bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparative study of the cutaneous microflora of normal feet with low and high levels of odour
Authors: Marshall J. , Holland K.T. , Gribbon E.M.
Published: March 2008

A comparison of the cutaneous microflora found on normal feet with varying levels of odour has been made. High population densities of staphylococci and aerobic coryneform bacteria predispose to foot odour. There was no association between odour and the carriage on feet of any particular micro‐organism, including brevi‐bacteria. All organisms isolated were screened for exoenzyme activity. Only staphylococci produced lipase (78% of the staphylococci), whereas 97% of micrococci, 68% of aerobic coryneform bacteria, 25% of staphylococci and 94% of propionibacteria produced proteinase. The ability to degrade callous was exhibited by 47% of micrococci, 24% of aerobic coryneforms and 17% of the staphylococci. Feet with high odour had significantly higher population densities of micro‐organisms with the ability to produce these exoenzymes than feet with low odour. No association was observed between foot odour and the carriage of micro‐organisms capable of producing methanethiol. A hypothesis for the role of micro‐organisms in the production of foot odour is proposed.
Water hygiene of two swimming pools: microbial indicators
Authors: Tosti Elisabetta , Volterra Laura
Published: March 2008

The microbiological quality of the water of two swimming pools was evaluated to determine which organisms might be the best indicators of pollution. Membrane filtration gave low numbers of the common indicators of faecal pollution but high counts of the indigenous skin bacteria. As illnesses normally contracted in a swimming pool are mostly those of the skin rather than intestinal, it is suggested that the best indicators of the hygienic condition of water in a swimming pool are staphylococci because of their resistance to disinfection, high numbers in the environment, and ease of recovery.
Numerical taxonomy of some leuconostocs and related bacteria isolated from Scotch whisky distilleries
Authors: Priest F.G. , Pleasants J.G.
Published: March 2008

Forty‐six presumptive Leuconostoc strains and 13 lactobacilli isolated from malt and grain whisky fermentations together with 14 reference strains of Leuconostoc and Lactobacillus were examined for 99 characters. Data were analysed using a variety of similarity coefficients and clustering algorithms. Two aggregate clusters representing Leuconostoc and Lactobacillus were consistently recovered. Many of the presumptive leuconostocs from whisky fermentations were identified as Leuc. mesenteroides. A second large cluster of strains could not be positively identified. Although recovered within the Leuconostoc aggregate cluster, some of these strains hydrolysed arginine, a characteristic of lactobacilli. The study demonstrates a more diverse flora of lactic acid bacteria existing in the distillery fermentation than had been previously recognized.
Detection of salmonellas in confectionery products by conductance
Authors: Arnott M.L. , Gutteridge C.S. , Pugh S.J. , Griffiths J.L.
Published: March 2008

A modified lysine decarboxylase broth has been developed which could be used with a Bactometer M123 to differentiate salmonellas from other bacteria by the characteristics of the conductance detection curve. The medium was used in combination with a selenite cystine trimethylamine oxide dulcitol medium to screen 50 strains of salmonellas and 42 strains of other organisms to establish detection curve magnitude and rate values which could be used to identify curves specific to salmonellas. The combination of media detected all salmonellas tested except Salmonella pullorum. The two media were used to screen 100 inoculated product samples with the Bactometer instrument, in parallel with traditional plating procedures, and using various combinations of pre‐enrichment and selective enrichment incubation periods. After 24 h pre‐enrichment, the Bactometer system detected more positive samples than the conventional plating procedures after pre‐enrichment and selective enrichment. It is considered that these media used in parallel in the Bactometer after conventional pre‐enrichment could provide a 48 h screening procedure for salmonellas with a sensitivity comparable to present plating procedures.
Inactivation of bacteria by Purogene
Authors: Harakeh S. , Illescas A. , Matin A.
Published: March 2008

The bacteriocidal efficacy of Purogene, a stabilized aqueous solution of chlorine dioxide (ClO2) was examined using bacteria of concern to public health. The organisms tested were: Escherichia coli, Pseudomonas aeruginosa, Yersinia enterocolitica, Klebsiella pneumoniae, Streptococcus pyogenes Group A, Salmonella typhimurium and Bacillus subtilis. The test organisms responded differently to inactivation by Purogene. At least a 4 log reduction in bacterial counts was noted when Purogene was applied at a concentration of 0.75 mg/l. Since Purogene is a stabilized complex, it was necessary to provide a chemical environment suitable for the release of ClO2 in this solution. This was done by varying the pH of Purogene from 3.5 to 8.6 (pH of Purogene is 8.6) while keeping the pH of the experimental medium constant (pH 7.0). The results showed that Purogene was most efficacious at the lowest pH tested (pH 3.5). This indicates that as chlorine dioxide solutions were reduced to chlorite (which predominates at pH 8.6), their bacteriocidal efficacy was reduced, suggesting free chlorine dioxide as the active disinfecting species.
Variation in the behaviour of enterotoxigenic Staphylococcus aureus after heat stress in milk
Authors: BATISH V.K. , NATARAJ B. , GROVER SUNITA
Published: March 2008

