bluuebunny/crossref_metadata_2025 huggingface dataset:
The incidence of Yersinia enterocolitica and Yersinia enterocolitica‐like organisms in raw and pasteurized milk in Northern Ireland
Authors: Walker S. J. , Gilmour A.
Published: March 2008

Yersinia enterocolitica and Y. enterocolitica‐like bacteria were frequently isolated from samples of both raw bulked milk (34/150) and farm bottled (raw) milk (5/20). These bacteria were also found to contaminate creamery pasteurized milk (6/100 samples) and farm pasteurized milk (4/50 samples). Although Y. enterocolitica was the most commonly isolated species, Y. intermedia and Y. frederiksenii were also frequently obtained (52, 31 and 15% of isolates, respectively). Also, one atypical strain was identified as Y. aldovae. The Y. enterocolitica strains were largely biotype 1 (20/27) including five strains which could ferment lactose. One third of the Y. enterocolitica strains were not typable, but of those which were, the serotypes were 0:34 (18.5%), 0:5,27 (18.5%), 0:6,30 (15%), 0:4 (11%) and 0:7 (4%). Pre‐enrichment in trypticase‐soy broth (TSB) (at 22°C for 24 h) followed by selective enrichment in bile‐oxalate‐sorbose broth (at 22°C for 6 d) allowed the recovery of 92.3% of all isolates, as compared with 15.4% using cold enrichment in TSB at 4°C for 21 d.
Micro‐organisms associated with African locust bean (Parkia filicoidea Welw) fermentation for ‘dawadawa’ production
Authors: Antai S. P. , Ibrahim M. H.
Published: March 2008

Micro‐organisms associated with the fermentation of ‘dawadawa’, a traditionally prepared food condiment, were isolated and identified. Three species of bacteria (Bacillus subtilis, Leuconostoc mesenteroides and L. dextranicus) were the predominant and most actively involved organisms. The other organisms did not appear to play any major role in the fermentation because they were present in relatively low numbers in the fermenting mash. The temperature and the pH increased sharply during the fermentation process.
The effect of water activity on Legionella spp. growth and survival
Authors: Danielson R. E. , Cooper R. C.
Published: March 2008

Growth and survival of Legionella spp. at various water activity (aw) levels were determined. Compared with Escherichia coli, the growth of Legionella spp. was limited to a high aw environment (≥0.98).
Comparative study of different methods for detection and enumeration of Salmonella spp. in natural waters
Authors: Moriñigo M. A. , Borrego J. J. , Romero P.
Published: March 2008

Seven enrichment media (two proposed by the authors) for detecting salmonellas from polluted freshwater were compared. The Most Probable Number technique for enumeration of salmonellas in water samples was used, directly adding filtered water to buffered peptone water as the pre‐enrichment medium. The results indicate that Rappaport‐Vassiliadis/43 and Rappaport‐Vassiliadis/43 supplemented with 10 μg of sodium novobiocin per ml are the best media for the recovery and enumeration of salmonellas from water samples.
The effect of pH on the growth and metabolism of Streptococcus bovis in continuous culture
Authors: Finlayson Heather J.
Published: March 2008

Streptococcus bovis H13/1 was grown anaerobically at pHs between 5.0 and 6.5 in a glucose‐limited chemostat at a dilution rate of 0.05/h. The growth yield and the production of acetate, ethanol and formate decreased at pHs less than 6.5 whereas the production of lactate increased at the lower pH values. When a culture was subjected to sequential pH changes, growth yield and fermentation products were influenced not only by the pH existing in the culture medium but also by the metabolic activity of the cells at the preceding pHs in the sequence. The results are discussed in relation to the mechanisms available for the maintenance of pH homeo‐stasis and for the metabolic control of fermentation pathways in Strep. bovis.
Virulence plasmid‐associated adhesion of Escherichia coli and its significance for chlorine resistance
Authors: Hicks S. J. , Rowbury R. J.
Published: March 2008

Introduction of the ColV, I‐K94 virulence plasmid into strains of Escherichia coli led (for four out of five strains tested) to a marked increase in the ability of organisms to adhere to glass beads. For strain 1829, the plasmid led to increased attachment to other materials including sand, agar, agarose, chitin and cellulose. The increased adhesion to glass beads was due to the presence of the plasmid and not to its introduction into a variant with altered adhesive properties. The plasmidencoded VmpA protein did not appear to be necessary for the ColV, I‐K94‐promoted adhesion but adhesion was absolutely dependent on the presence of derepressed levels of transfer components in the ColV+ strains and partially dependent on the presence of colicin components. The extent of the plasmid‐promoted adhesion was greatest for organisms grown at 30°, 37° or 42°C and adhesion was almost abolished by growth at 21° or 25°C; this finding is in accord with transfer and colicin components being involved in adhesion. Of several other plasmids tested for their effects on adhesion, those with derepressed transfer properties showed a marked effect as did the RI resistance plasmid. Because of the ease of handling glass bead‐attached organisms, such preparations were used as a model for studying the relevance of attachment to the resistance of E. coli to chlorination in the water purification process. Organisms of 1829 ColV, I‐K94, attached to glass beads, were more resistant to damage and killing by chlorine than were unattached organisms. Three findings suggest that such chlorine resistance may be significant for survival during water chlorination. Firstly, ColV, I‐K94+ bacteria became attached if incubated in sewage effluent with glass beads at 20°C. Secondly, ColV+ organisms already attached to glass beads maintained their attachment during 24 h incubation in effluent at 20°C and thirdly such effluent incubated organisms remained chlorine resistant provided that they retained their attachment.
Characterization of production of cholesterol oxidases in three Rhodococcus strains
Authors: Aihara H. , Watanabe K. , Nakamura R.
Published: March 2008

