bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of markedly lipid‐dependent Malassezia pachydermatis isolates from healthy dogs
Authors: Bond R. , Anthony R.M.
Published: March 2008

When 244 Malassezia colonies which had been isolated from a colony of Beagle dogs using modified Dixon's agar were sub‐cultured on Sabouraud's dextrose agar to determine their lipid dependence, 30 showed poor growth resembling M. furfur, whereas the remainder were typical of M. pachydermatis. Eight of the 10 poor growing isolates selected for further study formed colonies typical of M. pachydermatis after five passages on Sabouraud's dextrose agar at 4 d intervals and two continued to show poor growth. Nine isolates had enzyme profiles identical to those of typical M. pachydermatis isolates, and one resembled M. furfur. However, seven of the poor growing isolates which were karyotyped had patterns typical of M. pachydermatis. Poor growing isolates and their non‐lipid‐dependent ‘revertants’had identical restriction fragment length polymorphism patterns and poly(GT) hybridization profiles. These observations show that some M. pachydermatis isolates grow poorly when sub‐cultured onto Sabouraud's dextrose agar and may be incorrectly identified as M. furfur if further studies are not performed.
Growth of food‐borne pathogenic bacteria in oil‐in‐water emulsions: II—Effect of emulsion structure on growth parameters and form of growth
Authors: Brocklehurst T.F. , Parker Mary L. , Gunning P.A. , Coleman Heather P. , Robins Margaret M.
Published: March 2008

The growth rates and yields of Listeria monocytogenes and Yersinia enterocolitica were determined in liquid culture media, and in model oil‐in‐water emulsions that contained 30, 70 or 83% (v/v) hexadecane. In emulsions with a mean droplet size of 2 μm containing 83% (v/v) hexadecane, the growth of both organisms resulted in decreased yields. Additionally, in these emulsions adjusted to pH 5·0 or 4·4 the growth rate of L. monocytogenes was significantly less than in other model systems which had an aqueous phase of equivalent chemical composition. Microscopic examination of the 83% (v/v) emulsion showed that its microstructure immobilized the bacteria, which were constrained to grow as colonies. Bacteria behaved similarly in model emulsions of either hexadecane or sunflower oil. Manipulation of the droplet size distribution of the emulsions changed the form and rate of growth of bacteria within them.
Isolation of mycobacteria from acidic forest soil samples: comparison of culture methods
Authors: Livanainen E.
Published: March 2008

To evaluate which combination of decontamination method and medium is most reliable when examining acidic, organic forest soils for mycobacteria, three decontamination methods and five media supplemented with cycloheximide were compared. Before decontamination, the samples were incubated at 37°C for 5 h to allow germination of microbial spores. The recovery of mycobacteria was significantly influenced both by the method and by medium. Decontamination with NaOH or H2SO4 both combined with malachite green and cycloheximide yielded higher viable counts of mycobacteria than decontamination with NaOH followed by oxalic acid. Egg media at pH 5·5 resulted in lower mycobacterial counts than egg media at pH 6·5 or Mycobacteria 7H11 agar. The numbers of slopes totally free of contaminants revealed Mycobacteria 7H11 agar medium to be more prone to contamination than the four egg media tested. The highest counts of mycobacteria and a low rate of contamination were obtained when decontamination with NaOH‐malachite green–cycloheximide was combined with culture on glycerol and cycloheximide supplemented egg medium at pH 6·5.
Exopolysaccharide production on low‐grade maple sap by Enterobacter agglomerans grown in small scale bioreactors
Authors: Morin A. , Heckert M. , Poitras E. , Leblanc D. , Brion F. , Moresoli C.
Published: March 2008

Enterobacter agglomerans isolated from a soil sample collected in the vicinity of a sugar house was grown on low‐grade maple sap: When cultivated in shake flask, Ent. agglomerans produced exopolysaccharide and α‐ketoglutarate. No polysaccharide and no α‐ketoglutarate were produced during growth at dissolved oxygen concentrations lower than 1% saturation in a 3.5 1 bioreactor, but succinate, lactate and formate were accumulated. In order to increase polysaccharide production, various agitation systems were adapted to 7 1 bioreactors with working volumes of 41. Highest polysaccharide yield (Yp/s= 0.70) and biomass yield (Yx/s= 0.17) were obtained with bioreactors agitated with four‐and six‐bladed Rushton turbines. Accumulation of mixed organic acids during polysaccharide production indicated that both aerobic and anaerobic conditions prevailed inside the bioreactors. Maple sap concentration higher than 60 g 1−1 (as sucrose equivalent) decreased both growth and exopolysaccharide production.
Identification of Leuconostoc oenos from South African fortified wines by numerical analysis of total soluble cell protein patterns and DNA‐DNA hybridizations
Authors: Dicks L.M.T. , Loubser P.A. , Augustyn O.P.H.
Published: March 2008

Eight ethanol‐tolerant (17% v/v) strains of Leuconostoc were isolated from South African fortified wines which underwent spoilage in the bottle. The levels of genotypic relatedness of these strains to Leuconostoc oenos, Leuconostoc lactis, Leuconostoc argentinum, Leuconostoc mesenteroides subsp. mesenteroides, Leuconostoc mesenteroides subsp. dextranicum and Leuconostoc paramesenteroides (recently reclassified as Weissella paramesenteroides) were determined by performing numerical analysis of total soluble cell protein patterns and DNA‐DNA hybridizations. The fortified wine strains grouped at r≥ 0.90 into one cluster with the reference strains of Leuc. oenos and shared a DNA homology of 82–95% with the type strains of Leuc. oenos (NCFB 1674T). The fortified wine strains were genotypically unrelated to the non‐acidophilic Leuconostoc spp.
In situ characterization of Clostridium botulinum neurotoxin synthesis and export
Authors: Call J.E. , Cooke P.H. , Miller A.J.
Published: March 2008

