to a fresh culture of sensitive cells it produced a rapid inactivation. A decrease in optical density (O.D.) over time, indicative of cell lysis, was also observed. These characteristics allowed us to identify the inhibitory compound as a bacteriocin which we termed Lactocin 705.
The effects of medium and rate of freezing on the survival of chlamydias after lyophilization
Authors: Theunissen J.J.H. , Stolz E. , Michel M.F.
Published: March 2008

The effects of suspension media and rate of freezing on the survival of Chlamydia trachomatis LGV2 and Chlamydia pneumoniae after lyophilization were assessed. The highest loss in infectious elementary bodies (EBs) occurred during lyophilization. The survival was higher after freezing at a rate of 1°C min‐1 and lyophilization than that after rapid freezing at ‐ 70°C or ‐ 196°C. The recovery (± 5%) was higher when fetal calf serum (FCS) containing glucose, saccharose or lactose were used as lyophilization media than that (0.5–3%) when yolk‐sac, skimmed milk or phosphate buffer containing sucrose, glutamine and 10% FCS (SPG) were used. After lyophilization, the survival was not affected in the tested range from 104 to 5 times 106 inclusion‐forming units (ifu) ml‐1 prior to freezing. After storage for 4 months at 4°C, the numbers of ifu of both Chlamydia serovars that were recovered were identical to the numbers of ifu immediately after lyophilization. It was concluded that chlamydias can be stored and transported in lyophilized form. However, a loss of 95% in infectious EBs should be taken into account.
Binding and degradation of lectins by components of rumen liquor
Authors: Baintner K. , Duncan Sylvia H. , Stewart C.S. , Pusztai A.
Published: March 2008

The binding of 15 different plant lectins to feed particles and microbes in rumen liquor, and their degradation were studied in vitro. The rate of degradation assessed from the label released when radioactive iodine‐labelled lectins were incubated with rumen liquor conflicted with the rates calculated from measurements of the survival of the antigenic structure (immuno‐rocket electrophoresis) or the biological function (haemagglutination) of the lectins. Thus solubilization of the radioactive label indicated that Concanavalin A (Con A), but not the soyabean agglutinin, SBA, or kidney bean phytohaemagglutinin, PHA‐E3L, was stable to rumen proteolysis. In contrast, both SBA and PHA‐E3L were shown by immuno‐rocket electrophoresis or haemagglutination tests to be highly resistant to breakdown, while the degradation of Con A proceeded at a constant slow rate under the same conditions. This was in accord with the previously established general stability of lectins in the gut of single‐stomach animals.

Of the 15 lectins, SBA, favin (Vicia faba lectin) and Con A were bound by hay and the particle fraction of rumen liquor. This was, in part, specific and reversible in the presence of appropriate sugars. Most pure bacterial strains preferentially bound lectins with specificity for glucose/mannose (favin and Con A), while rumen fungi reacted with SBA. The level of binding was low with other lectins. However, inter‐strain differences of lectin‐binding were found in Selenomonas ruminantium and Ruminococcus flavefaciens.

Clearly, as some lectins were not fully degraded in the rumen, they could be expected to depress the utilization of the diet not only in single‐stomach animals but, possibly, also in ruminants.
Characterization and classification of virulent lactococcal bacteriophages isolated from a Cheddar cheese plant
Authors: Casey C.N. , Morgan E. , Daly C. , Fitzgerald G.F.
Published: March 2008

C.N. CASEY, E. MORGAN, C. DALY AND G.F. FITZGERALD, 1993. Twenty‐two bacteriophages, isolated from cheese‐vat whey samples over a period of 4 years, were found to be active against one or more of four different strains of Lactococcus lactis subsp. cremoris used in a defined strain starter system in an Irish Cheddar cheese factory. All the phages were small isometric‐headed with non‐contractile tails, a baseplate and a collar; they had genome sizes of approximately 30 kb, and belonged to a single DNA hybridization group. All 22 phages could be classified into four distinct groups based on restriction analysis which overlapped perfectly with those based on host range. Each group of phage examined showed cross‐reactive host ranges. None of the phage DNAs hybridized to the chromosomes of any of the seven cultures used in the factory during the four cheesemaking seasons, and neither could phages be induced from any of the strains by mitomycin‐C or ultraviolet light treatment.
Digoxigenin‐labelled inv‐ and ail‐probes for the detection and identification of pathogenic Yersinia enterocolitica in clinical specimens and naturally contaminated pig samples
Authors: Goverde Rosalina L.J. , Jansen W.H. , Brunings H.A. , Huis in‘t Veld J.H.J. , Mooi F.R.
Published: March 2008