The production of cholesterol oxidase in two strains of Rhodococcus equi No. 23 from butter, and Rhodococcus sp. No. 33 from bacon, which had properties on biochemical and physiological tests almost similar to the strains of R. equi, was compared with that of the type strain (ATCC 6939) of R. equi. The intensity of cholesterol oxidase activity, both extracellular and membrane‐bound, from the three strains was in the order No. 23, ATCC 6939 and No. 33. More extracellular enzyme was produced by strain No. 23 than by the other two strains. Halo formation on the agar medium containing cholesterol depended on the conversion of cholesterol to 4‐cholesten‐3‐one by the extracellular cholesterol oxidase.
Elevation of the heat resistance of Salmonella typhimurium by sublethal heat shock
Authors: Mackey B. M. , Derrick Christine M.
Published: March 2008

The survival of Salmonella typhimurium after a standard heat challenge at 55°C for 25 min increased by several orders of magnitude when cells grown at 37°C were pre‐incubated at 42°, 45° or 48°C before heating at the higher temperature. Heat resistance increased rapidly after the temperature shift, reaching near maximum levels within 30 min. Elevated heat resistance persisted for at least 10 h. Preincubation of cells at 48°C for 30 min increased their resistance to subsequent heating at 50°, 52°, 55°, 57° or 59°C. Survival curves of resistant cells were curvilinear. Estimated times for a ‘7D’ inactivation increased by 2.6‐ to 20‐fold compared with cells not pre‐incubated before heat challenge.
Storage of pathogenic leptospires in liquid nitrogen
Authors: Palit A. , Haylock L. M. , Cox J. C.
Published: March 2008

The virulence and viability of various serovars of Leptospira interrogans were successfully preserved by storage in liquid nitrogen. Dimethyl sulphoxide at a final concentration of 2.5% (v/v) was added as cryoprotectant to a culture of leptospires grown in Ellinghausen‐McCullough‐Johnson‐Harris medium. Ampoules were cooled at a controlled rate of 1°–3°C/min to −70°C, then transferred to the liquid phase of a liquid nitrogen storage unit. Glycerol was discounted as a cryoprotectant as it was found to be approximately 10 times more toxic than dimethyl sulphoxide to four of five serovars used in this study. The viability of nine strains has so far been observed over a period of 8–22 months storage in liquid nitrogen and full viability of all strains has been preserved over this period. Virulence of strains of serovars pomona and hardjo was well preserved, as demonstrated by challenge tests in guinea pigs and domestic pigs.
A note on starch hydrolysis and β‐glucuronidase activity among flavobacteria
Authors: Petzel J. P. , Hartman P. A.
Published: March 2008

Most flavobacteria tested with the fluorogenic substrate 4‐methylumbelliferyl‐β‐D‐glucuronide possessed β‐glucuronidase (GUD), but when some of the same strains were tested with the API ZYM gallery, all were negative for GUD. Conflicting reports also appear in the literature about starch hydrolysis among flavobacteria. We observed that the results obtained can depend on the medium used and the length of incubation. Our results indicate that GUD activity and starch hydrolysis are more widely distributed in the genusFlavobacteriumthan previously reported.
A probability matrix for the identification of species of Vibrio and related genera
Authors: Bryant T. N. , Lee J. V. , West P. A. , Colwell R. R.
Published: March 2008

A matrix for the probabilistic identification of species of Vibrio and related genera has been constructed using the data from 1091 strains collected throughout the world and classified. Thirty‐eight phenons are included in the matrix, 31 of these represent previously identified species or biovars and seven represent phenons which could not be identified and may represent new species. The identification matrix incorporates 81 characters although a subset of 30 tests can be used to distinguish the 38 phenons from each other. The additional 51 tests were included to assist the identification of some strains for which the initial 30 tests were inadequate. No significant cluster overlap was found at the 5% level and the identification score for the Hypothetical Median Organism of each cluster exceeded 0.9999 in all cases.
NH+/4‐N assimilation by Rhodobacter capsulatus ATCC 23782 grown axenically and non‐axenically in N and C rich media
Authors: Suhaimi M. , Liessens J. , Verstraete W.
Published: March 2008

Assimilation of NH+/4‐N and formation of cell biomass in Rhodobacter capsulatus ATCC 23782 were studied in batch cultures as a function of N and C concentration and light intensity. Growth occurred satisfactorily up to N and C levels of 1.2 and 6.0g/1, respectively. The maximum biomass density achieved was 2.3 g biomass‐C/l at 0.8 g N/l and 4.0g C/l. Media containing initial C/N ratios of 5 provided good growth and almost complete assimilation and recovery of NH+/4‐N and lactate‐C, respectively. A light intensity of about 120 μE/m2/s was adequate for efficient growth. At low levels of NH+/4‐N (<0.05 g N/l), the photobacterium could not maintain dominance under non‐axenic growth conditions. Chloroxuron was necessary to prevent algal overgrowth. At concentrations of 0.2 and 0.4 g NH+/4‐N/l, the photo‐bacterium maintained dominance over several months under the appropriate conditions of temperature (30°C), light intensity (120μE/m2/s), carbon supply (C/N = 5) and cell residence time (5.5d). The protein of Rhb. capsulatus ATCC 23782 was rich in essential amino acids.
The cutaneous microbiology of normal human feet
Authors: Marshall J. , Leeming J. P. , Holland K. T.
Published: March 2008