A monoclonal antitoxin/colloidal gold probe and sequential centrifugation were used to study synthesis, translocation and export of Clostridium botulinum strain 62A neurotoxin (NT). Exponential growth occurred after 5 h of anaerobic incubation of spores and continued for 15–16 h. NT was detected at 15 h using the probe and transmission electron microscopy (TEM), 2 h earlier than the first detection by the mouse bioassay. During exponential growth, the probe localized NT primarily in the cytoplasm, on the inner side of the cytoplasmic membrane and in the cell wall. During stationary and death phases, the NT was located within the cytoplasm, cell wall and extracellularly. NT was released from the cell during cell wall exfoliation. Cells retained NT after repeated gelatin‐phosphate washes and sequential centrifugations, consistent with the TEM observation that the NT is bound to the cell wall. These observations indicate that the process of Cl. botulinum type A NT production follows a sequence of synthesis, translocation across the cytoplasmic membrane and export through the cell wall.
Ketocarotenoids in halobacteria: 3‐hydroxy‐echinenone and trans‐astaxanthin
Authors: Calo P. , de Miguel T. , Sieiro C. , Velazquez J.B. , Villa T.G.
Published: March 2008

HPLC testing of the carotenoid content of the halobacteria Halobacterium salinarium, Haloarcula hispanica and Haloferax mediterranei showed that all contained high amounts of ketocarotenoids. Halobacterium salinarium produced 2400 μg of total carotenoids per gram of dried bacteria, including 265 μg of trans‐astaxanthin (11%), and 588 μg of 3‐hydroxy‐echinenone (24%). The biotechnological properties of Halobacterium salinarium as a natural pigment source are also presented. The results are compared with those from the yeast Phaffia rhodozyma currently used in the industry as a source of trans‐astaxanthin.
Penner serotyping of Campylobacter isolates from poultry, with absorbed pooled antisera
Authors: Jacobs‐Reitsma W.F. , Maas H.M.E. , Jansen W.H.
Published: March 2008

The Penner serotyping system, based on detection of heat‐stable antigens with a passive haemagglutination technique, was used in studies on Campylobacter epidemiology in poultry. Preparation of specific antisera by absorption allowed the use of pooled antisera. Over 80% of the Campylobacter isolates were typable with this modified Penner serotyping system. Typability of strains was clearly affected by storage of the strains before actual typing. Extracted antigens appeared to be stable for at least 6 months at 4°C. Therefore, it is advisable to store extracted antigens from freshly isolated Campylobacter strains instead of reculturing frozen‐stored strains, when actual typing cannot be performed directly after primary isolation. Untypability of isolates may partly be explained by the detection of Campylobacter serovars not yet represented in the serotyping system. Experiments on repeated serotyping of several Campylobacter strains did not suggest any serovar instability within the strains.
Amino acid requirements and peptidase activities of Streptococcus salivarius subsp. thermophilus
Authors: Neviani E. , Giraffa G. , Brizzi A. , Carminati D.
Published: March 2008

The aim of this work was to investigate the relationship between amino acid requirements and peptidase enzyme systems in three Streptococcus salivarius subsp. thermophilus strains. A synthetic medium without nitrogen components and a milk (RD milk) without its non‐protein nitrogen fraction were prepared with different mixtures of amino acids. The strains showed different amino acid requirements. Some amino acids proved to be essential, some were required, while others did not affect growth. In the synthetic medium, only leucine and glutamic acid were essential for growth. In RD milk, the amino acid requirements were found to be lower, with only the absence of glutamic acid causing complete inhibition of growth. Relationships between aminopeptidase activities of the strains and their amino acid requirements were observed. Strains with higher amino acid requirements were also found to express a wider range of peptidases.
Some factors affecting the airborne survival of bacteria outdoors
Authors: Handley B.A. , Webster A.J.F.
Published: March 2008

Airborne survival of two pseudomonads and a reference strain of Escherichia coli (strain MRE 162) was studied outdoors using a modified microthread technique. When cells of E. coli were‐suspended as clusters, survival was much greater than single cells, particularly outdoors. Culture age had a highly significant effect on survival of Pseudomonas maltophila with survival of 24 h cultures being more than 100‐fold higher than 48 h cultures. Survival of Pseudomonas fluorescens was variable and depended also upon the method of culture. Survival of E. coli and Ps. maltophila was studied at three locations differing in air quality and was found to be significantly reduced outdoors, particularly when held in direct daylight. Outdoor survival was not significantly different at the three locations but was reduced at increasing temperatures. There was no apparent effect of wind direction or air quality. Results are discussed with reference to the release of genetically‐modified micro‐organisms.
Strain‐specific fingerprints of Rhizobium galegae generated by PCR with arbitrary and repetitive primers
Authors: Selenska‐Pobell S. , Gigova L. , Petrova N.
Published: March 2008

