bluuebunny/crossref_metadata_2025 huggingface dataset:
Protoplast‐induced curing of bacteriocin plasmid in Lactococcus lactis subsp. lactis 484
Authors: Gupta R.K. , Batish V.K.
Published: March 2008

Plasmid‐specified traits like lactose metabolism and bacteriocin production could be eliminated from Lactococcus lactis subsp. lactis 484 culture during production and regeneration of protoplasts with lysozyme at the concentration of 300 μg/ml after 3 h treatment. Plasmid‐free strains and cured derivatives harbouring only a single plasmid (2 MDa) were also obtained. Loss of high molecular weight (65 MDa) low copy number Lac plasmid occurred more frequently compared with low molecular weight (2 MDa) high copy number plasmid. Treatment of L. lactis subsp. lactis 484 cells with lysozyme at concentrations of 1000 μg/ml could produce a large number of Lac− Bac− variants at a very high frequency (94%). The curing data confirmed the linkage of Lac and Bac phenotypes to 65 and 2 MDa plasmids, respectively.
Comparative study on the antimicrobial effects of Hexomedine and Betadine on the human skin flora
Authors: Chevalier J. , Crémieux A.
Published: March 2008

Studies were carried out to detect the modifications, if any, on the peri‐umbilical flora of six healthy volunteers after two or three daily applications of Hexomedine solution (HEX) and Betadine solution (PVI) repeated for five consecutive days. A standardized scrubbing method was used for bacterial sampling. Surviving bacteria were selected with both selective and non‐selective media, and then identified by gas chromatographic fatty acid analysis. Both antiseptics were highly effective, showing both immediate and residual antimicrobial activities. The use of HEX led to a slight increase in Gram‐positive cocci and a small decrease in coryneforms, but PVI produced a marked increase in Gram‐positive cocci and a sharp decrease in coryneforms. The two antiseptics, however, caused no major alteration in the cutaneous microbial population. Indeed, neither the overgrowth of Gram‐negative bacilli nor the emergence of resistant species was observed.
Study of the bacterial flora of a non‐carbonated natural mineral water
Authors: Mavridou Athena
Published: March 2008

Natural mineral water from a UK spring was monitored at various stages after it was pumped from the ground, through to bottling and during shelf life before consumption. Samples were collected in commercial PVC bottles, in PVC bottles previously sterilized and hand‐filled and in glass bottles. The bacterial flora was counted on plate count agar (PCA) and on PCA diluted 10 times (PCA/10). The predominant bacteria were identified to genus level. Growth rates and nutrient types of isolates were determined by the nutrient‐tolerance test (NT). The plate counts at the prebottling stage were low. During storage larger numbers of bacteria grew in glass than PVC bottles; the largest number grew in PVC bottles filled by hand. Most of the pigmented bacteria isolated were oligocarbotolerant.
A comparison of the sensitivity of wound‐infecting species of bacteria to the antibacterial activity of manuka honey and other honey
Authors: Willix D.J. , Molan P.C. , Harfoot C.G.
Published: March 2008

Both honey and sugar are used with good effect as dressings for wounds and ulcers. The good control of infection is attributed to the high osmolarity, but honey can have additional antibacterial activity because of its content of hydrogen peroxide and unidentified substances from certain floral sources. Manuka honey is known to have a high level of the latter.

Seven major wound‐infecting species of bacteria were studied to compare their sensitivity to the non‐peroxide antibacterial activity of manuka honey and to a honey in which the antibacterial activity was primarily due to hydrogen peroxide. Honeys with activity in the middle of the normal range were used. A comparison of the median response of the various species of bacteria showed no significant difference between the two types of activity overall, but marked differences between the two types of activity in the rank order of sensitivity of the seven bacterial species. The non‐peroxide antibacterial activity of manuka honey at a honey concentration of 1.8% (v/v) completely inhibited the growth of Staphylococcus aureus during incubation for 8 h. The growth of all seven species was completely inhibited by both types of honey at concentrations below 11% (v/v).
Contaminated marine wounds—the risk of acquiring acute bacterial infection from marine recreational beaches
Authors: Kueh C.S.W. , Kutarski P. , Brunton M.
Published: March 2008

An animal model was used to determine the potential for causing wound infections of bacteria isolated from marine recreational beaches in Hong Kong. Water samples were characterized physically, chemically and bacteriologically and used to inoculate artificially‐induced wounds in rats. Morbidity and mortality correlated significantly (P < 0.01) with MacConkey plate counts and faecal coliform counts (membrane filtration) and inversely with salinity of the water. The majority of deaths were due to infection caused by marine and estuarine bacteria rather then enteric organisms. A total of 318 bacterial strains was isolated from the wounds and blood of animals inoculated with seawater, of which 242 were marine/estuarine (predominantly Vibrio spp., Aeromonas hydrophila and Pseudomonas putrefaciens) and 40 were enterobacteria. The virulence of the animal strains were comparable with those from clinical sources.
Susceptibility of the brine shrimp Artemia and its pathogen Vibrio parahaemolyticus to chlorine dioxide in contaminated sea‐water
Authors: Puente M. Esther , Vega‐Villasante F. , Holguin Gina , Bashan Y.
Published: March 2008