A non‐radioactive colony hybridization method was developed for the rapid detection of Yersinia enterocolitica in primary isolates and for differentiation between pathogenic and non‐pathogenic strains. The method is based on, respectively, the presence of the inv‐locus in all Yersinia spp. and the presence of the ail‐gene in pathogenic Y. enterocolitica only. Hybridization results with ail‐probes of 132 strains of Y. enterocolitica were in good agreement with pathogenicity phenotypes as indicated by a tissue culture invasion (TCI) assay and by serotyping. All TCI+ strains and only two TCI‐ strains were positive by hybridization with ail. Hybridization results with inv‐ or ail‐probes of 150 primary isolates of human, animal or slaughterhouse origin were compared with those of conventional methods to detect and identify Y. enterocolitica. All samples that were positive for Yersinia spp. by cultivation (four of 66) or were positive for pathogenic Y. enterocolitica by cultivation and serotyping (six of 84) were also positive by hybridization with, respectively, the inv‐ or ail‐probe. In three slaughterhouse swab samples, in which Yersinia spp. were not detected by cultivation (2%), strong positive hybridization signals were obtained with the inv‐ and/or ail‐probe. Four other swab samples which were negative by cultivation produced weak positive signals by hybridization with inv‐ and/or ail‐ probes. These results indicate that the method can be used for (1) the identification of pathogenic Y. enterocolitica isolates and (2) the detection of Yersinia spp. in primary isolates of naturally contaminated samples.
Some factors affecting airborne survival of Pseudomonas fluorescens indoors
Authors: Handley B.A. , Webster A.J.F.
Published: March 2008

The effect of relative humidity (RH) on the airborne survival of a Pseudomonas fluorescens strain was studied at 20, 40, 60 and 80% RH indoors. The aero‐stable spore of Bacillus subtilis subsp. niger, used as a tracer of physical losses was compared with a light scattering particle counter, as there were doubts about the reliability of the spore as tracer. The Rion counter was validated before use and found to give a good estimate of relative physical losses providing spray suspensions contained between 107 and 109 cfu ml−1 cells and that the humidity was not more than 80% RH. Pseudomonas fluorescens, strain P+ S+, suspended in distilled water survived best at mid humidities and least at 80% RH. When suspended in 1% glycerol there was an apparent ‘increase’ in viability after an initial rapid reduction. This was thought to be due to delay in equilibration of glycerol in the cell membrane after concentration on dehydration. The cells were thought to be unstable and sensitive to the stress of rehydration before equilibration occurred. The findings are discussed in relation to Cox's theories of outer membrane damage on aerosolization.
Isolation and attempted introduction of sugar alcohol‐utilizing bacteria in the sheep rumen
Authors: Wallace R.J. , Walker Nicola D.
Published: March 2008

R.J. WALLACE AND N.D. WALKER. 1993. Bacteria that use sorbitol, xylitol, maltitol and dulcitol (galactitol) were isolated from the sheep rumen following enrichments in which bacteria were grown in rumen fluid medium where the sugar alcohol was the only added energy source. Only isolates obtained with sorbitol and maltitol grew sufficiently rapidly to be considered for enrichment by the sugar alcohol in vivo. Isolate SS2, a strain of Selenomonas ruminantium var. lactilytica which grew on sorbitol at 0.87 h‐1 was selected for further study and a rifampicin‐resistant mutant, SS2/R5, was isolated to facilitate tracking in the mixed population. Despite an initial transient increase in numbers, a significant population of S. ruminantium SS2/R5 failed to establish in sheep which were dosed twice daily with 10 g of sorbitol. Continuous infusion of sorbitol increased numbers only slightly compared with twice‐daily dosing. In vitro experiments indicated that strain SS2/R5 grew less well in the presence of other rumen organisms, particularly ciliate protozoa, than in pure culture. Furthermore, the concentration of sorbitol in vivo was lower than predicted from in vitro experiments, indicating that sorbitol was absorbed rapidly from the rumen. Similar observations were made with xylitol, dulcitol and maltitol. Proposed enrichment strategies that use sugar alcohols or other materials to support the growth of introduced bacteria will thus have to take account of the combined problems of microbe‐microbe interactions and the loss of the compounds by absorption from the rumen.
The effects of βbT‐lactams on the isoelectric focusing of βbT‐lactamases
Authors: Payne D.J. , Amyes S.G.B.
Published: March 2008

