- Volume 132, Issue 7, 1986
Volume 132, Issue 7, 1986
- Biochemistry
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Characterization of Extracellular Metallo- and Serine-proteases of Aeromonas hydrophila Strain B51
More LessSummary: The extracellular proteases of Aeromonas hydrophila B51 were stable on heating (56 °C) and on storage at 4 °C or −20 °C. Inhibitor studies showed that 72% of the total activity was inhibited by EDTA (a metalloprotease inhibitor) and 26% was inhibited by phenylmethanesulphonyl fluoride (a serine protease inhibitor). Analytical isoelectric focussing revealed the presence of 33 proteins in the crude extracellular products. Using a casein overlay technique three separate zones of proteolytic activity were detected: a zone with pI 6.5–6.8, formed of two closely focussed bands (possibly isomers of the same protease) and completely inhibited by EDTA; a single band with pI 7.0, which was inhibited by EDTA; and a diffuse zone with pI 8.3–8.5, which was only partially inhibited by EDTA. It is concluded that the serine protease activity focussed in this latter zone. These results indicate the presence of at least four, and possibly five proteases. Our results differ substantially from those reported by other workers using different isolates and it is suggested that significant differences in the character of extracellular products and extracellular proteases exist between different isolates of A. hydrophila
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Activation of Clostridium botulinum Type E Toxin Purified by Two Different Procedures
More LessSummary: Clostridium botulinum type E toxin was purified from culture supernates and from cell extracts by two methods. The specific activity [2 × 104mouse LD50 (mg protein)−1] of the toxin purified from cell extract under slightly acidic conditions was lower than that [3 × 105LD50 (mg protein)−1] of the toxin purified from culture supernate under slightly alkaline conditions. Both toxin preparations were activated by trypsin treatment, but to different extents, the degree of activation of the toxin from cell extract being about 30-fold higher than that of the toxin from culture supernate. The two toxin preparations had the same electrophoretic mobility on SDS-polyacrylamide gels and antigenic specificity as revealed by agar gel double-immunodiffusion tests. The antigenic specificity of the two toxin preparations was unaltered by trypsin treatment. In SDS-polyacrylamide gel electrophoresis, a single band of M r 144 000 was demonstrated before trypsin treatment and two bands of M r 100 000 and 55 000 appeared after trypsin treatment. The two toxin preparations were labelled with 125I and chymotryptic peptide maps were obtained before and after trypsin treatment. The two toxin preparations without trypsin treatment demonstrated many differences in their peptide maps, but the preparations after trypsin activation had similar peptide maps. These results indicate that the toxin obtained from culture fluid was a partially activated form, and that its molecular conformation was different from that of the toxin from cell extract. Differences in specific activity and activation ratio by trypsin treatment may be due to differences in the conformation of the toxin molecules.
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Purification and Regulation of a Cloned Thiobacillus ferrooxidans Glutamine Synthetase
More LessSummary: Glutamine synthetase (GS) (EC 6.3.1.2) was purified from an Escherichia coli glnA deletion strain containing the Thiobacillus ferrooxidans GS structural gene. The apparent Mr of the cloned T. ferrooxidans GS subunit was approximately 60000. This indicates a particle Mr for the undissociated enzyme of 720000, assuming the enzyme is the typical dodecamer. Electron microscopy of purified GS revealed characteristic disc shaped molecules with central holes. The cloned T. ferrooxidans GS was regulatedby Mg2+ or Mn2+,adenylylation, and nitrogen source but was not affected by feedback modifiers. The GS has a γ-glutamyltransferase isoactivity point of pH 7.71.
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Structure and Properties of Assimilatory Nitrate Reductase from the Yeast Candida nitratophila
More LessSummary: NAD(P)H nitrate reductase (EC 1.6.6.2) from the yeast Candida nitratophila has been purified to electrophoretic homogeneity. The concentrated enzyme has a molecular mass of 365 kDa and consists of four subunits each of 95 kDa, but appears to dissociate into dimers after dilution. The absorption spectrum of the homogeneous protein is typical of a b-type cytochrome and its isoelectric point is pH 5.4. The enzyme utilizes both NADH and NADPH but is more active with NADH. Preincubation of pure enzyme with NAD(P)H and cyanide, but not NAD(P)H and ADP, leads to a reversible redox inactivation of the enzyme. Preincubation with NAD(P)H alone activates the enzyme.