Adults and nauplii of the brine shrimp, Artemia, together with Vibrio parahaemolyticus, were placed in sewage‐contaminated sea‐water which had been treated with chlorine dioxide (Hallox E‐100TM) to test its potential as a disinfectant for salt water aquaculture. The nauplii were very susceptible to low concentrations of chlorine dioxide (47 μg/1 Cl‐), but the adults were slightly more resistant. Sterile sea‐water treated with lower concentrations of chlorine dioxide (less than 47 μg/1 Cl‐) had no effect on the shrimp, but inhibited the growth of V. parahaemolyticus. In sewage‐contaminated sea‐water, chlorine dioxide levels of 285–2850 μg/1, necessary for the inactivation of V. parahaemolyticus and any native bacteria, destroyed the Artemia culture. Hallox E‐100TH persisted in sea‐water for 18 h, but later decayed. We conclude that: (i) Artemia nauplii are a sensitive and convenient test‐organism to determine low concentrations of chlorine dioxide in sea‐water; (ii) chlorine dioxide is efficient for controlling V. parahaemolyticus in sea‐water; and (iii) chlorine dioxide should be further evaluated as a potential disinfectant for aquaculture, but, for higher organisms than Artemia.
Evaluation of a model biofilm for the ranking of biocide performance against sulphate‐reducing bacteria
Authors: Whitham T.S. , Gilbert P.D.
Published: March 2008

A model artificial biofilm was developed and evaluated for ranking the performance of biocides for application in oil production pipelines. The biofilm consisted of an alginate gel matrix into which were incorporated bacteria, scrapings from the inner surfaces of oil production pipelines and some crude oil.

The viability and sulphide‐respiration rates of sulphate‐reducing bacteria (SRB) within freshly‐prepared artificial biofilm remained largely unchanged during a 2‐week storage period. Furthermore, storage of the model biofilm did not alter the susceptibility of the incorporated SRB to a biocide. These findings showed that artificial biofilm may be produced in advance of a biocide assessment study and stored for at least 2 weeks over the course of the study without the model system undergoing changes which affected the relative performance of the biocides assessed. Artificial biofilms were found to be more resistant to biocides than planktonic bacteria and the addition of oil pipeline scrapings and crude oil to the artificial biofilm was found to increase further the resistance of biofilm to biocides.
Effects of low concentrations of ampicillin in feed on the intestinal Escherichia coli of chicks
Authors: Al‐Sam Selwa , Linton A.H. , Bennett P.M. , Hinton M.
Published: March 2008

Ampicillin in low concentrations (1.7 and 5 g t‐1) was incorporated in the feed given to 1‐d‐old chicks for 2 weeks. This was sufficient to select, in the intestinal contents, resistant Escherichia coli strains for which the minimum inhibitory concentration of ampicillin was > 100 μg ml‐1. Different clones of E. coli were identified by their biotype, pattern of resistance to antibacterial agents and plasmid profile (designated P‐P types). The experiment was repeated twice and the average proportion of ampicillin‐resistant P‐P types among 72 isolates of E. coli from chicks given feed containing 0, 1.7 and 5 g ampicillin t‐1 were 10%, 31% and 46% respectively.
Antimicrobial activity of lactic acid bacteria isolated from sour doughs: purification and characterization of bavaricin A, a bacteriocin produced by Lactobacillus bavaricus MI401
Authors: Larsen Anette G. , Vogensen F.K. , Josephsen Jytte
Published: March 2008

Three hundred and thirty‐five lactic acid bacteria were isolated from sour doughs and screened for antagonistic activity. Of these 145 showed activity against one or several of the indicator strains used in the screening. The antimicrobial activity of 18 isolates were due to a proteinaceous compound. These 18 isolates belonged to three different Lactobacillus species: Lactobacillus bavaricus, Lactobacillus curvatus and Lactobacillus plantarum. The spectrum of antimicrobial activity for the three species suggested that the inhibitory components were different. The inhibitory compound from Lact. bavaricus MI401 was chosen for further study. The proteinaceous nature, antimicrobial activity against closely‐related species, heat resistance and sensitivity to alkaline treatment strongly indicated that this substance was a bacteriocin, which we designated bavaricin A. The bacteriocin was purified to homogeneity by ammonium sulphate precipitation, ion exchange, hydrophobic interaction and reverse‐phase chromatography. The purification resulted in 193000‐fold increase in specific activity. SDS‐PAGE of bavaricin A showed a molecular weight of 3500—4000 Da. By amino acid sequencing 41 amino acids were determined. Bavaricin A had a bactericidal mode of action and inhibited nine out of 10 Listeria monocytogenes. Lactobacillus bavaricus MI401 produced bavaricin A at temperatures from 4°C to 30°C. The production of active bavaracin A was inhibited at increasing sodium chloride concentration. In the presence of 3% sodium chloride at 4°C no active bavaricin A could be detected. Nitrite (100 ppm) did not affect the production of active bavaricin A.
Effect of sub‐inhibitory concentrations of antibiotics on the virulence of Staphylococcus aureus
Authors: Doss S.A. , Tillotson G.S. , Amyes S.G.B.
Published: March 2008

The production of virulence factors by various bacteria can be influenced by sub‐inhibitory concentrations of antibiotics. The effect of six antibiotics on the production of representative extracellular enzymes and toxins produced by Staphylococcus aureus was investigated. The production of the virulence determinants coagulase, protein A, alpha and delta haemolysin was monitored in the presence of ciprofloxacin, enoxacin, chloramphenicol, gentamicin, tetracycline and methicillin. The protein synthesis inhibitors reduced the production of coagulase and protein A, and almost completely inhibited the production of the haemolysins. Haemolysin production was also reduced by ciprofloxacin and enoxacin, but these antibiotics had little effect on the production of coagulase and protein A. Methicillin stimulated the production of alpha and delta haemolysins but had no effect on the production of coagulase and protein A.
The effect of tetronasin and monensin on fermentation, microbial numbers and the development of ionophore‐resistant bacteria in the rumen
Authors: Newbold C.J. , Wallace R.J. , Walker Nicola D.
Published: March 2008