A range of concentrations of ceftazidime (4–64 mg I‐1) was shown to cause no induction of the TEM‐1 and TEM‐5 β‐lactamases produced by Escherichia coli Nb. Increasing the concentration of ceftazidime in cultures of E. coli Nb caused a concomitant increase in the intensity of a satellite band of pI 5.2. The same increase in this satellite band was observed when ceftazidime was added to cell‐free β‐lactamase peparations from E. coli Nb and the separate addition of 11 different β‐lactams to TEM‐1 showed that each compound produced its own unique pattern of satellite bands. In addition, the mixing of ceftazidime with TEM‐1 and 13 other TEM‐derived β‐lactamases caused a similar satellite band to be observed but ceftazidime did not have the same effect on PSE or SHV β‐lactamases. Consequently, the addition of ceftazidime to a β‐lactamase preparation prior to isoelectric focusing (IEF) may help to verify if a particular β‐lactamase is TEM‐derived. Purification of the satellite bands by electrodialysis and their subsequent re‐focusing demonstrated that the ceftazidime‐induced satellite bands can revert to a protein which has a pI similar to the parent band, illustrating the possible reversibility and dynamic nature of β‐lactamase satellite bands on IEF. These results enable a better interpretation to be made of β‐lactamase satellite bands observed on IEF.
Adaptation of a strain of Spirulina platensis to grow in cobalt‐and iodine‐enriched media
Authors: Singh Y. , Kumar H.D.
Published: March 2008

Cobalt‐ and iodide‐enriched (adapted, tolerant) strains of the protein‐rich cyanobacterium, Spirulina platensis, were produced by repeated sub‐culturing in increasing concentrations of the two trace elements. The strains enriched with cobalt and iodide showed higher uptake of these elements than the controls. The LD50 values for the parent and cobalt‐adapted strains were 95 and 231 μmol 1‐1 Co2+, respectively. Likewise, the LD50 values for parent and iodide‐adapted strains were 12 and 42 mmol‐1 I‐1. The carotenoid : chlorophyll a ratio of the parent strains increased after cobalt addition. The cobalt‐adapted strain showed a much higher ratio than the cobalt‐grown parent (sensitive) cells which remained unchanged after cobalt addition.

Intracellular Co2+ uptake by the cells was concentration‐dependent and followed Michaelis‐Menten kinetics with saturation in uptake occurring in the parent and adapted strains at 126 and 189 μmol 1‐1 Co2, respectively. At saturating concentrations, the maximum Co2+ uptake was 39.73 and 158.43 nmol Co2+ mg‐1 protein, respectively for the parent and adapted strains. The adapted strain also showed greater cobalt adsorption. The Km of intracellular Co2+ uptake was lower in the case of adapted cells as compared with the parent, whereas Vmax showed an opposite trend. Thus, the adapted cells appear to be more efficient than the parent strain in intracellular uptake of cobalt. Differences between kinetic constants of both the strains suggest that the strains may be physiologically different. Likewise, iodide uptake was significantly higher in iodide‐adapted cells than in controls.
The metabolism of sugar and malic acid by Leuconostoc oenos: effect of malic acid, pH and aeration conditions
Authors: Firme M. Paula , Leitão M. Cristina , Romão M. Vitória San
Published: March 2008

The co‐metabolism of sugars by Leuconostoc oenos was studied under different environmental conditions. Under aerobic conditions, growth and sugar metabolism were poorer than under CO2 or N2 atmosphere and acetic acid accumulated to a larger extent. Glycerol was found in the aerobic cultures while erythritol was detected under N2 or CO2. When medium conditions make growth difficult (low pH, aerobic conditions, low nutrients), sugars were only slightly metabolized and growth was very slow while malic acid was rapidly and completely degraded, leading to an increase in the yATP. Aeration effects on the malic acid degradation rate depended on the nutrients and carbon source in the medium. Malic acid clearly stimulated bacterial growth, allowing an increase in the molar growth yields and ATP production. The results suggest that under adverse conditions cells are not able to grow and malic degradation supplies additional energy production.
Identification of lactic acid bacteria isolated from Portuguese wines and musts by SDS‐PAGE
Authors: Patarata L. , Pimentel Maria Serpa , Pot B. , Kersters K. , Faia Arlete Mendes
Published: March 2008