A survey has been made of the bacterial and fungal populations carried at three different sites on the feet of 60 individuals. The bacteria found at the three sites were quantitatively similar and Micrococcaceae and aerobic coryneform bacteria predominated. The carriage of other bacterial groups was generally low. There was a quantitative variation between sites—mean total counts were 1.04 ± 107 cfu/cm2 skin in the fourth toe cleft, 4.08 ± 105 cfu/cm2 skin on the sole and 1.21 ± 103 cfu/cm2 skin on the dorsal surface. Staphylococci were most often dominant on the sole and dorsal surface whereas aerobic coryneforms predominated in the majority of fourth toe clefts. The higher the total count at a given site the more likely it was that aerobic coryneform bacteria predominated. The skin surface pH was significantly higher on the sole (mean value 6.25) than on the dorsal surface (mean value 5.23). Factors controlling the microbial ecology of the foot are discussed.
Correlation between antibiotic sensitivity testing by conventional and conductivity measurements
Authors: Hogg G. M. , Patterson M. F. , Barr J. G.
Published: March 2008

A high correlation in the susceptibilities of 44 strains isolated from clinical material to a variety of antimicrobial agents was found between the minimum inhibitory concentration and conductivity measurements. Some discrepancy was found for vancomycin and teicoplanin when tested against 21 strains of staphylococci. Similarly, discrepancies were seen with azlocillin, chloramphenicol and gentamicin when tested against strains of aerobic and facultatively anaerobic Gram‐negative bacilli. In the majority of cases in which discrepancies were noted, this reflected differences in relative, and not absolute, susceptibility. With five strains of Pseudomonas however, there was a poor correlation with three of four antibiotics studied. The advantage of this technique is that sensitivities are available within 4–6 h.
Conventional taxonomy of lactobacilli surviving radurization of meat
Authors: Hasting J. W. , Holzapfel W. H.
Published: March 2008

All of the 113 catalasc‐negative, Gram‐positive, rod‐shaped strains isolated from radurized minced beef (5 kGy) were homofermentative, non‐thermophilic, and belonged to the sub‐genus Streptobacterium. The majority of the strains (100) were identified as Lactobacillus sake. These were divided into four sub‐groups based on their sugar fermentation pattern: group IA1 (melibiose (+), maltose (—), amygdalin (—), 76 strains); group IA2 (melibiose (+), maltose (—), amygdalin (+), 14 strains); group IB1 (melibiose (+), maltose (+), amygdalin (+), four strains); group IB2 (melibiose (+), maltose (+), amygdalin (—), six strains). Of the remaining strains, two produced L(+)‐lactic acid and were identified as L. farciminis, three were identified as L. curvatus and eight showed characteristics of both ‘L. sake and L. curvatus and were designated ‘L. sake/curvatus.’ With one exception, all strains were aciduric and relatively insensitive to the chemical preservatives tested. Most L. sake strains produced significant amounts of H2O2. Electron microscopy confirmed a possible relationship between the thickness of the cells and radiation resistance. The problems and limitations of this type of taxonomic study and possible reasons for the predominance of L. sake species in radurized meat are discussed.
Cell surface hydrophobicity and charge of Staphylococcus aureus and coagulase‐negative staphylococci from bovine mastitis
Authors: Mamo W. , Rozgonyi F. , Brown Anna , Hjertean S. , Wadstroum T.
Published: March 2008

The effects of seven growth media on cell surface hydrophobicity of a collection of Staphylococcus aureus and coagulase‐negative staphylococci isolated from bovine mastitis were compared in the salt‐aggregation test. Thirty‐three per cent of Staph. aureus strains showed extremely high cell surface hydrophobicity (auto‐aggregated) and 28% were moderately hydrophobic while 26% were hydrophilic after growth on horse blood agar at 37°C for 18 h. There were great variations in the proportion and degree of the hydrophobicity depending on the medium used. Cultivations on/in capsule‐inducing media caused a shift from a high to a low degree of hydrophobicity, although a microscopically detectable capsule or slime layer was seen in only one strain. This strain and encapsulated reference strains had a hydrophilic cell surface and migrated faster in free zone electrophoresis than cells of unencapsulated strains. Cells of strains grown on staphylococcus medium 110 agar migrated faster than those grown on horse blood agar regardless of their capsule production. Coagulase‐negative staphylococci showed uniformly hydrophilic cell surface after cultivation on horse blood agar, but not when grown in tryptic soy broth or proteose peptone broth. It was concluded that most of the Staph. aureus strains from bovine mastitis under a variety of growth conditions in stationary phase culture constantly expressed hydrophobic cell surface.
Transfer of the Rhizobium leguminosarum biovar trifolii symbiotic plasmid pRtr5a to a strain of Rhizobium sp. that nodulates on Hedysarum coronarium
Authors: Espuny M. R. , Ollero F. J. , Bellogin R. A. , Ruiz‐Sainz J. E. , Perez‐Silva J.
Published: March 2008

The Rhizobium leguminosarum biovar trifolii symbiotic plasmid pRtr5a was transferred to the Rhizobium sp. (Hedysarum coronarium) strain RB16. Transconjugants carrying pRtr5a ineffectively nodulated Trifolium repens, T. pratense and T. alexandrinum and were unable to nodulate H. coronarium plants. Agarose gel electrophoresis of transconjugants showed that all had lost an indigenous plasmid (230 Md). These results suggest that this plasmid harbours the symbiotic determinants for nodulation on H. coronarium.
The effect of a surfactant in media for the enumeration, growth and identification of airborne fungi
Authors: Madelin Theresa M.
Published: March 2008