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Regulation of Nitrate Reductase Synthesis in the Yeast Candida nitratophila
More LessSummary: Immunoelectrophoresis, using antibodies raised against homogeneously pure nitrate reductase (NR; EC 1.6.6.2), was used to study the regulation of NR synthesis in Candida nitratophila. Extracts from ammonium-grown cultures did not contain cross-reacting material, but cross-reacting material was detected in cultures transferred to nitrogen-free and nitrate medium. The appearance of NR activity in these extracts appeared to be the result of de novo protein synthesis. The possible role of nitrate in the stimulation of active NR synthesis is discussed. Losses of NR activity that occurred in nitrate-grown cultures transferred to ammonium medium correlated with decreases in cross-reacting material.
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- Development And Structure
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A Comparative Study of the Morphology and Viability of Hyphae of Penicillium expansum and Phytophthora nicotianae during Freezing and Thawing
More LessSummary: The changes in morphology of Penicillium expansum Link and Phytophthora nicotianae Van Breda de Haan during freezing and thawing in a growth medium with and without the cryoprotective additive glycerol were examined with a light microscope fitted with a temperature-controlled stage. Viability of 0.5–1.0 mm diameter colonies of both fungi was determined after equivalent rates of cooling to −196 °C in the presence or absence of glycerol. In P. expansum shrinkage occurred in all hyphae at rates of cooling of less than 15 °C min−1; at faster rates intracellular ice nucleation occurred. The addition of glycerol increased the rate of cooling at which 50% of the hyphae formed intracellular ice from 18°C min−1to 55 °C min−1. This species was particularly resistant to freezing injury and recovery was >60% at all rates of cooling examined. At rapid rates of cooling recovery occurred in hyphae in which intracellular ice had nucleated. In contrast, during the cooling of Ph. nicotianae in the growth medium, shrinkage occurred and no samples survived on thawing from −196 °C. However, on the addition of glycerol, shrinkage during freezing decreased and viable hyphae were recovered upon thawing; at rates of cooling over 10 °C min−1the loss of viability was related to glycerol-induced osmotic shrinkage during cooling rather than to the nucleation of intracellular ice.
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Differences in Actin Localization during Bud and Hypha Formation in the Yeast Candida albicans
More LessSummary: Stationary phase cells of Candida albicans can form either a bud or a hypha, depending upon the pH of the medium into which they are released. At low pH, cells form an ellipsoidal bud and at high pH, cells form an elongated hypha. By staining cells with rhodamine-conjugated phalloidin, we have compared the dynamics of actin localization during the formation of buds and hyphae. Before evagination, actin granules were distributed throughout the cytoplasmic cortex in both budding and hypha-forming cells. Just before evagination, actin granules clustered at the site of evagination, then filled the early evagination in both budding and hypha-forming cells. With continued bud growth, the actin granules then redistributed throughout the cytoplasmic cortex. In marked contrast, with continued hyphal growth, the majority of actin granules clustered at the hyphal apex. This distinct difference in actin granule localization may be related to the distinct differences in the expansion zones of the cell wall recently demonstrated between growing buds and hyphae. The spatial and temporal dynamics of the large neck actin granules and of actin fibres are also described.
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- Ecology
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Phospholipid Ester-linked Fatty Acid Biomarkers of Acetate-oxidizing Sulphate-reducers and Other Sulphide-forming Bacteria
More LessSummary: The phospholipid ester-linked fatty acids were examined in four Desulfobacter strains (2ac9, AcBa, 3acl0 and 4acll), a Desulfobacter-like ‘fat vibrio’ (AcKo) and Desulfotomaculum acetoxidans (5575), which are all sulphate-reducing bacteria that oxidize acetate. A thermophilic sulphate reducer, Desulfovibrio thermophilus, and two sulphur-reducing bacteria, Desulfuromonas acetoxidans (11070) and a Campylobacter-like spirillum (5175), were also studied. The Desulfobacter spp. were characterized by significant quantities of 10-methylhexadecanoic acid. Other 10-methyl fatty acids were also detected in Desulfobacter spp. No 10-methyl fatty acids were detected in the other organisms examined, supporting the use of 10-methylhexadecanoic acid as a biomarker for Desulfobacter. High levels of cyclopropyl fatty acids, including two isomers of both methylenehexadecanoic (cyl7:0) and methyleneheptadecanoic (cyl8:0) acids, were also characteristic of Desulfobacter spp. The influence of the volatile fatty acids (VFA) propionate, isobutyrate, isovalerate and 2-methylbutyrate on the lipid fatty acid distribution was studied with two Desulfobacter strains (2ac9, AcBa) and Desulfotomaculum acetoxidans. Although these sulphate reducers cannot oxidize the VFA, their presence in the acetate growth medium caused a shift in the fatty acid distribution in favour of odd-numbered and branched chains by apparent direct incorporation into the fatty acids as chain initiators. The Desulfobacter strains were distinguished from other sulphide-forming bacteria by the percentage of unsaturated and the percentage of branched fatty acids.