Thirty‐two strains were isolated from spoiled port wines, from musts and from various styles of young, Northeastern Portuguese red table wines that had undergone spontaneous malolactic fermentation. Comparison of their SDS‐PAGE whole‐cell protein patterns with an SDS‐PAGE database of lactic acid bacteria indicated that the isolates were members of the species Leuconostoc oenos or Lactobacillus paracasei subsp. paracasei. The latter were found in low acidity table wines and in port wine. The isolation of Lactobacillus paracasei strains from wines indicates the importance of using known strains for wine deacidification because spontaneous malolactic fermentation of table wines can occur from an indigenous flora, adapted to the particular composition of the wine.
A variable response of degrading bacteria to phosphorus added to natural water
Authors: Ramadan M.A.
Published: March 2008

The effect of inorganic phosphorus (P) on the degradation of 10 mg l‐1 of para‐nitrophenol (PNP) or 2,4‐dichlorophenoxyacetic acid (2,4‐D) by three test bacteria inoculated into Nile water samples was investigated. The response of the organisms to P depended mainly on their affinity for the available P. Thus, Corynebacterium sp, at an initial density of 3.3 times 104 cells ml1 readily degraded 10 mg l‐1 of PNP in filter‐sterilized Nile water supplemented with 22.8 mg l‐1 of P. The same effect was observed when Pseudomonas cepacia was inoculated into Nile water amended with PNP and supplemented with 2.28–22.8 mg l‐1 of P. The bacteria grew in Nile water and the final densities were related to the level of the added P. On the other hand, the addition of P, at concentrations ranging from 2.28 to 22.8 mg l‐1, to sterile Nile water inoculated with Pseudomonas sp. and amended with 10 mg l‐1 of 2,4‐D did not stimulate the degradation compared with that obtained with the unsupplemented samples. The affinity of the three strains to P was demonstrated in P‐deficient medium amended with PNP or 2,4‐D as a sole carbon source. The pH of the medium was adjusted with 0.1 mol l‐1 Tris buffer. Pseudomonas sp. at an initial density of 3.3 times 104 cells ml‐1 degraded 10 mg l‐1 of 2,4‐D in non‐sterile Nile water without added P. A slight enhancement of degradation was observed in water samples amended with a high concentration of P. The addition of P to non‐sterile Nile water inoculated with Corynebacterium sp. and amended with 10 mg l‐1 of PNP stimulated degradation, which was rapid and extensive in Nile water receiving 22.8 mg l‐1 of P. It is suggested that contaminated natural water with P limitation could be inoculated with a degrading strain that has low affinity for P to bring about biodegradation.
Multilocus enzyme electrophoresis on agarose gel as an aid to the identification of entomopathogenic Bacillus sphaericus strains
Authors: Zahner Viviane , Rabinovitch L. , Cavados C.F.G. , Momen H.
Published: March 2008

Sixty strains of Bacillus sphaericus, including 31 insect pathogens were studied by multilocus enzyme electrophoresis and were classified into 44 zymovars (electrophoretic types). Among the entomopathogenic strains, 11 belong to the same zymovar (Z59) indicating a widespread frequent genotype. Bands of enzyme activity were not detected among the strains for the loci GPI (E.C.5.3.1.9), G6P (E.C.1.1.1.49), 6PG (E.C.1.1.1.44) and ME (E.C.1.1.1.40). The enzymatic loci NP (E.C.2.4.2.1) and ACON (E.C.4.2.1.3) were monomorphic while the other enzymes, MDH (E.C.1.1.1.37), LeDH (E.C.1.4.1.9), ADH (E.C.1.4.1.1), EST (E.C.3.1.1.1), PEP‐2 (E.C.3.4.11.1), PEP‐3 (E.C.3.4.11) and PEP‐D (E.C.3.4.13.9) were polymorphic. The genetic variation in the non‐insect pathogenic group seemed to be greater than in the entomopathogenic group. This latter group appears to be distinct from other strains of these species. All insect pathogens were recovered in the same phenetic cluster and a diagnostic allele is reported for the identification of entomopathogenic strains.
Assessment of the marker value of various components of the coli‐aerogenes group of Enterobacteriaceae and of a selection of Enterococcus spp. for the official monitoring of drinking water supplies
Authors: Charriere G. , Mossel D.A.A. , Beaudeau P. , Leclerc H.
Published: March 2008