Strain‐specific genomic patterns of Rhizobium galegae were generated by PCR using both arbitrary and repetitive (BOX, ERIC and REP) primers. The identification of the strains was achieved also by RFLP analysis. However, the PCR genomic fingerprinting has significant advantages: it is not only simpler and faster, but it is also much more discriminative because it deals with the full bacterial genome and not only with parts of it as is the case with RFLP. In addition, both kinds of PCR fingerprinting (using arbitrary or repetitive primers) generated highly specific and reproducible patterns when parallel reactions with total bacterial DNA, extracted from independent liquid cultures were performed. The latter shows that AP‐ and rep‐PCR are convenient for controlling the production and application of Rhizobium inoculants.
Purification and characterization of the major β‐1,4‐endoglucanase from Thermomonospora curvata
Authors: Lin Shih‐Bin , Stutzenberger F.J.
Published: March 2008

The major β‐1,4‐endoglucanase (EG) of the thermophilic actinomycete, Thermomonospora curvata, contributed over 80% of the total EG activity recovered from cell‐free culture fluid after growth on cellulose. The enzyme was purified to electrophoretic homogeneity by ammonium sulphate precipitation, ion‐exchange chromatography and size exclusion HPLC. This monomeric enzyme had a specific activity of 750 IU mg−1 when assayed with 2.5% (w/v) carboxymethyl cellulose (CMC) at 70°C, pH 6.0. Highest activity was observed on CMC with a degree of polymerization of 3200. The EG was stable for 48 h at 60°C, pH 6.0 and had a half‐life of 30 min at 80°C; temperature and pH optima were 70–73°C and 6.0–6.5, respectively. The mol. wt was 100000 and the pI was 4.0. The Km and Vmax values were 7.33 mg ml−1 and 833 μmol min−1, respectively. EG activity was inhibited by Fe2 +, Hg2 +, Ag+ and Pb2 +, and enhanced by dithiothreitol and Zn2 +. The first 12 amino acid residues at the N‐terminus were: Asp‐Glu‐Val‐Asp‐Glu‐Ile‐Arg‐Asn‐Gly‐Asp‐Phe‐Ser. Glutamic and aspartic acid constituted 24% of the total amino acid composition; no amino sugar was found.
Bioremediation of colour of methyl violet and phenol from a dye‐industry waste effluent using Pseudomonas spp. isolated from factory soil
Authors: Sarnaik S. , Kanekar P.
Published: March 2008

Methyl violet, a basic dye, is manufactured using phenol and dimethylaniline as the raw materials. It is, therefore likely that the waste effluent arising from such units may contain the dye and unused chemicals. Since such pollutants may be toxic, their removal becomes necessary. The studies were therefore aimed at their bioremediation using microbial species.

Four species of Pseudomonas, namely Ps. alcaligenes, Ps. mendocina, Ps. putida biovar B and Ps. stutzeri, were isolated from cattle dung enrichments and the soil samples in the premises of the factory manufacturing methyl violet, nearby Pune.

All the four species of Pseudomonas were able to remove phenol and methyl violet with simultaneous reduction in chemical oxygen demand (COD), total organic carbon (TOC) and ammoniacal nitrogen from the waste effluent and the removal was found to be optimum at the original alkaline pH (range 7.45–10.6) of the waste effluent, at ambient temperature (28 ± 2°C under aerated culture condition, at inoculum density of 1.5 × 108 cells ml−1 of the waste effluent and incubation period of 24–48 h. Thus, Pseudomonas spp. isolated from the environment of the dye industry itself and thus naturally adapted could be used for bioremediation of these pollutants.
Quantitative structure—activity relationship study on the inhibitory effect of some herbicides on the growth of soil micro‐organisms
Authors: Nemes‐Kósa S. , Cserháti T.
Published: March 2008

The effect of eight herbicides on the growth of six soil bacteria and three microscopic fungi, and on the amylase, cellulase and dehydrogenase activity in a Hungarian soil was determined. Herbicide decomposition rate in the soil was also assessed. Qualitative structure‐activity relationship (principal component analysis, spectral mapping technique and stepwise regression) analysis showed that the overwhelming majority (about 80%) of the effect of herbicides can be explained by one background variable showing the similarity between their mode of action. The two‐dimensional non‐linear map of principal component loadings and spectral map characteristics suggested that the number of substituents may be important in the determination of the toxic effects. The inhibition of bacterial growth, inhibition of fungal growth, and effects on enzyme activity and decomposition rate all formed different clusters on the maps indicating that herbicides influence these processes differently. Of the nine physicochemical parameters considered, only the electron withdrawing capacity of substituents significantly influenced the biological activity of herbicides, suggesting that electrostatic interactions between the herbicide molecules and micro‐organisms is important.
Cultural conditions for production of glucoamylase from Lactobacillus amylovorus ATCC 33621
Authors: James J. A. , Lee B. H.
Published: March 2008

Lactobacillus amylovorus ATCC 33621 is an actively amylolytic bacterial strain which produces a cell‐bound glucoamylase (EC 3.2.1.3). Conditions of growth and glucoamylase production were investigated using dextrose‐free de Man‐Rogosa‐Sharpe (MRS) medium in a 1.5 I fermenter, with varying dextrin concentration (0.1–1.5% (w/v)), pH (4.5–6.5) and temperature (25–55°C). Cell extracts were prepared by subjecting cells to treatment with a French Pressure cell in order to release intracellular proteins. Glucoamylase activity was then assayed. The effects of pH (4.0–9.0), temperature (15–85°C) and substrate (dextrin and starch, 0–2% w/v) concentration on crude enzyme activity were investigated. Optimal growth was obtained in MRS medium containing 1% (w/v) dextrin, at pH 5.5 and 37°C. Glucoamylase production was maximal at the late logarithmic phase of growth, during 16–18 h. Crude enzyme had a pH optimum of 6.0 and temperature optimum of 60°C. With starch as the substrate, maximal activity was obtained at a concentration of 1.5% (w/v). The effects of ions and inhibitors on glucoamylase activity were also investigated. Enzyme activity was not significantly influenced by Ca2+ and EDTA at 1 mmol 1−1 concentration; however Pb2+ and Co2+ were found to inhibit the activity at concentrations of 1 mmol 1−1. The crude enzyme was found to be thermolabile when glucoamylase activity decreased after about 10 min exposure at 60°C. This property can be exploited in the brewing of low calorie beers where only mild pasteurization treatments are used to inactivate enzymes. The elimination of residual enzyme effect would prevent further maltodextrin degradation and sweetening during long‐term storage, thus helping to stabilize the flavour of beer.
Random amplified polymorphic DNA and restriction enzyme analysis of PCR amplified rDNA in taxonomy: two identification techniques for food‐borne yeasts
Authors: Couto M. M. Baleiras , Vogels J. T. W. E. , Hofstra H. , Veld J. H. J. Huis in't , van der Vossen J. M. B. M.
Published: March 2008