The survival of several strains of Staphylococcus aureus after heat stress in different menstrua was not logarithmic and F‐values were determined to express their resistance to heat. Of the strains tested, Staph, aureus 234 (enterotoxin B) was the most heat resistant and Staph. aureus 790 (enterotoxin E) was the most heat sensitive. Buffalo milk gave the best protection to all the strains of Staph. aureus against heat, followed by cow's milk; phosphate‐buffered saline gave the least protection. Soyabean casein digest agar gave maximum recovery of survivors followed by brain heart infusion and Baird‐Parker medium. At 50°C there was no marked variation in coagulase production by the surviving strains but at 55 and 62–5dE C there was complete loss of coagulase activity. There was a decreased deoxyribonuclease (DNase) production by all the strains of Staph. aureus after heat stress. Heat‐treatment at 55 and 62mD5dE C resulted in loss of enterotoxin production by all the survivors except S6 and 234, the surviving cells of which still prodused enterotoxin B after heat treatment at 55dE C. Most of the survivors regained lost characteristics such as coagulase, DNase and enterotoxin production after four to five passages through BHI which suggests that subculture of Staph. aureus recovered from heat‐processed milk is necessary to avoid false results.
Development and evaluation of a starter culture for the industrial production of gari
Authors: Ofuya C.O. , Nnajiofor C.
Published: March 2008

Gari starter cultures (Gastat) were developed by mixing pure single strains of the organisms that ferment cassava. They were propagated and maintained as granules on dried cocoyam slurry. The cultures were tested for fermentative and acid‐producing activity. The acidity produced at 30°C varied from 0.07% to 0.85% lactic acid with maximum levels occurring after 48 h. High levels of reducing sugar were produced during the first 24 h. The amounts produced were about 50% more than those from the self‐inoculated cassava. The quality of the gari produced by the starter cultures was good and well accepted. The texture was similar to that produced by natural fermentation. These results highlight the possibility of using starter cultures in the large‐scale production of gari.
Investigation of a simple amperometric electrode system to rapidly quantify and detect bacteria in foods
Authors: Patchett R.A. , Kelly Alison F. , Kroll R.G.
Published: March 2008

A two electrode system mounted as a single probe was developed to measure electrochemically the rate of reduction of a redox mediator (thionine) by bacteria. The system gave a rapid (2 min) bacterial‐dependent current above 2.5×105 cfu/ml with pure cultures of bacteria, but when applied to the measurement of the bacterial contamination in samples of meat and milk it was unable to detect or quantify the contamination reliably. Incubation of samples for a few hours before examination enabled the system to detect bacteria in excess of 106 cfu/ml.
An improved ELISA method for the detection of Salmonella typhimurium
Authors: Prusak‐sochaczewski E. , Luong J.H.T.
Published: March 2008

The applicability of enzyme‐linked immunosorbent assay (ELISA) for the detection of salmonellas in foodstuffs was investigated. Several factors affecting the sensitivity of the ELISA, such as the type of protein used for plate post‐coating, the method of antibody labelling, and accelerators for antigen‐antibody and enzyme‐substrate reactions, were studied. Labelling of the antibody with horseradish peroxidase and the use of o‐phenylenediamine as substrate in the detection system were demonstrated to be most suitable for the enzyme assay.

Based on these findings, an improved ELISA method was developed for the detection of Salmonella typhimurium. The improved technique was able to detect as few as 5×104‐105 cell/ml of salmonellas, and about 24 h were required to enrich the bacteria in food samples and to perform the test. With some modifications, the ELISA assay could reach a very high level of sensitivity and provide excellent repro‐ducibility.
The pectinolytic enzyme of Selenomonas ruminantium
Authors: Heinrichova Kvetoslava , Wojciechowicz Maria , Ziolecki A.
Published: March 2008

A cell‐bound pectinolytic enzyme was isolated from cells of Selenomonas ruminantium and purified about 360‐fold. The optimum pH and temperature for enzyme activity was 7.0 and 40°. The enzyme degraded polymeric substrates by hydrolysis of digalacturonic acid units from the non‐reducing end; the best substrate was nona‐galacturonic acid. Unsaturated trigalacturonate was also degraded, but 30% slower than the saturated analogue. The enzyme was classified as a poly (1,4‐aP‐D‐galactosiduronate) digalacturono‐hydrolase; EC 3.2.1.82. Another enzyme, hydrolysing digalacturonic acid to monomers, was also produced in a very small amount by this organism.
Whey fermentation by immobilized cells of Propionibacterium shermanii
Authors: CHAMPAGNE C.P. , BAILLARGEON‐CÔTÉ C. , GOULET J.
Published: March 2008

Growth of Propionibacterium shermanii B‐123 was faster on media containing lactate than on that containing lactose. Cheese whey was therefore fermented with Lactobacillus helveticus and neutralized with NaOH or Ca(OH)2, before inoculation with B‐123. Fermentation rate by immobilized propionibacteria was best in Ca(OH)2‐neutralized whey, and at lactate concentrations between 1 and 2%. Calcium propionate concentrations of 1 and 3% reduced fermentation rates by 40% and 55% respectively. Optimum temperature for propionate fermentation by immobilized cells was 37°C. Ratios of propionic acid to acetic acid increased as incubation temperature was increased. Agitation increased propionic acid fermentation rates but lowered the ratio of propionic acid to acetic acid. Beads containing immobilized propionibacteria were re‐utilized for ten consecutive fermentations. Fermentation rates increased upon re‐utilization. Escherichia coli and Staphylococcus aureus were inhibited by the propionic fermentation but did not die; they kept growing at a reduced rate.
The D(‐)lactic acid and acetoin/diacetyl as potential indicators of the microbial quality of vacuum‐packed pork and meat products
Authors: PABLO BEGOÑA DE , ASENSIO M.A. , SANZ B. , ORDONEZ J.A.
Published: March 2008

