bluuebunny/crossref_metadata_2025 huggingface dataset:
High levels of spontaneous drug resistance in Lactobacillus
Authors: Curragh Helen J. , Collins M.A.
Published: March 2008

A range of lactobacilli was screened to find the naturally occurring levels of drug resistance. During the screening process two cultures exhibited variation in their sensitivity to nitrofurazone. Further examination showed that for a number of lactobacilli, nitrofurazone‐resistant cells arose at a high spontaneous frequency (10−4‐10−5). The frequency/rate of mutation to resistance was investigated for a further five antibiotics, the results suggesting that high spontaneous mutation frequencies are not uncommon.
The use of biofertilizer of Calothrix sp. M103, enhanced by addition of iron and siderophore production
Authors: Mahasneh I.A. , Tiwari D.N.
Published: March 2008

Calothrix sp. M103, enhanced by addition of iron and siderophore production was used as a biofertilizer. The strain was isolated from a colony on the surface root of a rice plant from a rice field in Bangladesh. It showed a marked and immediate increase in nitrogenase activity in response to the addition of iron and also a normal activity (compared with the control) under siderophore production. The addition of iron to iron‐limited cultures resulted in a rapid increase in algal iron (11‐fold) followed by a marked increase (9‐fold) in nitrogenase activity, reaching about 11.8 kg N/ha/crop. This was more than twice the amount of nitrogen usually fixed by the alga during normal growth (controlled conditions), suggesting that pulsing algal inocula with iron would increase the efficiency of algae as a biofertilizer. Indeed, the use of an iron‐pulsed inoculum of this strain as a biofertilizer resulted in an increase in the yield of sweetcorn by ca 143% over that produced by the control (no algal inoculation) and to ca a 73% increase over that produced by the normal inoculum (unpulsed with iron). The ability of this strain to produce siderophores has also led to both normal (compared with the control) nitrogenase activity as well as normal growth, which shows a marked contrast to other circumstances where the non‐siderophore producing strains showed no growth at all. The significance of these observations on the enhancement of biofertilizer technology is discussed.
Lactic fermentation during the storage of ‘Alorena’ cultivar untreated green table olives
Authors: García P. García , del Carmen Duran Quintana M. , Balbuena M. Brenes , Fernández A. Garrido
Published: March 2008

The development of lactic fermentation processes for the storage of directly brined olives (Aloreña cultivar) was investigated by three procedures: (1) a modification of the traditional method with an initial brine containing 9% (w/v) NaCl and 0.2% (w/v) acetic acid; (2) induced lactic fermentation with 6% NaCl and 0.2% acetic acid; and (3) conservation in acidified brine containing 6% NaCl and 0.6% acetic acid. In all cases, strains of Lactobacillus plantarum and Pediococcus spp. were present in each, indicating the great tolerance of these micro‐organisms to high levels of lactic and acetic acids. They also appeared in an altered sequence. Counts of Pediococcus remained moderate (higher than Lact. plantarum) throughout the last part of the preservation period. A commercial starter improved colonization by Lact. plantarum. Yeasts coexisted with the lactic bacteria throughout the preservation period although their importance in the fermentation process was very limited. The brine characteristics obtained after fermentation were suitable for assured product preservation. There was no spoilage. These results encourage research on the mechanism of lactic acid bacteria inhibition in brines and the development of lactic fermentation processes for directly brined olives from other olive cultivars.
Analysis of polar lipids from some representative enterobacteria, Plesiomonas and Acinetobacter by fast atom bombardment‐mass spectrometry
Authors: Aluyi H.S. , Boote Valerie , Drucker D.B. , Wilson J.M. , Ling Y.H.
Published: March 2008

Fast atom bombardment‐mass spectrometry (FAB‐MS) was used to analyse lipid extracts of bacteria to assess its usefulness for analysing anionic phospholipids of potential chemotaxonomic value. The following micro‐organisms were tested: Acinetobacter calcoaceticus, Acinetobacter sp., Citrobacter freundii, Enterobacter cloacae (2 strains), Escherichia coli (3 strains), Hafnia alvei, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Plesiomonas shigelloides, Proteus mirabilis (3 strains), Serratia liquefaciens and Serratia marcescens. Negative‐ion spectra provide data for twenty‐seven major carboxylate anions (m/z 209–325) and for thirty‐seven major phospholipid anions (m/z 645–774). Generally, the largest carboxylate peaks were due to 16: 1, 16: 0, cyc17 and 18: 1 while the largest phospholipid anion peaks were due to PE(32: 1), PE(33: 1), PE(34: 1), PE(34: 2), PG(30: 2), PG(31: 2), PG(32: 2), PG(34: 1) and PS (33: 0). However, quantitative differences were observed. For example, Acinetobacter lacked PE (33: 1) but had exceptionally high peaks at m/z 748, PS(33: 0), and m/z 281, octadecanoate. Unknown ‘carboxylate’ peaks were detected at m/z 254, 256, 261, 268, 282 and 301. In some cases, unknown peaks appeared to constitute possible homologous series being separated by Δ m/z of 14(≡ methylene). For chemotaxonomic purposes, the complexity of the data required numerical analysis. Using the Pearson coefficient of linear correlation, as a measure of association, it was possible to compare all strains analysed. Typical results for strain comparisons were as follows: Ent. cloacae vs Ent. cloacae, r= 0.90 (Ent. cloacae vs Ac. calcoaceticus, r= 0.46). Thus FAB‐MS represents an excellent means of obtaining large quantities of data on polar lipids of a range of bacterial isolates, which may be suitable for chemotaxonomic purposes.
Globicatella sanguis gen.nov., sp.nov., a new Gram‐positive catalase‐negative bacterium from human sources
Authors: Collins M.D. , Aguirre M. , Facklam R.R. , Shallcross J. , Williams A.M.
Published: March 2008