The random amplified polymorphic DNA (RAPD) assay and the restriction enzyme analysis of PCR amplified rDNA are compared for the identification of the common spoilage yeasts Zygosaccharomyces bailii, Z. rouxii, Saccharomyces cerevisiae, Candida valida and C. lipolytica. Both techniques proved to be adequate tools for yeast identification. Since the RAPD does provide less stable patterns than restriction enzyme analysis of PCR amplified rDNA, and a large amount of data had to be compared without data reduction, Principal Component Analysis (PCA) was applied successfully for clustering the RAPD patterns. The success of PCA is highly influenced by the primer used in RAPD and the amount of reference samples. A large amount of reference samples improves the performance of clustering in PCA. The primer of choice was shown to be important with respect to the discriminatory power of the RAPD method. Some primers used enabled discrimination on the subspecies level. The results collected with both typing methods justify the conclusion that the present typing system can be applied for taxonomical purposes.
Degradation and fermentation of fructo‐oligosaccharides by oral streptococci
Authors: Hartemink R. , Quataert M.C.J. , van Laere K.M.J. , Nout M.J.R. , Rombouts F.M.
Published: March 2008

Fructo‐oligosaccharides (FOS) are claimed to have a positive effect on the intestinal flora. They are being used in functional foods in Japan and Europe. This group have tested the degradation of two commercial FOS preparations by oral streptococci in order to predict the cariogenicity of these products. Both preparations could be fermented to some extent by the species of oral streptococci tested.

The enzymes necessary for the degradation of FOS were inducible. Each strain showed a specific degradation pattern. All strains, particularly Streptococcus mutans rapidly produced acid, mainly lactic acid. Streptococcus mitis also produced high concentrations of acetic acid. Plaque formation by Strep. mutans was similar to the sucrose control. It is concluded that FOS are cariogenic to a similar extent as sucrose.
Separation and concentration of bacteria with immobilized antibody fragments
Authors: Molloy P. , Brydon L. , Porter A.J. , Harris W.J.
Published: March 2008

P. MOLLOY, L. BRYDON, A.J, PORTER AND W.J. HARRIS. 1995. New methods to quantitatively remove bacteria from food and water samples are required to meet modern safety standards. The recent development of techniques to make Fab/Fv/scFv fragments in bacteria has provided the opportunity to exploit antibodies as specialized chemicals for affinity removal technologies. Single‐chain fragments against Pseudomonas aeruginosa have been expressed in Escherichia coli, purified via a fused poly‐histidine tail and immobilized upon polystyrene beads. The resulting immunoaffinity columns have been shown to effectively remove greater than 90% of an applied 10 million bacteria after a single passage through the column. Column material in the absence of single‐chain retained less than 10% of the bacteria. Pseudomonas were also removed from milk, mixed bacterial cultures and when present at low cell densities.
Antibiotic activity of isoxazolylnaphthoquinone imines on mice infected with Staphylococcus aureus
Authors: Albesa I. , Bogdanov P. , Eraso A. , Sperandeo N.R. , de Bertorello M.M.
Published: March 2008

I. ALBESA, P. BOGDANOV, A. ERASO, N.R. SPERANDEO AND M.M. DE BERTORELLO. 1995. The antibiotic activity of new synthetic isoxazolylnaphthoquinone imines was studied. Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922 were resistant to the four compounds studied (MIC > 128 µg ml−1), but Staphylococcus aureus ATCC 25923, ATCC 29213 and 30 clinical isolates of Staph. aureus were inhibited by 2‐hydroxy‐N‐(3,4‐dimethyl‐5‐isoxazolyl)‐1,4‐naphthoquinone‐4‐imine (I). This compound diminished bloodstream infection of mice injected i.m. with Staph. aureus; septicaemia decayed significantly when I was applied at the beginning of the infection while when I was given 3 d after bacterial challenge, a significant protection was afforded. Bactericidal activity in serum increased during the 5 h after I was administered i.p.