The suitability of D(‐)lactic acid and/or acetoin/diacetyl as indicators of spoilage of vacuum‐packed meat and meat products has been studied. When pork was vacuum‐packed, these substances reached measurable amounts after storage for only about 10 days. Although microbial counts stabilized from the 20th day of storage, the D(‐)lactic acid and acetoin/diacetyl concentrations increased progressively. These substances could therefore be potential indicators of the storage time of vacuum‐packed pork. From a survey carried out with several vacuum‐packed meat products from the market, it was concluded that the D(‐)lactic acid content could be used as an indicator of the storage time of these products. No consistent results were obtained with acetoin/diacetyl.
An oxygen electrode‐based assay of catalase activity as a rapid method for estimating the bacterial content of foods
Authors: KROLL R.G. , FREARS EMMA R. , BAYLISS ANITA
Published: March 2008

An oxygen electrode‐based assay of catalase was developed as a simple method of assessing contamination by bacteria capable of respiration. The method gave a rapid and reasonable quantification of cell numbers in pure cultures and was able to detect 103 bacteria/ml in some cases. The sensitivity of the method was dependent on the identity of the culture and when applied to foods the sensitivity was reduced due to the presence of non‐microbial catalase. The use of electropositively charged filters to remove the organisms from the food sample improved the sensitivity and the relationship between catalase activity and cell numbers in some foods.
Interaction of the bisbiguanides chlorhexidine and alexidine with phospholipid vesicles: evidence for separate modes of action
Authors: CHAWNER JUDI A. , GILBERT P.
Published: March 2008

Strains of Providencia stuartii with demonstrated resistance towards chlorhexidine did not show such resistance towards either of the related biguanide antiseptics, alexidine or vantocil. Alexidine promoted a significantly faster alteration in the permeability of Escherichia coli cell membranes towards various metal cations than chlorhexidine. Differential thermal analysis of various mixed lipid vesicles and pure phospholipid vesicles showed alexidine to share with vantocil the property of producing lipid phase separation and domain formation. It is suggested that the nature of the end‐group on the biguanides affects the ability to produce lipid domains in cell membranes and this this might, in turn, affect activity and resistance patterns observed.
A comparison of the adhesive properties and surface ultrastructure of the fibrillar Streptococcus sanguis 12 and an adhesion deficient non‐fibrillar mutant 12 na
Authors: WILLCOX M.D.P. , WYATT JANET E. , HANDLEY PAULINE S.
Published: March 2008

Streptococcus sanguis 12 and a naturally occurring mutant, 12 na, were screened for their ultrastructure and adhesive properties in vitro. Negative staining showed that Strep. sanguis 12 carried three types of surface structure. The majority of cells carried long fibrils that in different batches ranged in length from 80 to 207 nm, and shorter fibrils which were 51mD0 PT 15mD7 nm long. Both types of fibrils were primarily located at the poles of the cells. Occasionally cells were seen that carried fimbriae, which are structurally distinct from fibrils, and were 3mD4 nm wide and <1mD μm long. Strain 12 na carried no detectable surface structures. Ruthenium red staining revealed that both strains carried a loose, amorphous, extracellular polysaccharide layer attached to the cell wall. Streptococcus sanguis 12 na was 83% less adhesive than strain 12 in a saliva‐coated hydroxyapatite assay, and 50% less adhesive in a buccal epithelial cell adhesion assay. In contrast, strain 12 na was more sensitive to aggregation by parotid saliva than strain 12, and both strains were equally aggregated by whole saliva. The cell surface hydrophobicity of the two strains was similar. Extraction of surface proteins by sodium lauroyl‐sarcosinate followed by sodium dodecylsulphate polyacrylamide gel electrophoresis demonstrated that Strep. sanguis 12 expressed more high mol.wt proteins on its surface than strain 12 na. Using immunogold labelling, the fibrils of strain 12 labelled well with antiserum directed against the long fibrils, but so did the cell surfaces of both Strep. sanguis 12 and 12 na. High molecular weight proteins and cell surface fibrils may be associated with adhesion in this strain.
Rapid photometric assay of growth of Mycoplasma mycoides subsp. capri
Authors: MEUR S.K. , SIKDAR A. , SRIVASTAVA N.C. , SRIVASTAVA S.K.
Published: March 2008

A new spectrophotometric technique for evaluation of early growth in liquid culture of Mycoplasma mycoides subsp. capri has been developed. As turbidity does not appear until after incubation to 18 h the method utilizes the change in absorbance of the medium at 550 nm to monitor growth. The change in absorbance of the medium (which contains phenol red) occurs when the pH changes due to microbial growth. For measurement of growth at later stages when turbidity is proportional to number of colony forming units, two other wavelengths (450 nm and 700 nm) have been suggested.
Amino acid requirements for the growth and production of some exocellular products of Staphylococcus aureus
Authors: TAYLOR D. , HOLLAND K.T.
Published: March 2008