Air sampling on to culture media for viable fungi is complicated by the presence of fast‐growing species. A non‐ionic surfactant (Triton N‐101) incorporated into the medium effectively reduced the spread of such species and thus facilitated the enumeration and identification of fungal colonies collected by an Andersen sampler. The concentration of surfactant from 250 to 8000 ppm was not critical. Sixteen species of common moulds inoculated on surfactant media showed restricted radial growth but never total inhibition. Surfactant did not prevent sporulation and did not greatly affect morphological characteristics. Rose bengal media performed poorly in comparative tests. These observations indicate the practical value of this surfactant in aeromycological studies.
The effect of sucrose on the colonization of acrylic by Candida albicans in pure and mixed culture in an artificial mouth
Authors: Richards S. , Russell C.
Published: March 2008

The roles of sucrose and microbial interactions in the colonization of acrylic by Candida albicans in an artificial mouth were investigated. The acrylic was colonized by pure cultures of the organism but a visible plaque was not produced whether or not sucrose was present. Salivary bacteria had no effect in the absence of sucrose but when sucrose was present the numbers of C. albicans were significantly increased. It is suggested that this phenomenon is related to the production of extracellular polysaccharides by salivary streptococci in the presence of sucrose. In mixed culture of C. albicans and Streptococcus salivarius CJ2, growth of the latter was inhibited in the presence of sucrose. This inhibition was due to factors other than pH, although no such antagonism could be demonstrated on solid media.
The effect of ampicillin and tylosin on the faecal enterococci of healthy young chickens
Authors: Kaukas Anne , Hinton M. , Linton A. H.
Published: March 2008

Enterococcal isolates from young chickens were differentiated into one of three species, namely Enterococcus faecalis, Ent. faecium and Ent. gallinarum. The proportion of each species among the enterococcal population changed with time in birds not dosed with antibiotics. This pattern of change was modified in birds dosed with either tylosin or ampicillin even though ampicillin did not select for ampicillin resistance among the enterococcal population. A gradual increase in tylosin resistance was recorded with time among the enterococci of the ‘undosed’ control birds. This was associated with an increase in the proportion of Ent. faecium, a species commonly resistant to tylosin, among the enterococci of the birds as they grew older.
Kocho fermentation
Authors: Gashe B. A.
Published: March 2008

Kocho, an acidic starchy food, is prepared by fermenting a mixture of the scraping of the trunk and pulverized stem and corm of ensette (Ensette ventricosum). Leuconostoc mesenteroides is responsible for initiating the fermentation. Because of the activities of this species and, to some extent, of Streptococcus faecalis, the pH of the fermenting kocho was reduced from 6˙5 to 5˙6. These organisms were then succeeded by the homofermentative bacteria Lactobacillus coryneformis subsp. coryne‐formis and Lact. plantarum. Through the activities of the Lactobacillus species, the pH was further reduced to 4˙2. Pediococcus cerevisiae, although present in kocho, did not achieve prominence because of the relatively low fermentation temperature (14°‐18°C). Spore‐formers were present in fairly high numbers during the first 15 d of fermentation. It was suspected that the butyrous odour which was detected during the first 2 weeks in fermenting kocho might be due to the activities of certain clostridial species. Yeasts were also present in fairly high numbers.
Effect of thermal treatments in oils on bacterial spore survival
Authors: Ababouch L. , Busta F. F.
Published: March 2008

The heat resistance of Bacillus cereus F4165/75, Clostridium sporogenes PA 3679 and Cl. botulinum 62A spores suspended in buffer (pH 7˙2), olive oil and a commercial oil (a mixture of rapeseed oil and soy oil) was investigated. Linear survivor curves were obtained with B. cereus spores in the three menstrua and with 62A and PA 3679 spores suspended in buffer. However, the inactivation kinetics of the clostridial spores suspended in oils were concave upward with a characteristic tailing‐off for 62A spores suspended in olive oil. These deviations from the semi‐log model could not be ascribed to a heterogeneity in heat resistance of the spore population or to the variation of aw during heating. Spore resistance to heat increased in the order: buffer ⋖ commercial oil < olive oil. The greater heat resistance of oil‐suspended spores was ascribed to the low aw (0˙479 and 0˙492 for commercial oil and olive oil, respectively) and to the composition of the oils. The difference in z values (ca 28°C in oils and 10°‐12°C in buffer) suggested that the mechanism of inactivation differs for spores suspended in lipids and in aqueous systems. The thermodynamic data were consistent with this hypothesis.
Tailing of survivor curves of clostridial spores heated in edible oils
Authors: Ababouch L. , Dikra A. , Busta F. F.
Published: March 2008

Tailing of survivor curves was observed for Clostridium sporogenes PA 3679 and Cl. botulinum 62A spores heated whilst suspended in edible oils, but not for the same spores suspended in buffer (pH 7˙2) or mineral oil or for Bacillus cereus F4165/75 spores suspended in buffer or oils. The tailing cannot be ascribed to a genetic or developmental heterogeneity in the resistance of the spore population or to a heterogeneity of the treatment severity during heating. Heat adaptation due to the release of protective factor(s), to the selection for resistant spores or to the diffusion of oil constituents inside the spore protoplast to protect key molecules from heat denaturation was also ruled out. The tailing can be ascribed to spore clumping during the course of heating or to a heterogeneity in heat resistance of germination system(s) within spores, concurrently with the activation of a dormant germination system. It is probably caused by some oleic acid containing triglycerides.
Model for combined effect of temperature and salt concentration/water activity on the growth rate of Staphylococcus xylosus
Authors: McMeekin T. A. , Chandler R. E. , Doe P. E. , Garland C. D. , Olley June , Putro S. , Ratkowsky D. A.
Published: March 2008