The acetyl derivative of I had a high MIC but when inoculated orally in mice decreased the Staph. aureus counts in circulation. This protection occurred only when the schedule of administration started close to the bacterial challenge. Antibiotic activity in vivo may be associated with in vitro effects.
Measurement and prediction of the susceptibility of lager beer to spoilage by lactic acid bacteria
Authors: Fernandez Jacqueline L. , Simpson W.J.
Published: March 2008

J.L. FERNANDEZ AND W.J SIMPSON. 1995. The ability of 14 strains of hop‐resistant lactic acid bacteria (Lactobacillus spp., Pediococcus spp.) to grow in 17 different lager beers was assessed using a biological challenge test. All beers were spoiled by at least one strain: all strains could grow in at least one beer. The sensitivity of different beers to spoilage by lactic acid bacteria varied. Spoilage potential could be described in the form of a ‘Resistance to Spoilage Value’ (RSV) based on the ability of the organisms to grow in each beer. Parameters which correlated to RSV included pH, beer colour and the content of free amino nitrogen, total soluble nitrogen, a range of individual amino acids, maltotriose and the undissociated forms of SO2 and hop bitter acids. Predictive models based on the technique of partial least squares regression and constructed using values for undissociated SO2 content, undissociated hop bitter acids content, polyphenol content, maltotriose content, free amino nitrogen content and a colour intensity component allowed RSV to be predicted.
Comparative studies of the degradation of grass fructan and inulin by strains of Lactobacillus paracasei subsp. paracasei and Lactobacillus plantarum
Authors: Müller Marina , Steller J.
Published: March 2008

Four strains of Lactobacillus paracasei subsp. paracasei and Lact. plantarum are investigated within 16 d in order to determine the formation of metabolites during the degradation of grass fructan and inulin as well as the subsequent fermentation to lactic acid. The decrease of the total content of fructans throughout the entire time of investigation shows differences specific for strains as for either fructan substrate. The strain Lact. plantarum V 54/6 completely degrades the grass fructan and inulin within no longer than 13 d. The utilization of fructan by the other strains is temporally delayed, and in a smaller degree of degradation, especially remarkable for inulin cleavage. The structural modifications of decomposed fructans are characterized by a noticeable shift of the mean DP from approximately 80 to the oligomeric range analysed by anion exchange chromatography. Additionally, a newly formed series of peaks of oligomeric saccharides was detected during the degradation of grass fructan and inulin. Part of the fructose that is derived from cleavage of fructans is fermented immediately by the LAB strains into differently high amounts of lactic acid. The abundance of formed fructose is enriched in the medium to a varying extent, depending on the strain as well as the substrate used. From these results a number of fructan degradative enzymes in lactobacilli have been concluded to possibly vary their modes of regulation: strain specific exo‐ and endohydrolases with different activities against β‐2,1 and β‐2,6 linked fructan.
Indicator organism sources and coastal water quality: a catchment study on the Island of Jersey
Authors: Wyer M.D. , Kay D. , Jackson G.F. , Dawson Helen M. , Yeo Janette , Tanguy Lisa
Published: March 2008

Compliance monitoring of bathing waters at La Grève de Lecq on the North coast of Jersey revealed a significant deterioration in water quality between 1992 and 1993, as indexed by presumptive coliform, presumptive Escherichia coli and streptococci concentrations. During the 1993 bathing season the beach failed to attain the compliance with the EC Guideline criteria for presumptive E. coli and streptococci. A bacteriological survey of the stream catchment draining to the beach revealed that: (i) concentrations of faecal indicator organisms were enhanced at high discharge after rainfall; and (ii) a captive water fowl population, which expanded between 1990 and 1993, was a potential source of faecal pollution. Strategies for catchment management are discussed.
Development of a detection system for histidine decarboxylating lactic acid bacteria based on DNA probes, PCR and activity test
Authors: Le Jeune Christine , Lonvaud‐Funel Aline , ten Brink B. , Hofstra H. , van der Vossen J.M.B.M.
Published: March 2008

On the basis of the comparison of the nucleotide sequences of the histidine decarboxylase genes (hdc A) of Lactobacillus 30A and Clostridium perfringens and the amino acid sequences of these histidine decarboxylases and those of Lactobacillus buchneri and Micrococcus, oligonucleotides unique to the hdc A genes were synthesized and used in PCR. All histidine‐decarboxylating lactic acid bacteria gave a signal with primer set JV16HC/JV17HC in PCR. In addition to this primer set, CL1/CL2 and CL1/JV17HC were also useful for the detection of histamine‐forming Leuconostoc œnos strains in PCR. The 150 base pair amplification product of the decarboxylating Leuc. œnos strain generated with primer set CL1/CL2 was sequenced. Alignment studies showed a high degree of relatedness among the hdc A gene products of Gram‐positive bacteria.

The amplification products of the hdc A genes from Lact. buchneri and Leuc. œnos were used to serve as a DNA probe in hybridization studies. All histidine‐decarboxylating lactic acid bacteria gave a hybridization signal with the DNA probes. In hybridization only one false‐positive signal with a Lactobacillus lindneri strain was observed, which was anticipated to contain a truncated hdc A gene.

In addition to these DNA probe tests, a simple and reliable activity test is presented, which can be used during starter selection to test strains for histidine decarboxylase activity.
Characterization of atypical Aeromonas salmonicida isolates by ribotyping and plasmid profiling
Authors: Pedersen K. , Dalsgaard I. , Larsen J. L.
Published: March 2008

A total of 38 strains of atypical Aeromonas salmonicida, three oxidase‐negative but otherwise typical Aer. salmonicida, three typical Aer. salmonicida, and two reference strains, isolated from several countries and fish species were examined with respect to rRNA gene restriction patterns (ribotypes) and plasmid profiles. Most epidemiologically unrelated strains had different ribotypes, whereas isolates from the same outbreak were identical. All strains, except one, carried one or more large plasmids (> 55 kbp) and all strains, except two, additionally carried one or more smaller plasmids. Many strains isolated from the same outbreak showed different plasmid profiles although some plasmids were identical. The results suggest the existence of several atypical Aer. salmonicida. It also seems that ribotypes are stable properties for these bacteria while the plasmids are more labile.
Survival and persistence of bioluminescent Xanthomonas campestris pv. campestris on host and non‐host plants in the field environment
Authors: Dane F. , Shaw J. J.
Published: March 2008