A simple, defined synthetic medium has been developed for the growth of a toxic‐shock‐syndrome‐associated Staphylococcus aureus strain (FRI 1187) in continuous culture, which gives a high growth yield and assayable amounts of acid phosphatase, haemolytic activity, hyaluronate lyase and toxic‐shock‐syndrome toxin‐1. It consists of multiple ions, ammonium sulphate, glucose, cystine, aspartate, glutamate, arginine, glycine, proline, nicotinic acid and thiamine.
The effect of cooling rate, freeze‐drying suspending fluid and culture age on the preservation of Campylobacter pylori
Authors: OWEN R.J. , ON S.L.W. , COSTAS M.
Published: March 2008

The effects of freezing rate, suspending fluid and age of culture on the ability of four strains of Campylobacter pylori to survive and recover from freeze‐drying were examined. Freeze‐drying by standard procedures generally resulted in an overall loss in viability of between 3 and 7 log units. The exact cause of poor recovery by C. pylori was not established but strain differences were detected, with NCTC 11637 (type strain) surviving better than NCTC 11638 and NCTC 11639. Recovery of the poorest growing strain (NE 26695) was notably more erratic. The largest loss in viability occurred at the primary drying stage. Losses resulting from freezing and secondary drying were less marked and the rate of freezing had only a marginal effect on recovery. Nineteen different freeze‐drying suspending fluids were investigated. Overall the best recovery results were obtained with 5% inositol‐broth (or horse serum) plus 25% glucose, at pH 7.0, in which loss of viability was typically about 4 log units. Other factors, such as age of culture and number of viable bacteria in the before‐dry suspension, did not have a significant effect on survival. We conclude from these results that C. pylori can survive freeze‐drying, albeit in small numbers, but the degree of recovery is apparently largely strain dependent.
A comparative study of enzyme variation in Bacillus cereus and Bacillus thuringiensis
Authors: Zahner Viviane , Momen H. , Salles C. A. , Rabinovitch L.
Published: March 2008

Thirty‐two strains of Bacillus spp. were examined in a multilocus enzyme study by agarose gel electrophoresis. The organisms were Bacillus thuringiensis (21 strains), B. cereus (8), including two of var. mycoides, and B. megaterium (3). Strains having similar enzyme variants were grouped into zymovars. A total of 10 of 11 enzyme loci studied were polymorphic and 27 zymovars were distinguished among the 32 strains. The results were subjected to numerical analysis, phenetic affinities and genetic distances between the strains were calculated. The numerical analysis was unable to differentiate between B. thuringiensis and B. cereus. Our results indicated that based on this multilocus enzyme study these zymovars should be considered as belonging to the same species. A mycoides variant of B. cereus was the most distinctive strain studied and clearly belonged to a separate species, B. mycoides. The technique also allowed for identification of contamination and mislabelling of strains.
Factors affecting the formation of polysaccharide depolymerase and glycoside hydrolyase enzymes by Butyrivibrio fibrisolvens NCDO 2249
Authors: Williams A. G. , Withers Susan E.
Published: March 2008

Specific activities of hemicellulose‐degrading polysaccharide depolymerase and glycoside hydrolase enzymes were measured in batch and continuous cultures of Butyrivibrio fibrisolvens NCDO 2249 grown on cellobiose or a hemicellulosic carbohydrate. Enzyme activities were influenced by the growth substrate and by the rate and stage of growth of the micro‐organism. In cellobiose batch cultures specific activities were maximal as the growth rate declined and in the initial stages of the stationary phase. The growth substrate did not affect the range of glycoside hydrolases formed, although specific activities were substrate‐dependent, with activity increases (up to 200‐fold) occurring in enzymes essential for effective substrate utilization. Appreciable xylanase activity was present only in xylan‐grown cultures. The substrate effects were also evident in chemostat cultures. The activity response of the nine enzymes monitored to growth rate changes differed in that while the activity of some enzymes, including xylanase, declined at high dilution rates the activities of others were not growth rate‐dependent and were maintained over the range of dilution rates examined. Exocellular activities were detected only in spent media from cultures grown with a polymeric (hemicellulosic) carbohydrate.
Bacterial contaminants of micropropagated plant cultures
Authors: Leifert C. , Waites W.M. , Nicholas J.R.
Published: March 2008

Bacterial contaminants of micropropagated plant cultures were isolated and characterized with standard bacteriological tests and appropriate API strips. Results obtained were analysed by the API identification software. Of 198 bacterial strains isolated from nine plant species, 90% were identified as Bacillus, Enterobacter, Micrococcus, Staphylococcus, Pseudomonas or Lactobacillus species. Possible sources of contamination are discussed.
Molecular cloning and expression in Saccharomyces cerevisiae and Neurospora crassa of the invertase gene from Neurospora crassa
Authors: Carú M. , Cifuentes V. , Pincheira G. , Jiménez A.
Published: March 2008

A plasmid (named pCN2) carrying a 7.6 kb BamHI DNA insert was isolated from a Neurospora crassa genomic library raised in the yeast vector YRp7. Saccharomyces cerevisiae suc0 and N. crassa inv strains transformed with pNC2 were able to grow on sucrose‐based media and expressed invertase activity. Saccharomyces cerevisiae suc0 (pNC2) expressed a product which immunoreacted with antibody raised against purified invertase from wild type N. crassa, although S. cerevisiae suc+ did not. The cloned DNA hybridized with a 7.6 kb DNA fragment from BamHI‐restricted wild type N. crassa DNA. Plasmid pNC2 transformed N. crassa Inv‐ to Inv+ by integration either near to the endogenous inv locus (40% events) or at other genomic sites (60% events). It appears therefore that the cloned DNA piece encodes the N. crassa invertase enzyme. A 3.8 kb XhoI DNA fragment, derived from pNC2, inserted in YRp7, in both orientation, was able to express invertase activity in yeast, suggesting that it contains an intact invertase gene which is not expressed from a vector promoter.
The preservation of micro‐organisms in biological specimens stored at – 70°C
Authors: Ludlam H.A. , Nwachukwu B. , Noble W.C. , Swan A.V. , Phillips I.
Published: March 2008