Phylogenetic studies were performed on some Gram‐positive catalase‐negative cocci from human clinical sources of uncertain taxonomic position. 16S rRNA sequence analysis demonstrated that the isolates represent a hitherto unknown line of descent within the low G + C Gram‐positive bacteria for which the name Globicatella sanguis gen.nov., sp.nov. is proposed.
Characterization of bacteria by multiparameter flow cytometry
Authors: Allman R. , Hann A.C. , Manchee R. , Lloyd D.
Published: March 2008

An arc‐lamp based flow cytometer was used to obtain high resolution measurements of the light scattering characteristics and DNA contents of eight different bacteria. Light scatter profiles of bacteria are a useful first step when flow cytometry is used to characterize organisms. Scanning and transmission electron microscopy of the bacterial samples demonstrate that the structural basis of the light scattering profiles is not always clear, i.e. some organisms appear to have anomalous light scattering characteristics. The use of a third measurement parameter, DNA content, allowed much better discrimination of the organisms. Flow cytometry shows great promise as a method for the rapid discrimination and identification of bacterial populations.
Relatedness of Pseudomonas syringae pv. tomato, Pseudomonas syringae pv. maculicola and Pseudomonas syringae pv. antirrhini
Authors: Hendson M. , Hildebrand D.C. , Schroth M.N.
Published: March 2008

The relationships among strains of Pseudomonas syringae pv. tomato, Ps. syr. antirrhini, Ps. syr. maculicola, Ps. syr. apii and a strain isolated from squash were examined by restriction fragment length polymorphism (RFLP) patterns, nutritional characteristics, host of origin and host ranges. All strains tested except for Ps. syr. maculicola 4326 isolated from radish (Raphanus sativus L.) constitute a closely related group. No polymorphism was seen among strains probed with the 5.7 and 2.3 kb Eco RI fragments which lie adjacent to the hrp cluster of Ps. syr. tomato and the 8.6 kb Eco RI insert of pBG2, a plasmid carrying the β‐glucosidase gene(s). All strains tested had overlapping host ranges. In contrast to this, comparison of strains by RFLP patterns of sequences homologous to the 4.5 kb Hind III fragment of pRut2 and nutritional properties distinguished four groups. Group 1, consisting of strains of pathovars maculicola, tomato and apii, had similar RFLP patterns and used homoserine but not sorbitol as carbon sources. Group 2, consisting of strains of pathovars maculicola and tomato, differed from Group 1 in RFLP patterns and did not use either homoserine or sorbitol. Group 3 was similar to Group 2 in RFLP patterns but utilized homoserine and sorbitol. This group included strains of the pathovars tomato and antirrhini, and a strain isolated from squash. Group 4, a single strain of Ps. syr. maculicola isolated from radish, had unique RFLP patterns and resembled Group 3 nutritionally. The evolutionary relationships of these strains are discussed.
Antibacterial spectrum of lactoferricin B, a potent bactericidal peptide derived from the N‐terminal region of bovine lactoferrin
Authors: Bellamy W. , Takase M. , Wakabayashi H. , Kawase K. , Tomita M.
Published: March 2008

A physiologically diverse range of Gram‐positive and Gram‐negative bacteria was found to be susceptible to inhibition and inactivation by lactoferricin B, a peptide produced by gastric pepsin digestion of bovine lactoferrin. The list of susceptible organisms includes Escherichia coli, Salmonella enteritidis, Klebsiella pneumoniae, Proteus vulgaris, Yersinia enterocolitica, Pseudomonas aeruginosa, Campylobacter jejuni, Staphylococcus aureus, Streptococcus mutans, Corynebacterium diphtheriae, Listeria monocytogenes and Clostridium perfringens. Concentrations of lactoferricin B required to cause complete inhibition of growth varied within the range of 0.3 to 150 μg/ml, depending on the strain and the culture medium used. The peptide showed activity against E. coli O111 over the range of pH 5.5 to 7.5 and was most effective under slightly alkaline conditions. Its antibacterial effectiveness was reduced in the presence of Na+, K+, Mg2+ or Ca2+ ions, or in the presence of various buffer salts. Lactoferricin B was lethal, causing a rapid loss of colony‐forming capability in most of the species tested. Pseudomonas fluorescens, Enterococcus faecalis and Bifidobacterium bifidum strains were highly resistant to this peptide.
Range of action and genetic bacteriocin codification of Pseudomonas aeruginosa isolated from three different ecological niches
Authors: Padilla C. , Salazar M. , Faúndez O.
Published: March 2008

Strains of Pseudomonas aeruginosa isolated from sediments in wells showed a greater bacteriocinogenic activity in those isolated from river and clinical specimens. More than half of all the strains examined had extrachromosomal DNA. Plasmid DNA was extracted from all the strains and in only 24/120, all from different origins, was the curing achieved; all these strains coded their bacteriocins in the chromosomal DNA.
The survival of bacteria exposed to desiccation on surfaces associated with farm buildings
Authors: Bale M.J. , Bennett P.M. , Beringer J.E. , Hinton M.
Published: March 2008