Dispersal and persistence of a pathogenic strain of Xanthomonas campestris pv. campestris, genetically engineered to bioluminesce, was followed in and on host and non‐host plants in the field environment. Black rot susceptible cabbage plants were mist inoculated with the bioluminescent strain only, or were mist inoculated with X. campestris pv. vesicatoria or a weakly pathogenic strain of X. c. campestris 1 week before challenge inoculation with the bioluminescent strain. Growth of the bioluminescent strain was detected with a low‐light, charge‐coupled device camera or through bioluminescence measurements of broth‐enrichment cultures of leaf disk samples. Bioluminescent X. c. campestris could often be observed as populations on symptomless leaves or in lesions, and persisted as a vascular endophyte for more than 6 months throughout the winter growing season. Dispersal to cruciferous and non‐cruciferous weeds was frequently detected. Pre‐inoculation with X. c. vesicatoria or the weakly pathogenic X. c. campestris did not significantly affect the movement and persistence of the bioluminescent strain nor reduce the incidence of black rot disease.
Influence of pH, temperature and initial yeast: bacteria ratio on the stimulation of Lactobacillus hilgardii by Saccharomyces florentinus isolated from sugary kefir grains
Authors: Leroi F. , Courcoux P.
Published: March 2008

The effects of pH, temperature and initial yeast: bacteria ratio on Lactobacillus hilgardii and Saccharomyces florentinus cultivated either in pure or mixed culture were studied. Quadratic polynomial as a function of factors was proposed to express the lactic acid production at different sampling times, and the percentage increase in lactic acid production by Lact. hilgardii in mixed culture compared with pure culture. Temperature was the factor which had the main influence on lactic acid production in mixed culture, whereas stimulation of bacteria depended greatly on pH value. In the range 0·1‐20%, the initial yeast: bacteria ratio had no effect on these responses, but presence of the yeast was absolutely necessary to obtain high production of lactic acid. Optimum culture conditions were determined to maximize these characteristics.
Effects of substrates and phosphate on INT (2‐(4‐iodophenyl)‐3‐(4‐nitrophenyl)‐5‐phenyl tetrazolium chloride) and CTC (5‐cyano‐2,3‐ditolyl tetrazolium chloride) reduction in Escherichia coli
Authors: Smith J.J. , McFeters G.A.
Published: March 2008

The effects of substrates of primary aerobic dehydrogenases, and inorganic phosphate on aerobic INT and CTC reduction in Escherichia coli were examined. In general, INT produced less formazan than CTC, but INT (+) cell counts remained near values of CTC (+) cells. INT and CTC (+) cell numbers were higher than plate counts on R2A medium using succinate, formate, lactate, casamino acids, glucose, glycerol (INT only) and no substrate. Formate resulted in the greatest amount of INT and CTC formazan. Reduction of both INT and CTC was inhibited above 10 mmol 1‐1 phosphate, and this appeared to be related to decreased rates of O2 consumption. Formation of fluorescent CTC (+), but not INT (+) cells was also inhibited in a concentration dependent manner by phosphate above 10 mmol 1‐1. From light microscopic observations it appeared CTC formed increasing amounts of poorly or non‐fluorescent formazan with increasing phosphate. Therefore, use of phosphate buffer in excess of 10 mmol 1‐1 may not be appropriate in CTC and INT reduction assays.
Comparison of chemical dehydration and critical point drying for the stabilization and visualization of aging biofilm present on interior surfaces of PVC distribution pipe
Authors: Carr J.H. , Anderson R.L. , Favero M.S.
Published: March 2008

In this study, fixation of attached glycocalyx on the interior surfaces of polyvinyl chloride distribution pipe remnants was compared with and without ruthenium red/osmium tetroxide and, in the final preparatory phase, with chemical dehydration and critical point drying. SEM examination of interior surface of the polyvinyl chloride pipe showed varying concentrations of adherent bacteria, depending on the preparatory technique used. It was concluded that using a combination of ruthenium red/osmium tetroxide and critical point drying is the optimum method for visually demonstrating aging biofilm on the interior surface of contaminated polyvinyl chloride pipe.
Alkaline phosphatase activity of Escherichia coli starved in sterile lake water microcosms
Authors: Ozkanca R. , Flint K.P.
Published: March 2008

Escherichia coli grown in high or low phosphate medium was inoculated into a lake water starvation medium. The viable count decreased at 37°C but not at the lower temperatures over 70 d. Alkaline phosphatase was monitored using a colorimetric assay with pNPP as the substrate. Derepression of the enzyme occurred in cultures starved for > 30 d in the lake water and within 5 d in lake water microcosms supplemented with carbon and nitrogen sources where there was rarely an increase in viable count. Chloramphenicol prevented the synthesis of alkaline phosphatase suggesting that, even under starvation conditions, de novo synthesis of the enzyme occurs.
Quantitative structure activity relationship for the effect of benzoic acids, cinnamic acids and benzaldehydes on Listeria monocytogenes
Authors: Ramos‐Nino M.E. , Clifford M.N. , Adams M.R.
Published: March 2008

