Showing papers in "Fems Microbiology Letters in 1984"
TL;DR: The system described here gives a direct and precise method for determining DNA base composition by reversed-phase high-performance liquid chromatography (HPLC).
Abstract: DNA base composition was determined by reversed-phase high-performance liquid chromatography (HPLC). DNA was hydrolysed into nucleosides with nuclease P1 and bacterial alkaline phosphatase. The mixture of nucleosides was applied to HPLC without any further purification. One determination by chromatography needed 2 μg of hydrolysed nucleosides and took only 8 min. The relative standard error of nucleoside analysis was less than 1%. The system described here gives a direct and precise method for determining DNA base composition.
2,468 citations
TL;DR: The present publication briefly describes the technique and its modifications, summarizes results obtained using this method, and suggests several directions for further investigation.
Abstract: Bacterial adherence to hydrocarbons (BATH) is a simple and rapid technique for determining cell-surface hydrophobicity. During recent years, this method has found application in the study of the surface characteristics of a wide variety of bacteria and bacterial mixtures. Correlations have been found between the adherence of bacteria to hydrocarbons and their attachment to other surfaces, including non-wettable plastics, epithelial cells, and teeth. A slight modification of the assay enables the isolation of nonhydrophobic mutants. The present publication briefly describes the technique and its modifications, summarizes results obtained using this method, and suggests several directions for further investigation.
407 citations
Journal Article•
TL;DR: The system described here gives a direct and precise method for determining DNA base composition and the relative standard error of nucleoside analysis was less than 1%.
Abstract: DNA base composition was determined by reversed-phase high-performance liquid chromatography (HPLC). DNA was hydrolysed into nucleosides with nuclease P1 and bacterial alkaline phosphatase. The mixture of nucleosides was applied to HPLC without any further purification. One determination by chromatography needed 2 μg of hydrolysed nucleosides and took only 8 min. The relative standard error of nucleoside analysis was less than 1%. The system described here gives a direct and precise method for determining DNA base composition.
385 citations
Journal Article•
TL;DR: This initial study gives the first direct biochemical evidence that mucoid P. aeruginosa grows under iron restricted conditions in the lungs of the cystic fibrosis patient.
Abstract: The outer membrane protein composition of mucoid Pseudomonas aeruginosa recovered without subculture from the sputum of a cystic fibrosis patient was studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The results indicated that three outer membrane proteins in the range of Mr 80 000–90 000 were induced. The induction of these proteins can be simulated by growing the same isolate under iron-restricted conditions in laboratory media. This initial study gives the first direct biochemical evidence that mucoid P. aeruginosa grows under iron restricted conditions in the lungs of the cystic fibrosis patient.
154 citations
TL;DR: The outer membrane protein composition of mucoid Pseudomonas aeruginosa recovered without subculture from the sputum of a cystic fibrosis patient was studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis as discussed by the authors.
Abstract: The outer membrane protein composition of mucoid Pseudomonas aeruginosa recovered without subculture from the sputum of a cystic fibrosis patient was studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The results indicated that three outer membrane proteins in the range of Mr 80 000–90 000 were induced. The induction of these proteins can be simulated by growing the same isolate under iron-restricted conditions in laboratory media. This initial study gives the first direct biochemical evidence that mucoid P. aeruginosa grows under iron restricted conditions in the lungs of the cystic fibrosis patient.
146 citations
TL;DR: Eight Nif− mutants of Azospirillum brasilense were obtained by N-nitrosoguanidine mutagenesis and isolated by growth on glutamate medium and evidence will be presented that one of these mutants is defective in a nifA type regulatory gene.
Abstract: Eight Nif− mutants of Azospirillum brasilense were obtained by N-nitrosoguanidine mutagenesis and isolated by growth on glutamate medium. Three of these mutants had no nitrogenase activity, possessed no nitrogenase structural proteins and were complemented by Klebsiella pneumoniae nifA. Evidence will be presented that one of these mutants is defective in a nifA type regulatory gene but the other two were also complemented by K. pneumoniae ntrC and may be ntrC−-type mutants. A fourth mutant was defective in the MoFe component protein of nitrogenase.