The survival of 11 species of Gram‐negative and Gram‐positive bacteria was examined on different surfaces exposed to desiccation. There were large variations between species; Pseudomonas spp. and Rhizobium leguminosarum biovars survived for less than 2 d, whilst Enterococcus spp. survived for more than 11 weeks. The type of surface on to which the bacteria were deposited affected survival, but with different effects between species. In addition the survival of spontaneous nalidixic acid‐resistant (Nal‐r) mutants of a natural Escherichia coli isolate were compared. Overall the differences were slight, but of seven resistant mutants, five survived better than the parent whilst one survived less well. Nine transposon insertion derivatives of one of the Nal‐r mutants (ECO80) which survived better than the parent were compared; all survived similarly to the parent except ECO883 which survived less well. The growth characteristics of ECO883 and ECO80 were compared; at high osmotic pressures (>0.4 mol l‐1 NaCl) ECO883 grew more slowly and showed a longer lag time than the parent. Of the osmoregulatory functions studied, ECO883 appeared to be altered with respect to K+ transport or accumulation, although the transposon insertion had occurred in a gene distant from known K+ transport genes.
Higher alcohol and acetoin production by Zygosaccharomyces wine yeasts
Authors: Romano Patrizia , Suzzi Giovanna
Published: March 2008

Seventy strains of Zygosaccharomyces isolated from grape musts were investigated for their ability to produce higher alcohols and acetoin in synthetic medium and grape must. The Zygosaccharomyces strains produced generally low amounts of higher alcohols. Within this genus, Z. fermentati behaved differently from Z. bailii producing less isobutanol in synthetic medium and more amyl alcohols and isobutanol in grape must. Zygosaccharomyces fermentati did not form detectable amounts of acetoin in any conditions whereas Z. bailii produced it both in synthetic medium and in grape must. These strains were found to contribute to aroma and taste of wine.
Analysis of yeast diversity during spontaneous and induced alcoholic fermentations
Authors: Schütz M. , Gafner J.
Published: March 2008

The diversity of yeast species and strains was monitored by physiological tests and a simplified method of karyotyping of yeast chromosomes. During the first phase of investigated alcoholic fermentations, the yeast species Metschnikowia pulcherrima and Hanseniaspora uvarum were predominant, irrespective of the origin of the grape must. At the beginning of fermentation H. uvarum was even present in the case of induced fermentations with dried yeast. Middle and end phase of the alcoholic fermentation were clearly dominated by the yeast species Saccharomyces cerevisiae. In the case of spontaneous fermentations, several different strains of S. cerevisiae were present and competed with each other, whereas in induced fermentations only the inoculated strain of S. cerevisiae was observed. A competition of strains of S. cerevisiae also occurred during the fermentation with dried yeast product consisting of two different strains. An effect of H. uvarum on taste and flavour of wines can be postulated according to the frequency of its appearance during the first phase of fermentation. With the method of rapid karyotyping and supplementary physiological tests it was possible to make reliable assertions about the yeast diversity during alcoholic fermentation.
A modified creatine sucrose medium for differentiation of species in Penicillium subgenus Penicillium
Authors: Pitt J.I.
Published: March 2008

The creatine sucrose agar originally described by Frisvad was modified by varying the sucrose and creatine concentrations and pH over a wide range. After extensive tests with commonly occurring species in Penicillium subgenus Penicillium, a new formulation was derived, which is termed neutral creatine sucrose agar. This medium produced eight different reactions among the 20 species tested, and hence has the potential to be a very useful taxonomic medium for species in this difficult subgenus.
Genetic diversity of Helicobacter pylori indexed with respect to clinical symptomatology, using a 16S rRNA and a species‐specific DNA probe
Authors: Desai M. , Linton D. , Owen R.J. , Cameron H. , Stanley J.
Published: March 2008

DNA probes are described which identify group and fingerprint strains of the human gastric pathogen Helicobacter pylori, on the basis of well‐defined band homologies. A 544 bp internal fragment of the 16S ribosomal RNA gene was generated by polymerase chain reaction (PCR) with primers derived from the Escherichia coli rRNA gene sequence. In genomic Southern blots this probe detected restriction site variation around these loci, generating simple but strain‐specific molecular fingerprints. A small conserved chromosomal fragment of 1.2 kbp, Hps, species‐specific for H. pylori, was obtained by cloning random Hind III fragments into pUC19. It was useful for dot‐blot identification, and also separated isolates into one major and two minor groups. When results for these two probes were combined, a baseline characterization of genotype was obtained. A band‐matching database of molecular fingerprints for the type strain and 63 clinical isolates of H. pylori from asymptomatic, ulcer and gastritis contexts is presented. No significant association between the genotypes at this level of definition and the associated clinical symptomatology of the isolates was detected.
Comparison of isopropyl cinodine with nalidixic acid in the direct viable count
Authors: Servis N.A. , Lytle M.S. , Midthun D.B. , Leake R.A. , Adams J.C.
Published: March 2008

Isopropyl cinodine and nalidixic acid were compared in the direct viable count. With raw water and biofilms, elongated cells were seen in the presence of isopropyl cinodine. Increased incubation time led to an increased direct viable count. Individual bacteria responded differently to isopropyl cinodine. Five organisms grew in the presence of 0.01 μg ml‐1 of isopropyl cinodine but were inhibited by 0.1 μg ml‐1. These values for a sixth organism were 0.1 μg ml‐1 and 1.0 μg ml‐1 respectively. The direct viable count was done with inocula taken when the cells were in either lag, log or stationary phases of growth. No differences were seen in the percentage of elongated cells within an experiment but there was variation between experiments. The effect of nalidixic acid and isopropyl cinodine appeared to be additive with respect to inhibition of growth, but little or no additive effect was seen upon the percent of nutrient responsive cells.
Interaction between isolation source, cellular fatty acid composition and stress tolerance in Saccharomyces cerevisiae and its subspecies
Authors: Guerzoni Maria Elisabetta , Sinigaglia Milena , Gardini F.
Published: March 2008

