bluuebunny/crossref_metadata_2025 huggingface dataset:
Purification and properties of extracellular polysaccharide (EPS) antigens produced by different mould species
Authors: Notermans S. , Wieten G. , Engel H. W. B. , Rombouts F. M. , Hoogerhout P. , van Boom J. H.
Published: March 2008

Extracellular polysaccharide (EPS) antigens produced by different mould species were purified and partially characterized. Purification included (NH4)2SO4 treatment, Sepharose CL‐4B column chromatography and Con A‐sepharose chromatography. The EPS of Penicillium digitatum, Mucor racemosus and Cladosporium cladosporioides showed high antigenic capacities. Immunologically the EPS were partially genus‐specific, but cross‐reactivity was observed. The EPS antigens produced by species of Penicillium, Aspergillus repens and Geotrichum candidum lost their immunological activity upon heating (100C) at pH 18, while the EPS antigen of M. racemosus, Rhizopus oligosporus and C. cladosporioides were stable under the same conditions. The dominant monosaccharides present in the EPS antigen were mannose, galactose and glucose. The EPS obtained from cultures of M. racemosus and R. oligosporus also contained rhamnose. In the EPS produced by Penicillium spp. and A. repens the galactose residues were determined to be immunodominant.
An investigation into the sources of lactic acid bacteria in grass silage
Authors: Fenton Margaret P.
Published: March 2008

During the 1983 silage making season an investigation was carried out to determine the contribution made by farm machinery to the numbers of lactic acid bacteria present on grass. Although no lactic acid bacteria were isolated from the standing crop, up to 103/g were found in the grass as it entered the clamp. Examination of machinery in close contact with the grass revealed lactic acid bacteria on the mower blades and on the forks of the rough‐terrain vehicle used to pack the grass into the clamp. During the 1984 season the occurrence of lactic acid bacteria in particular batches of grass from the standing crop through to silage after 2 d in the clamp was studied. There was a gradual increase in numbers of lactic acid bacteria in the grass during the process of mowing and collection. Wilting resulted in a greater initial increase in numbers but non‐wilted silage had the highest count after 48 h. The majority of organisms isolated from machinery before silage making were streptococci. After silage making the number and proportions of organisms changed, with numbers increasing in all cases, particularly from the mower with lactobacilli and streptococci predominating which indicates that passage through the machinery served to inoculate the grass.
A numerical taxonomic study of psychrotrophic bacteria associated with lipolytic spoilage of raw milk
Authors: Shelley A. W. , Deeth H. C. , Macrae I. C.
Published: March 2008

Raw milk samples were stored for 1–4 d and examined for bacterial growth and lipase activity. Thirty‐six samples in which an increase in the heat‐stable lipase activity was observed during storage were selected for further study. From these raw milk samples 205 lipolytic psychrotrophic strains were selected using butterfat agar and subsequently characterized with 86 taxonomic tests. Complete linkage cluster analysis of the taxonomic data produced two major and six minor clusters at the 83% similarity level. Pseudomonas fluorescens and Ps. fragi accounted for 63.9 and 31.2%, respectively, of the isolates.
Efficacy of some methods and media for detecting and enumerating Campylobacter jejuni in frozen chicken meat
Authors: Beuchat L. R.
Published: March 2008

Four of five strains of Campylobacter jejuni survived in chicken meat stored at — 18C for 12 months. Direct plating of samples was superior to the most probable number technique for enumerating C. jejuni. Enrichment culture using the Doyle & Roman enrichment method resulted in the highest rates of detection. Packaging under an atmosphere of CO2 did not substantially influence survival.
Incidence of infantile diarrhoea due to enteropathogenic Escherichia coli in Port Harcourt metropolis
Authors: Antai S. P. , Anozie S. O.
Published: March 2008

Five hundred diarrhoeal stool samples from the University of Port Harcourt Teaching Hospital were investigated for enteropathogenic Escherichia coli. Results showed that the organism was endemic in Port Harcourt metropolis and was responsible for about 15% of the incidence of infantile diarrhoea in the community. Detailed analysis revealed that 13 serotypes were involved. It was also observed that babies aged between 0 and 18 months were more susceptible than those aged between 19 and 36 months. Male infants were also shown to be more at risk than females. Antibiotic sensitivity tests showed that the enteropathogenic E. coli isolated were highly resistant to most common antimicrobial drugs but were highly sensitive to genticin and cefotaxime.
Effect of alternating current exposure on the resistivity of resting Escherichia coli B cells to crystal violet and other basic dyes
Authors: Shimada K. , Shimahara K.
Published: March 2008

Phosphate buffer suspensions of resting Escherichia coli B cells at pH 70 were anaerobically exposed to alternating current (a.c.) of 50 Hz at a current density of 600 60 mA/cm2 and 34 3C. The minimum inhibitory concentrations of eight basic dyes: crystal violet, malachite green, brilliant green, fuchsin, methylene blue, toluidine blue, safranin and acriflavine for exposed cells were decreased to about the half values of those for unexposed ones when both cells were grown in the minimal medium including one of the dyes. The integrated viabilities of exposed cells tended to decline with increasing concentration of the dyes markedly more than those of unexposed ones, whereas the exposed cells took up the dyes less readily than the unexposed cells. These results suggested that a.c. exposure may serve as an agent which renders E. coli cells susceptible to the basic dyes.
Volatile compounds produced by meat pseudomonads and related reference strains during growth on beef stored in air at chill temperatures
Authors: Edwards R. A. , Dainty R. H. , Hibbard C. M.
Published: March 2008