143 citations
TL;DR: It is concluded that the protein formed is a genuine glucose dehydrogenase, but that it is not functional in growing cells due to their inability to synthesize the appropriate cofactor (PQQ), at least under these conditions.
Abstract: When grown on glucose in K+-limited chemostat culture, or in batch culture with or without 2,4-dinitrophenol, several strains of Escherichia coli (including the type strain) were found to synthesize a quinoprotein glucose dehydrogenase apoenzyme. The pyridine nucleotides, NAD+ and NADP+, would not serve as cofactor, but activity could be demonstrated upon addition of 2,7,9-tricarboxy-1 H-pyrrolo(2,3-f)quinoline-4,5-dione (PQQ). Thus, in the presence of PQQ, but not in its absence, glucose was oxidized to gluconic acid. A mutant of E. coli PC 1000 was isolated that lacked Enzyme I of the phosphoenolpyruvate phosphotransferase system (PTS) but still synthesized the glucose dehydrogenase apoenzyme. Whereas this mutant would not grow on glucose in the absence of PQQ, it would do so in the presence of low concentrations (1 μM) of this cofactor. On the basis of these observations, it is concluded that the protein (apoenzyme) formed is a genuine glucose dehydrogenase, but that it is not functional in growing cells due to their inability to synthesize the appropriate cofactor (PQQ), at least under these conditions.
125 citations
TL;DR: The cyanobacterium Microcystis aeruginosa was grown in light-limited chemostat cultures with various light—dark rhythms providing a total periodicity length of 24 h and the buoyant density of the cells changed in parallel with the carbohydrate content.
Abstract: The cyanobacterium Microcystis aeruginosa was grown in light-limited chemostat cultures with various light—dark rhythms providing a total periodicity length of 24 h. The buoyant density of the cells changed in parallel with the carbohydrate content. Short incubation experiments with different light intensities, and experiments with the inhibitors iodoacetic acid and arsenate, showed that the buoyant density changes were due to variations in the cellular carbohydrate content. It seems likely that the low dark-growth yield on carbohydrate, which had been stored during the light period, served to facilitate buoyancy changes.
111 citations
TL;DR: The quinone composition of the recognized species of the phototrophic purple nonsulfur bacteria, the Ectothiorhodospiraceae, and some Chromatiaceae species has been determined and Rhodoquinone is present in Rhodospirillum rubrum and Rhodospira photometricum.
Abstract: The quinone composition of the recognized species of the phototrophic purple nonsulfur bacteria, the Ectothiorhodospiraceae, and some Chromatiaceae species has been determined. Altogether more than 50 strains of 33 species have been investigated. Some of the purple nonsulfur bacteria have Q-10 as sole quinone component, while others have Q-10, Q-9, or Q-8, respectively, together with menaquinones of the same isoprenoid chain length as the major components. Rhodoquinone is present in Rhodospirillum rubrum and Rhodospirillum photometricum. The Ectothiorhodospira species have either Q-8 and MK-8, like the Chromatiaceae species, or Q-7 and MK-7 as the major components.
109 citations
TL;DR: A gene block controlling sucrose-fermenting ability, nisin resistance and nisin production was found to be transmissible by a conjugation-like process and possibilities for increased nisin yield by genetic manipulation in S. lactis 712 must exist.
Abstract: A gene block controlling sucrose-fermenting ability, nisin resistance and nisin production was found to be transmissible by a conjugation-like process The ‘pSN’ (sucrose nisin) plasmid was transferred from 8 different nisin-producing donor strains into MG1614, a plasmid-free derivative of Streptococcus lactis 712 In the new host low yields of a plasmid of approx 30 MDa were isolated but its authenticity as a pSN plasmid has not yet been established Possibilities for increased nisin yield by genetic manipulation in S lactis 712 must exist
105 citations
TL;DR: A lignin-degrading enzyme has been detected in culture supernatants of Phanerochaete chrysosporium strain INA-12 grown under non-limiting nitrogen conditions.