The physiological properties and fatty acid content of 59 strains of Saccharomyces cerevisiae isolated from soft‐drink factories, a fruit puree factory, a fuel‐alcohol distillery and a winery were compared. Discriminant analysis of the results allocated the strains to four groups according to their source. Resistance to preservatives and temperature stress were correlated with differences in fatty acid composition. The fatty acid C18: 1Δ11, growth at pH 2 and in the presence of 200–600 mg 1‐1 benzoate or sorbate, and maximal growth rate at 42°C were characteristics associated with yeasts from particular environments. However, tolerance of thermal stress and content of the C18: 2 fatty acid were associated with subspecies: the former species S. capensis, S. chevalieri, etc. The relative content of C10 : 0, C12 : 0 and C18 : 0 acids varied according to both isolation source and subspecies.
Taxonomic studies on some leuconostoc‐like organisms from fermented sausages: description of a new genus Weissella for the Leuconostoc paramesenteroides group of species
Authors: Collins M.D. , Samelis J. , Metaxopoulos J. , Wallbanks S.
Published: March 2008

Taxonomic studies were performed on some unknown Leuconostoc‐like organisms from fermented Greek sausage. Comparative 16S rRNA sequence analysis showed the unidentified organisms represent a new line within the Leuconostoc paramesenteroides group of species. On the basis of the results of this and earlier phylogenetic investigations, it is proposed that Leuconostoc paramesenteroides and related species be reclassified in a new genus Weissella. In addition a new species, Weissella hellenica, is proposed for the isolates from fermented sausage.
Insertional mutagenesis, cloning and expression of gentisate pathway genes from Pseudomonas alcaligenes NCIB 9867
Authors: Tham J.M.L. , Poh C.L.
Published: March 2008

An artificial transposon, Omegon‐km, was used for insertional mutagenesis of Pseudomonas alcaligenes NCIB 9867. Insertion mutants were recovered at approximately 6 times 10‐6 per recipient cell; 12.6% of the Omegon‐km insertion mutants were catabolic mutants deficient in gentisate pathway enzymes. A specific insertion mutant, p44S, was found to lack two gentisate pathway enzymes, viz. xylenol methylhydroxylase and 3‐hydroxy‐4‐methylbenzoate specific 6‐hydroxylase, but expressed low levels of gentisate 1,2‐dioxygenase. Chromosomal DNA encoding gentisate pathway genes adjacent to Omegon‐km insertions were subcloned into a pRK415 vector and expressed in a cured derivative of Ps. putida NCIB 9869. Removal of both transcriptional and translational stop signals by subcloning was found to relieve suppression of all three enzymes, thus confirming the polar nature of the insertion. It was postulated that both xylenol methylhydroxylase and 6‐hydroxylase were present together in a single transcriptional and translational unit, separate from gentisate 1,2‐dioxygenase. The use of Omegon‐km, a transposable element for in vivo insertional mutagenesis, has enabled the rapid cloning of gentisate pathway genes and the construction of a restriction map comprising of a gene cluster involving at least three enzymes for 2,5‐xylenol degradation.
Interaction of Helicobacter pylori with extracellular matrix proteins
Authors: Moran A.P. , Kuusela P. , Kosunen T.U.
Published: March 2008

Binding of 11 isolates of the gastroduodenal pathogen Helicobacter pylori from three geographical regions to extracellular matrix proteins was investigated. None of the strains bound soluble proteins, but a proportion (27%) bound immobilized laminin, fibronectin, and types I and V collagens. Microaerobic conditions were required to demonstrate reproducible binding. Contrary to previous reports, interstrain variation in the pattern of binding to various proteins was observed, possibly reflecting pathogenic or virulence differences between strains. Binding was strongest to laminin. Purified lipopolysaccharide completely inhibited the binding of H. pylori to laminin indicating that this bacterial surface molecule is involved in the adhesion process.
Sulphate‐reducing bacteria in deep aquifer sediments of the London Basin: their role in anaerobic mineralization of organic matter
Authors: Johnson A.C. , Wood M.
Published: March 2008

Sulphate‐reducing potential was measured in sandy aquifer sediments of the London Basin. Sulphate reduction could be stimulated in the laboratory by saturating the sands with groundwater, and creating an anaerobic environment. The stimulation of vigorous sulphate reduction through the addition of an external substrate was associated with an increase in FeT concentration. Molybdate and selenate were added to sediment/groundwater slurries as specific inhibitors of sulphate‐reducing bacteria. Under sulphate‐reducing conditions acetate accumulated, but was inhibited by molybdate and selenate. 14C‐acetate was used to measure the rate of acetate metabolism in the sediments.
Detection of irradiated deep‐frozen foodstuffs by comparison of DEFT and APC counts
Authors: Copin Marie‐Pierre , Jehanno Dominique , Bourgeois C.M.
Published: March 2008

The suitability of a microbiological method based on the comparison of an aerobic plate count (APC) with a count obtained with the direct epifluorescent filter technique (DEFT) for the detection of irradiation of deep‐frozen foodstuffs was evaluated. The study was carried out on parsley, mechanically deboned poultry meat (MDPM) and liquid egg white. The foodstuffs were stored at—18°C and examined after storage for 0, 4 and 12 months.