Volatile compounds produced by 31 strains of pseudomonads and by reference strains of Pseudomonas fragi and Ps. fluorescens biotype 1 during growth on beef stored at 6°C in air were analysed by gas chromatography‐mass spectrometry of headspace gases. Compounds of major sensory significance were ethyl and methyl esters of C2–C8 fatty acids and sulphur‐containing compounds which included methane‐ and isopropanethiols and their related sulphides and thioesters but not hydrogen sulphide. Ester production was mainly associated with growth of some, but not all, Ps. fragi and related meat strains but sulphur‐containing compounds were produced by all but a single meat strain. A minority of other meat strains produced greater amounts of methyl ketones, secondary alcohols and unsaturated hydrocarbons believed to be of lipid origin.
Comparison of most probable number and pour plate procedures for isolation and enumeration of sulphite‐reducing Clostridium spores and Group D faecal streptococci from oysters
Authors: Easterbrook T. J. , West P. A.
Published: March 2008

A comparative study of methods to enumerate sulphite‐reducing Clostridium spores and Group D faecal streptococci in oysters demonstrated that pour plate solid agar techniques gave higher counts than liquid broth most probable number procedures. Reinforced clostridial broth with supplements to detect sulphite reduction was compared with pour plates of egg yolk‐free tryptose sulphite cycloserine agar incubated at 37°C for 24 h. Azide dextrose broth was compared with pour plates using Slanetz and Bartley (SB) agar or KF‐streptococcus agar at 37°C. Most probable number procedures used for both groups of organisms gave excessive numbers of improbable tube combinations. For enumeration of Group D faecal streptococci, a pour plate technique using SB agar incubated at 37°C for 48 h is recommended.
Characterization and DNA homology of Lactobacillus strains isolated from pig intestine
Authors: Axelsson L. , Lindgren S.
Published: March 2008

Twenty strains of the genus Lactobacillus were isolated from pig intestines and characterized with phenotypic tests. Eleven of these strains, together with selected reference strains, were subjected to DNA homology studies. Three major groups could be distinguished by biochemical/physiological tests and by DNA homology studies: one homofermentative group of the subgenus Thermobacterium and two heterofermentative groups. The DNA homology studies revealed that strains from the homofermentative group were related to Lactobacillus acidophilus strain VPI 1754, but showed a low relationship to the type strain of Lact. acidophilus. One group of the heterofermentative strains was related to the type strain of Lact. reuteri; the other group, consisting of three strains, showed a low relationship to all reference strains used. These three strains had the unusual property of producing succinic acid in large amounts.
Uptake hydrogenase in fast‐growing strains of Rhizobium sp. (Sesbania) in relation to nitrogen fixation
Authors: Saini I. , Dogra R. Chander , Nagpal P.
Published: March 2008

Eight of 104 fast‐growing strains of Rhizobium sp. (Sesbania) tested possessed a hydrogen recycling system. Depression of uptake hydrogenase occurred in poor as well as in rich carbon media. A statistically significant increase (> 22%) in total plant nitrogen content and dry matter yield was observed by the inoculation of hup+ strains over hup‐ strains.
Bactericidal properties of an organic N‐chloramine formed in situ
Authors: Elder Elisabeth D. , Worley S. D. , Williams D. E.
Published: March 2008

Agent I (3‐chloro‐4,4‐dimethyl‐2‐oxazolidinone) formed in situ was compared with pre‐formed agent I as a disinfectant against Staphylococcus aureus. In situ formation involved combining the non‐chlorinated oxazolidinone precursor with calcium hypochlorite to form 5 and 10 mg/l total chlorine concentrations of agent I. The variables included in the study were temperature, pH and concentration. Overall the bacteria were killed more rapidly at 22° than at 4°C. The in situ formation appeared to occur most rapidly at pH 7˙0, slightly slower at pH 9˙5, and very slowly at pH 4˙5 as evidenced by the presence of residual free chlorine. In the in situ experimental runs the 5 and 10 mg/l concentrations were equally effective in obtaining a six log decline in cfu/ml. This study indicates the potential for using the organic N‐chloramine as a general purpose disinfectant while omitting the laboratory synthesis of the final product.
The effect of sodium chloride and temperature on the rate and extent of growth of Clostridium botulinum type A in pasteurized pork slurry
Authors: Gibson Angela M. , Bratchell N. , Roberts T. A.
Published: March 2008

A selective medium was used to enumerate Clostridium botulinum growing in the presence of natural spoilage organisms in a model cured pork slurry. The growth responses of a mixed spore inoculum of six strains of Cl. botulinum type A were studied at 15°, 20° and 27°C with 1˙5, 2˙5, 3˙5 or 4˙5% (w/v) salt added (aw range 0961–0990). Gompertz and logistic curves, which have a sigmoid shape, were fitted to the data and lag times, growth rates, generation times and time to maximum growth rates were derived. Variation in germination rates of the spores occasionally gave a falsely extended lag time resulting in an exceptionally high estimate for growth rate. Products containing 4˙5% (w/v) NaCl would be capable of supporting growth of proteolytic strains of Cl. botulinum, even at 15°C, although the lag period would be extended. In products where absence of Cl. botulinum cannot be assured additional preservative measures are essential. The information obtained provides a framework to investigate the effects of a wider range of additives or variables on the growth responses of Cl. botulinum.
Surface properties of lactobacilli isolated from the small intestine of pigs
Authors: Wadstroum T. , Andersson K. , Sydow M. , Axelsson L. , Lindgren S. , Gullmar B.
Published: March 2008