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- Genetics And Molecular Biology
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Construction of a Novel Gene Bank of Bacillus subtilis Using a Low Copy Number Vector in Escherichia coli
More LessSummary: Low copy number vector plasmid pCT571 was constructed to clone Bacillus subtilis genomic fragments in Escherichia coli. pCT571 confers KmR, TcRand CmR in E. coli and CmR in B. subtilis. It has unique restriction sites within the KmR and TcRmarkers to allow screening for recombinant plasmids by insertional inactivation of these genes. It contains the pSC101 replicon and replicates normally at six to eight copies per chromosome equivalent in E. coli. It also contains oriV RK2, which when supplied with the product of the trfA gene of RK2 in trans, allows pCT571 to replicate at 35−40 copies per chromosome equivalent. A B. subtilis gene bank was created by cloning partially Sau3A-digested and size-fractionated fragments of B. subtilis chromosomal DNA into the BamHI site of pCT571. DNA from 1097 KmRTcStransformants was extracted and analysed electrophoretically as supercoiled DNA and after digesting with EcoRI or EcoRI and SalI. Approximately 1000 hybrid plasmids were found with reasonably sized B. subtilis fragments. The mean size of the inserts in pCT571 is 8 kb, ranging from 4 to 20 kb in different plasmids. The gene bank covers most of the B. subtilis chromosome, as demonstrated by the results of screening the gene bank for selectable nutritional markers in E. coli and B. subtilis. Hybrid plasmids which complement E. coli mutants for arg, his, lys, met, pdx, pyr and thr markers were identified from the gene bank. In B. subtilis the presence of argC, cysA, dal, hisA, ilvA, leuA, lys, metB, metC, phe, purA, purB, thr and trpC was established by transformation experiments. The effects of copy number on cloning and long-term maintenance in the bacterial strains were also investigated. At high copy number some hybrid plasmids cannot be maintained at all, while others show an increased rate of structural deletions and rearrangements.
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Isolation and Characterization of a Clone of the spoVE Locus of Bacillus subtilis
More LessSummary: The Bacillus subtilis spoVE locus was isolated from a λ clone bank and a 4.7 kbp EcoRV fragment subcloned into the shuttle vector pHV33. The resulting plasmid complemented chromosomal spoVE mutations. Its structure was stable in recE4 strains, but plasmid and chromosomal rearrangements occurred in rec +strains. New spoVE mutations were obtained by mutagenesis of the plasmid; all the mutations tested mapped within three adjacent HindIII fragments of total length 1140 bp.
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Nucleotide Sequence of the Bacillus subtilis Developmental Gene SpoVE
More LessSummary: We have determined the nucleotide sequence of a 1159 bp DNA fragment containing the spoVE locus of Bacillus subtilis. The locus contained a single open reading frame of 293 codons. On the basis of the predicted amino acid sequence, the product of the spoVE gene is believed to be a protein with an M r of 31539. The amino-terminal portion of the spoVE gene was used to construct a translational fusion with the lacZ’ gene. The hybrid spoVE-lacZ’ gene was shown to be expressed in Escherichia coli and, therefore, it seems reasonable to conclude that the proposed open reading frame for the spoVE gene does indeed function in vivo.
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Purification and Partial Characterization of DNA-dependent RNA Polymerase from Rhodomicrobium vannielii
N. W. Scott and C. S. DowSummary: DNA-dependent RNA polymerase has been isolated from Rhodomicrobium vannielii. Like those from other eubacteria, the enzyme contained four subunits: beta and beta prime (M r 155000), alpha (M r 38000), and sigma (M r 98000). Analysis by isoelectric focussing showed that both alpha and sigma had several forms with different isoelectric pH values. The enzyme was sensitive to rifampicin (5 ng rifampicin ml−1gave 50% inhibition) and capable of specific promoter selection with DNA from R. vannielii, calf thymus and phage T7D111.