The results showed that this method is discriminating during the whole storage period. Nevertheless, it has been observed that for non‐irradiated liquid egg white the difference between DEFT and APC tends to increase with the time of storage. This phenomenon which did not limit the interest of the test, was not observed for the other products tested.
Lactobacillus cells in the rabbit digestive tract and the factors affecting their distribution
Authors: Yu B. , Tsen H.Y.
Published: March 2008

Lactobacillus fermentum was present in small numbers in the caecum and colon of only one of 16 rabbits. Studies aimed at elucidating the factors affecting the colonization of lactobacilli in rabbit gut were thus performed. These studies included investigation of the effect of gastric juice and bile salts on the viability of lactobacilli, assay of the survival rates of lactobacilli in the gastrointestinal tracts of the rabbits with or without ileum cannulation and measurement of the adhesive capability of lactobacilli to the rabbit intestinal epithelial cells. Results showed that, although some lactobacilli were resistant to the rather low pH levels of rabbit gastric juice, lack of adhesive capability may prevent them from colonizing in the intestinal tract. Therefore, if lactobacilli are to be used as probiotics for rabbit, factors that affect their viability and ability to colonize should be considered.
Aspects of the resistance of lactic acid bacteria to hop bitter acids
Authors: Fernandez Jacqueline L. , Simpson W.J.
Published: March 2008

Resistance to trans‐isohumulone is found only in those lactic acid bacteria which can grow in beer. The degree of resistance could not be altered by plasmid curing, or mutation induced by u.v. light. Organisms resistant to trans‐isohumulone were resistant to the related hop acids(‐)‐humulone and colupulone. Equally, organisms sensitive to trans‐isohumulone were also sensitive to related compounds. No other features correlated with hop resistance, including cell morphology, colony morphology, pH range for growth, sugar utilization profile, products of metabolism, manganese requirement and sensitivity to superoxide radicals, expression of cellular proteins, and resistance or sensitivity to selected antibacterial agents.
Electrotransformation of meat lactobacilli. Effect of several parameters on their efficiency of transformation
Authors: Aymerich M.T. , Hugas M. , Garriga M. , Vogel R.F. , Monfort J.M.
Published: March 2008

Intact cells of several lactobacilli isolated from Spanish dry fermented sausages (Lactobacillus curvatus, Lact. sake, Lact. plantarum and Lact. bavaricus) were transformed by electroporation. With pNZ12 as a vector, transformation efficiencies of 2.4 times 105, 3.8 times 103 and 8.8 times 102 transformants μg‐1 DNA were observed for Lact. curvatus CTC435, Lact. sake CTC335 and Lact. bavaricus CTC232, respectively.

Effects of variation in experimental parameters on transformation efficiency were evaluated. Strains, vectors and buffers were the determinant parameters. The growth phase of the culture, cell concentration, voltage, use of cell wall weakening agents and the purity of the vector influenced the transformation efficiency in most strains.
Kinetic and metabolic effects of nitrogen, magnesium and sulphur restriction in Xanthomonas campestris batch cultures
Authors: Roseiro J. Carlos , Gírio Francisco M. , Kará Alida , Collaço M.T. Amaral
Published: March 2008

By reducing the concentration of nitrogen (from 5.0 to 2.5 mmol 1‐1), batch cultures of Xanthomonas campestris induced the enzyme UDP‐glucose dehydrogenase and stimulated the Entner‐Doudoroff pathway enzyme glucose‐6‐P dehydrogenase. The surplus energy generation was directed to xanthan biosynthesis resulting in a 10% polysaccharide increase. The nitrogen restriction led to a higher consumption of nitrogen (93%) whereas glucose consumption did not surpass 75% utilization. Low concentrations of both magnesium and sulphur exerted a negative effect on xanthan formation. Both restrictions reduced the phosphomannose isomerase enzyme activity by 10‐fold turning the mannose transference presumably into the rate‐limiting step for xanthan biosynthesis. Conversely, the rate of synthesis of glucuronic acid residues did not affect the rate of xanthan biosynthesis. Polysaccharide synthesis in magnesium and sulphur cultures was negatively affected in comparison with cell formation as the cell volumetric production rate increased from 0.037 to 0.091 g 1‐1 h‐1 and the xanthan volumetric production rate dropped from 0.133 g 1‐1 h‐1 to the minimum obtained at 0.083 g 1‐1 h‐1. The efficiency of the carbon substrate conversion was also greatly changed.
Deoxyribonucleic acid relatedness of 21 strains of Xanthomonas species and pathovars
Authors: Palleroni N.J. , Hildebrand D.C. , Schroth M.N. , Hendson M.
Published: March 2008

The relationship of 17 Xanthomonas campestris pathotype strains, three additional X. campestris strains, and the type strain of Xanthomonas albilineans were examined by DNA‐DNA hybridization tests. The results coupled with those of a previous study (Hildebrand et al. 1990) support the hypothesis that X. campestris does not constitute a single bacterial species. There were low levels of DNA‐DNA reassociation among many of the different pathovars examined. Six clusters of related pathovars were discerned. In addition, four of the pathovars were only distantly related to each other and to the six clusters. Xanthomonas albilineans was not closely related to any of the other xanthomonads tested.