The Gram‐negative rumen bacteria Fibrobacter succinogenes S85, Prevotella ruminicola M384 and Veillonella parvula L59 were grown in media containing successively increasing concentrations of the ionophores, monensin and tetronasin. All three species became more resistant to the ionophore with which they were grown. Increased resistance to one ionophore caused increased resistance to the other, and cross‐resistance to another ionophore—lasalocid—and an antibiotic—avoparcin. Recovery of tetronasin‐resistant bacteria from the rumen of monensin‐fed sheep increased and vice versa, indicating that similar cross‐resistance occurred in vivo.
Fluorescent detection‐polymerase chain reaction (FD‐PCR) assay on microwell plates as a screening test for salmonellas in foods
Authors: Cano R.J. , Rasmussen S.R. , Fraga Gloria Sánchez , Palomares J.C.
Published: March 2008

This study evaluates a polymerase chain reaction assay coupled with a fluorescent detection in microwell plates for salmonellas in food samples. Chelex 100‐extracted cultures and bulk and processed food samples were used as templates for a PCR assay in microwell plates, with a primer pair that amplifies a 206 bp segment of IS200. The PCR products were then denatured by heat and transferred to CovaLink NH plates (Nunc) to which capture oligonucleotides were covalently bound. Hybridization was performed for 1 h at 55°C, the microwells were washed and an alkaline phosphatase‐labelled probe, complementary of an internal sequence of the PCR product, was added. After stringent washes, 100 μl of 1 mmol 1‐1 AttoPhosTM (JBL Scientific) was then added to the wells and the fluorescence measurement system (Millipore). The level of detection of the assay was as low as 1–10 cfu. A total of 172 food samples were tested, both by culture and FD‐PCR. Of these 53 were culture positive and 119 culture negative. The sensitivity of the FD‐PCR assay was 100% and the specificity was 90.1%. Positive and negative predictive values were 82.8 and 100%, respectively. Based on the results obtained in this study it appears that the FD‐PCR. assay described here can be useful to screen a large number of food samples for contamination by salmonellas.
Glucose oxidase production by Penicillium variabile P16: effect of medium composition
Authors: Petruccioli M. , Federici F.
Published: March 2008

The effect of medium composition on glucose oxidase (GOD) production by the strain Penicillium variabile P16 was studied in shake culture. All the experiments were performed in a medium containing glucose and sodium nitrate as carbon and nitrogen sources, respectively. Addition of Fe2+ to the medium was important to stimulate GOD production. Calcium carbonate was extremely important in maintaining the medium at a pH high enough so that the enzyme was not inactivated. The time course of growth and enzyme production by P. variabile P16 in the optimized medium is reported.
Serological and conductimetric assays for the detection of Pseudomonas syringae pathovar pisi in pea seeds
Authors: Fraaije B.A. , Franken A.A.J.M. , van der Zouwen P.S. , Bino R.J. , Langerak C.J.
Published: March 2008

Test protocols for detecting Pseudomonas syringae pv. pisi, the causal agent of bacterial blight, in pea seeds are generally based on dilution‐plating assays. These assays are usually very specific and reliable, but are time‐consuming and laborious. Tests suited for large scale screening of seed lots are therefore needed. Conductimetric assays, immunofluorescence microscopy (IF) and an enzyme‐linked immunosorbent assay (ELISA) for detecting Ps. syr. pv. pisi in pea seed extracts were compared with dilution‐plating by two extraction methods, viz. 6 h soaking of seeds and 2 h soaking of flour of ground pea seeds in water. In general, the detection of Ps. syr. pv. pisi with conductimetric, IF and dilution‐plating assays in the suspension water of the ground and 2 h‐soaked pea samples was less sensitive than detection in suspension water of the 6 h‐soaked pea seeds. The detection threshold of these assays varied per seed lot between 0 and 4.08 log cfu ml‐1 for the 6 h soaking procedure. The detection threshold of ELISA varied for both extraction methods generally between 4.08 and 6.08 log cfu ml‐1. Detection times recorded in conductimetric assays correlated well (— 0.89 < r < —0.98) with the log colony‐forming units of Ps. syr. pv. pisi added to seed extracts at 27 as well as 17°. However, confirmation of results by isolation on semi‐selective media after conductimetry was more successful at 17° than at 27°, because of the relatively lower activity of saprophytic Pseudomonas spp. at this temperature.
Extracellular serine protease synthesis by mosquito‐pathogenic strains of Bacillus sphaericus
Authors: Dumusois Catherine , Priest F.G.
Published: March 2008

Nine strains of Bacillus sphaericus toxic to mosquito larvae produced haloes of hydrolysis when cultured on casein‐nutrient agar. In batch culture, protease synthesis by B. sphaericus BSE 18 occurred during exponential growth and was repressed by high concentrations of peptone. Extracellular protease from this bacterium showed optimal activity at about pH 10.2, was inhibited by phenylmethylsulphonyl chloride and chymostatin but not soybean trypsin inhibitor or EDTA. Hydrolysis of N‐CBZ‐glycine‐nitrophenyl ester was consistent with the major enzyme being a serine protease.
Examination of raw beef products for the presence of Vero cytotoxin producing Escherichia coli, particularly those of serogroup O157
Authors: Willshaw G.A. , Smith H.R. , Roberts D. , Thirlwell J. , Cheasty T. , Rowe B.
Published: March 2008