The inhibition of a cocktail of 18 strains of Listeria monocytogenes by 24 mono‐, di‐ and tri‐substituted benzoic and cinamic acids and 16 benzaldehydes was evaluated using the concentration (C) required to give a 50% growth inhibition under anaerobic conditions at 35°C and pH 6·2 as a measure of biological activity (BAV). Using the method of least squares, multiple regression equations were obtained which described the contribution of some physicochemical and other structural properties of the compounds to their biological activity. The equation that best described the activity of benzoic and cinnamic acids was

where K is a lipophilicity parameter determined by RP‐HPLC and the effect of ionization is represented by pKa. Benzaldehydes behaved differently, their activity being best described by the equation

where the activity is controlled by a steric parameter, the van der Waals volume (Vw), and an electronic‐steric parameter for ortho substituents. Absence of a lipophilicity parameter indicates that partitioning into the cell membrane might not be required for antimicrobial activity. The models were tested in several food systems which showed that in food with a high protein or lipid content antilisterial activity was much lower than predicted, making the models unacceptable in such circumstances.
Effect of water activity on production of β‐lactam antibiotics by Streptomyces clavuligerus in submerged culture
Authors: Cochet N. , Demain A.L.
Published: March 2008

The amount of available water in the environment of micro‐organisms, defined as water activity (aW), has been shown to affect growth, respiration, enzyme synthesis, sporulation and other physiological functions. The aim of this study was to examine the impact of aW on production/excretion of a secondary metabolite. For this purpose, the production of β‐lactam antibiotics and biomass of Streptomyces clavuligerus was studied in relation to the aW‐depressing agents glucose, sorbitol and NaCl. These were chosen because NaCl and sorbitol are often used to depress aW and glucose was not thought to be taken up by S. clavuligerus. The filamentous bacterium S. clavuligerus NRRL 3585 (ATCC 27064) is a prokaryotic producer of penicillin N, cephalosporins including cephamycin C and clavulanic acid. Under water stress conditions, a greater effect upon antibiotic biosynthesis than upon growth was consistently observed. When aW was decreased to below 0·997, antibiotic production began to decrease. For growth, inhibition was much more gradual and did not become intensive until an aW of 0·990 was reached.
A method for the selective isolation of Microtetraspora glauca and related four‐spored actinomycetes from soil
Authors: Hayakawa M. , Momose Y. , Yamazaki T. , Nonomura H.
Published: March 2008

An effective plate culture method for the isolation and enumeration of four‐spored actinomycetes belonging to the Microtetraspora glauca group of Thiemann et al. is described, in which a water suspension of a soil sample given dry heat (110°C, 1 h) is subjected to a treatment with 0·05% benzethonium chloride (BC) and cultured on the new medium LSV‐SE agar which is supplemented with kanamycin, norfloxacin and nalidixic acid. The LSV‐SE agar, based on a commercial lignin (dealkaline; 1 g 1‐1 as the major carbon source, specifically supported adequate growth and good sporulation for the M. glauca‐group species, thus facilitating the detection and enumeration of this rare actinomycete group in the sample. The addition of the antibacterial agents to the LSV‐SE agar, as well as the dry heat and BC treatment, provided a selective effect of reducing the nonfilamentous bacteria and undesirable actinomycetes associates occurring on the isolation plates. A total of 26 different natural samples were examined. From 18 samples (16 of field and forest soils, and two of stream and lake sediments), the new method consistently achieved the selective isolation of the M. glauca group, which accounted for 2–27% of the total population recovered. Definite evidence of biological activity which degrades the grass lignocellulose was found in all of the 39 test M. glauca‐group isolates. Of these, 14, or 36%, possessed antimicrobial activity.
Listeria monocytogenes in poultry and poultry products: epidemiological investigations in seven Danish abattoirs
Authors: Ojeniyi B. , Wegener H.C. , Jensen N.E. , Bisgaard M.
Published: March 2008

Listeria monocytogenes was isolated from 11/236 (4·7%) caecal samples from parent flocks, providing broilers to the abattoirs investigated. Caecal samples from 2078 broilers representing 90 randomly selected broiler flocks were negative for L. monocytogenes. A total of 3080 samples from seven abattoirs including poultry processing line samples, and final products were also examined for L. monocytogenes. Listeria monocytogenes was isolated in 0·3% to 18·7% of the samples collected in the different abattoirs. Epidemiological typing of 247 L. monocytogenes isolates, including serotyping, phage typing, pulsed‐field gel electrophoresis and ribotyping revealed 62 different clones. Based upon typability and discriminatory power, DNA typing methods used were found equally suitable as epidemiological markers. Serotyping and phage typing were not found useful as epidemiological markers for poultry isolates of L. monocytogenes since only 120/247 (48·6%) isolates were typable by phage typing and 230/247 (93·1%) L. monocytogenes belonged to serotype 01 while 6/247 (2·4%) belonged to 04. The discovery of a few dominating clones in each abattoir might indicate an endemic occurrence of L. monocytogenes. It is concluded that L. monocytogenes in the broiler production is primarily localized to the abattoirs. The incidence of L. monocytogenes may be reduced by improving the hygiene.
Hemicellulose‐degrading bacteria and yeasts from the termite gut
Authors: Schäfer A. , Konrad R. , Kuhnigk T. , Kämpfer P. , Hertel H. , König H.
Published: March 2008