Mapping and superimposing the botanical families of the host plants upon a three‐dimensional genomic distance matrix of the xanthomonads confirms previous observations that pathovars that infect plants of the same botanical family do not necessarily belong to the same genomic group. Six legume‐infecting pathovars cluster within one genomic group, but one pathovar, X. cam. pv. pisi is only distantly related to this group. There was also no genomic relationship between X. cam. pv. oryzicola and X. albilineans both of which infect Gramineae. Consequently, pathogenicity toward members of the same plant family is not a good indicator of the genomic relationships among xanthomonads nor is it a good taxonomic determinant.
Usefulness of nutritional screening for the identification of Xanthomonas campesths DNA homology groups and pathovars
Authors: Hildebrand D. C. , Hendson M. , Schroth M. N.
Published: March 2008

A nutritional screen of 143 carbon sources was done on 88 strains of xanthomonads from 39 different Xanthomonas campestris pathovars, X. albilineans, X.fragariae, and ‘X. gardneri’. Six compounds, cellobiose, fructose, fumarate, glucose, L‐malate and succinate supported growth of all strains except X. albilineans, whereas 92 substrates were not utilized by any strain. Substrate utilization patterns appeared sufficiently uniform among the various genomic groups within Xanthomonas to allow their differentiation. The most easily distinguished pathovars were X. cam. pv. oryzicola and X. cam. secalis of genomic groups 4 and 3, respectively, because they used few substrates. Genomic group 1 was the most difficult to distinguish because utilization patterns differed substantially among the pathovars that comprise the group. Substrate utilization was useful for distinguishing pathovars within genomic groups. For example, X. campestris pv. pelargonii of genomic group 5 was differentiated from X. cam. carotae, X. cam. taraxaci, and ‘X. gardneri’ by growth on aconitate but not D‐tartrate. Similarly, use of D‐tartrate differentiated X. celebensis from X. cam. pv. juglandis within group 6. Sorbitol was utilized only by X. cam. pv. plantaginis of group 2 and arabitol was a useful substrate for identifying X. cam. pv. pisi and pv. eucalypti. Most patterns of carbon utilization were confirmed with Biolog tests but there were exceptions as was found with utilization of glycerol and D‐arabitol. The Biolog test also revealed some differences in carbon utilization not detected by standard tests of carbon substrates. It is concluded that nutritional screening has promise for identifying genomic groups and various pathovars within the genus Xanthomonas.
A study of the use of rapid methods for preservative efficacy testing of pharmaceuticals and cosmetics
Authors: Connolly P. , Bloomfield Sally F. , Denyer S.P.
Published: March 2008

Three rapid microbiological methods, impedance, the direct epifluorescence technique (DEFT‐MEM) and ATP bioluminescence (ATP‐B) were evaluated for their applicability to preservative efficacy testing (PET) of pharmaceuticals and cosmetics. A good correlation between rapid method response and total colony counts was obtained for untreated suspensions of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans with all three methods but, for Aspergillus niger, with impedance only. For chlorhexidine‐treated suspensions of Staph. aureus and C. albicans, a good dose—response curve was obtained with impedance, but ATP‐B and DEFT‐MEM methods underestimated the kill by the order of 1–6 logs. From the results of this study it is concluded that impedance offers an alternative method to colony counting methods for PET but, at their present level of method development, neither DEFT‐MEM nor ATP‐B can be considered as satisfactory.
Characterization of alpha‐galactosidase from Lactobacillus fermentum
Authors: Garro Marisa S. , de Giori Graciela S. , de Valdez Graciela F. , Oliver G.
Published: March 2008

α‐Galactosidase activity was studied in Lactobacillus fermentum strains. The optimum temperature was found to be 45°C. The enzyme was inactivated at temperatures higher than 55°C, but remained active during storage at low temperatures (0, ‐30 and ‐70°C) for 5 months. Enzyme activity was observed within a 5.0–6.5 pH range, while optimum pH was dependent on the particular strain assayed. The addition of Zn2+ to the reaction buffer exerted a slight negative effect upon the activity, while Hg2+ and p‐chloromercuribenzoate produced a strong inhibition. These results would indicate the presence of ‐SH groups in the catalytic site of the enzyme.
Identification and typing of Proteus penneri and Proteus vulgaris biogroups 2 and 3, from clinical sources, by computerized analysis of electrophoretic protein patterns
Authors: Costas M. , Holmes B. , Frith K.A. , Riddle C. , Hawkey P.M.
Published: March 2008

Seventy‐six strains of the Proteus vulgaris complex (Pr. penneri and Pr. vulgaris biogroups 2 and 3) were characterized by one‐dimensional SDS‐PAGE of cellular proteins. The protein patterns were highly reproducible. The strains came from various countries and were mainly of human origin: urine (28), respiratory tract (13), wounds (8), faeces (7), blood (3), miscellaneous sources (6) and unknown sources (11). The patterns of these strains, together with those of the type strains of seven Morganella, Proteus and Providencia species were subjected to two numerical analyses. In the first, in which the principal protein bands (in the 35.0–42.0 kDa range) were excluded, the strains of the Pr. vulgaris complex formed four clusters at the 83% similarity level. These corresponded to Pr. penneri, Pr. vulgaris biogroup 2, and two clusters (3a and 3b) represented biogroup 3. Each of these clusters was distinct from the Morganella, Proteus and Providencia reference strains. In the second analysis, which included all the protein bands, the 41 Pr. penneri strains showed little heterogeneity but 17 subphenons could be recognized among the 35 strains of Pr. vulgaris biogroups 2 and 3. These results support the division of biogroup 3 strains into at least two separate taxa. Other results indicate that biogroup 3 is heterogeneous and may contain further genomic groups. The method also provides a basis for typing clinical strains of Pr. vulgaris biogroups 2 and 3.
Isolation of a DNA probe for identification of glucan‐producing Pediococcus damnosus in wines
Authors: Lonvaud‐Funel Aline , Guilloux Y. , Joyeux Annick
Published: March 2008

Some Pediococcus damnosus strains isolated from spoiled wines were able to synthesize polysaccharide and increased viscosity. Three strains lost their ropy phenotype relatively frequently during successive transfers in a non‐alcoholic medium. They could not recover it when cultured in the presence of ethanol. Plasmid pattern comparison showed these variants had lost some of their plasmid DNA. Both ethanol and the plasmid were required to induce polysaccharide synthesis.