Abstract: A lignin-degrading enzyme has been detected in culture supernatants of Phanerochaete chrysosporium strain INA-12 grown under non-limiting nitrogen conditions. Highest levels of enzyme activity were observed when glycerol served as carbon source. Veratryl alcohol, a known secondary metabolite of P. chrysosporium, was also produced in high nitrogen/glycerol cultures of strain INA-12 and closely followed the development of the ‘ligninase’ activity. Evolution of 14CO2 from 14C-ring-DHP was readily observed when a hydrogen peroxide-generating system was added to 5-day-old high nitrogen/glycerol cultures which contained high amounts of enzyme.
TL;DR: A gas-liquid chromatographic method for the quantitative determination of hopanoids with an elongated side chain was developed in this paper, where the contents of extended hopanoid increased strongly with increasing temperature and moderately with decreasing pH.
Abstract: A gas-liquid chromatographic method for the quantitative determination of hopanoids with an elongated side chain was developed. After extraction of lipids from Bacillus acidocaldarius, periodate oxidation, reduction and acetylation the 1-hydroxyethane-29-hopane acetate was quantitated by comparison with 1-octadecanyl-glycerol ether. The contents of extended hopanoids increased strongly with increasing temperature and moderately with decreasing pH. Hopene showed no significant alteration with temperature and pH.
TL;DR: The nucleotide sequence of the gene encoding the K99 fimbrial subunit of enterotoxigenic Escherichia coli was determined and it appeared that the subunit is composed of 159 amino acid residues preceded by a N-terminal signal sequence.
Abstract: The nucleotide sequence of the gene encoding the K99 fimbrial subunit of enterotoxigenic Escherichia coli was determined. It appeared that the subunit is composed of 159 amino acid residues preceded by a N-terminal signal sequence of 22 amino acid residues. The secondary structure of the mature K99 polypeptide and the location of potential antigenic determinants were predicted. A comparison was made between the amino acid sequence of the K99 subunit and the subunits of other fimbrial adhesins.
Journal Article•
TL;DR: A gas-liquid chromatographic method for the quantitative determination of hopanoids with an elongated side chain was developed in this paper, where the contents of extended hopanoid increased strongly with increasing temperature and moderately with decreasing pH.
Abstract: A gas-liquid chromatographic method for the quantitative determination of hopanoids with an elongated side chain was developed. After extraction of lipids from Bacillus acidocaldarius, periodate oxidation, reduction and acetylation the 1-hydroxyethane-29-hopane acetate was quantitated by comparison with 1-octadecanyl-glycerol ether. The contents of extended hopanoids increased strongly with increasing temperature and moderately with decreasing pH. Hopene showed no significant alteration with temperature and pH.
TL;DR: Small inverse isotope effects of 1–3‰ were consistently observed for the oxidation of sulfide to elemental sulfur during anaerobic photometabolism by Chromatium vinosum, and may indicate that C. vinoum (and other photosynthetic bacteria) utilizes H2S rather than HS− as the substrate during sulfide oxidation.
Abstract: Small inverse isotope effects of 1–3‰ were consistently observed for the oxidation of sulfide to elemental sulfur during anaerobic photometabolism by Chromatium vinosum. The inverse fractionation can be accounted for by an equilibrium isotope effect between H2S and HS−, and may indicate that C. vinosum (and other photosynthetic bacteria) utilizes H2S rather than HS− as the substrate during sulfide oxidation.
TL;DR: Oxalic acid production as an important factor of virulence in S. sclerotiorum is emphasized and its effect on the phenolic metabolism of the host via inhibition of polyphenoloxidase is suggested.
Abstract: Sunflower plants were inoculated with a virulent isolate of Sclerotinia sclerotiorum and with the same isolate nutritionally conditioned to produce small amounts of oxalic acid. The preconditioned isolate behaved as hypovirulent. Tomato plants were inoculated with four S. sclerotiorum isolates of increasing virulence. A close correlation among disease severity, accumulation of oxalic acid, decrease in pH and inhibition of polyphenoloxidase in both infected host tissues was demonstrated. Oxalic acid production as an important factor of virulence in S. sclerotiorum is emphasized and its effect on the phenolic metabolism of the host via inhibition of polyphenoloxidase is suggested.