Termites play a major role in the recycling of photosynthetically fixed carbon. With the aid of their symbiotic intestinal flora, they are able to degrade extensively wood constituents such as cellulose and hemicellulose. Nevertheless, the microbial species involved in the degradation of hemicelluloses are poorly defined. The purpose of this paper was to examine the microflora involved in hemicellulose degradation. Different aerobic and facultatively anaerobic bacteria and yeasts were isolated using xylan, arabinogalactan and carboxymethylcellulose as substrates. Gram‐positive isolates belonged to the genera Bacillus, Paenibacillus, Streptomyces or the actinobacteria group, while the Gramnegative strains were assigned to the genera Pseudomonas, Acinetobacter, Ochrobactrum, and to genera belonging to the family Enterobacteriaceae. The spectrum and activity of xylan‐ and arabinogalactan‐hydrolysing glycosidases of these new isolates, together with additional bacterial strains originally obtained from enrichments with aromatic compounds were determined.
Effect of lactic starter cultures on the organic acid composition of milk and cheese during ripening—analysis by HPLC
Authors: González de Llano D. , Rodriguez A. , Cuesta P.
Published: March 2008

The major function of lactic starter cultures in cheese making is to produce lactic and other organic acids from the carbohydrates present in milk. The activity of six starter cultures consisting of two Lactococcus lactis ssp. lactis, two Lactococcus lactis ssp. lactis biovar. diacetylactis and two Leuconostoc strains, was tested by monitoring the evolution of the organic acid composition of milk by a modified HPLC method. In addition, their performance as cheese starters was also tested. The HPLC method developed proved to be a precise tool to monitor the organic acid content. Thus, it can be used to follow the fermentation ability of starter cultures, providing information about the type of fermentation. The use of any of the six starters assayed is suggested for manufacturing Afuega'l Pitu cheese.
Taxonomic characterization of Lactobacillus delbrueckii subsp. bulgaricus isolates from a Cameroonian zebu's fermented raw milk
Authors: Millière J.B. , Abidi F.Z. , Lefebvre G.
Published: March 2008

Atypical thermophilic homofermentative lactobacilli were isolated as one of the major microflora from Pindidam, an indigenous Cameroonian zebu's fermented raw milk. On the basis of their physiological characteristics, obtained isolates constituted a homogeneous group belonging to the species Lactobacillus delbrueckii. Nevertheless, their carbohydrate fermentation pattern was unusual and their identification to one of two subspecies Lact. delbrueckii subsp. bulgaricus (Lact. d. bulgaricus) or Lact. delbrueckii subsp. lactis (Lact. d. lactis) was rendered difficult. DNA‐DNA hybridization confirmed that they belonged to the species Lact. delbrueckii and the electrophoretic mobility of the D‐(—)‐lactate dehydrogenase (LDH) furthermore precisely assigned them to Lact. d. bulgaricus. Whole‐cell protein profiles were only able to weakly discriminate between these wild isolates and type strains of the species Lact. delbrueckii. The isolates from Pindidam were well adapted to their specific environmental conditions and demonstrated both high growth rates and ability to support elevated acidic levels in fermented milk.
Regulation of the nisin operons in Lactococcus lactis N8
Authors: Qiao M. , Ye S. , Koponen O. , Ra R. , Usabiaga M. , Immonen T. , Saris P. E. J.
Published: March 2008

The antibiotic peptide nisin produced by Lactococcus lactis is used as a food preservative due to its activity against spores and vegetative cells of Gram‐positive bacteria. The post‐translational maturation of this secreted peptide includes dehydration of serine and threonine residues, lanthionine formation and a proteolytic processing of 23 amino acids from the N‐terminus. Mutations in the nisZ, nisB and nisP genes of the biosynthetic nisZBTCIPRK nisin operon were made by gene replacement or integration of a plasmid. The mutations caused a drastic decrease of the transcription from the promoters upstream of the nisZBTCIPRK and nisFEG operons resulting in loss of nisin production and nisin immunity. The transcription of the nisin operons and nisin immunity could be partially restored by adding nisin to the growth medium of the cells. Nisin induction of the mutant strains also increased the level of the putative immunity NisI protein. These results showed that the nisZBTCIPRK operon is positively autoregulated and that the nisFEG operon is in the same regulon.
Conductance method for quantitative determination of Photobacterium phosphoreum in fish products
Authors: Dalgaard P. , Mejlholm O. , Huss H.H.
Published: March 2008

This paper presents the development of a sensitive and selective conductance method for quantitative determination of Photobacterium phosphoreum in fresh fish. A calibration curve with a correlation coefficient of −0.981 was established from conductance detection times (DT) for estimation of cell levels. Less than 50 cells g−1 of fish could be detected in less than 45 h. The selectivity of the method in relation to other Photobacteria or other bacteria isolated from spoiled fish was good. DTs for 10–100 cfu ml−1 of P. phosphoreum were shorter than DTs for 106 cells ml−1 of the other organisms tested. In naturally contaminated fresh fish, P. phosphoreum was specifically enumerated when it made up 0.1% of the total level of micro‐organisms. The repeatability (S.D.%) of the conductance assay ranged from 2.9% to 7.3%.
Phylogenetic characterization of a novel salt‐tolerant Bacillus species: description of Bacillus dipsosauri sp. nov.
Authors: Lawson P.A. , Deutch C.E. , Collins M.D.
Published: March 2008

The taxonomic position of a novel halophilic endospore‐forming bacterium previously isolated from a desert iguana was investigated by 16S rRNA gene sequencing. Comparative sequence analyses showed the unidentified bacterium to be phylogenetically loosely associated with some other spore‐forming (Bacillus pantothenticus, Sporosarcina halophila) and non‐spore‐forming (Marinococcus albus) halotolerant bacteria. Based on the phenotypic and phylogenetic distinctiveness of the unidentified bacterium, it is proposed that it is classified in the genus Bacillus as a new species, Bacillus dipsosauri.