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Temperature-dependent Plasmid Integration into and Excision from the Chromosome of Bacillus stearothermophilus
More LessSummary: A Transformant of Bacillus stearothermophilus carrying a recombinant plasmid, pLP11 (9.5 MDa), on which the penicillinase gene (penP) and kanamycin resistance gene (kan) were located was subjected to mutagenesis, and a mutant plasmid (9.5 MDa; penP kan), designated pTRA 117, obtained. A transformant of B. stearothermophilus carrying pTRA117 could grow at 63 °C in medium containing kanamycin, whereas a transformant carrying pLP11 could not. Although pTRA117 was deteeted as covalently closed circular (ccc) DNA when it was extracted from transformants cultured at 48 °C, it was integrated into the host chromosome when the culture temperature was shifted up to 63 °C. If the culture temperature was lowered to 48 °C from 63 °C, a new plasmid (10.7 MDa; penP kan), designated pTRZ117, could be detected as ccc DNA, the size of this plasmid suggested that it was pTRA117 plus a 1.2 MDa DNA fragment of the host chromosome, and this was confirmed by Southern hybridization. pTRZ90 (7.9 MDa; kan) was constructed from pTRZ117 by the deletion of a 2.8 MDa DNA fragment that contained penP. Fresh transformants of B. stearothermophilus that carried either pTRZ117 or pTRZ90 could grow at 65 °C.
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- Pathogenicity And Medical Microbiology
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A Probability Matrix for the Identification of Gram-negative, Aerobic, Non-fermentative Bacteria that Grow on Nutrient Agar
More LessSummary: Results of the identification of 621 strains of Gram-negative, aerobic, non-fermentative bacteria by a computer-based probabilistic method are given. Although many of the strains were atypical and have caused difficulty in identification in the medical diagnostic laboratory, the identification rate on this matrix was 91.5%.
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Comparative Esterase Electrophoretic Polymorphism of Escherichia coli Isolates Obtained from Animal and Human Sources
PH. Goullet and B. PicardSummary: To determine whether enzyme electrophoretic polymorphism in Escherichia coli populations was influenced by environmental background, the mobilities of four electrophoretically variable esterases (A, B, C and I) were examined. The distinction between isolates was established by significant differences in the electrophoretic distribution and the genetic diversity coefficient of individual esterases. Principal components analysis on each population and on all strains revealed three groups of allozymes. The first, characterized by slow electrophoretic mobilities of esterase B, was frequently observed in strains obtained from human extra-intestinal infections and rarely in commensal organisms. The second, characterized by fast mobilities of esterases A and B, was frequently found in animal isolates. The third, characterized by prominence of the most common mobilities of esterases B and A, was recovered in all populations. These results were confirmed by discriminant analysis. Among the 610 strains investigated, 316 electrophoretic types (distinctive combinations of allozymes of the four varieties of esterases) were distinguished, illustrating high esterase polymorphism.
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Highly Pathogenic Strains of Escherichia coli Revealed by the Distinct Electrophoretic Patterns of Carboxylesterase B
Ph. Goullet and B. PicardSummary: One hundred and ninety one strains of Escherichia coli isolated from extra-intestinal infections and 85 strains isolated from the stools of healthy human beings were compared for electrophoretic mobility and isoelectric point of carboxylesterase B, and for production of α-haemolysin and the presence of mannose resistant haemagglutinin. Fast and slow electrophoretic mobilities were distinguished among the strains. The frequency of strains showing slow mobilities was considerably higher when they originated from extra-intestinal infections (40%) than when they were obtained from the stools of healthy individuals (7%). In a two-dimensional electrophoretic profile, the fast and slow mobility variants of carboxylesterase B were resolved into two patterns, B1 and B2, respectively. The frequency of pathogenic strains that concomitantly produced α-haemolysin and mannose resistant haemagglutinin was 48.7% for strains of pattern B2 but only 2.8% for strains of pattern B1. Thus, the electrophoretic pattern B2 of carboxylesterase B appears to be a molecular marker for a group of highly pathogenic E. coli strains which are frequently implicated in extra-intestinal infections.
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Incompatibility between E Colicin Plasmids
More LessSummary: We have tested the ability of pairs of colicin E plasmids to replicate stably in the same cell line. Although many of the pairs of E colicin plasmids were compatible, plasmids ColE3-CA38, ColE7-K317 and ColE8-J were mutually incompatible, as were ColE5-099, ColE6-CT14 and ColE9-J. Incompatibility between ColE6-CT14 and ColE5-099 or ColE9-J was asymmetrical, whereas incompatibility between the other plasmid pairs was symmetrical.
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Analysis of Lipopolysaccharide from Root Nodule Bacteroids of Rhizobium leguminosarum Using Monoclonal Antibodies
More LessSummary: Monoclonal antibodies (McAb) that react with components of the bacteroid cell wall were isolated after immunization of rats with sonicated Rhizobium bacteroids from pea root nodules. More than 90% of the McAb reacted with lipopolysaccharides (LPS) from bacteroids and all of these cross-reacted with LPS from free-living cultures of the corresponding Rhizobium strains. Although LPS derived from free-living cultures of Rhizobium is very heterogeneous, detected as a ladder of immuno-staining bands after SDS–PAGE and electroblotting, the LPS from bacteroids is predominantly of the fast-migrating form. This observation suggests that LPS from bacteroids carries the core polysaccharide but lacks the repeating O-antigen oligosaccharide substituents that are usually found in free-living cultures. Three classes of McAb differed in their specificity for different Rhizobium strains, and differences in antigenicity were also observed between bacteroid and free-living cultures of the same strain.