Fifty‐four of 310 (17%) samples of raw beef products contained Vero cytotoxin (VT)‐producing Escherichia coli (VTEC) detected by DNA probes for the VT genes. VTEC strains examined in detail from a selection of the positive samples belonged to several O serogroups, some of which have been associated with human diarrhoea or haemolytic uraemic syndrome. Some of the strains possessed properties that may contribute to virulence in man. None of the food samples contained VT‐producing E. coli O157 when tested by a combination of VT probe tests and colony immunoblotting with commercially available anti‐O157 serum. Quantification of the immunoblotting technique indicated that O157 VTEC could be recovered from artificially‐inoculated meat samples at a level of less than one organism per gram. Five of the food samples carried E. coli O157 strains that did not produce VT and differed in other properties from O157 VTEC.
Characterization of interactions between Lactobacillus hilgardii and Saccharomyces florentinus isolated from sugary kefir grains
Authors: Leroi Françoise , Pidoux M.
Published: March 2008

Stimulation of the growth of Lactobacillus hilgardii and production of lactic acid in the presence of Saccharomyces florentinus have already been observed in a poor glucose medium. In this study we showed that CO2, pyruvate, propionate, acetate and succinate excreted by the yeast were responsible for this phenomenon, whereas ethanol, fumarate and a cocktail of vitamins had no effect. Fermentation by the yeast did not enrich the total nitrogen or free amino acid content of the medium. The use of proteases confirmed that it was improbable that any nitrogenous compound could be responsible for the bacterial activation. Between values of 0.1 and 5%, the initial yeast: bacteria ratio had no effect on the stimulation of Lact. hilgardii, even though yeast fermentation was drastically affected by a low initial value. The interactions differed greatly according to the sugar source. With monosaccharides, stimulation began after 48 h of culture, and was higher on glucose than on fructose. With sucrose, stimulation appeared at the beginning of fermentation. Different mechanisms seemed to be involved.
Effects of some ionophore antibiotics and polyoxins on the growth of anaerobic rumen fungi
Authors: Cann I.K.O. , Kobayashi Y. , Onoda A. , Wakita M. , Hoshino S.
Published: March 2008

The growth of mixed rumen fungi in vitro was suppressed by both ionophore antibiotics (salinomycin, monensin and portmicin) and polyoxins (polyoxin B and D: inhibitors of chitin synthesis). The fungistatic effect of the ionophores on a Piromonas spp. was more pronounced than on a Neocallimastix spp. The polyoxins, however, were more potent fungistatically against the Neocallimastix spp. than the Piromonas spp. Higher concentrations of the polyoxins were required to elicit the same effect as that observed with the ionophores. Salinomycin administration decreased fungal count in the rumen of sheep, but fungal count increased after the cessation of the feeding of the antibiotic. Polyoxin D also suppressed the growth of fungi in vivo, but the effect was short‐lived. Nevertheless, both bacterial and protozoal counts tended to increase during and after the administration of polyoxin D. Total volatile fatty acid concentrations in the rumen tended to increase during the period of polyoxin D administration. This increasing tendency was maintained for 10 d after the cessation of antibiotic administration. Offering polyoxin D to sheep increased production of propionate (P < 0·05), while decreasing that of acetate. The results indicate that the rumen fungi are sensitive to chitin synthesis inhibitors as well as ionophores, and are essential members of microbes in the rumen ecosystem.
Freeze‐dried mixed cultures as reference samples in quantitative and qualitative microbiological examinations of food
Authors: and M. Peterz , Steneryd A.‐C.
Published: March 2008

Two simulated food samples in the form of mixtures of bacteria, freeze‐dried in small glass vials, were tested for their suitability as reference materials in food microbiology. Stability and homogeneity of the samples were assessed during a 1 year period when stored at 2–6°C. Samples were examined for aerobic plate counts, coliform counts, Staphylococcus aureus, Clostridium perfringens, Bacillus cereus, enterococci, yeasts and salmonellas. The samples were homogeneous but the number of colony forming units of some organisms declined during the time period studied. The maximum rate of decline (0·8 log units per year) was observed for the coliforms. Precision estimates (reproducibility and repeatability) for the different testing methods used are given. When compared with these data, the rate of decline was considered to be of less importance.
Microculture model studies on the effect of sorbic acid on Penicillium chrysogenum, Cladosporium cladosporioides and Ulocladium atrum at different pH levels
Authors: Marie Skirdal Inger , Eklund T.
Published: March 2008

The minimum growth‐inhibitory concentration of sorbic acid has been determined for Penicillium chrysogenum, Cladosporium cladosporioides and Ulocladium atrum at pH 4·1–7·6 by using a microculture technique. This technique had earlier been applied to bacteria and Candida albicans and gave very reliable minimum inhibitory values. This investigation has shown that it is suitable also for determination of mould growth. The minimum inhibitory concentrations of sorbic acid were at the tested pH levels 1–230 mmol 1‐1 for P. chrysogenum, 0·3–18·0 mmol 1‐1 for C. cladosporioides and 0·2–33·0 mmol 1‐1 for U. atrum. A mathematical model for combined inhibition by dissociated and undissociated acid, which gave a good description of the minimum inhibitory concentration data earlier obtained for bacteria and Candida albicans, was suitable also for moulds. Both dissociated and undissociated acid contributed to growth inhibition.
Deterioration in bacteriological quality of water through fish farms
Authors: Davis S.H. , Goulder R.
Published: March 2008