One hundred wild‐type strains of the genus Lactobacillus were isolated from the small intestine of newly‐slaughtered pigs up to 6 months of age. Cell surface hydrophobicity and capsule formation were studied on a number of strains. Strains showing high surface hydrophobicity as measured by the salt‐aggregation test and hydrophobic interaction chromatography on Octyl Sepharose were commonly found to adhere in high numbers to isolated pig intestinal epithelial cells. Heat and protease treatment of bacteria of high surface hydrophobicity, including autoaggregating strains in phosphate‐buffered saline, showed a drastic decline in this surface property. Three hydrophilic strains (LBp 1044, 1068 and 1073) also showed binding to intestinal cells but at a lower level (approx. 5 bacteria/cell) as compared with the best binding hydrophobic strain (LBp 1063, approx. 11 bacteria/cell). These findings suggest that different or multiple adhesion mechanisms may be involved in the colonization of the small intestinal mucosa of pigs. Cultures of selected strains grown in liquid media rich in carbohydrates did not affect their hydrophobic cell surface character. Therefore it seems less likely that carbohydrate capsule polymers are the major determinants of intestinal colonization of lactobacilli in pigs.
Factors affecting production of coccoid forms by Campylobacter jejuni on solid media during incubation
Authors: Moran A. P. , Upton Mary E.
Published: March 2008

Conditions influencing the conversion of oxygen into toxic derivatives in media were investigated for their effects on production of coccoid forms in cultures of the enteric pathogen Campylobacter jejuni. Compared with stored media, production of coccoid forms was less on freshly prepared media. Whether freshly prepared or stored before use, brucella agar media produced the fewest coccoid forms under the test conditions. Addition of supplements used as detoxifying agents minimized production of these forms on media but antibiotic formulations used in selective media did not influence production of coccoid forms. Furthermore, the type of incubation atmosphere and the strain of C. jejuni influenced the proportions of coccoid forms in cultures. It was deduced from electron microscopy observations during prolonged incubation of cultures that the process of conversion to coccoid forms involves a loss of spiral morphology, a shortening of the cell and retraction of the cytoplasm towards a cell terminal region. Coccoid forms and some intermediate forms in thin sections were found to lack cell integrity. It is concluded that coccoid form production in cultures is a degenerate response to toxic oxygen derivatives in cultures.
The hydrophobicity of ‘viridans’ streptococci isolated from the human mouth
Authors: Hogg S. D. , Manning J. E.
Published: March 2008

The hydrophobicity of human oral streptococci was measured with the hexadecane assay modified by the incorporation of polyethylene glycol 6000. Large variability in the hydrophobicity between cultures of some strains grown on different occasions was observed whereas other strains were less variable. The variation in hydrophobicity was significantly reduced by growing the cells in continuous culture in a chemostat under glucose‐limiting conditions. The Streptococcus mutans strains used all had low hydrophobicity and the mean hydrophobicity of this species was significantly lower (P < 0.05) than the mean hydrophobicity of Strep. salivarius, Strep. sanguis Type I and Strep. sanguis Type II strains. This finding supports the view that hydrophobicity is a contributing factor in the adhesion of viridans streptococci to oral surfaces.
Numerical analysis of electrophoretic protein patterns of Providencia rustigianii strains from human diarrhoea and other sources
Authors: Costas M. , Holmes B. , Sloss L. L.
Published: March 2008

Twenty strains of Providencia rustigianii (including the type strain of Prov. friedericiana) have been characterized by one‐dimensional SDS‐PAGE of cellular proteins. They comprised 12 strains (almost exclusively associated with the intestinal tract) from humans, plus eight largely from the intestinal tract of pig, penguin and environmental sources. The protein patterns, which contained 45–50 discrete bands, were highly reproducible and were used as the basis for two numerical analyses. In the first, which included all the protein bands, the 20 Prov. rustigianii strains formed six clusters at the 88% S level. One of these clusters included the type strains of both Prov. friedericiana and Prov. rustigianii, thereby confirming the synonymy of these two species. In the second analysis, the principal protein bands were excluded. At the 86% S level the 20 Prov. rustigianii strains formed a single cluster, whilst a field strain of Morganella morganii and the respective type strains of three other Providencia species remained unclustered. The total protein pattern of the type strain of Prov. alcalifaciens was very similar to that of Prov. rustigianii phenon 3 and the M. morganii field strain, which indicates that careful biochemical characterization may be necessary to ascribe strains to a species before typing by the PAGE technique. Alternatively, a selective analysis of the protein bands may be used to confirm the identity of the strains, as shown in this study.
The specific detection of indole production by Erwinia species and some other enterobacteria on agar
Authors: Cother E. J. , Blakeney A. B.
Published: March 2008

Indole reacts with glutaconic aldehyde to produce a red‐violet polymethine dye. Glutaconic aldehyde is an unstable reagent but may readily be generated by the alkaline cleavage of 1‐(4‐pyridyl) pyridinium chloride. Bacterial colonies grown on agar containing 0˙2% tryptophan may be tested in situ or smeared on reagent‐impregnated filter paper. Residual tryptophan does not interfere with the reaction which, on paper, is indole‐specific even in the presence of nitrite. Test papers are easily prepared and have a shelf‐life of at least 2 years.
Nitrogen fixation and indole acetic acid production by Azospi‐rillum sp. as influenced by an insecticide, carbofuran
Authors: Jena P. K. , Adhya T. K. , Rao V. Rajaramamohan
Published: March 2008