TL;DR: Only strains previously isolated from rodents were able to form thick continuous layers on the gastric epithelial surface, comparable to layers seen in animals associated with strains from rodents.
Abstract: Strains of Lactobacillus isolated from animals of several species were examined for their capacity to colonize the lumens and form layers on the keratinized nonsecreting epithelium in the stomachs of monoassociated ex-germfree mice. All strains tested could be cultured at comparable population levels from the stomachs of the mono-associated mice. With one exception, however, only strains previously isolated from rodents were able to form thick continuous layers on the gastric epithelial surface. The exception was a strain isolated from calf feces. This strain formed a layer on the epithelial surface, comparable to layers seen in animals associated with strains from rodents.
TL;DR: In Streptococcus cremoris SK11, different permutations of a total of 8 plasmids were observed within and between cultures of various origins, and those variants which carried a 34-MDa plasmid, pSK112, were resistant to bacteriophage oSK11G, whereas those from which theplasmid was absent or had been cured were sensitive to this phage.
Abstract: In Streptococcus cremoris SK11, different permutations of a total of 8 plasmids were observed within and between cultures of various origins. All showed similar growth rates in milk. Those variants which carried a 34-MDa plasmid, pSK112, were resistant to bacteriophage oSK11G, whereas those from which the plasmid was absent or had been cured were sensitive to this phage. Plasmid pSK112 was shown to confer resistance by reduced phage adsorption. These observations have important potential for the development of phage-resistant dairy cultures.
TL;DR: Evidence is presented, from laboratory-based experiments, which show that A. salmonicida survives in freshwater, beyond the period necessary for plate counts to reach zero, and may be assumed that this bacterium survives outside of fish, by entering a dormant phase.
Abstract: By definition, Aeromonas salmonicida is found in fish but never in surface water. However, this does not explain the reason for explosive out-breaks of furunculosis among populations of salmonid fish which have never been exposed to the disease. Evidence is presented, from laboratory-based experiments, which show that A. salmonicida survives in freshwater, beyond the period necessary for plate counts to reach zero. These cells may subsequently be re-activated by the addition of nutrient. It may be assumed, therefore, that A. salmonicida survives outside of fish, by entering a dormant phase.
TL;DR: It is possible to stain live bacteria with rhodamine 123 (R123) and Gram-negative strains were stained with different efficiency, presumably reflecting the different constitutions of the outer membrane.
Abstract: It is possible to stain live bacteria with rhodamine 123 (R123). The stained fluorescent cells still keep the ability to replicate (Staphylococcus aureus, Bordetella pertussis) and to swim (e.g., Salmonella minnesota). Dead cells or cells with a dissipated transmembrane potential showed markedly diminished fluorescence. Gram-negative strains were stained with different efficiency, presumably reflecting the different constitutions of the outer membrane.
TL;DR: Hydrogenase and pyruvate synthase were undetectable in several of the entodiniomorph species investigated and were found to be morphologically and enzymically similar to hydrogenosomes from the rumen holotrichs.
Abstract: The distribution of hydrogenosomal enzymes in several species of rumen entodiniomorphid protozoa grown in vivo and in vitro was investigated. Eudiplodinium maggii and Epidinium ecaudatum caudatum were shown to possess pyruvate synthase and hydrogenase enzyme activities associated with a fraction sedimentable at 105/ g/min and enriched in granular microbody-like organelles about 0.3 μm in diameter; these organelles are therefore morphologically and enzymically similar to hydrogenosomes from the rumen holotrichs. However, hydrogenase and pyruvate synthase were undetectable in several of the entodiniomorph species investigated.
TL;DR: An enzyme catalyzing the ATP-dependent phosphorylation of HPr of the bacterial phosphotransferase system has been purified from Streptococcus faecalis and is largely inhibited by Pi and EDTA, but Mg2+ and Mn2+ could overcome inhibition by EDTA.