S.H. DAVIS AND R. GOULDER, 1993. Abundance of bacteria, as direct counts and colony‐forming units, bacterial metabolism, and extracellular enzyme activity, increased in water flowing through trout farms in NE England. Seven of 12 farms had settling lagoons but these did not counteract the deterioration in bacteriological quality.
Production and survival during storage of spray‐dried Bradyrhizobium japonicum cell concentrates
Authors: Mary P. , Moschetto N. , Tailliez R.
Published: March 2008

Production of Bradyrhizobium japonicum cell concentrates by spray‐drying in skim milk plus sucrose medium and the feasability of storing dried inocula over long periods were investigated. Storage of spray‐dried cells under mild vacuum was equivalent to storage under nitrogen. Oxygen and ambient temperature were found detrimental for survival of dried cells. High initial cell concentration and storage under low relative humidities (< 23% RH) at 4°C increased the longevity of the inocula (> 109 cfu g‐1 during at least a 25 week storage period) without altering the symbiotic properties of B. japonicum.
Comparison of classical isolation protocols with a 24 h screen to detect viable salmonellas in faeces
Authors: Cherrington Christina A. , Huis in't Veld J.H.J.
Published: March 2008

A 24 h screen which detects three viable salmonella cells per g of faeces was compared with classical isolation procedures for their ability to identify salmonella‐positive samples from a pig rearing unit. The screen involved an overnight enrichment in Muller‐Kauffmann tetrathionate (MK) broth, subculture for 4 h in M broth containing 10 μg ml−1 novobiocin, followed by detection of the presence of salmonellas by BacTrace and Salmonella‐tek ELISAs. The classical protocols were: (1) an overnight and 48 h incubation in MK or selenite cysteine broth; or (2) overnight incubation in buffered peptone water and 24 h subculture in Rappaport‐Vassiliadis broth (BPW‐RV). Salmonellas were isolated from the broth cultures on xylose lysine deoxycholate and brilliant green agars. Thirty four of 100 samples were positive for salmonellas but no single isolation protocol identified all of them. The best of the classical isolation protocols, 48 h incubation in MK broth, identified 27 (79%) of the 34 positive samples whilst the screen identified 26 (76%) of the 34 positive samples. False‐positive results were obtained from all isolation protocols except BPW‐RV.
The effect of wiping and spray‐wash temperature on bacterial retention on abraded domestic sink surfaces
Authors: Stevens R.A. , Holah J.T.
Published: March 2008

The relative cleanability of artificially abraded stainless steel, enamelled steel, mineral resin and polycarbonate domestic sinks was assessed by examining bacterial retention after cleaning. Two cleaning regimes were used: the mechanical action of wiping combined with a spray‐rinse, and spray‐washing at a range of temperatures. After wiping, stainless steel retained 0.5–1 log order fewer bacteria than the enamel sinks which in turn were 0.5 log order cleaner than the mineral resin and polycarbonate sinks. After spray‐washing, stainless steel retained 0.5 log order fewer bacteria than enamel which in turn was 0.5 log order cleaner than the polycarbonate and mineral resin. Extending the number of wipes or increasing spray‐wash temperature enhanced bacterial removal but, in general, did not change the relative cleanability of the sink materials. As a cleaning technique, wiping was shown to be more effective than spray‐washing in reducing bacterial numbers. SEM studies showed that bacteria were typically retained in surface imperfections, particularly pits and crevices such that surfaces which sustained the most extensive damage due to abrasion retained higher numbers of bacteria.
Fibronectin and proteolytic fragments of fibronectin interfere with the adhesion of Staphylococcus epidermidis to plastic
Authors: Dunne W.M. , Burd Eileen M.
Published: March 2008

W.M. DUNNE AND E.M. BURD. 1993. The adhesion of five strains of slime‐positive Staphylococcus epidermidis to plastic microwells was significantly diminished (P < 0.005) in a concentration‐dependent fashion when wells were previously coated with increasing concentrations (1.6–13.1 μg cm‐2) of human fibronectin (FN). The adhesion of four of five strains was significantly reduced when wells were coated with 3.2 μg cm‐2 of FN and at concentrations ≥6.5 μg cm‐2 the adhesion of all slime‐positive strains was significantly reduced. The coating of microwells with chymotryptic fragments of FN containing the heparin‐binding, gelatin‐binding, or cell‐binding domains also reduced bacterial adhesion but none of the fragments exceeded the anti‐adhesive activity of intact FN. A comparison of FN‐coated or albumin‐coated microwells showed that both proteins caused a significant reduction in the adhesion of test strains to plastic but that the anti‐adhesive activity of FN was greater than albumin at all concentrations tested. The adhesion of the slime‐negative phase variant of one of the test strains to plastic was neither enhanced nor reduced by FN coating indicating that the production of an exopolysaccharide by Staph. epidermidis influences interactions with protein‐coated surfaces. These results support the contention that FN does not mediate the adhesion of all strains of Staph. epidermidis to plastic surfaces.
Viable but non‐culturable salmonellas in soil
Authors: Turpin P.E. , Maycroft K.A. , Rowlands C.L. , Wellington E.M.H.
Published: March 2008