The preservation of micro‐organisms that may be found on the skin was studied by storage in liquid media at ‐70°C. In the first part of the study the performance of 12 varieties of suspending media was evaluated with pure cultures of 17 species of micro‐organisms maintained in the laboratory. After storage for 1 year the best medium (Oxoid Nutrient Broth with 15% glycerol) showed a mean survival for all organisms studied of 83.8%, with no significant differences between organisms. Even the worst medium (distilled water) permitted greater than 40% survival at 1 year. No changes in the characteristics of these micro‐organisms were detected after 6 months storage in glycerol broth. In the second part of the study nose swabs were suspended in one representative medium (Bacto Nutrient Broth containing 7% glycerol). The mean percentage survival of staphylococci in these suspensions after 1 year's storage at ‐70°C was 75.4%. These results indicate that coagulase‐negative staphylococci in samples of skin flora may be stored under these conditions for long periods, greatly reducing the work‐load in epidemiological studies of infection.
16S Ribosomal ribonucleic acid sequence analyses of lactococci and related taxa. Description of Vagococcus fluvialis gen. nov., sp. nov.
Authors: Collins M.D. , Ash C. , Farrow J.A.E. , Wallbanks S. , Williams A.M.
Published: March 2008

The phylogenetic status of members of the genus Lactococcus and some motile strains which react with Lancefield group N antiserum was examined by reverse transcriptase sequencing of 16S ribosomal ribonucleic acid. In agreement with earlier nucleic acid hybridization and immunological studies of superoxide dismutase the 16S sequence data clearly demonstrate that the lactococci represent a distinct phylogenetic group equivalent in rank to the genera Enterococcus and Streptococcus. The motile group N strains from chicken faeces and river water, however, were found to be phylogenetically unrelated to lactococci but displayed a closer, albeit loose, association with members of the genus Enterococcus. On the basis of the present sequence data and earlier chemotaxonomic studies it is proposed that the motile group N strains be classified in a new genus Vagococcus, as Vagococcus fluvialis sp. nov. The type strain of V. fluvialis is NCDO 2497.
The effect of acetic acid bacteria upon the growth and metabolism of yeasts during the fermentation of grape juice
Authors: Drysdale G.S. , Fleet G.H.
Published: March 2008

The influence of species of Acetobacter and Gluconobacter upon growth of the wine yeasts Saccharomyces cerevisiae, Kloeckera apiculata and Candida stellata was examined during mixed culture in grape juice. Acetobacter pasteurianus, A. aceti and Gluconobacter oxydans grew in conjunction with yeasts during juice fermentation. As determined by viable counts, yeast growth was only slightly impaired by the presence of bacteria. However, as judged by the concentrations of glucose, fructose, ethanol, glycerol, acetaldehyde, ethyl acetate, iso‐amyl alcohol and organic acids in the fermented juice, acetic acid bacteria significantly influenced the alcoholic fermentation by yeasts.
Plasmid analysis and variation in Pseudomonas syringae
Authors: King G. J.
Published: March 2008

Total plasmid DNA was successfully isolated from 46 of 55 strains of Pseudomonas syringae. Electrophoretic separation after digestion with restriction endonuclease EcoRI gave reproducible banding patterns. Cluster analysis of banding data grouped all strains of pathovar (pv.) pisi separately from pv. glycinea, pv. phaseolicola and pv. syringae. Pathovars glycinea and phaseolicola were more similar to each other than to pv. pisi. A relationship between fragment banding patterns and race structure within pv. pisi was observed.
Repression of sporulation: isolation and characterization of repression‐resistant mutants of Bacillus subtilis
Authors: Bhaduri Saswata , Bandyopadhyay S. , Bose S. K.
Published: March 2008

The sporulation of Bacillus subtilis B34 was repressed by 24 h if glutamine or ammonium chloride but not glutamate was added at late log phase (70 h) when glucose and glutamate were nearly exhausted. Glutamine‐resistant mutants were isolated by selective heat treatment during the delay period induced by glutamine. Glutamine‐resistant mutants showed cross resistance not only against ammonium chloride but also against glucose just as glucose‐resistant mutants showed resistance against nitrogenous catabolites.
Phenotypic characterization of Leuconostoc species
Authors: Milliere J.B. , Mathot Anne‐Gabrielle , Schmitt P. , Divies C.
Published: March 2008