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Detection of a Species-specific Antigen of Gardnerella vaginalis by Western Blot Analysis
More LessSummary: Western blot analysis was used to identify antigenic components of Gardnerella vaginalis.Polypeptides bound to nitrocellulose membranes were probed with murine antisera raised to two strains of G. vaginalis. and antibody-antigen complexes were detected with 125I-labelled antimouse immunoglobulin followed by autoradiography. Although there was inter-strain variation in immunogenic polypeptide profiles, all 23 strains of G. vaginalis examined contained a common antigen of molecular mass 41 kDa. This antigen was not found in any of six other bacterial genera.
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- Physiology And Growth
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Influence of the Carbon: Nitrogen Ratio of the Growth Medium on the Cellular Composition and the Ability of the Methylotrophic Yeast Hansenula polymorpha to Utilize Mixed Carbon Sources
Th. Egli and J. R. QuayleSummary: The methylotrophic yeast Hansenula polymorpha was grown in a chemostat with a medium containing a mixture of glucose (C6) and methanol (C1) (87.8% C6: 12.2% C1 w/w) as sole carbon source and as sole nitrogen source. At a constant growth rate (D 0.10 h−1) the influence of the carbon: nitrogen ratio (C:N) of the inflowing medium on the cellular and enzymic composition of the cells was studied. Three distinct growth regimes were recognized. A medium with a C: N ratio <12 resulted in carbon-limited growth (high cellular protein content, low carbohydrate content) and under these conditions glucose and methanol were utilized simultaneously. A medium with a C:N ratio >31 resulted in nitrogen-limited growth (low protein but high carbohydrate content of the cells) and the cells metabolized only glucose. A transition growth regime was observed during growth on media with intermediate C: N ratios (12 < C:N > 31). When assessed from both substrate consumption and cellular composition, growth was double-substrate (carbon and nitrogen)-limited. In this transition growth regime, changes in carbon metabolism and the cellular and enzymic composition of the cells were found. With increasing C:N ratios in the growth medium a gradual repression of the synthesis of methanol-assimilating and dissimilating enzymes was found. This effect was most pronounced for alcohol oxidase, and as a consequence the cells switched from the utilization of the carbon substrate mixture to growth on glucose alone. The data presented suggest that the range within which double-substrate-limited growth can be expected is predictable from the composition of cells grown under single substrate limitation.
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Active Role of Oxygen and NADH Oxidase in Growth and Energy Metabolism of Leuconostoc
More LessSummary: Growth of 12 Leuconostoc strains in a broth medium with and without aeration was compared. In general, the aerated cultures grew faster and produced more biomass, at the expense of glucose and other sugars, than unaerated cultures. The more efficient growth correlated well with the production of acetate rather than ethanol as an end-product of metabolism in aerated cultures; unaerated cultures produced little or no acetate.
Mutants of L. mesenteroides X2 were isolated that had lost the capacity to be stimulated by aeration; they were completely deficient in NAD(P)H oxidase activity and did not accumulate acetate in aerobic cultures. Without NAD(P)H oxidase the mutants rely on the ethanol branch of the heterolactate pathway to regenerate NAD(P)+ from NAD(P)H, irrespective of the presence or absence of O2. The presence of NAD(P)H oxidase in parental cultures allows them to utilize O2 as a terminal electron acceptor and produce more ATP per mol of sugar utilized when O2 is available than when it is limiting.
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Autotrophic Growth and Nitrogen Fixation in Derxia gummosa
More LessSummary: Initial attempts to grow N2-fixing Derxia gummosa autotrophically on H2, CO2, O2 and N2 in a closed system yielded variable results. Poor growth was found to be due to rapid O2 depletion and the requirement for an agar surface. In a closed system, C2H2 reduction assays could not be carried out due to complete consumption of H2. Hence a flow-through culturing technique was developed to supply gases at a constant partial pressure and to perform C2H2 reduction assays in a continuous flow system. Hydrogenase of autotrophic D. gummosa was not inhibited by C2H2, even at 0.5 atm, and the K m of hydrogenase for H2 was approximately 0.15 atm. The effects of O2 and H2 on C2H2 reduction were examined, using the flow-through assay system. The rate of C2H2 reduction decreased below 0.074 atm H2, suggesting that ATP and reductant supply were limiting the nitrogenase activity.