The traditional indicators Escherichia coli (in practice currently, though ecologically inaccurately, represented by ‘thermotolerant coliforms’ at 44°C) and Enterococcus spp. proved to be suitable for the diagnosis of heavy and frequent faecal pollution observed in potentially dangerous waters, especially those originating from karstic aquifers. On the other hand, natural and treated waters, slightly and inconsistently contaminated, occasionally showed a variable Gram‐negative flora, difficult to classify by routine tests. In that case, complete identification of isolates may be necessary to ensure a valid decision on the potability of the supply. At any rate some of the Enterobacteriaceae contained in the ‘faecal coliform’ group and many other ‘coliforms’, distinct from E. coli, lack sanitary significance although their presence at certain levels may indicate inadequate disinfection, hiatuses in the integrity of the distribution system or both.
Identification of infant food as a vehicle in a nosocomial outbreak of Citrobacter freundii: epidemiological subtyping by allozyme, whole‐cell protein and antibiotic resistance
Authors: Thurm V. , Gericke B.
Published: March 2008

A total of 38 Citrobacter freundii strains was isolated from patients and their environment at a neonatal intensive care unit of a large hospital where colonization and clinical diseases due to the agent had been observed. Epidemiological investigations were carried out by subtyping, for which a combination of allozyme, whole‐cell protein and resistance pattern analysis was used. Infant formula was identified as a vehicle of nosocomial spread. This shows that the role of foods in the transmission of hospital infections should not be underestimated.

The combination of methods applied, in particular a limited enzyme set, is recommended also for epidemiological investigations of food‐borne infections and establishment of their causes.
Dominance of Lactobacillus plantarum strains in grass silage as demonstrated by a novel competition assay
Authors: Duffner Fiona , Fitzsimons A. , Brophy G. , O'Kiely P. , O'Connell M.
Published: March 2008

An assay was developed for assessing the competitive ability of potential Lactobacillus plantarum silage inoculants. This assay was based on the ability of the test inoculant to outcompete a standard strain (Lact. plantarum DCU101) co‐inoculated at the same rate of 5 × 105 colony forming units g‐1 of grass. Total populations of Lact. plantarum were enumerated with a selective medium and Lact. plantarum DCU101 was identified with a strain‐specific DNA probe. The DNA probe was based on a small (2.2 kb), cryptic, indigenous plasmid which was cloned into pAT153, a multicopy cloning vector. Seven Lact. plantarum strains, six of which were isolated from well‐preserved grass silages, were used to inoculate laboratory scale silos, and variation in strain dominance was monitored over the 14 d ensilage period.
Identification of Campylobacter jejuni, Campylobacter coli and Campylobacter lari by the nucleic acid amplification system NASBR
Authors: Uyttendaele M. , Schukkink R. , van Gemen B. , Debevere J.
Published: March 2008

M. UYTTENDAELE, R. SCHUKKINK, B. VAN GEMEN AND J. DEBEVERE. 1994. NASBAR, an isothermal amplification technique for nucleic acids, was evaluated for the specific identification of Campylobacter jejuni, Camp. coli and Camp. lari. A set of primers and a probe were chosen from the 16S rRNA sequence of Campylobacter. The probe was hybridized in solution with the amplified nucleic acids of 12 Campylobacter species and nine other Gram‐negative bacteria. The probe was shown to hybridize specifically to the amplified single‐stranded RNA of Camp. jejuni, Camp. coli and Camp. lari in an enzyme‐linked gel assay (ELGA). In a Camp. jejuni model system the combination of NASBAR and ELGA was able to detect ca 1000 rRNA molecules. The presence of an excess of Gram‐negative bacteria did not influence the sensitivity of detection. A number of 6 cfu of Camp. jejuni, present in a total count of 4 times 106 cfu of Gram‐negative bacteria, resulted in a positive hybridization signal.
Effect of heating rate on the thermal inactivation of Listeria monocytogenes
Authors: Stephens P.J. , Cole M.B. , Jones M.V.
Published: March 2008