Abstract: An enzyme catalyzing the ATP-dependent phosphorylation of HPr of the bacterial phosphotransferase system has been purified from Streptococcus faecalis. Size exclusion chromatography and sodium dodecyl sulfate (SDS) polyacrylamide gels revealed an Mr of 65000. Beside HPr of S. faecalis the protein kinase also phosphorylates HPr of Streptococcus lactis, Streptococcus pyogenes, Bacillus subtilis and Streptococcus aureus, but not HPr of Escherichia coli. The kinase is largely inhibited by Pi and EDTA. Mg2+ and Mn2+ could overcome inhibition by EDTA. 2-Phosphoglycerate and glucose-6-phosphate, previously reported to stimulate kinase activity in crude extracts, had no effect on the purified enzyme. Fructose-1,6-diphosphate stimulated the protein kinase.
TL;DR: The activity of pyrrolo-quinoline quinone (PQQ)-dependent glucose dehydrogenase (GDH) was determined in Acinetobacter and Pseudomonas species, grown under different conditions, indicating that control of GDH activity by PQQ synthesis maybe widespread among bacteria.
Abstract: The activity of pyrrolo-quinoline quinone (PQQ)-dependent glucose dehydrogenase (GDH) was determined in Acinetobacter and Pseudomonas species, grown under different conditions. In Acinetobacter lwoffi which, in contrast to Acinetobacter calcoaceticus , is unable to oxidize glucose to gluconic acid, the absence of GDH activity was not due to the absence of GDH protein (apoenzyme) but to the absence of its prosthetic group, PQQ. GDH activity could be restored by addition of PQQ to cell suspensions. Taxonomic implication of these results are discussed. Pseudomonas aeruginosa , strain PAO1 is known to contain active GDH when grown aerobically on glucose, but to lack this activity when grown anaerobically with nitrate. Also in this organism the absence of active GDH was due to lack of PQQ synthesis under these conditions, since GDH activity could be reconstituted by addition of PQQ to cell-free extracts. Similar observations were made with cultures of Pseudomonas acidovorans and Rhodopseudomonas sphaeroides , indicating that control of GDH activity by PQQ synthesis maybe widespread among bacteria.
TL;DR: It is proposed that in nature possession of an intracellular magnet allows the microaerophilic cell to pursue the most efficient aerotactic behaviour; orientation in the geomagnetic lines of force eliminates the need for twiddling, long runs and short runs.
Abstract: Cells of a magnetic spirillum exhibited a chemotactic (aerotactic) response when suspended in a solution of 2-mercaptoethanesulfonate, mercaptoethanol, or thioglycolate. In a slide preparation masses of cells formed bands. Cells in a band reversed their direction of motility along the applied magnetic lines of force without turning; the tactile response of cells occurred in a similar manner. It is proposed that in nature possession of an intracellular magnet allows the microaerophilic cell to pursue the most efficient aerotactic behaviour; orientation in the geomagnetic lines of force eliminates the need for twiddling, long runs and short runs.
TL;DR: A striking feature of methicillin resistance in Staphylococcus aureus is the considerable heterogeneity of expression of resistance by cells in clonal populations: some are sensitive (or almost so), others are highly resistant, and others show intermediate resistance to the antibiotic.
Abstract: A striking feature of methicillin resistance in Staphylococcus aureus is the considerable heterogeneity of expression of resistance by cells in clonal populations: some are sensitive (or almost so), others are highly resistant, and others show intermediate resistance to the antibiotic. Subclones generally are also heterogeneous, suggesting variable inheritance or control of expression of resistance.
The degree of heterogeneity and mean resistance is influenced by environmental parameters: temperature, osmolality, pH, light, anaerobiosis, chelating agents and metal ions, and prior exposure to β-lactam antibiotics.
TL;DR: In conclusion, IgG fractions of antisera against Streptococcus mutans cell-surface protein antigens A and B suggest that antigen B is an important factor in the adherence of S. mutans to saliva-coated hydroxylapatite.