Both indole acetic acid (IAA) accumulation and nitrogen fixation were increased in Azospirillum cultures isolated from rice roots and soils by carbofuran (2, 3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl‐N‐methyl carbamate), an insecticide widely used in rice cultivation. Addition of carbofuran at 5 and 10 parts/106 significantly stimulated nitrogen fixation in Azospirillum. Indole acetic acid accumulation by Azospirillum cultures was more pronounced at a lower level (250 g/50 ml) of carbofuran. Evidence is provided for carbofuran degradation by Azospirillum cultures. The 7‐benzofuranol (2, 3‐dihydro‐2–2‐dimethyl‐7 benzofuranol), a major degradation product of carbofuran, however, did not enhance the IAA accumulation. The higher accumulation of IAA in Azospirillum in the presence of carbofuran is probably related to the increased growth due to fixed N present in the insecticide. Results indicate the involvement of parent compound carbofuran and/or compounds other than the 7‐benzofuranol in the higher accumulation of IAA by Azospirillum sp.
Production, purification and characterization of an α‐amylase produced by Saccharomycopsis fibuligera
Authors: Gogoi B.K. , Bezbaruah R.L. , Pillai K.R. , Baruah J.N.
Published: March 2008

Saccharomycopsis fibuligera ST 2 produced high levels of extracellular amylase during the stationary phase of growth. Glucose or other low molecular weight metabolizable sugars did not repress the synthesis of the amylase, indicating the lack of catabolite repression in this organism. Of the nitrogen sources examined, yeast extract and corn steep liquor stimulated the highest yield of amylase. Ammonium sulphate inhibited α‐amylase synthesis. The enzyme was purified 118‐fold from the culture supernatant fluid by isopropanol precipitation and DEAE‐Sephadex A50 chromatography. The purified enzyme was characterized as an α‐amylase. The α‐amylase had the following properties: molecular weight, 40900 ± 500; optimum temperature, 60°C; activation energy, 1600 cal/mol; optimum pH, 4·8–6·0; range of pH stability, pH 4·0–9·4; Km (50°C, pH 5·5) for soluble starch, 0·572 mg/ml; final products of starch hydrolysis—glucose, maltose, maltotriose and maltotetraose.
The combined effect of sub‐optimal temperature and sub‐optimal pH on growth and toxin formation from spores of Clostridium botulinum
Authors: Graham Ann F. , Lund Barbara M.
Published: March 2008

Low‐acid foods (pH ≥ 4.5) are not sufficiently acidic to prevent growth of Clostridium botulinum in otherwise optimal conditions. The combination of sub‐optimal pH and sub‐optimal temperature may, however, result in a very significant reduction in the risk of growth of this bacterium compared with the risk in optimal conditions. The combined effect of incubation temperatures of 12° and 16°C and pH values between 5·2 and 5·5 on growth and toxin production from spores of Cl. botulinum during incubation for 28 d has been investigated. Growth and formation of toxin (type B) were detected only in medium at pH 5·5 and incubated at 16°C, corresponding to a probability of growth from a single spore within 14 d of 1·6 × 10‐5. The probability of growth in 28 d in the remaining conditions was <9 × 10‐6. After transfer of inoculated media from 12° to 30°C growth occurred at pH 5·2–5·5 within 19 d. After transfer of inoculated media from 12° to 20°C growth occurred at pH 5·5 and 5·4 but not at pH 5·3 or 5·2 in 40 d. Growth at pH 5·2–5·5 was accompanied by formation of toxin, in most cases of types A or B. In addition to the effect of sub‐optimal temperature and pH, chelation of divalent metal ions by citrate may have contributed to inhibition.
Ethanol production in table jelly by two species of Chrysosporium
Authors: Kinderlerer Judith L.
Published: March 2008

Different commercial brands of tablet jelly were stored in sealed containers for 12 weeks at an initial water activity of 0·90. The surface of those containing real fruit juice became covered with a dense white mould identified as Chrysosporium inops. That of those without fruit juice did not. This type of spoilage has been observed in commercially stored samples. When spores of this fungus and the closely related species, C. xerophilum, were added to commercial tablet jelly, the fungi grew only on samples containing real fruit juice. It is suggested that the fruit juice may provide some essential nutrient required for growth of these nutritionally fastidious species as well as the fungal spores themselves. Ethanol was detected in the headspace gas of stored samples of mouldy jelly. The production of ethanol by the two Chrysosporium species was confirmed by fermentation of glucose in liquid batch culture: approximately 2% ethanol was formed in 14 d. The ability of C. xerophilum and C. inops to utilize the Embden‐Meyerhof‐Parnas pathway may explain why these slow‐growing xerophilic moulds become dominant after storage at low oxygen tension.
The effect of incubation time and temperature on growth of Escherichia coli on gradient plates containing sodium chloride and sodium nitrite
Authors: McClure P.J. , Roberts T.A.
Published: March 2008