The combined effect of temperature and NaCl concentration/water activity on the growth rate of a strain of halotolerant Staphylococcus is described by the squareroot models which had been used previously to model temperature dependence only. The model r=b(T ‐ Tmin) is shown to be a special case of the BélehraAdek temperature function which is given by r=a(T ‐ aL)d. The constant aL is the so‐called ‘biological zero’ and equivalent to Tmin in the square‐root models. This and the exponent d= 2 were unaffected by changing NaCl concentration/water activity. The Bélehradek‐type equations are preferable to the Arrhenius equation in that their parameters do not change with temperature. The constancy of Tmin allows derivation of a simple expression relating growth rate of strain CM21/3 to temperature and salt concentration/water activity within the range of linear response to temperature predicted by the square‐root model.
Presence of Erwinia carotovora in surface water in North America
Authors: Harrison M. D. , Franc G. D. , Maddox D. A. , Michaud J. E. , McCarter‐Zorner N. J.
Published: March 2008

Erwinia carotovora was frequently isolated from samples of surface water collected from 66 rivers, springs, creeks, streams, lakes, reservoirs and ponds in 16 states in the US but was not found in the single fresh water sample collected in Canada. The organism was also isolated from water collected from the Pacific Ocean and the Gulf of Mexico. In Colorado and Wyoming, E. carotovora was isolated from water samples nearly every month of the year when monthly samples were collected from several streams. Erwinia carotovora subsp. carotovora represented 98–8% of the strains recovered from the water samples; E. carotovora subsp. atroseptica made up the remainder of the strains; E. chrysanthemi was not found.
The sporicidal activity and inactivation of chlorhexidine gluconate in aqueous and alcoholic solution
Authors: Gorman S. P. , Jones D. S. , Loftus A. M.
Published: March 2008

The sporicidal activity of chlorhexidine gluconate in aqueous and alcoholic solution against spores of Bacillus subtilis was examined over a broad temperature range. Activity was not observed at 20°C even with concentrations as high as 10% chlorhexidine. Temperatures of 37°–70°C in combination with such high concentrations were required for reductions in spore viability. No viable spores were recoverable after 4 h contact at 55°C with 10% aqueous chlorhexidine and none after 3 h contact with the alcoholic solution. Because of the high concentrations necessary for activity and the possibility of sporostasis occurring from inefficient chlorhexidine inactivation, existing inactivation systems were examined and modified to obtain satisfactory results. The spores of other Bacillus species examined (B. cereus, B. megaterium and B. stearothermophilus) proved to be considerably less resistant than those of B. subtilis. Presence of organic matter had little effect on the activity.
Dynamics of orange peel fermentation during ensilage
Authors: Ashbell G. , Pahlow G. , Dinter Barbara , Weinberg Z. G.
Published: March 2008

The dynamics of fermentation during ensilage were studied on orange peel (variety Shamouti) ensiled in 50 plastic containers, 10 kg in each, with an outlet for seepage. At predetermined intervals the containers were weighed and samples were taken from three of them for chemical and microbial analysis. Fermentation losses amounted to up to ca one‐third of the fresh peel dry matter (DM) content. Most losses occurred within 10 d of commencement of fermentation, and were attributable to gas release. The major fermentation products were ethanol, lactic and acetic acids (16, 3 and 3% of DM, respectively). The dominant microbial populations were lactobacilli and yeasts. Tests are in progress to inhibit the yeasts and thereby reduce fermentation losses.
The antibacterial activity of alamethicins and zervamicins
Authors: Jen W. ‐C. , Jones G. A. , Brewer D. , Parkinson V. O. , Taylor A.
Published: March 2008

Consistent results were obtained in biological assays of alamethicins on agar gels only when the antibiotics were allowed to diffuse under strictly defined conditions of temperature and time before inoculation. In liquid culture obligatory anaerobic rumen bacteria were sensitive to these antibiotics and in certain cases their ability to produce volatile fatty acids was reduced. Among the bacteria examined there was a 1000‐fold difference in their sensitivity. Modifications of the structure of the peptaibol, e.g. substitution of an alanine residue for a 2‐methylalanine residue resulted in ca two‐fold changes in activity.
Tracing Pediococcus acidilactici in ensiled maize by plasmid‐encoded erythromycin resistance
Authors: Torriani Sandra , Vescovo Marisa , Dellaglio F.
Published: March 2008

Curing experiments undertaken on Pediococcus acidilactici strain S364, isolated from maize silage, revealed a linkage between a resident 40 MD plasmid and resistance to erythromycin, oleandomycin and tylosin. The possibility of using erythromycin resistance to monitor the fate of this strain in a model ensiling system was also demonstrated.
Pectolytic clostridia isolated from sugar beet pulp silages in Italy
Authors: Suzzi Giovanna , Papa F. , Grazia L.
Published: March 2008

Twenty‐eight strains of pectolytic clostridia were isolated from sugar beet pulp silages. Seventeen non‐pigmented strains were presumed to be Clostridium acetobutylicum; the remaining 11 pigmented strains were similar to Cl. felsineum. The addition of molasses to sugar beet pulps favoured the growth of other bacteria, particularly lactic acid organisms, whereas pectolytic clostridia were only occasionally found. The pectolytic clostridia promoted the structure loss of simulated silages. The use of molasses in sugar beet pulp ensiling was suggested to prevent texture loss of the ensiled mass.
A numerical taxonomic study of Leuconostoc oenos strains from wine
Authors: Tracey R. P. , Britz T. J.
Published: March 2008