P.E. TURPIN, K.A. MAYCROFT, C.L. ROWLANDS AND E.M.H. WELLINGTON. 1993. An enzyme‐linked immunosorbent assay (ELISA) and a microwell fluorescent antibody (FA) direct count method have been developed for the monitoring of salmonellas in soil. Both methods have a minimum detection level of ca 106 cells per gram of soil. The FA direct count method gave a linear recovery for the inoculum range 106–109 cells per gram of soil. When monitored by plate counts the survival of salmonellas was greater in a sterile than in a non‐sterile soil. Evidence was found for the production of viable but non‐culturable salmonellas in non‐sterile soil; plate counts dropped rapidly with time, but FA direct counts and ELISA remained level. The salmonella cells became progressively smaller and rounder with time. Dead salmonella cells introduced into soil rapidly disappeared.
Microbial metabolism of 2‐arylpropionic acids: effect of environment on the metabolism of ibuprofen by Verticillium lecanii
Authors: Hanlon G.W. , Kooloobandi A. , Hutt A.J.
Published: March 2008

The effect of environment on the growth of Verticillium lecanii and its metabolic transformation of racemic ibuprofen are reported. The growth of V. lecanii exhibited a lag phase of up to 12 h followed by a period of rapid growth for up to 4 d. The optimal conditions for growth of the micro‐organism were determined to be 24°C at pH 7.0 with a culture volume of up to one‐tenth of the culture flask volume.

The metabolic oxidation of (R,S)‐ibuprofen occurred in both growing cultures and washed cell suspensions of V. lecanii. Examination of the stereochemical composition of the remaining substrate indicated that under both conditions the oxidation was substrate stereoselective for the R‐enantiomer of the drug. Using growing cultures of the micro‐organism, quantitative conversion of the substrate to the metabolite was achieved following incubation for 14 d. Examination of the enantiomeric composition of the metabolic product indicated an excess of the S‐isomer (ratio S/R = 2.1). The possible mechanisms for the apparent anomaly in the stereoselectivity of (R,S)‐ibuprofen metabolism and the enantiomeric composition of the metabolite are discussed.
Diversity of ethanol‐tolerant lactobacilli isolated from Douro fortified wine: clustering and identification by numerical analysis of electrophoretic protein profiles
Authors: Couto J.A. , Hogg T.A.
Published: March 2008

Eighty‐two ethanol‐tolerant (≥ 15% v/v) isolates of Lactobacillus were obtained from Douro fortified wines and associated winery equipment. The diversity and specific identity of these isolates was studied with computer‐assisted comparison of the whole‐cell, SDS‐solubilized protein profiles (as generated by SDS‐PAGE); with this method four species were identified. The majority of isolates (89%) were identified as Lact. hilgardii, and three differentiable electrophoretic groups of this species were evident. The identification was confirmed by DNA‐DNA dot‐blot hybridization studies. Also identified were one strain each of Lact. fructivorans, Lact. collinoides and Lact. mali.
Isolation from food sources, of lactic acid bacteria that produced antimicrobials
Authors: Vaughan Elaine E. , Caplice Elizabeth , Looney R. , O'Rourke Nollag , Coveney Helen , Daly C. , Fitzgerald G.F.
Published: March 2008

The potential of lactic acid bacteria, isolated from a variety of foods, to inhibit indicators representative of spoilage and pathogenic bacteria associated with food products was examined. Fruit and vegetables were a poor source of lactic acid bacteria but large numbers were readily isolated on MRS agar from cheese, milk and meat samples. Approximately 1000 isolates from each of the food samples were examined by the deferred antagonism procedure to determine their ability to inhibit Staphylococcus aureus, Listeria innocua and Pseudomonas fragi. Listeria innocua was the bacterium predominantly inhibited by isolates from the cheese, milk and meats, but antagonism was also observed to a lesser extent against the other indicators. The only inhibition observed for isolates from vegetable material was directed against Staph. aureus. The majority of inhibitor producers were effective against only one of the indicators but a small number were isolated which inhibited two or three.
Physiological aspects of disinfection resistance in Pseudomonas cepacia
Authors: Pyle B.H. , Watters Shelley K. , McFeters G.A.
Published: March 2008

A Pseudomonas cepacia population was isolated which had reduced susceptibility to iodine and maintained resistance when subcultured several times in phosphate buffer. This population was also resistant to iodine after growth in a minimal medium containing glycerol but not glucose. Addition of cAMP to glucose‐grown cells caused increased resistance to iodine. Iodine‐resistant cultures also demonstrated reduced susceptibility to chlorination but not to heat or metals (Cu/Ag). The results indicate that halogen resistance can be expressed in varying degrees, dependent on the carbon source, and cAMP may promote this expression. Thus, a catabolite repression‐like mechanism may cause resistant cultures grown in some media to become more sensitive to halogens.
Substrate affinity from bacterial strains and distribution water biofilms
Authors: Frías J. , Ribas F. , Lucena F.
Published: March 2008

Biodegradable dissolved organic carbon (BDOC) is almost the only limiting factor of bacterial growth in drinking water. Two representative bacterial strains were isolated from a two‐column reactor for the determination of BDOC (from respectively the first and the second column) and used to estimate their growth kinetics in two different types of water: finished water from a water treatment plant and water collected at the outlet of the first column of the BDOC reactor. Ks, the substrate saturation constant, was calculated by analogy with Michaelis‐Menten enzyme kinetics, and for each strain a lower Ks value was observed for the type of water that it normally receives.