Two‐dimensional gradient plates are a convenient way of screening antimicrobial effects of preservative factors acting in combination across a broad range of physical and chemical conditions. We report the effects of sodium chloride, sodium nitrite and incubation temperature on the growth of Escherichia coli by staining, laser densitometry and computer graphics. Staining not only more easily distinguished the growth area but also gave an indication of the viability of cells present. 2‐(p‐iodophenyl)‐3‐(p‐nitrophenyl)‐5‐phenyl tetrazolium chloride was the more useful of the two stains used. Inhibitory concentrations of sodium chloride decreased with reduced incubation temperature. The response of E. coli to combinations of salt and nitrite on gradient plates was very similar to its response in liquid medium.
Use of plasmid profiles to detect changes in strains of Staphylococcus aureus during poultry processing
Authors: Dodd C.E.R. , Adams B.W. , Mead G.C. , Waites W.M.
Published: March 2008

The plasmid profiles of Staphylococcus aureus strains isolated at different stages in three poultry processing plants have been examined. Changes in profiles were seen in two plants after the plucking stage and the appearance of these new profiles correlated with the presence of an endemic strain, as suggested previously by increases in bacterial counts and changes in biotypes at the same stage. A third plant in which such changes did not occur showed no change in profiles. Plasmid profiles are therefore a rapid and sensitive method for distinguishing endemic strains within a plant from the flora of the incoming birds. Certain profiles also appeared to correspond with particular biotypes and certain phage types.
The inhibition of Staphylococcus hyicus on a selective medium for staphylococci
Authors: Harvey J. , Gilmour A.
Published: March 2008

Growth of Staphylococcus hyicus subsp. hyicus and Staph. hyicus subsp. chromogenes strains was found to be severely inhibited when broth cultures of these organisms were streaked on Schleifer and Kramer's staphylococcal (SK) medium. Of the selective agents contained in SK medium, potassium thiocyanate was found to be inhibitory towards both subspecies of Staph. hyicus and sodium azide had an additional inhibitory effect on Staph. hyicus subsp. chromogenes. Of six different media supplements examined, sheep blood and Tween 80 were found to improve the growth of both Staph. hyicus subspecies when added to SK medium. These findings were confirmed in subsequent work where the supplemented SK media were used to isolate potential enterotoxin‐producing organisms from simulated raw milk (Staph. aureus, Staph. hyicus subsp. hyicus, Staph. hyicus subsp. chromogenes, Staph. intermedius). SK medium supplemented with sheep blood proved more effective in allowing satisfactory recovery of Staph. aureus, Staph. hyicus subsp. hyicus and Staph. intermedius. However, neither supplement enabled satisfactory recovery of Staph. hyicus subsp. chromogenes to be achieved.
A low‐cost antifoam additive for agar‐based culture media
Authors: Blenkharn J. I. , Wood Sharon
Published: March 2008

A highly effective, low‐cost silicone‐based antifoam emulsion is described which, at a final concentration of 100 ppm, prevents bubble formation during the preparation and dispensing of agar media. The compound is heat‐stable, has a long shelf‐life and offers considerable savings in cost by reduction in wastage of time and materials. It has no demonstrable deleterious effect on the growth of a wide range of pathogenic and commensal bacteria, or on antibiotic disc susceptibility testing, when examined using a range of different media.
Two‐dimensional gel resolution of polypeptides specific for autotrophic growth in Thiobacillus versutus
Authors: Read Dorothy L. , Matin A.
Published: March 2008

Seven polypeptides specific for autotrophic growth by oxidation of thiosulphate have been identified in proteins of Thiobacillus versutus analysed by two‐dimensional gel electrophoresis. Their molecular weights ranged from 32 to 100 kD and PI values from pH 6 to pH 7. Their probable relationships to previously reported Thiobacillus proteins involved in autotrophy, in particular ribulose bis‐phosphate carboxylase, are discussed. These polypeptides will serve as useful landmarks in genetic study and manipulation of sulphur oxidation in these organisms.
Isolation and identification of a N2‐fixing zoogloea‐forming bacterium from kallar grass histoplane
Authors: Bilal Rakhshanda , Malik K. A.
Published: March 2008

Semi‐solid medium was used to isolate an aerobic, N2‐fixing (C2H2‐reducing), H2‐utilizing bacterium from the roots of kallar grass (Leptochloa fusca). The organism was identified by morphological, cultural and biochemical characteristics. The N2‐fixing, zoogloeal floc‐forming isolate described here is a new species.
Microflora associated with the internal surfaces of rubber and stainless steel milk transfer pipeline
Authors: Lewis Stephanie J. , Gilmour A.
Published: March 2008

Sterile sections of rubber and stainless steel milk transfer pipeline were inserted sequentially into a milking installation and soiled with fresh raw milk over a period of 5 d. The resultant adherent microbial population was removed and the generic composition of mesophilic and psychrotrophic types was determined. In all cases Acinetobacter spp. were found to predominate (59.5–75.6%). The generic composition of the raw milk used to soil the milking unit (with inserted pipe section) was determined once during each 5‐d soiling period. In general the milk was found to contain a mixed flora in which Gram‐positive organisms predominated.
Cellular fatty acid composition in moderately halophilic Gram‐negative rods
Authors: Monteoliva‐Sanchez Mercedes , Ramos‐Cormenzana A.
Published: March 2008

The fatty acid compositions for 40 strains of moderately halophilic Gram‐negative rods were determined by gas‐liquid chromatography. The strains studied were included in the genera: Vibrio, Deleya, Alteromonas, Chromobacterium, Flavobac‐terium and Pseudomonas. Although there were quantitative differences all strains showed more or less similar spectra of fatty acids ranging from C12 to C20 chain. The major fatty acid species were C16:0, C16:1 and C18:1. Most striking was the predominance of the C18:1 component, the major fatty acid in extracts of 29 of the 40 strains.
Evaluation of a fluorescent antibody technique for the rapid enumeration of Bacteroides fragilis group of organisms in water
Authors: Fiksdal L. , Berg J. D.
Published: March 2008