P.J. STEPHENS, M.B. COLE AND M.V. JONES. 1994. In order to quantify the effect of heating rate on the thermal inactivation of Listeria monocytogenes an accurate means of describing the inactivation kinetics at near instantaneous heating was used. Survivor curves for L. monocytogenes, at near instantaneous heating, were obtained over the temperature range 50–64d̀C. The use of a linear function to describe the data would have given only a poor approximation of the true inactivation kinetics. With a model based on a logistic algorithm extremely accurate descriptions were made. In processes which had rates of heating 5.0d̀C min‐1, significant deviations of real kill from predicted kill were observed. Predicted kill assumed that heating rate did not affect the inactivation kinetics of a thermal process. At rates of heating between 5.0 and 0.7d̀C min‐1 the deviation greatly increased as the rate of heating decreased; approximately a 1.7 times 105‐fold difference at 0.7d̀C min‐1. Maximum thermotolerance was induced at rates of heating 0.7d̀C min‐1. The increased thermotolerance during slow rates of heating was analogous to the induction of the heat‐shock response. The models described in this work allow for confident assessments of safety to be made not only at near instantaneous heating but also when the heating rate varies.
Rapid identification of Aeromonas species using 16S rDNA targeted oligonucleotide primers: a molecular approach based on screening of environmental isolates
Authors: Dorsch M. , Ashbolt N.J. , Cox P.T. , Goodman A.E.
Published: March 2008

M. DORSCH, N.J. ASHBOLT, P.T. COX AND A.E. GOODMAN. 1994. Published 16S rDNA sequencing data for Aeromonas species were analysed and the validity of signature sequences derived from our investigations of these sequences was examined by sequencing the corresponding 16S rDNA regions of 67 environmental isolates from sewage effluents and receiving waters around Sydney and one clinical isolate, all previously classified as Aeromonas species. Species‐specific probes for Aer. hydrophila and Aer. veronii were designed and tested in PCR assays and clearly discriminated these species from the other Aeromonas isolates as identified by 16S rDNA sequences.
Reisolation and enumeration of transformed Streptomyces strains from plant roots*
Authors: Elliott M.L. , Jardin E.A. Des , Bonito R. Di
Published: March 2008

A system was developed for the reisolation and enumeration of genetically‐modified Streptomyces strains introduced into the root system by seed treatment. Two chromogenic markers, melanin production and actinorhodin production, were evaluated. Plasmids containing the genes for these marker systems and thiostrepton resistance were used to transform protoplasts of a streptomycin‐resistant strain of Streptomyces griseus. A mineral salts medium containing starch as the carbon source and arginine as the nitrogen source (RASS) and amended with rifampicin, streptomycin and thiostrepton was found to be the most effective medium for reisolation and enumeration of the Streptomyces strains. Strains transformed with the actinorhodin marker system were shown to colonize wheat and alfalfa roots as well as the original strain.
The effect of Lactobacillus spp. on the attachment of enterotoxigenic Escherichia coli to isolated porcine enterocytes
Authors: Spencer R.J. , Chesson A.
Published: March 2008

A total of 43 strains of lactobacilli were isolated from the gastrointestinal tract of piglets at the time of weaning. Isolates, grown on solid media, were allocated to strongly adherent or non/weakly adherent groups on the basis of numbers attaching to isolated porcine enterocytes. Strains of Lactobacillus fermentum were disproportionally represented amongst the strongly‐adherent strains and Lact.acidophilus and Lact. salivarius amongst the non/weakly‐adherent group. Lactobacilli showed significantly better attachment ability when grown on agar than when grown in broth culture. Strongly adherent strains were not found to effect the attachment of enterotoxigenic Escherichia coli to porcine enterocytes, tested under the conditions of exclusion (lactobacilli added to the enterocytes before E. coli), competition (lactobacilli and E. coli added simultaneously) and displacement (E. coli added before lactobacilli). Tests were made with [14C]‐labelled E. coli. Suspensions of bacteria and enterocytes were passed through a filter selected to retain enterocytes but pass free bacterial cells. Counts (dpm) obtained from filters after solubilization were taken as a measure of E. coli attachment. Some strains of lactobacilli coaggregated with enterotoxigenic E. coli with K88 fimbriae, but not with a K88‐negative mutant strain. These were excluded from the competitive exclusion experiments. In the apparent absence of a direct effect on the association of E. coli with host tissue, removal of potential gut pathogens by aggregation could contribute to the probiotic properties ascribed to lactic acid bacteria.
Isolation and characteristics of a yeast from preserved fish hydrolysate notably resistant to propionic acid
Authors: Walters D.M. , Levin R.E.
Published: March 2008