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Glucose Regulation of Cephamycin Biosynthesis in Streptomyces lactamdurans is Exerted on the Formation of α-Aminoadipyl-cysteinyl-valine and Deacetoxycephalosporin C Synthase
More LessSummary: Glucose exerted a concentration-dependent negative regulation on the biosynthesis of cephamycin C by Streptomyces lactamdurans. Formation of the cephamycin precursor δ(α-aminoadipyl)-cysteinyl-valine was greatly decreased by excess glucose. The ring-expanding enzyme deacetoxycephalosporin C synthase was strongly repressed by glucose in vivo. Isopenicillin N synthase (cyclase) and isopenicillin N epimerase were not repressed by glucose. However, the activity of isopenicillin N synthase was inhibited in vitro by glucose 6-phosphate, and the activity of deacetoxycephalosporin C synthase was inhibited by inorganic phosphate, glucose 6-phosphate, fructose 2,6-diphosphate and fructose 1,6-diphosphate. The intracellular cAMP content decreased as growth proceeded and remained lower in glucose-supplemented cells than in control cultures. cAMP did not seem to be involved in glucose control of cephamycin biosynthesis.
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Effect of Osmotic Stress on the Ultrastructure and Viability of the Yeast Saccharomyces cerevisiae
More LessSummary: Exposure of the yeast Saccharomyces cerevisiae to hypertonic solutions of non-permeating compounds resulted in cell shrinkage, without plasmolysis. The relationship between cell volume and osmolality was non-linear; between 1 and 4 OSM there was a plateau in cell volume, with apparently a resistance to further shrinkage; beyond 4 OSM cell volume was reduced further. The loss of viability of S. cerevisiae after hypertonic stress was directly related to the reduction in cell volume in the shrunken state. The plasma membrane is often considered to be the primary site of osmotic injury, but on resuspension from a hypertonic stress, which would have resulted in a major loss of viability, all cells were osmotically responsive. The effects of osmotic stress on mitochondrial activity and structure were investigated using the fluorescent probe rhodamine 123. The patterns of rhodamine staining were altered only after extreme stress and are assumed to be a pathological feature rather than a primary cause of injury. Changes in the ultrastructure of the cell envelope were examined by freeze-fracture and scanning electron microscopy. In shrunken cells the wall increased in thickness, the outer surface remained unaltered, whilst the cytoplasmic side buckled with irregular projections into the cytoplasm. On return to isotonic solutions these structural alterations were reversible, suggesting a considerable degree of plasticity of the wall. However, the rate of enzyme digestion of the wall may have been modified, indicating that changes in wall structure persist.
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- Systematics
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Enzyme-linked Immunosorbent Assay (ELISA) as a Means of Taxonomic Analysis of Streptomyces and Related Organisms
More LessSummary: Fourteen Streptomyces strains from various numerical taxonomic classes and representatives of three other genera of actinomycetes were studied using an indirect enzyme-linked immunosorbent assay (IND-ELISA) to determine their serological relationships. The IND-ELISA results agreed with those from previous numerical taxonomic analyses and Ouchterlony double-diffusion studies. The IND-ELISA method is quicker, more quantitative and less subjective than Ouchterlony assays and thus should be useful in Streptomyces taxonomy. The results indicated that Frankia sp. CpI1 was related to Streptomyces.
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The Influence of Culture Age on the Cellular Fatty Acid Composition of Four Selected Yeasts
More LessSummary: Cellular fatty acids were extracted from cells of Debaryomyces vanrijiae, Saccharomycodes ludwigii, Endomyces fibuliger and Metchnikowia reukaufii at different growth stages of batch growth and analysed by gas chromatography. A high degree of variation in relative concentrations, as well as in composition, of fatty acids, was observed during the exponential and early stationary growth phases. Greater reproducibility and a relatively stable fatty acid composition were obtained with cells harvested in the late stationary phase.
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Numerical Taxonomy of Red-pigmented Bacteria Isolated from a Lowland River, with the Description of a New Taxon, Rugamonas rubra gen. nov., sp. nov.
More LessSummary: Twenty red-pigmented bacterial strains, isolated from river water, and 15 named reference cultures were analysed using numerical taxonomic procedures. A simplified dendrogram, based on the simple matching coefficient and unweighted average linkage clustering algorithm, showed that the environmental isolates were recovered in two phenetic groups, defined at or above the 89% similarity level. Nine strains were contained in phenon 1, which exhibited the general characteristics of the Pseudomonadaceae, but did not match the descriptions of any of the existing genera within this family. A new genus and species, Rugamonas rubra, is proposed for these isolates. The 11 red-pigmented environmental strains in phenon 2 were identified as Serratia rubidaea. The red pigment of R. rubra contains at least two compounds related to prodigiosin. The major component produced a mass spectrum compatible with its being 6-methoxy-2-methyl-3-heptylprodigeosene (m/e 351). A second component produced a mass spectrum indistinguishable from that of prodigiosin itself (m/e 323).