K
s for in situ biofilms, from both first and second column and the same types of water, were also calculated according to a technique which uses a curve‐matching method with kinetic results from the non‐steady‐state experiments. In this case, the results were similar for the first and second column biofilms. However, a higher affinity was observed for finished water than for the water from the outlet of the first column in both biofilms.
Comparison of polymerase chain reaction and conventional culture for the detection of legionellas in hospital water samples
Authors: Maiwald M. , Kissel K. , Srimuang S. , von Knebel Doeberitz M. , Sonntag H.‐G.
Published: March 2008

A detection system for Legionella spp. based on the polymerase chain reaction (PCR) was used to assess the diagnostic value of PCR for the surveillance of contamination of man‐made water systems by legionellas. A previously‐published primer system was chosen to amplify a fragment of the 5S‐ribosomal gene of Legionella spp. A total of 78 water samples from various sources were examined by PCR and culture on MWY Legionella selective agar. Fifty‐seven of 78 water samples were positive by both test systems (73%), nine were positive by PCR only (11.5%), another nine were positive by culture but negative by PCR (11.5%), and three were negative by both techniques (3.8%). The PCR was inhibited when large amounts of rust were present in the samples. Culture failed to detect legionellas in samples that contained large numbers of other bacteria capable of overgrowing the legionellas. These results show that PCR is a rapid and sensitive technique for the detection of legionella contamination in water samples and that PCR and culture complement each other in monitoring of environmental water samples.
Internal quality control samples for water bacteriology
Authors: Lee R.J. , Cole S.R.
Published: March 2008

A method is described for the preparation and application of a bacteriological quality control system for use with tests for plate counts and the enumeration of indicator organisms in water. Statistical limits are obtained and control charts prepared which are analagous to those used in analytical chemistry and clinical biochemistry laboratories. This approach has been applied successfully in this laboratory but needs to be tested more widely. Such numerically‐based systems have seldom been attempted in microbiology, especially where multiple organisms have been included for the simultaneous control of several tests.
What is Microthrix parvicella ?
Authors: Kocianova Eva , Forster C.F. , Foot R.J.
Published: March 2008

Microthrix parvicella is one of the filamentous bacteria that is known to create problems in the operation of activated sludge plants. Its physiology has already been investigated, although primarily in the context of its being a bulking species. It is now recognized that it is one of the major foam‐forming organisms and, as such, needs further study. The initial isolation of M. parvicella did not prove to be as easy as would be expected from the earlier work and, eventually, micromanipulation was required. Growth studies showed that it exhibited several morphological forms, only one of which was that described previously. This has led to doubts about the classification of this species which does not yet have a clearly defined bacteriological designation.
Induced lactic acid fermentation during the preservation stage of ripe olives from Hojiblanca cultivar
Authors: Durán M.C. , García P. , Brenes M. , Garrido A.
Published: March 2008

The influence of initial sodium chloride concentration (6 and 0%, w/v), acetic acid concentration (0.6, 0.3 and 0.0%, v/v), type of process (natural and inoculated), and storage system (anaerobic and aerobic) on the inducement of a lactic fermentation for the preservation stage of Hojiblanca cultivar ripe olives was investigated. The addition of 6% NaCl prevented colonization by lactic acid bacteria in all cases. A high level of acetic acid (0.6%) was effective in preserving olives for 2 months, although yeast growth was not inhibited for longer periods of storage. Natural growth of Lactobacillus plantarum did not occur. Inoculation with this micro‐organism was effective only in the two treatments with tap water (with no NaCl) as the initial covering solution, although survival was reduced to a half of the added organisms when the initial pH was corrected with 0.3% acetic acid. In these two treatments pH quickly reached appropriate values (<4.0) for olive stabilization. Aerobic conditions led to low concentrations of carbon dioxide, without disturbing growth of lactic acid bacteria. Thus, the aerobic lactic acid fermentation, with tap water initially, was the most adequate preservation procedure for the storage of ripe olives prior to their oxidation treatment. Results of trials conducted on an industrial scale showed the same pattern and confirmed the viability of the new procedure.
Assessment of a microwave‐based clinical waste decontamination unit
Authors: Hoffman P.N. , Hanley M.J.
Published: March 2008

P.N. HOFFMAN AND M.J. HANLEY. 1994. A clinical waste decontamination unit that used microwave‐generated heat was assessed for operator safety and efficacy. Tests with loads artificially contaminated with aerosol‐forming particles showed that no particles were detected outside the machine provided the seals and covers were correctly seated. Thermometric measurement of a self‐generated steam decontamination cycle was used to determine the parameters needed to ensure heat disinfection of the waste reception hopper, prior to entry for maintenance or repair. Bacterial and thermometric test pieces were passed through the machine within a full load of clinical waste. These test pieces, designed to represent a worst case situation, were enclosed in aluminium foil to shield them from direct microwave energy. None of the 100 bacterial test pieces yielded growth on culture and all 100 thermal test pieces achieved temperatures in excess of 99d̀C during their passage through the decontamination unit. It was concluded that this method may be used to render safe the bulk of ward‐generated clinical waste.
Interaction between the effects of bacteria and dry storage on the opening and water relations of cut rose flowers
Authors: van Doorn W.G. , D'hont Karen
Published: March 2008