A numerical taxonomic analysis was performed on 81 strains belonging to the Gram‐positive, heterofermentative genus Leuconostoc. These came from different raw milk samples used for cheese manufacture, milk starters, wine and culture collections. Strains were examined for 197 phenotypic characters. On the basis of carbohydrate fermentation, citrate use and dextran production, all the strains were recovered in three clusters at a similarity level of 38% Sj. One cluster was composed entirely of the 11 L. mesenteroides subsp. cremoris strains, characterized by a poor carbohydrate fermentation capacity. The second cluster was very heterogeneous: it contained 60 strains that fermented many carbohydrates, but it was not possible to discriminate between the named species. The third cluster consisted of the 10 L. oenos strains. The addition of antibiotic resistance responses and enzymatic profiles (arylamidase, esterase and hydrolase activities) yielded no significant difference between the strains and did not allow a better discrimination. Only the attribution of a taxonomic weight to some carbohydrate fermentation tests and the use of genetic analyses can resolve the strain identification.
Nitrogen fixation (N‐15 dilution) with soybeans under Thai field conditions. IV. Effect of N addition and Bradyrhizobium japonicum inoculation in soils with indigenous B. japonicum populations
Authors: Kucey R.M.N. , Chaiwanakupt P. , Boonkerd N. , Snitwongse P. , Siripaibool C. , Wadisirisuk P. , Arayangkool T.
Published: March 2008

The effects of Bradyrhizobium japonicum inoculation and pre‐plant additions of N fertilizer on soybean (Glycine max L. Merrill) yields and levels of N2 fixation were studied under field conditions at two sites in Thailand. Bacterial inoculants were composed of B. japonicum strains selected for high N2 fixation levels in Thai soils. Nitrogen fertilizer addition rates used were from 0 to 250 kg N/ha in 50 kg N/ha increments. At the Chiang Mai site in northern Thailand, bacterial inoculation increased nodule weights on plants receiving 100 kg N/ha or less. Increases in nodule parameters due to inoculation were evident at 45 d after planting (DAP) but disappeared by 60 DAP. Addition of N fertilizers decreased the incidence of nodulation and sap ureide contents and decreased the contribution of N2 fixation to the N content of plants at maturity as measured by N‐15 isotope dilution methods. At the Kampang Saen site in central Thailand, bacterial inoculation had significant positive effects on nodule numbers and weights, ARA, sap ureide contents and levels of N2 fixed as measured by N‐15 isotope dilution methods. Addition of N fertilizers at this site also reduced the effectiveness of N2‐fixing symbioses. It was concluded that small additions of N fertilizer added before planting did not significantly decrease N2 fixation levels, but did have a significant positive effect on plant growth. Larger N additions would reduce N2 fixation levels in excess of the benefits of adding more N in chemical form.
A novel method for the identification and distinction of the beta‐lactamases of the genus Acinetobacter
Authors: Hood J. , Amyes S.G.B.
Published: March 2008

The characterization of the chromosomal beta‐lactamases of Acinetobacter has proved difficult because of the poor focusing of these enzymes in conventional isoelectric focusing on polyacrylamide gels. We describe a novel isoelectric focusing method, which employs an agarose gel incorporating a detergent with sorbitol and urea, to examine the beta‐lactamases produced by eight clinical strains of Acinetobacter calcoaceticus; we have identified four different beta‐lactamases. The molecular masses of each of the beta‐lactamases was estimated and most of them ranged from 600000 to > 1000000. These are the largest beta‐lactamases so far described and their size is likely to be one reason for their poor solubility in conventional polyacrylamide systems.
Seasonal variations of pollution indicators in a wildfowl reserve (Do∼nana National Park, Spain)
Authors: Rivilla R. , González Carmen C.
Published: March 2008

Pollution indicators in Do∼nana National Park show a cyclic seasonal pattern with maximum level in the autumn and minimum in the spring. While faecal streptococci proved to be the best indicator micro‐organisms in this type of salty, alkaline environment, total coliforms gave an overestimation of pollution because of the presence of hydroteluric coliforms.
Modelling the growth response of Staphylococcus xylosus to changes in temperature and glycerol concentration/water activity
Authors: CHANDLER R. E. , MCMEEKIN T. A.
Published: March 2008

The growth response of Staphylococcus xylosus strain CM21/3 to changes in temperature and water activity (glycerol concentration) was similar to that observed when water activity was adjusted by added NaCl. At each water activity level the effect of temperature on bacterial growth rate was described well by the square root model. TMIN (the notional minimum temperature for growth) was found to be constant and was similar to the value obtained for the same organism grown in media containing NaCl. Growth rate was proportional to glycerol concentration/water activity allowing the combined effect of this factor and temperature to be modelled by substitution of the constant b in the basic square root model by a term for water activity. The observed minimum water activity for growth at the optimum temperature was close to that predicted by the model.
Preliminary in vitro observations on the bacteriology of the black plug layer phenomenon associated with the biofouling of golf greens
Authors: Lindenbach S.K. , Cullimore D.R.
Published: March 2008

Nine sand columns were developed and subjected to various conditions thought to be associated with the bacterial generation of a black plug layer. Five axenic cultures which were originally isolated from a natural black plug layer (BPL) and a clay‐like plug layer (CLPL) were used. These cultures were applied individually and in various combinations to biofoul and possibly synthesize a BPL or CLPL in sterile vertical sand columns. Biofilm formation was monitored by gravity water flow impedance and through an observation of visual changes.