Plasmid DNA of a wild strain was cloned into Escherichia coli with pTZ18R and pBR 322. Specific clones were selected by differential hybridization of transformed E. coli with plasmid DNA from a ropy strain and its non‐ropy variant. Clones which hybridized with total plasmid DNA from the ropy strain and not with that of the non‐ropy strain carried an insert of the plasmid involved. One of these was chosen. Its DNA proved to be specific and usable as a probe in identifying and detecting ropy Ped. damnosus strains.
Detection of interactions between yeasts and lactic acid bacteria isolated from sugary kefir grains
Authors: Leroi Françoise , Pidoux M.
Published: March 2008

Different techniques were tested for studying the synergism between the micro‐organisms of sugary kefir grains. Agar cultures in Petri dishes did not give reproducible results. In sequential cultures, i.e. growing one organism, sterile filtering and then inoculating the other, 10 of 18 selected lactic acid bacteria/yeast pairs revealed stimulation of bacterial growth in a poor glucose medium. In mixed culture, Saccharomyces florentinus supported better survival of Lactobacillus hilgardii and a significant increase in lactic acid production; at the same time, the growth and alcoholic fermentation of S. florentinus were drastically reduced. The inter‐relationships between these two strains were the same when immobilized in calcium alginate beads, even though total metabolite production was always lower than with free cells. The stimulation of Lact. hilgardii by Candida lambica in sequential culture was not confirmed in mixed culture, where the two organisms grew as in pure culture, and bacterial growth and lactic acid production were inhibited in the immobilized system.
Purification, partial characterization and plasmid‐linkage of pediocin SJ‐1, a bacteriocin produced by Pediococcus acidilactici
Authors: Schved F. , Lalazar A. , Henis Y. , Juven B.J.
Published: March 2008

Pediococcus acidilactici SJ‐1, isolated from a naturally‐fermented meat product, produced an antibacterial agent active against selected strains of Lactobacillus spp., Clostridium perfringens and Listeria monocytogenes. The agent was bactericidal against sensitive indicators, and sensitive to proteolytic enzymes; it was identified as a bacteriocin, and was designated as pediocin SJ‐1. It was stable over a wide pH range (3–9), and apparently most stable in the lower part of that range. At pH 3.6, pediocin SJ‐1 was stable at heat‐processing temperatures within the range 65–121°C; its activity decreased significantly, however, when it was heated at pH 7.0. The activity of pediocin SJ‐1 on sensitive indicator cells was lost in the presence of α‐amylase, suggesting that it contains a glyco moiety, necessary for its antibacterial action.

Native pediocin SJ‐1 exists in the form of monomers and aggregates (with molecular weights in the range 80–150 kDa). Pediocin SJ‐1 was purified 262‐fold by direct application of cell‐free supernatant fluids to a cation‐exchange chromatography column, and was resolved by SDS‐PAGE as a single peptide band with a MW of ca 4 kDa. The original pediocin SJ‐1‐producing strain (bac+) harbours three plasmids of 4.6, 23.5, and 45.7 MDa. Production of pediocin SJ‐1, but not immunity to SJ‐1, is associated with the 4.6 MDa plasmid.
Adaptation of Pseudomonas aeruginosa to 2,2′‐methylenebis (4‐chlorophenol)
Authors: Brözel V.S. , Cloete T.E.
Published: March 2008

A culture of Pseudomonas aeruginosa, isolated from a cooling water system, was grown in the presence of sub‐inhibitory concentrations of 2,2′‐methylenebis(4‐chlorophenol) (MBC). It adapted to increasing concentrations from an initial minimum inhibitory concentration of 36 μg ml‐1 to the highest, 80 μg ml‐1. Resistant cultures exhibited a higher survival rate when exposed to 320 μg ml‐1 than did the original strain. Lipopolysaccharide and outer membrane protein profiles were determined by SDS PAGE. No changes were detected in lipopolysaccharide profiles. The quantity of OprP, the phosphate uptake protein in the outer membrane, decreased to a low level correlating with decreased phosphate (Pi) uptake during growth. It is proposed that OprP is the place of entry for MBC and that the cell can adapt by decreasing the level of OprP in the outer membrane.
Interactions among xerophilic fungi associated with dried salted fish
Authors: Wheeler Kathryn A. , Hocking Ailsa D.
Published: March 2008

Interactions were investigated among five xerophilic fungi, Polypaecilum pisce, Basipetospora halophila, Eurotium rubrum, Aspergillus wentii and A. penicillioides, isolated from Indonesian dried salted fish. A range of water activities (aw) (0·98, 0·95, 0·90 and 0·84) and temperatures (15°, 25° and 30°C) were studied on agar media in Petri dishes, and with dried fish as a substrate at 0·90 and 0·84 aw at 30°C. Generally, the fungi exhibited one of two interaction types: mutual inhibition on contact, or inhibition of one or both species on contact, with the inhibited species continuing to grow at a significantly reduced rate. On glucose‐based agar media A. wentii and E. rubrum were most competitive at all aw values and temperatures studied, while on NaCl media P. pisce and B. halophila were usually most competitive. The Petri dish system was a useful model, but did not completely simulate the interactions observed on dried fish. Polypaecilum pisce and B. halophila were able to compete more strongly on fish than on agar media, especially at 0·90 aw. This study provides some evidence that each species examined had a niche in which it was dominant, and that species interactions as well as environmental factors are important in determining the dominant fungal species on dried salted fish.
A method for multiple synchronous collection of airborne organisms and the effects on colony counts of various processing procedures
Authors: and G.J.S Taylor , Leeming J.P.
Published: March 2008