Phenotypic data of 108 tests conducted on 70 malolactic bacteria, including 54 presumptive Leuconostoc oenos strains, five presumptive pediococci isolated from wine and 11 reference strains, were analysed by numerical taxonomic techniques. Using the simple matching coefficient, 58 strains were grouped in six clusters at the 87% S level. Cell wall analysis of the interpeptide bridges and morphology was also used to differentiate between the strains. No L. oenos reference strains were found to group in any cluster. The hypothetical median organism (HMO) of cluster A was related at only the 63% S level to the L. oenos type strain and it is proposed that these strains be regarded as ‘L. gracile’. The majority of the L. oenos strains (35) grouped together at above the 91% S level in cluster B, with the HMO of this cluster related at the 75% S level to the L. oenos type strain. Results indicate that the majority of L. oenos strains included in this study are closely related, but more research is needed to justify the separation of these strains into more than one species.
Survival of Listeria monocytogenes in raw milk treated in a pilot plant size pasteurizer
Authors: Garayzabal J. F. Fernandez , Rodriguez L. Dominguez , Boland J. A. Vazquez , Ferri E. F. Rodriguez , Dieste V. Briones , Cancelo J. L. Blanco , Fernandez G. Suarez
Published: March 2008

The survival of Listeria monocytogenes in raw milk treated in a pilot plant size pasteurizer was investigated. Raw milk was inoculated with different initial concentrations of L. monocytogenes and heated at temperatures ranging from 69° to 73°C. Listerias were not isolated from any of the milk samples immediately after thermal treatment. They were isolated, however, from 46.6% of heated samples (none from samples heated at 73°C) after variable periods at refrigeration temperature. The results suggest that a low number of listerias survive some thermal treatments, but a cold enrichment is necessary to repair the thermally injured cells and detect these organisms in milk. The importance of the isolation technique in the recovery of listerias from pasteurized milk samples is discussed.
Amines in fresh beef of normal pH and the role of bacteria in changes in concentration observed during storage in vacuum packs at chill temperatures
Authors: Edwards R.A. , Dainty R.H. , Hibbard C.M. , Ramantanis S.V.
Published: March 2008

Edwards, R.A., Dainty, R.H., Hibbard, C.M. & Ramantanis, S.V. 1987. Amines in fresh beef of normal pH and the role of bacteria in changes in concentration observed during storage in vacuum packs at chill temperatures.

The amine content of fresh and vacuum‐packaged beef of normal pH stored at 1°C was evaluated by high performance liquid chromatography of dansyl derivatives. Fresh samples contained five amines, viz. putrescine, cadaverine, histamine, sperm‐ine and spermidine. Development of a natural spoilage flora during storage led to increases in concentration of putrescine and cadaverine and the production of a sixth amine, tyramine. Pure culture meat inoculation experiments showed tyramine formation to be restricted to lactobacilli and to strains of Lactobacillus divergens and Lact. carnis in particular; strains of leuconostocs, Enterobacteriaceae, Pseudomonas spp. and Brochothrix thermosphacta were negative. Production of tyramine at cell densities >log10 6/cm2 indicated its potential as an objective measure of acceptability/spoilage.
A modified conductance medium for the detection of Salmonella spp.
Authors: Ogden I.D. , Cann D.C.
Published: March 2008

Selenite‐Cystine/trimethylamine oxide/dulcitol medium has been used in conjunction with conductance instruments to detect the presence of Salmonella spp. in foods and faeces. However, a small but significant number of salmonella strains were missed by this method. The majority of these strains were detected when dulcitol was substituted by mannitol and tested on two separate Malthus conductance instruments. Some strains of Citrobacter freundii and Escherichia coli continued to give false positive results. Attempts are made to explain why the substitution of mannitol for dulcitol gives an improved medium.
Influence of specific growth rate and nutrient limitation upon the sensitivity of Escherichia coli towards chlorhexidine diacetate
Authors: Wright Naomi E. , Gilbert P.
Published: March 2008

The sensitivity of Escherichia coli to chlorhexidine has been assessed for cells grown in a chemostat at a variety of specific growth rates, under conditions of carbon, nitrogen, phosphorus and magnesium limitation. At slow rates of growth (ca 0.08/h) little difference in sensitivity was observed. As growth rate was increased, however, the sensitivity of nitrogen‐ and carbon‐limited cells increased whilst that of magnesium‐ and phosphate‐limited cells decreased. It was not possible to correlate the observed patterns of chlorhexidine sensitivity with any single measure of cell envelope composition (phospholipid content, lipopolysaccharide, envelope proteins, etc.). The results presented are not consistent, therefore, with any simple model for chlorhexidine binding or action and more probably reflect subtle interaction between chlorhexidine, phospholipid‐lipopolysaccharide complexes and cations within the envelope.
Reduced adherence of micro‐organisms to human mucosal epithelial cells following treatment with Taurolin, a novel antimicrobial agent
Authors: Gorman S. P. , McCafferty D. F. , Woolfson A. D. , Jones D. S.
Published: March 2008

Taurolin, a non‐antibiotic antimicrobial agent, significantly reduced the adherence of buccal and vaginal strains of Candida albicans blastospores and urine isolates of Escherichia coli and Staphylococcus saprophyticus to epithelial cells. Light microscopy and radio‐isotopic counting methods were used to quantify the adherence of the micro‐organisms to either uroepithelial or buccal epithelial cells. A maximum reduction in adherence of approximately 65% was obtained. The anti‐adherence capacity was time‐dependent, requiring a contact time of 30 min to achieve maximum effect. Taurolin at sub‐minimum inhibitory concentrations (MIC) significantly reduced the adherence of Candida and E. coli. A concentration slightly higher than the MIC was required for Staph. saprophyticus. Treatment of either epithelial cells or micro‐organisms with Taurolin resulted in reduced adherence of microorganisms.
Enterobacteriaceae, coliforms, faecal coliforms and salmonellas in raw ewes'milk
Authors: Gaya Pilar , Medina Margarita , Nuntez M.
Published: March 2008