Combinations (consortia) of the isolated cultures were found to form a synthetic BPL rather than where individual strains were used. All strains caused some flow impedance biofouling. Rapid plugging of the sand columns occurred in the first 3 d of the experiment. This plugging tended to occur at the top and bottom of the sand column around the upper in‐ and lower out‐flow ports to the medium circulation system. There was no relationship between the black colour associated with BPL and the development of the initial plugging. A clear biofilm developed initially in all cases to cause plugging. When sulphur‐reducing bacteria were incorporated into the column inoculum, visible black sulphide deposits were observed to develop after 3 d to form the BPL. Insoluble gases were produced in all of the columns and could be observed through the generation of fracture cavities and pockets within the sand column with associated increases in internal pressures resulting in back pressures and port disruption.
Comparison of methods for estimating Erwinia carotovora numbers on potato tubers
Authors: Chard J.M. , Oxley S.J.P.
Published: March 2008

Two methods for estimation of the numbers of Erwinia carotovora on potato tubers were compared using 17 naturally infected stocks. The ‘wash’ method estimates the surface count, whereas the ‘peel’ method is based on a subcuticular count. A correlation of 0.79 was obtained. Comparisons between methods were also made using a bactericide, Myacide As, and on stocks during chitting. Erwinia carotovora counts were reduced in treated tubers with the ‘wash’ method, but not with the ‘peel’ method.
The distribution and ecology of Malassezia furfur and cutaneous bacteria on human skin
Authors: Leeming J.P. , Notman F.H. , Holland K.T.
Published: March 2008

The prevalence and abundance of Malassezia furfur on clinically normal skin at 20 sites has been determined. All of the 16 subjects studied (young adults) had high counts on the upper trunk and on at least one site on the head. Counts obtained from the lower trunk and upper thighs of male subjects were considerably higher than those from female volunteers. Organisms isolated, grouped according to their colony morphologies, had distributions consistent with those noted for ‘Pityrosporum ovale’and ‘P. orbiculare’in previous studies. Mean M. furfur counts were compared with aerobic and anaerobic bacterial counts performed at the same sites. Propionibacteria and M. furfur distributions were similar but not identical. Some factors which might limit the range of M. furfur are discussed.
Possible mechanisms for the revival of glutaraldehydetreated spores of Bacillus subtilis NCTC 8236
Authors: Power E.G.M. , Dancer B.N. , Russell A.D.
Published: March 2008

Spores of Bacillus subtilis NCTC 8236 were exposed to 2% alkaline glutaraldehyde and subsequently subjected to various treatments in an attempt to revive injured spores. Treatment with alkali (sodium or potassium hydroxide or, to a lesser extent, sodium bicarbonate) proved to be most successful. Some revival was achieved after thermal treatment. No revival was obtained with lysozyme or with various types of coat‐removing agents. Experiments designed to distinguish between germination and outgrowth in the revival process established that sodium hydroxide (optimum concentration, 20 mmol/l) added to glutaraldehyde‐treated spores increased the potential for germination. In contrast, spores which had been allowed to germinate before exposure to low concentrations of glutaraldehyde and then to sodium hydroxide were inhibited at the outgrowth phase to a much greater extent than germinated spores treated with the dialdehyde without subsequent alkali exposure. The results overall are discussed in terms of the possible mechanism and site of action of glutaraldehyde and the practical implications and significance of its use as a sporicide.
Novel filamentous spore‐forming iron bacteria causes bulking in activated sludge
Authors: Emtiazi G. , Habibi M.H. , Setareh M.
Published: March 2008

Several Gram‐positive iron bacteria were isolated from bulking sludge. They were filamentous and had false branching. They had sheaths with iron deposits and formed spores on modified sucrose casitone yeast extract agar. They did not grow on influsion agar for longer than 1 month but could withstand 80°C for 1 h on the same medium. Adding them to sewage before aeration increased the biochemical oxygen demand of waste water and caused poor settling properties of activated sludges. They were the predominant filamentous micro‐organisms in bulking activated sludges. At present, these strains cannot be assigned to recognized taxa of Bacillus spp. or sheathed iron bacteria.
A highly selective two‐stage isolation method for the enumeration of Staphylococcus aureus in foods
Authors: ISIGIDI B.K. , DEVRIESE L.A. , CROEGAERT TH. , VAN HOOF J.
Published: March 2008

A plate method for enumerating Staphylococcus aureus is described which combines a 1‐h recovery period for stressed cells on a relatively non‐selective Baird‐Parker agar base followed by a 24‐h growth phase in a highly selective, supplemented Baird‐Parker medium added as an overlay. Tests with pure cultures showed satisfactory recovery of stressed Staph. aureus and other bacteria. Similar results were obtained with the conventional Baird‐Parker procedure and with the two‐stage isolation method for shrimps and poultry neck skins, but for raw minced meat, recoveries were higher with the combined method than with the conventional medium.

All colonies visible after 24 h on the two‐stage medium can be counted as Staph. aureus, whereas longer incubation times and confirmatory tests are necessary to differentiate it from other organisms on conventional Baird‐Parker medium.
Rapid impedance detection of salmonellas in confectionery using modified LICNR broth
Authors: BULLOCK R.D. , FRODSHAM D.
Published: March 2008

A commercially available broth, with the addition of inhibitors, was used for the rapid impediometric detection of salmonellas in confectionery. Pre‐enrichment in skimmed milk was followed by lysine‐iron‐cystine‐neutral red broth in a Bactometer 123 system. Results were obtained 3d earlier than is possible with conventional microbiological tests. Some false positives were obtained predominantly with Citrobacter freundii but this problem is also frequently encountered with traditional methods. Organisms responsible for false positives may be isolated and identified more rapidly than is possible by conventional methods.
Comparison of dot blot with in‐situ hybridization for the detection of Neisseria gonorrhoeae in urethral exudate
Authors: SCHOONE G.J. , CORNELISSEN W.J.G. , VEENHUIJSEN P.C. , SCHÖNEMAN C.E. , TERPSTRA W.J.
Published: March 2008