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Characterization of Corynebacterium Group JK by Whole-cell Protein Patterns
More LessSummary: A total of 102 strains received as Corynebacterium ‘group JK’ were characterized by SDS-PAGE of their whole-cell proteins. Numerical taxonomy based on the protein pattern absorbance profiles indicated that 91 of the strains formed a cluster. Seventy strains isolated in the UK were identified as group JK, indicating the increasing detection of this group as opportunistic pathogens. Fine differences between strain patterns were visible but it was not possible to associate these with any particular clinical source.
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A Non-luminescent Strain of Xenorhabdus luminescens (Enterobacteriaceae)
More LessSummary: The first case of a non-luminescent symbiont of a Heterorhabditis sp. is reported. The bacterium, isolated from a previously unknown species of Heterorhabditis, was identified as a biovar of Xenorhabdus luminescens. Ultrastructural study of the bacterium revealed membranous and crystalline inclusions comparable with those of luminescent strains of X. luminescens
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Mycoplasma felifaucium, a New Species Isolated from the Respiratory Tract of Pumas
More LessSummary: Mycoplasmas isolated from the throats of three pumas (Felis concolor) were each cloned and examined in detail. All three were serologically and biologically indistinguishable from each other, and were serologically distinct from 83 recognized Mycoplasma and Acholeplasma species. They were designated as a new species, Mycoplasma felifaucium, with strain PU (NCTC 11703) as the type strain.
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Use of Penicillin-binding Proteins for the Identification of Enterococci
More LessSummary: The results of 20 physiological and fermentation tests and examination of the penicillin-binding proteins (PBPs) of 85 enterococcal strains demonstrated that the genus Enterococcus could be divided into at least nine distinct species: E. faecalis, E. faecium, E. durans, E.hirae, E.avium, E. gallinarum, E. casselifiavus, E. malodoratus and E. mundtii. Each species had a specific pattern of at least five PBPs, with molecular masses in the range of about 40–130 kDa. The pattern of PBPs may be useful for identification purposes, since some strains with unusual fermentation characteristics were assigned to species by this technique.
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- Short Communication
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Analysis of Surface Receptor Expression on Bacteria Isolated from Patients with Endocarditis
More LessSummary: Fifteen bacterial isolates (12 streptococcal and 3 staphylococcal strains) from patients with bacterial endocarditis were screened for a variety of surface receptors, in an attempt to identify a common feature that might contribute to their ability to attach to and colonize damaged heart tissue. The bacterial receptors screened for, using a dot-blot autoradiographic procedure, included those for the Fc region of human IgG, fibrinogen, fibronectin and human Clq. Bacteria with receptors for each of the probes used could be identified, but no common receptor was present on all endocarditis-causing strains.
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Water Stress Plating Hypersensitivity of Yeasts
More LessSummary: Saccharomyces cerevisiae, when growing exponentially in batch culture, passed through a phase in which, on average, one cell in 104 survived plating onto a low water activity (a w) agar medium. Stationary phase cultures were resistant as were all other species tested, with the exception of Candida krusei. In continuous culture, S. cerevisiae was more resistant at low than at high dilution rates. Plating at low a w was lethal to those cells that were not protected by an adequate content of compatible solute. In naturally resistant yeasts and in S. cerevisiae that had been exposed to an adaptation process, the compatible solute was one or more types of polyhydric alcohol. Resistance in stationary phase was attributable to a different cause.
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Modelling of Nutrient Gradients in a Bacterial Colony
More LessSummary: Oxygen and substrate gradients were simulated with a finite-volume method for a variety of bacterial colony sizes and substrate concentrations. A spherical segment geometry and a Monod relationship for simultaneous substrate and O2 consumption were assumed. The results agreed well with previous theoretical and experimental estimates for gradients in microbial colonies.