W.G. VAN DOORN AND K. D'HONT. 1994. Flowering stems of four rose cultivars (Sonia, Madelon, Jacaranda and Frisco) were placed in aqueous suspensions of bacteria at 104 and 108 colony‐forming units (cfu) ml‐1 for 24 h at 5d̀C, then stored dry or held in water for 24 h at 8d̀C and subsequently placed in vase‐water at 20d̀C. The effects of these treatments on vase‐water uptake were similar to the effects on flower opening. In Sonia and Madelon roses flower opening was negatively affected both by 108 cfu ml‐1 of bacteria and by dry storage. No effect was found at 104 cfu ml‐1, but this concentration had a detrimental effect on flower opening when combined with dry storage. Although flower development in Jacaranda roses was not affected by the bacteria treatments it was inhibited by dry storage. This inhibition was progressively greater when the stems had previously been pulse‐treated with a larger number of bacteria. Flower opening in Frisco roses was not affected by even the highest concentration of bacteria, nor by the period of dry storage. It is concluded that placing flowers in water containing bacteria (up to 108 cfu ml‐1) may not always have a negative effect on flower development in cut rose flowers but, together with the effects of dry storage, the presence of even a low number of exogenous bacteria (104 cfu ml‐1) inhibits the development in several cultivars. Such bacterial counts are nearly always found in samples of water used for standing roses during distribution to the consumers.
Simple method of purification and sequencing of a bacteriocin produced by Pediococcus acidilactici UL5
Authors: Daba H. , Lacroix C. , Huang J. , Simard R.E. , Lemieux L.
Published: March 2008

H. DABA, C. LACROIX, J. HUANG, R.E. SIMARD AND L. LEMIEUX. 1994. A bacteriocin produced by a strain of Pediococcus acidilactici was successfully purified sequentially by acid extraction (at pH 2) and reverse‐phase high‐performance liquid chromatography (HPLC). Cell extracts of derivative strains deficient in bacteriocin production exhibited a similar HPLC elution profile to the active extracts except for the two peaks containing bacteriocin activity. The sequence of the antibacterial peptide consisted of 44 amino acid residues of which 42 were identified, and its molecular weight was 4624 Da, as determined by mass spectrometry. Moreover, according to the molecular weight of the peptide, the unidentified residues in the bacteriocin sequence must correspond to two tryptophan residues, confirming that the peptide isolated from Ped. acidilactici UL5 is pediocin PA‐1. However, oxidized forms of the bacteriocin produced during storage also showed bacteriocin activity and resulted in a second peak with activity in the chromatograms. HPLC chromatograms of cell surface preparations from the active and from the deficient strains were confirmed by capillary electrophoresis. The purification method used is simple and effective in comparison with traditional methods, permitting a selective recovery of cell‐associated bacteriocin at low pH, and its isolation in pure form for sequencing.
Identification and composition of the streptococcal and enterococcal flora of tonsils, intestines and faeces of pigs
Authors: Devriese L.A. , Hommez J. , Pot B. , Haesebrouck F.
Published: March 2008

Streptococcus suis was the most frequent Streptococcus spp. in pig tonsils, followed by the beta‐haemolytic porcine ‘equisimilis’ecovar of Strep. dysgalactiae. The intestinal streptococcal flora was composed of Strep. bovis, Strep. hyointestinalis and Strep. suis. Many of these intestinal Strep. suis belonged to a beta‐glucuronidase‐negative biotype which is infrequent in lesions. Nearly half of the strains presumptively identified as Strep. alactolyticus produced acid from lactose. This species was not found in tonsils and intestines but was about equally prevalent as Strep. hyointestinalis in pig faeces and rectal swabs. Other streptococci were rare in this material.

Enterococci were much less frequently identified than streptococci in tonsils and faeces. In intestinal samples Enterococcus faecalis, Ent. faecium, Ent. hirae and Ent. cecorum were most frequently found. In faeces Ent. faecium was the most prevalent enterococcus.

The characteristics of the less well known species Strep. alactolyticus and Strep. hyointestinalis are described in detail, and guidelines for their differentiation from Strep. bovis and Strep. suis given.
Citrate metabolism in 16 Leuconostoc mesenteroides subsp. mesenteroides and subsp. dextranicum strains
Authors: Bellengier Pascale , Hemme D. , Foucaud Catherine
Published: March 2008

Citrate metabolism was studied in non‐growing cells of Leuconostoc mesenteroides subsp. mesenteroides and subsp. dextranicum with respect to energetics, formation of degradation products and stoichiometry. The use of selective ionophores and uncoupler showed that citrate utilization was coupled to the proton motive force generated by ATP hydrolysis. Differences in citrate metabolism observed in 20 Leuconostoc strains were related to strains but not to the species or subspecies studied. Citrate metabolism was stimulated by glucose up to a concentration of 25 mmol 1‐1 and decreased at higher concentrations. The main degradation products resulting from the co‐metabolism of citrate (10 mmol 1‐1) and glucose (2 mmol 1‐1) were acetate, lactate and pyruvate. Only four Leuconostoc strains produced low levels of acetoin and diacetyl. No strains produced ethanol or acetaldehyde. Citrate degradation ability was stable for at least 130 generations in 81% of the Leuconostoc strains.
Evaluation of different antimicrobial agents used as selective supplements for isolation and recovery of Yersinia enterocolitica
Authors: Toora S. , Budu‐Amoako E. , Ablett R.F. , Smith J.
Published: March 2008

Seventeen antimicrobial agents were evaluated separately or in combination for their efficiency as selective supplements in a broth medium against six different serotypes of Yersinia enterocolitica and 20 selected strains of different Gram‐negative bacteria. Irgasan (DP300, 5‐chloro‐2‐(2,4‐dichlorophenoxy) phenol) at a concentration of 4 μg ml‐1 inhibited the growth of most Gram‐negative bacteria with the exceptions of Aeromonas hydrophila, Morganella morganii, Pseudomonas aeruginosa and Serratia liquefaciens. Other antimicrobial agents incorporated in the growth medium, separately or in combination with Irgasan, either inhibited some strains of Y. enterocolitica or did not inhibit the growth of Irgasan‐resistant Gram‐negative bacteria.