Dot blot hybridization and in‐situ hybridization with DNA probes prepared from total genomic gonococcal DNA were compared with Gram staining and culturing for the detection of gonococci in urethral exudates. Fifteen of 60 patients were positive by at least one of the four methods. Gram staining and in‐situ hybridization scored best with 13 positives but culture and dot blot hybridization yielded only 10 and 9 positives respectively. The failure to detect gonococci in culture can be explained by overgrowth in one case and possibly self medication with ampicillin before culture in another. The in‐situ hybridization test is a fast and sensitive hybridization method for the detection of gonococci in urethral exudate from men.
Influence of mucin on glycosidase, protease and arylamidase activities of human gut bacteria grown in a 3‐stage continuous culture system
Authors: MACFARLANE G.T. , HAY S. , GIBSON G.R.
Published: March 2008

Human intestinal bacteria were grown in a 3‐stage continuous culture system on a medium containing complex polysaccharides and proteins as carbon and nitrogen sources. Selected bacterial populations were enumerated and glycosidase, protease and arylamidase activities measured. Comparison of arylamidase and glycosidase activities in the multichamber system (MCS) and faeces showed that the predominant faecal enzymes were also produced by bacteria growing in the MCS. After 48 d operation, porcine gastric mucin (5.8 g/d) was independently fed to vessel 1. Elevated levels of volatile fatty acid (VFA) formation showed that the glycoprotein was actively fermented. The increase in carbohydrate availability as a result of breakdown of the mucin oligosaccharides stimulated bacterial growth and activities. The enzymological measurements showed that mucin increased production of both cell‐bound and extracellular glycosidases, such as β‐galactosidase, α‐glucosidase and N‐acetyl‐β‐glucosaminidase. Protease activities were profoundly influenced by mucin. These were largely cell‐bound in non‐mucin cultures but were predominantly extracellular and collagenolytic when mucin was present. Experiments with protease inhibitors showed that cysteine proteases were the major cell‐bound and extracellular enzymes in both mucin and non‐mucin cultures, but that serine and metalloproteases were also present. The effect of mucin on arylamidase formation was less marked, although there was increased production of these enzymes in vessels 1 and 2 of the MCS. These results suggest that host‐produced substances such as mucin glycoprotein may play a role in modulating the growth and activity of bacteria growing in the human large intestine.
Cellular fatty acid composition of Leuconostoc oenos
Authors: TRACEY R.P. , BRITZ T.J.
Published: March 2008

The cellular fatty acid composition of 70 lactic acid bacteria was examined by capillary gas chromatography. Fifty‐four Leuconostoc oenos strains, including three reference, type strains from the other Leuconostoc spp., nine Pediococcus spp. and two Lactobacillus spp. were studied. Eighteen fatty acids were determined, of which 10 were identified by gas chromatography‐mass spectrometry. The relative percentages of the 18 fatty acids of the Leuconostoc strains were analyzed numerically and grouped using the unweighted pair‐group method. Results show that four clusters could be defined at r= 0.920, with five strains unassigned. The major fatty acids of the Leuc. oenos strains were found to be palmitic acid (C16:0), palmitoleic acid (C16:1–9), oleic acid (C18: 1–9), vaccenic acid (C18: 1–11), dihyrosterculic acid (C19‐cyclopropane‐9) and lactobacillic acid (C19‐cyclopropane‐11). It was mainly on the basis of the amounts of oleic acid and the C19‐cyclopropane fatty acids that the strains of Leuc. oenos could be distinguished from each other. This is the first report of the occurrence of dihydrosterculic acid in lactic acid bacteria. For the majority of Leuc. oenos strains, the result obtained with the cellular fatty acid analysis confirmed the phenotypic relationships.
A chemotaxonomic method for classification of asymmetric penicillia by means of cross‐partition in aqueous two‐phase systems combined with SIMCA pattern recognition analysis
Authors: STRÖM GUNNAR , BLOMQUIST GÖRAN , SÖDERSTRÖM BENGT
Published: March 2008

Conidia of three strains each of three closely related Penicillium species in the P. viridicatum group were subjected to cross‐partition in aqueous polymer two‐phase systems. The cross‐point values, the percentage of conidia in the upper phases at the cross‐point and at certain pH values, together with growth‐rate measurements on different culture media were determined and statistically treated using a multivariate classification computer program (SIMCA). The results showed that the different species were well separated, corresponding with the characterization based on mycotoxin production. Moreover, the various strains grouped well within the species. The number of culture media, and thereby the number of variables used in the analysis, could be reduced without changing the separation properties.
Effect of minocycline on subgingival plaque bacteria
Authors: Wilson M. , O'Connor B. , Newman H.N.
Published: March 2008

The effects of minocycline on subgingival plaque samples from patients with chronic periodontitis were investigated in vitro. Minocycline concentrations as low as 1.0 μg/ml inhibited 95.7% of the cultivable bacteria in the samples but 256 μg/ml was necessary to inhibit all of the cultivable bacteria in the samples. Although up to 99.9% of bacteria in the plaque samples were killed by a 6 h exposure to 8.0 μg/ml of minocycline, large numbers of viable bacteria remained. These results imply that adequate reductions in the numbers of viable subgingival plaque bacteria are unlikely to occur after exposure to minocycline at concentrations attainable in gin‐gival crevicular fluid after systemic administration.