A fermentative film‐forming yeast, designated PR1, notably resistant to propionic acid, was isolated from hydrolysed fish gurry that had been initially adjusted to a pH of 3.5 with phosphoric acid and preserved with 0.2% propionic acid. Growth on a variety of culture media yielded only budding cells. Bipolar budding with multiple buds at each pole was commonly encountered. Neither ascospores nor pseudomycelium were produced. Colonies on orange serum agar were 3–5 mm in diameter whereas, on tryptic soy agar containing 0.5% glucose, giant colonies were formed that filled most of the area of the plates within 48 h. Off‐odours were not produced nor were disaccharides utilized. The isolate exhibited poor growth in 0.4% propionic acid at pH 4.0 and was completely inhibited by 0.5% propionic acid.
Inter‐strain relationships among wine leuconostocs and their divergence from other Leuconostoc species, as revealed by low frequency restriction fragment analysis of genomic DNA
Authors: Tenreiro R. , Santos M.A. , Paveia H. , Vieira G.
Published: March 2008

Thirty Leuconostoc oenos strains, representing 28 different isolates, were distributed into 20 genomic groups according to PFGE patterns of restriction digests. The 8 bp‐specific enzymes Sfi I, Not I and Asc I cleaved the Leuc. oenos DNA in a mean of 17, 11 and four fragments respectively and Sma I produced more than 50 fragments per genome. The strain differentiating capacity of the four enzymes was similar; only two related genomic groups failed to be distinguished by Asc I or Not I. Genomic relationships between Leuc. oenos strains were quantified by numerical analysis of Not I and Sfi I banding patterns. More than half of the strains, including the starters ML34 and PSU‐1, formed a major cluster. The average size of the Leuc. oenos genome was estimated as 1.86 Mb. Although similar values were obtained for the genomes of Leuc. mesenteroides, Leuc. pseudomesenteroides, Leuc. gelidum and Leuc. citreum, a significant divergence between wine and non‐wine species was inferred from comparisons of genome cleavage frequencies, determined with five different enzymes.
Characterization and identification of Vagococcus fluvialis strains isolated from domestic animals.
Authors: Pot B. , Devriese L.A. , Hommez J. , Miry Cora , Vandemeulebroecke Katrien , Kersters K. , Haesebrouck F.
Published: March 2008

Strains of Vagococcus fluvialis, a species of Gram‐positive catalase‐negative cocci, related to the genera Enterococcus and Carnobacterium, were isolated from various lesions of pigs, from lesions and tonsils of cattle and cats and from tonsils of a horse. Most lesion strains were isolated in mixed culture from animals with disease conditions unrelated to coccal infection. Certain differences with the species description of Vagococcus fluvialis were found: only a proportion of the strains was motile; many strains gave positive reactions to Voges‐Proskauer, alkaline phosphatase and leucine arylamidase tests or produced acid from galactose and D‐tagatose. SDS‐PAGE of whole‐cell protein patterns, however, confirmed the phenotypic identification. Guidelines for identification of Vagococcus fluvialis are given and an emended description of the species is proposed.
Comparison of the gut bacterial flora of start‐feeding larval turbot reared under different conditions
Authors: Munro P.O. , Barbour A. , Blrkbeck T.H.
Published: March 2008

P.D. MUNRO, A. BARBOUR AND T.H. BIRKBECK. 1994. Bacterial colonization of the gut of turbot larvae coincided with the start of feeding and the gut microflora was then dominated by Vibrio and Aeromonas species. The detection of similar bacterial isolates over several days indicated the presence of a stable microflora during the rotifer feeding stage, probably reflecting a stable flora in the rotifer culture. There was no correlation between the number of bacteria in the gut and larval survival rates; incidences of high mortalities were not associated with high numbers of recognized fish pathogens, although an Aeromonas species was implicated as an opportunistic pathogen. Potential pathogens were isolated, albeit in low numbers, from batches of apparently healthy larvae with high survival rates. It is probable that the bacterial flora plays an important role in determining the survival of larval fish and that the establishment of a beneficial flora is possible, although the criteria for such a flora have still to be elucidated.
Partial purification and biochemical properties of acid and alkaline phosphatases from Myxococcus coralloides D
Authors: González F. , Fárez‐Vidal M. Esther , Arias J.M. , Montoya E.
Published: March 2008