Thirty‐nine samples of freshly drawn ewes' milk collected at 13 farms, and 120 samples of raw ewes' milk collected on arrival at a dairy were examined. Farm samples had geometric mean counts of 4.4 × 102 Enterobacteriaceae/ml, 3.9 × 102 coliforms/ml and 2.0 × 102 faecal coliforms/ml, whereas the respective mean counts were 6.2 × 103/ml, 5.4 × 103/ml and 1.3 × 103/ml for dairy samples. Salmonellas were not detected by enrichment procedures in any of the 159 samples examined. Escherichia coli (47.5% strains), Enterobacter cloacae (17.7%), Ent. agglomerans (11.3%), Hafnia alvei (6.5%) and Klebsiella oxytoca (6.0%) were the predominant species in 434 Enterobacteriaceae strains isolated from farm samples. Levels and species of Enterobacteriaceae found in the present work in raw ewes' milk imply a considerable risk of early blowing in cheese‐making from unpasteurized milk.
Incidence of Staphylococcus aureus, coliforms and antibiotic‐resistant strains of Escherichia coli in rural water supplies in Port Harcourt
Authors: Antai S. P.
Published: March 2008

The bacteriological quality of some rural water supplies in Port Harcourt was monitored over a 3 month period. The supplies were unsatisfactory as judged by standard plate counts (103/ml) and the presence of presumptive and faecal coliforms and Staphylococcus aureus. The recovery of potentially pathogenic bacteria (e.g. Pseudomonas aeruginosa) further substantiated the existence of health hazards. The most frequently isolated coliforms were Escherichia coli, Enterobacter aerogenes and Klebsiella pneumoniae. Coliform contamination was greater in well water than in river or stream water samples. An antibiotic sensitivity test revealed that 17.5–27.2% of E. coli strains were resistant to three or more antibiotics. Escherichia coli isolated from well water samples exhibited the greatest degree of multiple resistance. Some strains were resistant to all the six antibiotics tested. The danger of an epidemic of waterborne diseases in the communities as a result of drinking water from these non‐potable sources is noted.
Yoghurt: an unlikely source of Campylobacter jejuni/coli
Authors: ČUk Z. , Annan‐Prah A. , Janc M. , Zajc‐Satler J.
Published: March 2008

Knowledge of the relative insensitivity of Campylobacter jejuni to moderately acid environments prompted us to study its survival in different batches of yoghurt of pH range 4.2–5.3 and the role of organic or inorganic acid in the die‐off of this pathogen. None of the 11 strains of C. jejuni or C. coli survived more than 25 min in yoghurt. Suspecting that this rapid die‐off cannot be accounted for by the pH of the yoghurt we compared the survival rates of C. jejuni in milk, whose pH had been adjusted by lactic, propionic and hydrochloric acid respectively, with that of yoghurt. Even for an inoculum of 105–108 cfu/ml propionic acid was bactericidal in minutes. Lactic acid reduced the bacterial populations by 3–5 logs in 30 min. Strong inorganic acid HC1, by contrast, had little or no effect on the populations. Although lactic acid is quite bactericidal for C. jejuni, it is apparently not the only factor to which the prompt elimination of this pathogen from yoghurt could be attributed.
Evaluation of a monoclonal antibody‐based immunoassay for detecting type A Clostridium botulinum toxin produced in pure culture and an inoculated model cured meat system
Authors: Gibson Angela M. , Modi N. K. , Roberts T. A. , Shone C. C. , Hambleton P. , Melling J.
Published: March 2008

A monoclonal antibody‐based amplified enzyme‐linked immunosorbent assay (ELISA) method for detecting Clostridium botulinum type A toxin was evaluated for its ability to detect the toxin in the supernatant fluid of pure cultures and after growth from Cl. botulinum spores inoculated into pork slurries. Slurries containing NaCl (1.5–4.5% w/v) and polyphosphate (0.3% w/v) were either unheated or heated, 80°C/5 min + 70°C/2 h, before storage at 15°, 20° or 27°C. The presence of specific toxin was confirmed by mouse bioassay and results compared with those of the amplified ELISA method. A total of 49 strains, 39 Cl. botulinum and 10 Cl. sporogenes (putrefactive anaerobes), aiid 95 slurry samples were tested. Fourteen of 15 strains of type A Cl. botulinum and 34 of 36 slurry samples containing type A toxin were positive by ELISA. No false positive reactions occurred with Cl. botulinum types B, C, D, E and F, or with the 10 strains of Cl. sporogenes. However, toxin produced by one strain of Cl. botulinum type A (NCTC 2012) was not detected by the amplified ELISA.
The long‐term survival of Escherichia coli in river water
Authors: Flint K. P.
Published: March 2008

Escherichia coli introduced into autoclaved filtered river water survived for up to 260 d at temperatures from 4° to 25°C with no loss of viability. Survival times were less in water which was only filtered through either a Whatman filter paper or a 0.45 μm Millipore filter or in untreated water, suggesting that competition with the natural microbial flora of the water was the primary factor in the disappearance of the introduced bacteria. Survival was also dependent upon temperature with survival at 4°C > 15°C > 25°C > 37°C for any water sample. Direct counts showed that bacterial cells did not disappear as the viable count decreased. The possession of the antibiotic resistance plasmids, R 1drd‐19 or R144‐3, did not enhance survival nor cause a faster rate of decay, indicating that the metabolic burden imposed by a plasmid was not a factor in survival under starvation conditions. There was no evidence of transfer of either plasmid at 15°C or of loss of plasmid function during starvation.
Growth energetics of Clostridium sporogenes NCIB 8053: modulation by CO2
Authors: Dixon N.M. , Lovitt R.W. , Morris J.G. , Kell† D.B.
Published: March 2008