The Bacteroides fragilis group has been evaluated as a prospective rapid indicator of faecal contamination of water. Fluorescent antibody (FA) stained B. fragilis group bacteria were enumerated microscopically and compared with faecal coliform or Escherichia coli counts as indicators of faecal contamination. Environmental samples included surface waters (raw drinking water and known contaminated water). Laboratory disinfection experiments with ozone, chlorine and u. v. radiation were also performed. Bacteroides FA counts specifically detected recent human faecal contamination in field samples in 2–3 h. Samples with a high content of particulates or debris limited the sensitivity to about 10 FA counts/ml. Viable counts showed that the sensitivity to all three disinfection agents was essentially the same for Bacteroides and E. coli. Fluorescent antibody counts of Bacteroides, conversely, were not altered by any of the agents. Therefore, the Bacteroides FA method is not recommended for routine monitoring but may be useful for cases where extensive human faecal contamination is suspected (e.g. pipeline rupture or pollution of recreational water) and where rapid remedial action must be taken to protect the public health.
Associative cellulolysis and N2 fixation by co‐cultures of Trichoderma harzianum and Clostridium butyricum: the effects of ammonium‐N on these processes
Authors: Veal D. V. , Lynch J. M.
Published: March 2008

Mixed cultures of the cellulolytic fungus Trichoderma harzianum with the anaerobic diazotroph Clostridium butyricum were shown to co‐operatively degrade cellulose and utilize the degradation products for N2 fixation. Cellulose degradation and N2 fixation were stimulated by small (0.1 mg/ml) additions of (NH4)2SO4. The (NH42SO4 stimulates cellulolysis thereby increasing the supply of cellulose degradation products to the diazotroph. In aerobic environments the anaerobe depends on the respiration of the aerobe to create anaerobic microsites. The N source increased O2 uptake by the fungus increasing the number of sites suitable for the development of the anaerobe. Stimulation in the growth of T. harzianum by (NH42SO4 resulted in increased growth and N2 fixation by Cl. butyricum.
The detection of irradiated foods using the Direct Epifluorescent Filter Technique
Authors: Betts R. P. , Farr L. , Bankes P. , Stringer M. F.
Published: March 2008

A method was evaluated which has the potential to detect a food sample which has been irradiated. The technique will give an indication of the total number of viable micro‐organisms present before irradiation. It is based on the comparison of an aerobic plate count (APC) with a count obtained using the Direct Epifluorescent Filter Technique (DEFT). When the APC of an irradiated sample was compared with the DEFT count on the same sample, the APC was considerably lower than that obtained by DEFT. The count of orange fluorescing cells after irradiation, however, correlated well with an APC of the same sample before irradiation. For the samples examined the DEFT count determined the viable microbial population in the sample before irradiation. The difference between the APC and the DEFT count gave the number of organisms rendered non‐viable by the process.
An improved procedure for shipboard enumeration of faecal indicator bacteria in marine sediments from sewage sludge disposal areas
Authors: West P. A.
Published: March 2008

An improved membrane filtration procedure for use on board ship to enumerate Escherichia coli and Group D faecal streptococci in marine sediments is described. Ultrasonication extraction combined with resuscitation of sublethally‐injured cells yielded significantly higher counts of E. coli than sediments shaken by hand. Counts of E. coli were also higher on mFC agar (without rosalic acid) after a period of resuscitation on tryptone‐soy agar supplemented with 0.1% yeast extract than on a 4% Teepol‐lactose medium. Ultrasonication of sediments made no significant difference to counts of Group D faecal streptococci on KF‐streptococcus agar. These improved isolation procedures allowed better discrimination of the area affected by sewage sludge at a disposal site off the northeast coast of England.
Antibiotic resistance among coliforms and Pseudomonas spp. from bodies of water around Port Harcourt, Nigeria
Authors: Sokari T. G. , Ibiebele D. D. , Ottih R. M.
Published: March 2008

Samples from municipal waste water, the Bonny River estuary and wells in and around Port Harcourt were examined for bacteriological quality over a 9 month period. A total of 157 Pseudomonas spp., 133 Escherichia coli and 282 other coliforms were isolated and tested for the incidence of resistance to 10 antibiotics. All of the Pseudomonas spp. were resistant to at least one of the antibiotics while 96.2% were resistant to two or more. Most (83.5%) of the E. coli and other coliforms (91.8%) were resistant to at least one antibiotic. All strains were susceptible to gentamicin. Minimal inhibitory concentrations of ampicillin and tetracycline for E. coli ranged from 6.25 to 50 and 6.25 to 12.5 μg/ml, respectively. Minimal inhibitory concentrations of ampicillin and tetracycline were 1000 and 25 μg/ml for the Pseudomonas strains. The high incidence of bacterial resistance to antibiotics is discussed in relation to the widespread use of antibiotics, and possible public health implications.
Survival and infectivity of a Rhizobium meliloti strain maintained in water and buffer suspensions
Authors: Boiardi J.L. , Moreni N. , Galar M.L.
Published: March 2008