A method is described for synchronous collection on agar of 10 similar specimens of airborne bacterial colony‐forming units (cfu) for comparative experiments. The system delivers 50 to 100 cfu per specimen with a coefficient of variance of 13 among the 10 specimens. After collection, different methods for removing colonies from the agar surface and counting them were employed. A progressive increase in colony counts was noted when increasingly destructive procedures were used. The increases noted were 4% by wetting, 30% by jet lavage, 58% by pulsed jet lavage, 82% by blending, 130% by spreading and 340% by grinding. As airborne cfu consist mainly of skin squames with multiple organisms attached, disruption of cfu is proposed as the cause of the increases. Membrane filtration of wash fluld containing cfu from the air resulted in a 47% decrease in colony counts when compared with pour‐plating. Destructive processing techniques also resulted in increased variability in colony counts. The break up of occasional exceptionally large cfu is a probable explanation. The procedure described is suitable for investigating the behaviour of airborne micro‐organisms and can be modified to model surgical wound contamination by replacing the agar with tissue.
Effect of formulation pH and storage temperatures on the preservative efficacy of some gases used as propellants in cosmetic aerosols
Authors: Ibrahim Y.K.E. , Sonntag H.‐G.
Published: March 2008

The effects of changes in formulation pH and storage temperature on the preservative activities of some aerosol propellants—butane, carbon dioxide, dimethylether and their combinations were investigated. A preservative challenge test method was used to determine the survival rates of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus niger at formulation pH levels 5·80, 7·28 and 8·10 and storage temperatures of 20°, 30° and 40°C.

A significant decrease in the pH of formulations was observed with no corresponding changes in the antimicrobial effectiveness when carbon dioxide was incorporated. Alterations in the antimicrobial profiles of these propellants due to changes in formulation pH were dependent on the propellant and the species of the micro‐organism, especially when single propellants were used. Results also showed that the propellants exert antimicrobial activities against the various organisms at the three storage temperatures but there were significantly greater inhibitory activities at 40°C. With a combination of 10% butane/dimethylether (1:2) and 10 bar carbon dioxide there were no differences in the degree of microbial inhibition at the various formulation pH levels and storage temperatures. In most cases, the organisms were completely inactivated within 24 h. These findings showed that the combination of butane/dimethylether with carbon dioxide could be used to protect against microbial contamination and spoilage of formulations of different pH levels as well as those meant for storage at different temperatures.
Alternative antigens reduce cross‐reactions in an ELISA for the detection of Salmonella enteritidis in poultry
Authors: Baay M.F.D. , Huis in‘t Veld J.H.J.
Published: March 2008

Two alternative antigens for the use in detection of antibodies to salmonellas were investigated: firstly, lipopolysaccharide (LPS) from members of the D2 group, having antigens O : 9, 46, and flagella antigens. Whereas LPS from the D2 group did not discriminate sufficiently with control sera, flagella antigens reacted specifically with antibodies directed to serotype specific H antigens. When flagella antigens were used to screen sera from birds of commercial flocks, however, cross‐reactivity between flagella antigens was observed. When both LPS and flagella antigens were used to screen sera from chickens infected with Salmonella, enteritidis, the sera gave higher titres with flagella antigens during the early stages of infection, and titres with flagella antigens dropped earlier after infection had ended than titres with lipopolysaccharide.
Stimulatory effect of phenylmercuric acetate and benzene on the growth of a broad spectrum mercury‐resistant strain of Bacillus pasteurii
Authors: Pahan Kalipada , Ray S. , Gachhui R. , Chaudhuri J. , Mandal A.
Published: March 2008

A broad spectrum mercury‐resistant organism, Bacillus pasteurii DR2, was isolated from the effluents of Durgapur Steel Plant, India. In the presence of phenylmercuric acetate or benzene the rate of glucose uptake and the level of some metabolic enzymes increased significantly. Inhibition of the glucose oxidation rate by these chemicals in lysozyme‐treated cells indicated that these compounds facilitated the transport of glucose across the cell wall and thereby stimulated growth.
Use of the polymerase chain reaction and 16S rRNA sequences for the rapid detection of Brochothrix spp. in foods
Authors: Grant K.A. , Dickinson J.H. , Payne M.J. , Campbell Shona , Collins M.D. , Kroll R.G.
Published: March 2008

Oligonucleotide primers were designed against rRNA sequences to give a DNA‐based PCR assay for the rapid identification/detection of Brochothrix spp. The PCR products could be confirmed by hybridization to an internal oligonucleotide probe. The method successfully and sensitively detected/identified these organisms in pure cultures but was of limited value as a detection method because the detection sensitivity, in relation to conventional plate counts, varied and the assay sensitivity was reduced in the presence of staphylococci. Furthermore, sensitivity was also lost when the assay was applied directly to meat samples. However, a separation step using a lectin (from Agaricus bisporus) immobilized on magnetic beads prior to the PCR assay, allowed the direct detection of low numbers (> 10 cfu g‐1) of Brochothrix in meat samples within a working day.