Abstract: IgG fractions of antisera against Streptococcus mutans cell-surface protein antigens A and B were used to examine the role of these molecules in adherence to saliva-coated hydroxylapatite. Anti-B antibody inhibited S. mutans adherence by 20–50% depending upon the strain used, while anti-A antibody was without effect. Some IgG-mediated agglutination of cells occurred in the course of these experiments which was overcome by using Fab fragments prepared from the anti-A and anti-B IgG's. Anti-B Fab inhibited S. mutans adherence by 50% but anti-A Fab had no effect. These observations suggest that antigen B is an important factor in the adherence of S. mutans to saliva-coated hydroxylapatite.
TL;DR: The antigenicity of the outer membrane components of mucoid Pseudomonas aeruginosa directly isolated from the sputum of a cystic fibrosis patient and those of the same isolate cultivated under iron-depleted conditions was investigated by immunoblotting using the patient's own serum.
Abstract: The antigenicity of the outer membrane components of mucoid Pseudomonas aeruginosa directly isolated from the sputum of a cystic fibrosis patient and those of the same isolate cultivated under iron-depleted conditions in the presence of sub-in-hibitory concentrations of piperacillin and/or tobramycin was investigated by immunoblotting using the patient's own serum. The results indicated that iron-regulated membrane proteins as well as other major outer membrane proteins were antigenic and recognised by the patient's serum. The antibiotics used profoundly influenced the surface antigen pattern.
TL;DR: The applicability of the test for routine diagnostic use was demonstrated by a pilot study in which C. trachomatis was directly detected from genital specimens.
Abstract: Chromosomal DNA fragments from Chlamydia trachomatis serotype L2 were shotgun-cloned into pBR322. A C. trachomatis-specific clone was further subcloned to produce specific DNA reagents for the identification of C. trachomatis by nucleic acid sandwich hybridization. The chosen DNA reagents from serotype L2 also hybridized with all the other chlamydial serotypes tested, but not with the DNA from 41 unrelated organisms. The sensitivity of the sandwich hybridization test was 106 DNA molecules. The applicability of the test for routine diagnostic use was demonstrated by a pilot study in which C. trachomatis was directly detected from genital specimens.
TL;DR: The stability of plasmid pBR322 and a number of close derivatives was examined by continuous culture of Escherichia coli and three cosmids pHC79, pSJ55 and pJB8 were generally found to be less stable than the pBR 322-type plasmids from which they were derived.
Abstract: The stability of plasmid pBR322 and a number of close derivatives was examined by continuous culture of Escherichia coli. Cultures were subjected to either glucose, phosphate or magnesium limitation in non-selective medium at a dilution rate of 0.1/h. Under these conditions pBR322 was eventually lost from the population, but only after a distinct lag period. The closely related plasmids pBR325 and especially pBR327 and pBR328, but not pAT153, were lost more rapidly. Three cosmids pHC79, pSJ55 and pJB8 were generally found to be less stable than the pBR322-type plasmids from which they were derived. Chimaeric plasmids containing DNA from yeast and from a thermophilic bacillus were also unstable in E. coli.
TL;DR: In this article, outer-membrane vesicles from Escherichia coli K-12 produced typical phosphorus nuclear magnetic resonance (31P-NMR) spectra that were indicative of a lipid bilayer conformation.
Abstract: Outer-membrane vesicles from Escherichia coli K-12 produced typical phosphorus nuclear magnetic resonance (31P-NMR) spectra that were indicative of a lipid bilayer conformation. Upon the addition of the paramagnetic cation Eu III, spectra were broadened and shifted illustrating a direct interaction between the phosphoryl groups of the constituent outer-membrane (OM) molecules and the metal cation. The extent of the broadening, however, was atypical for Eu III and suggestive of a restriction in molecular motion within the OM vesicles. Bound europium (Z = 63) produced enough electron contrast for low-dose electron microscopic imaging and was also detected by energy-dispersive X-ray spectroscopy (EDS). Small electron-dense precipitates were associated with the OM vesicles and could be stable, neutrally charged, water-insoluble co-ordination complexes.