Rhizobium meliloti B323 cells were suspended in deionized water, phosphate buffer pH 6.5 and 5.5 and these buffers supplemented with Ca2+, Mg2+ (1 mmol/l) and Fe3+ (0.1 mmol/l). Initial cell count was 1.108 cells/ml. The viable count of rhizobia suspended in buffer at pH 6.5, with and without salts, remained constant or even increased during storage. Cells suspended in buffer at pH 5.5 with salts, decreased in numbers in the first 5 months, then, until the 10th month, the count remained at 105 cells/ml. Rhizobia suspended in buffer at pH 5.5 and deionized water decreased in viability almost to zero by the 10th month. In those suspensions where viability was maintained, the symbiotic infectivity of cells was also maintained as compared with a control performed with fresh cultured rhizobia. In suspensions in deionized water and buffer at pH 5.5 where the viability diminished during the experiment, the rhizobia lost their ability to infect roots immediately after inoculation but maintained their capacity to form late nodules on the hosts.
Bioinsecticide activity, bacterial cell lysis and proteolytic activity in cultures of Bacillus thuringiensis subsp. israelensis
Authors: Pearson D. , Ward O.P.
Published: March 2008

Pattern of bioinsecticide activity and cell lysis were monitored in a range of media. Maximum cell lysis, usually exceeding 90% of total cells, occurred at or after the point of maximum bioactivity. In the majority of media tested, insecticide synthesis and cell lysis phases occurred between 24 and 48 h, although they were between 12 and 24 h in some media and later in others. In some media a decline in insecticidal activity was observed after maximum bioactivity was reached. Bioactivity produced per 109 spores ranged from 0.10 to 0.23 mg of purified insecticidal crystal and 3.4 to 5.8 times 104 international toxic units. When proteolytic activity was monitored in cell cultures, extracellular endoprotease was observed before cell lysis and, in addition, there was a linear rise in activity during cell lysis. Aminopeptidase activity appeared in cell free supernatant fluids only during the cell lysis stage. Optima pH for endoprotease and aminopeptidase were 8.5 and 10.25 respectively. The decline in bioinsecticide activity observed may be due to proteolytic action.
Evidence for the conjugal transfer of the broad host range plasmid pIP501 into strains of Lactobacillus helveticus
Authors: Thompson J.K. , Collins M.A.
Published: March 2008

The conjugative broad host range plasmid pIP501 was transferred from Streptococcus faecalis to a series of strains of lactic streptococci used commercially as dairy starter cultures. With these transconjugants as donors the plasmid was exconjugated to two strains of Lactobacillus helveticus and a commercially used strain of Strep, thermophilus. There was evidence that the plasmid could transfer between isogenic derivatives of one of the strains of Lact. helveticus. Transfer from Lact. helveticus to Strep. faecalis was also detected but at a low frequency. There was no evidence for the conjugal transfer of plasmid pIP501 into a strain of Lact. bulgaricus by exconjugation from either lactic streptococci or Lactobacillus sp.
Use of wheat bran as a nutritive supplement for the production of ethanol by Zymomonas mobilis
Authors: Shamala T.R. , Sreekantiah K.R.
Published: March 2008

A strain of Zymomonas mobilis (ZYM‐TS 1) was isolated from fermenting palm wine (toddy). In addition to glucose, sucrose, and fructose, the organism utilized hydrolysates of corn (Zea mays) flour, corn starch and ragi (Eleusine coracana) flour. Amounts of ethanol produced in media (adjusted to 10% (w/v) total carbohydrates) fortified with wheat bran extract only, were comparable with those obtained from the defined media containing yeast extract, (NH4)2SO4, KH2PO4, and MgSO4.7H2O. The results indicate that wheat bran extract can supply all the necessary nutrients required for ethanol production by Zymomonas mobilis.
Characteristics of micro‐organisms of importance in the fermentation of fufu and ogi—two Nigerian foods
Authors: Adegoke G.O. , Babalola A.K.
Published: March 2008

Cassava tubers (Manihot esculenta) and maize grains (Zea mays) were steeped for 3 d for the preparation of fufu and ogi. The microflora of the fermenting fufu and ogi were characterized by phenotypic methods. The predominating micro‐organisms isolated from fufu were Streptococcus faecalis, coliforms, Bacillus subtilis, B. polymyxa, Lactobacillus fermentum, Lact. brevis and Saccharomyces cerevisiae. In the fermentation of ogi, B. subtilis, Klebsiella oxytoca, Staphylococcus aureus and Sacch. cerevisiae were isolated.
β‐Lactam and aminoglycoside production from streptomycetes
Authors: Berwick P. G.
Published: March 2008

Streptomyces cattleya, S. fradiae and S. griseus produced different amounts of growth when cultured sequentially through sporulation, vegetative and antibiotic production media. Only S. griseus grew well on all three types of medium. Streptomyces cattleya grew poorly on both sporulation and vegetative media. Growth was 1·6 and 8·0 mg/1/h respectively. For all three species, biomass yield in the final antibiotic production medium was dependent on amount of inoculum. Antibiotic yields were obtained only from production media. Under slow growth conditions l‐cysteine and l‐valine supplementation stimulated S. cattleyaβ‐lactam production, giving 1000 μg/ml β‐lactam equivalents compared with 45 μg/ml β‐lactam equivalents for no supplementation. For aminoglycosides the agar well diffusion bioassay was more sensitive towards the hydrochloride than the neutral salt. Paper chromatography confirmed the main antibiotic classes. RF values for replicate samples indicated aminoglycoside homogeneity and β‐lactam heterogeneity.
Experimental aflatoxin production in Manchego‐type cheese
Authors: Blanco J. L. , Domínguez L. , Gómez‐Lucía Esperanza , Garayzabal J. F. F. , Goyache J. , Suárez G.
Published: March 2008