F. GONZÁLEZ, M.E. FÁREZ‐VIDAL, J.M. ARIAS AND E. MONTOYA. 1994. Acid phosphatase and alkaline phosphatase from vegetative cells of Myxococcus coralloides D were purified by two chromatographic steps. The molecular weights were estimated by gel filtration and SDS‐PAGE. Optimum pH, stability, optimum temperature and thermal inactivation studies were made for both enzymes. EDTA and other chelating agents inhibited alkaline but not acid activity. Mg2+ activated the alkaline phosphatase, while the acid phosphatase was inhibited by fluoride. Both enzymes degraded a number of phosphomonoesters, but were unable to hydrolyse either polyphosphates or cAMP. The Km values of the acid and alkaline phosphatases for p‐nitrophenylphosphate were 5.0 times 10‐3 mol ***l‐1 and 1.5 times 10‐3 mol l‐1, respectively.
A Note: Comparison of different homogenization procedures for detecting Campylobacter spp. in sewage sludge
Authors: Höller Christiane , Schomakers‐Revaka Ursula
Published: March 2008

C. HÖLLER AND U. SCHOMAKERS‐REVAKA. 1994. Crude sewage sludge contains Campylobacter spp. in a concentration of 10‐1–103 cfu 100 ml‐1 on average. Because large variations in the number of bacteria are seen when samples are examined in parallel, we attempted to improve the detection method. Seeded sewage sludge samples were homogenized by a high‐speed blender, ultrasonic bath and ultrasonic bar. Bacterial counts were determined by the MPN method in triplicate. The recovery rate was < 10%. Subsequently, sludge samples without artificial contamination were also examined. The bacterial counts varied considerably, as seen earlier. In order to enhance the detection rate of campylobacters homogenization times and frequencies were increased, samples were diluted prior to treatment and pre‐enriched in non‐selective broth or supplemented with detergent. None of the methods applied proved satisfactory. The bacterial counts achieved with all methods varied greatly, with minimum and maximum values lying at least two orders of magnitude apart.
Bacteriological indicators of faecal contamination: result of a loading experiment with untreated urban wastewater
Authors: Ramos‐Cormenzana A. , Castillo A. , Incerti C. , Gomez‐Palma L.F.
Published: March 2008

Some observations were made on the behaviour of total coliforms, faecal coliforms, enterococci, numbers of aerobic bacteria, salmonellas and sulphur‐reducing clostridia as bacterial indicators of faecal contamination of groundwater. A controlled irrigation experiment was carried out with untreated residual water in the alluvial aquifer of the Vega of Granada (Spain). The results obtained confirm the value of these parameters as useful indicators of very recent faecal contamination; and changes were detected as the level of the freatic layer increased and the chemical composition of the groundwater changed. These groups of micro‐organisms persisted for about 200 h, with the exception of the aerobes which survived for much longer. Salmonellas were present at levels too low to calculate the extent of faecal contamination and sulphur‐reducing clostridia were not detected. The results obtained show that irrigation with untreated wastewater offers a lower risk of microbiological contamination of groundwater compared with the direct addition of waters decanted and/or previously filtered.
Multiplex riboprobes for the detection of virulent Yersinia enterocolitica and simple methods for their preparation
Authors: Fliss I. , Blais B.W. , Holley R. , Simard R.E.
Published: March 2008

A simple multiplex riboprobe system for detection of virulent Yersinia enterocolitica was developed using a pool of RNA probes specific for various chromosomal and plasmid‐borne virulence gene sequences (yadA, virC, ail and yst). Riboprobes were synthesized by a rapid, simple and efficient technique involving in vitro transcription of polymerase chain reaction‐generated templates incorporating bacteriophage T7 RNA polymerase promoter sequences in one of the priming oligonucleotides. After dot blotting target DNA samples on nitrocellulose and hybridization with the riboprobes, the RNA : DNA hybrids formed were detected by a simple immunoenzymic assay involving sequential reactions with an anti‐RNA : DNA hybrid monoclonal antibody, anti‐mouse Ig‐peroxidase conjugate and chromogenic or chemiluminescent enzyme substrate solution. This multiplex riboprobe system targeting both chromosomal and plasmid‐borne sequences permitted detection of virulent Y. enterocolitica, regardless of plasmid loss during handling of cultures, and was unreactive with avirulent Y. enterocolitica, other Yersinia and other bacteria. This system resulted in a significant improvement in the limit of detection in comparison to that obtained with individual probes.