The effects of the partial pressure of carbon dioxide on the growth energetics of Clostridium sporogenes NCIB 8053 grown in chemostat culture were investigated in defined minimal media. Both the ‘maintenance’ requirements and the growth yield coefficients were dependent upon the partial pressure of carbon dioxide in otherwise glucose‐limited cultures. Since growth yield coefficients decreased along with the apparent ‘maintenance’ requirements in essential amino acid/fatty acid medium when the partial pressure of carbon dioxide was increased above 0.5 atm, the occurrence of some type of metabolic uncoupling seemed likely. By contrast, when the organism was grown in amino acid complete medium both the maintenance requirements and the growth yield coefficients were increased when the partial pressure of carbon dioxide was raised above 0.5 atm partial pressure of carbon dioxide, suggesting an increased efficiency of growth. A futile cycle involving carbon dioxide is proposed as a factor contributing to the variable extent of free energy dissipation within this organism.
Evaluation of a monoclonal antibody‐based immunoassay for detecting type B Clostridium botulinum toxin produced in pure culture and an inoculated model cured meat system
Authors: GIBSON ANGELA M. , MODI N.K. , ROBERTS T.A. , HAMBLETON P. , MELLING J.
Published: March 2008

A monoclonal antibody‐based amplified ELISA method for detecting Clostridium botulinum type B toxin was evaluated for its ability to detect the toxin in the supernatant fluid of pure cultures and after growth from Cl. botulinum spores inoculated into pork slurries. Slurries containing NaCl (1.5–4.5%w/v) and polyphosphate (0.3%w/v) were either unheated or heated 80°C/5 min followed by 70°C/2 h before incubation at 15°, 20° or 27°C. Presence of specific toxin was confirmed by mouse bioassay and results were compared with those of the amplified ELISA method. A total of 48 strains, consisting of 38 Cl. botulinum and 10 Cl. sporogenes (putrefactive anaerobes), and 140 slurry samples were tested. Cultures of eight out of nine strains of type B Cl. botulinum and 73 of 101 slurry samples containing type B toxin were positive by ELISA; the remaining 28 slurry samples contained type B toxin at levels below or close to the detection limit (20 LD50/ml) of the type B ELISA. No falsepositive reactions occurred with Cl. botulinum types A, C, D, E or F, or with the 10 strains of Cl. sporogenes. Toxin produced by one strain of Cl. botulinum type B (NCTC 3807) was not detected by this single monoclonal antibody‐based amplified ELISA. With a mixture of two monoclonal antibodies, however, the toxin from NCTC 3807 could be detected without reducing the sensitivity of the ELISA.
Antimicrobial activity and inhibition of aflatoxin B1 formation by olive plant tissue constituents
Authors: Paster N. , Juven B.J. , Harshemesh H.
Published: March 2008

Ethanolic extracts of olive callus tissues, added at 0.5 or 1.0% to media on which Aspergillus flavus was grown, inhibited aflatoxin production by 90% without inhibiting the fungal growth. The extract was found to contain mainly caffeic acid and, to a lesser extent, catechin and coumarins. The fungicidal and bactericidal activity of caffeic acid, catechin, coumarin and p‐, o‐ or m‐coumaric acid were tested and only caffeic acid and o‐coumaric acid inhibited aflatoxin production. The inhibitory effect had no correlation with the growth of the fungus. Only coumarin at 10 mmol/1 totally inhibited fungal growth. Of the phenolic constituents of callus tissues tested, catechin and caffeic acid (10 mmol/1) showed bactericidal activity towards Pseudomonas aeruginosa and Staphylococcus aureus.
Bacterial blotch disease of the cultivated mushroomAgaricus bisporus: screening, isolation and characterization of bacteria antagonistic to the pathogen (Pseudomonas tolaasii)
Authors: Fermor T.R. , Lynch J.M.
Published: March 2008

Bacteria, mainly pseudomonads, were isolated from mushroom farms and from soil and plant materials. They were screened for antagonism toPseudomonas tolaasii, the cause of bacterial blotch of mushroom, using an exclusion zone assay against a bacterial lawn of the pathogen. Selected potential antagonists were identified by the API system and whole cell fatty acid profiles. These strains were tested further in the white line test and host pathogenicity test with mushroom caps. Some of the antagonists have been stable in their aggressiveness over 1 year and several transfers during storage on nutrient agar.
The use of direct epifluorescent microscopy (DEM) and the direct epifluorescent filter technique (DEFT) to assess microbial populations on food contact surfaces
Authors: Holah J.T. , Betts R.P. , Thorpe R.H.
Published: March 2008

Two rapid methods, direct epifluorescent microscopy (DEM) and the direct epifluorescent filter technique (DEFT) on swab resuspension fluids, were compared with the traditional total viable count (TVC) on swab resuspension fluids for their ability to enumerate surface populations of attached bacteria. The degree of error in estimating surface populations was shown to be significantly less with DEM than DEFT followed by TVC. DEM estimated populations in the range 3 times 103 to 5 times 107 colonies/cm2 whilst DEFT enumerated populations above 3 times 104 colonies/cm2 and TVC above 3 times 105 colonies/cm2 (as measured by DEM). Swabbing was shown to remove a constant proportion of organisms from the surface populations tested, although below 3 times 105 colonies/cm2 most of the organisms remained in the cotton matrix and were difficult to resuspend. DEFT was more able to enumerate swab resuspension fluids obtained from surface populations below 3 times 105 colonies/cm2 than was TVC.