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Volumes and issues
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Volume 170 (2024)
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Volume 169 (2023)
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Volume 168 (2022)
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Volume 167 (2021)
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Volume 166 (2020)
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Volume 165 (2019)
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Volume 164 (2018)
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Volume 163 (2017)
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Volume 162 (2016)
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Volume 161 (2015)
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Volume 160 (2014)
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Volume 159 (2013)
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Volume 158 (2012)
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Volume 157 (2011)
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Volume 156 (2010)
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Volume 155 (2009)
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Volume 154 (2008)
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Volume 153 (2007)
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Volume 152 (2006)
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Volume 151 (2005)
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Volume 150 (2004)
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Volume 149 (2003)
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Volume 148 (2002)
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Volume 147 (2001)
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Volume 146 (2000)
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Volume 145 (1999)
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Volume 144 (1998)
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Volume 143 (1997)
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Volume 142 (1996)
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Volume 141 (1995)
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Volume 140 (1994)
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Volume 139 (1993)
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Volume 138 (1992)
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Volume 137 (1991)
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Volume 136 (1990)
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Volume 135 (1989)
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Volume 134 (1988)
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Volume 133 (1987)
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Volume 132 (1986)
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Volume 131 (1985)
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Volume 130 (1984)
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Volume 129 (1983)
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Volume 128 (1982)
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Volume 127 (1981)
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Volume 126 (1981)
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Volume 125 (1981)
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Volume 124 (1981)
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Volume 123 (1981)
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Volume 122 (1981)
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Volume 121 (1980)
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Volume 120 (1980)
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Volume 119 (1980)
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Volume 118 (1980)
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Volume 117 (1980)
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Volume 116 (1980)
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Volume 115 (1979)
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Volume 114 (1979)
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Volume 113 (1979)
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Volume 112 (1979)
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Volume 111 (1979)
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Volume 110 (1979)
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Volume 109 (1978)
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Volume 108 (1978)
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Volume 107 (1978)
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Volume 106 (1978)
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Volume 105 (1978)
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Volume 104 (1978)
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Volume 103 (1977)
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Volume 102 (1977)
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Volume 101 (1977)
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Volume 100 (1977)
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Volume 99 (1977)
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Volume 98 (1977)
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Volume 97 (1976)
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Volume 96 (1976)
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Volume 95 (1976)
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Volume 94 (1976)
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Volume 93 (1976)
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Volume 92 (1976)
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Volume 91 (1975)
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Volume 90 (1975)
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Volume 89 (1975)
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Volume 88 (1975)
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Volume 87 (1975)
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Volume 86 (1975)
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Volume 85 (1974)
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Volume 84 (1974)
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Volume 83 (1974)
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Volume 82 (1974)
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Volume 81 (1974)
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Volume 80 (1974)
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Volume 79 (1973)
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Volume 78 (1973)
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Volume 77 (1973)
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Volume 76 (1973)
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Volume 75 (1973)
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Volume 74 (1973)
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Volume 73 (1972)
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Volume 72 (1972)
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Volume 71 (1972)
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Volume 70 (1972)
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Volume 69 (1971)
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Volume 68 (1971)
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Volume 67 (1971)
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Volume 66 (1971)
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Volume 65 (1971)
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Volume 64 (1970)
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Volume 63 (1970)
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Volume 62 (1970)
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Volume 61 (1970)
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Volume 60 (1970)
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Volume 59 (1969)
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Volume 58 (1969)
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Volume 57 (1969)
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Volume 56 (1969)
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Volume 55 (1969)
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Volume 54 (1968)
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Volume 53 (1968)
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Volume 52 (1968)
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Volume 51 (1968)
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Volume 50 (1968)
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Volume 49 (1967)
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Volume 48 (1967)
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Volume 47 (1967)
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Volume 46 (1967)
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Volume 45 (1966)
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Volume 44 (1966)
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Volume 43 (1966)
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Volume 42 (1966)
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Volume 41 (1965)
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Volume 40 (1965)
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Volume 39 (1965)
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Volume 38 (1965)
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Volume 37 (1964)
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Volume 36 (1964)
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Volume 35 (1964)
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Volume 34 (1964)
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Volume 33 (1963)
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Volume 32 (1963)
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Volume 31 (1963)
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Volume 30 (1963)
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Volume 29 (1962)
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Volume 28 (1962)
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Volume 27 (1962)
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Volume 26 (1961)
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Volume 25 (1961)
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Volume 24 (1961)
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Volume 23 (1960)
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Volume 22 (1960)
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Volume 21 (1959)
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Volume 20 (1959)
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Volume 19 (1958)
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Volume 18 (1958)
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Volume 17 (1957)
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Volume 16 (1957)
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Volume 15 (1956)
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Volume 14 (1956)
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Volume 13 (1955)
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Volume 12 (1955)
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Volume 11 (1954)
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Volume 10 (1954)
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Volume 9 (1953)
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Volume 8 (1953)
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Volume 7 (1952)
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Volume 6 (1952)
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Volume 5 (1951)
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Volume 4 (1950)
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Volume 3 (1949)
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Volume 2 (1948)
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Volume 1 (1947)