Manchego‐type cheese, a typical Spanish cheese, was inoculated in various ways with an aflatoxigenic organism, Aspergillus parasiticus NRRL 2999, to study the production of aflatoxin. When the original milk was contaminated with a spore suspension, aflatoxin was not detected in paraffin‐covered cheeses although it was present in the top layer of non‐paraffin‐covered cheeses after ripening at 15°C for 60 d. When the cheese surface was inoculated, no aflatoxins were detected in paraffin‐covered cheeses after ripening for 60 d although they were found when the cheeses were ripened for 30 d. In non‐paraffin‐covered cheeses aflatoxins were detected only in the top layer and in the second 10 mm layer when cheeses were incubated after the normal ripening at 28°C for 30 d. When the centre of the cheese was inoculated, no aflatoxins were detected although Aspergillus grew slightly along the inoculation area. When cheese portions were inoculated, fungal growth was evident after incubation at 28° and 15°C for 6 d but there was no growth at 10°C after 50 d. At 28°C aflatoxins were detected at a concentration of 132 μg/g after 13 d, the highest level obtained. In cheese paste at 28° and 15°C, growth was intense, but the level of aflatoxins detected was lower than in cheese portions. At 10°C the growth was heavy, but aflatoxins were not detected.
Evaluation of the Anderson Baird‐Parker direct plating method for enumerating Escherichia coli in water
Authors: Havelaar A. H. , During M.
Published: March 2008

The direct plating (DP) method for enumerating Escherichia coli in food was adapted for water analysis by membrane filtration and a standardized protocol was described. The DP method was found to give equal or better recoveries of E. coli than a membrane filtration method using 0·1% sodium lauryl sulphate agar; the repeatability of the DP method was markedly better. The necessity to transfer membranes from the non‐selective medium tryptone soy agar (TSA) to the selective medium tryptone bile agar (TBA) after pre‐incubation for 4 h was considered disadvantageous for practical purposes. A double‐layer method, where the membrane filter is placed on a layer of TSA poured over TBA, with incubation in an incubator that automatically switches from 37° to 44°C after 4 h, was found to be an acceptable alternative. Recovery of E. coli and inhibition of competitive flora were equal or only slightly less than for the standard DP method.
Identification and physiological characteristics of heterofermentative strains of Lactobacillus from South African red wines
Authors: Dicks L. M. T. , van Vuuren H. J. J.
Published: March 2008

Nineteen atypical heterofermentative strains of Lactobacillus spp. isolated from South African red wines were identified with the API 50 CHL system and by computerized comparison of their total soluble cell protein patterns. Eleven strains were identified as Lactobacillus hilgardii and eight strains as L. brevis. Three strains of L. hilgardii and three strains of L. brevis produced small amounts of H2S in peptone water supplemented with 001%l‐cysteine. All strains produced mannitol from fructose. Proteolytic activity was detected in all except two strains of L. hilgardii. Strains capable of digesting gelatine, hydrolized casein, but not vice versa. The excessive production of sulphur‐containing compounds, mannitol and acetaldehyde by lactic acid bacteria could have serious quality implications for the wine industry. Three strains of L. hilgardii and all strains of L. brevis decarboxylated l‐malic acid to l‐lactic acid.
A serogroup of non‐O1 Vibrio cholerae possessing the Inaba antigen of Vibrio cholerae O1
Authors: Shimada Toshio , Sakazaki Riichi
Published: March 2008

A serogroup of non‐O1 Vibrio cholerae, tentatively named Hakata, possessing the C (Inaba) factor but not the B (Ogawa) and A factors of V. cholerae O1 is described. Strains of this serogroup were isolated from river and estuarine waters and from frozen shrimps.
Identification of Enterobacteriaceae with the Minitek system
Authors: Holmes B. , Humphry P.S.
Published: March 2008

A total of 417 strains (361 Enterobacteriaceae, 56 Vibrionaceae) was examined in all the available Minitek system tests. The results were processed through four successive identification schemes devised by the manufacturer and the proportion of strains correctly identified, not identified or incorrectly identified determined for each scheme. From the results, a probability matrix was constructed incorporating all 35 Minitek tests. Test results for each strain were then processed through this matrix to determine its success in identification. From the matrix the order of separating value of the tests was determined. Forty‐three of the strains were each tested three times to assess the level of test reproducibility; the corrected error rate was 0.85%.
A note on the leavening activity of yeasts isolated from Nigerian palm wine
Authors: Okagbue R.N.
Published: March 2008

The role of the yeast flora of Nigerian palm wine in the leavening activity of the beverage was investigated by subjecting organisms from the wine to dough‐raising tests. Those with appreciable leavening activity were identified as Saccharomyces cerevisiae and Candida spp. They produced maximum dough volumes in 3–4 h at 37°C. The study has provided experimental evidence that yeasts contribute to the leavening activity of palm wine and has identified strains which have potential utility in commercial bread baking.
Simplified methods for the microbiological evaluation of bottled natural mineral waters
Authors: Rivilla R. , González Carmen
Published: March 2008

The conventional methods for the microbiological examination of natural mineral water were compared with a simplified procedure. The results indicate that when indicator micro‐organisms are present in water, they may not be detected in the simplified method. An alternative procedure, including the determination of Pseudomonas aeruginosa, is suggested.