- Volume 129, Issue 9, 1983
Volume 129, Issue 9, 1983
- Sgm Special Lecture
-
- Biochemistry
-
-
-
Characteristics of a High Molecular Weight Extracellular Protein of Streptococcus mutans
More LessA high molecular weight protein antigen, designated P1, has been isolated from the culture fluid of chemostat-grown Streptococcus mutans strain Ingbritt and shown to be free of other antigens including glucosyltransferase. Antiserum against the protein was used in rocket immunoelectro-phoresis to confirm and extend the previous observation that there were major differences in the amount of the protein produced under different growth conditions. Physico-chemical and serological studies indicated that protein P1 was indistinguishable from antigens B, I II and IF isolated in other laboratories. Mammalian tissue cross-reactivity of protein P1 was demonstrated by binding of antiserum to P1 to sections of normal rabbit tissues, particularly heart. There was also a statistically significant increase in the number of mononuclear leucocytes in heart tissue of rabbits which had been injected with protein P1, when compared with the levels in control uninjected rabbits; injection with whole cells of S. mutans Ingbritt did not produce this effect.
-
-
-
-
Penicillin-binding Proteins of the Stalk of Caulobacter crescentus
More LessProperties of stalks isolated from Caulobacter crescentus were studied. Isolated stalks possessed a density close to that of the cellular outer membrane, and contained a very low activity of succinate dehydrogenase. The protein patterns were similar to those of the outer membrane. These results suggest that the membrane component of the C. crescentus stalk comprises mainly outer membrane. The patterns of penicillin-binding proteins (PBPs) in isolated stalks were different from those of total cell envelopes. The stalks possessed neither PBP 1A nor PBP 3 which is localized in the inner membrane of growing cells. PBP X (mol. wt 93000) and PBP Y (mol. wt 85000), which are minor PBPs in the total cell envelope fraction were greatly enriched in the isolated stalks. A mecillinam-resistant, stalk-defective mutant, C. crescentus CB15 mcr-816, lacked both PBP X and PBP Y. It is concluded that PBP X and PBP Y are localized mainly in the stalk. Whether they are involved in the stalk development remains to be investigated.
-
-
-
Partial Purification and Some Properties of ATP: Citrate Lyase from the Oleaginous Yeast Lipomyces starkeyi
More LessATP:citrate lyase has been purified some 20-fold from the oleaginous yeast, Lipomyces starkeyi CBS 1809. The enzyme, which is labile, was stabilized by the addition of ATP and citrate to extraction buffers. Michaelis-Menten kinetics were exhibited towards ATP and citrate. The molecular weight of the enzyme was determined to be approximately 510000. There was a specific requirement for ATP for activity. No activity was observed in the absence of Mg2+, although Co2+ and Mn2+ could partially substitute for Mg2+. ADP inhibited activity (50% inhibition at 1 mM), as did long-chain fatty acyl-CoA esters (50% inhibition with 4m oleoyl-CoA). The possibility of control of ATP:citrate lyase activity by fluctuations in the prevailing energy charge or by changes in the intracellular concentrations of long-chain fatty acyl-CoA esters is discussed.
-
-
-
Tricarboxylic Acid Cycle Activity in Relation to Itaconic Acid Biosynthesis by Aspergillus terreus
More LessCell-free extracts of an itaconic acid producing strain of Aspergillus terreus contained NADP-dependent isocitrate dehydrogenase activity but no NAD-dependent activity was detected. During the acid-producing phase the activity of the NADP-linked enzyme fell to one-eighth of its value during the growth phase, whereas citrate synthase activity increased. Intact mitochondria were isolated from growth and production phase mycelium. The preparation from the growth phase oxidized exogenous NADH and all tricarboxylic acid cycle intermediates tested. That from the production phase oxidized tricarboxylic acid cycle intermediates at a reduced rate but exogenous NADH oxidation remained high. [2-14C]Acetate was incorporated into itaconic acid and over 90 % of the incorporated radioactivity was located in the methylene carbon. [1-14C]-Acetate was a poorer precursor and did not preferentially label the methylene carbon. These results support the view that itaconic acid biosynthesis in A. terreus occurs by decarboxylation of aconitic acid, the latter produced by the normal reactions of the tricarboxylic acid cycle.
-
- Development And Structure
-
-
-
Growth and the Inducibility of Mycelium Formation in Candida albicans: a Single-cell Analysis Using a Perfusion Chamber
More LessIn Candida albicans, cells actively growing in the budding form cannot be immediately induced to form a mycelium until they enter stationary phase. However, if exponential phase cells are starved for a minimum of 10 to 20 min, they are inducible. Using a video-monitored perfusion chamber, we found that starved cells were able to form mycelia regardless of their position in the budding cycle. When starved exponential cells were released into fresh nutrient medium at high temperature and pH, conditions conducive to mycelium formation, unbudded cells evaginated after an average lag period of 75 min and then grew exclusively in the mycelial form. Depending upon the volume, or maturity, of the bud, budded cells entered two different avenues of outgrowth leading to mycelium formation. If the daughter bud was small, growth resumed by apical elongation of the bud, leading to a ‘shmoo’ shape which tapered into an apical mycelium. If the daughter bud was large, the cell underwent a sequence of evaginations: first, the mother cell evaginated after an average period of 75 min; then the daughter bud evaginated 40 min later. Both evaginations then grew in the mycelial form. In this latter sequence, the evagination on the mother cell was positioned non-randomly, occurring in the majority of cells adjacent to the bud. All buds undergoing evagination contained a nucleus, but roughly 20% of buds undergoing apical elongation did not.
-
-
- Genetics And Molecular Biology
-
-
-
Cloning and Expression of the Tyrosinase Gene from Streptomyces antibioticus in Streptomyces lividans
More LessIn two separate studies a BclI-generated DNA fragment coding for the enzyme tyrosinase, responsible for melanin synthesis, was cloned from Streptomyces antibioticus DNA into two SLP1.2-based plasmid vectors (pIJ37 and pIJ41) to generate the hybrid plasmids, designated pIJ700 and pIJ701, using S. lividans 66 as the host. The fragment (1.55 kb) was subcloned into the multicopy plasmid pIJ350 (which carries thiostrepton resistance and has two non-essential BclI sites) to generate four new plasmids (pIJ702-pIJ705) with the tyrosinase insert located in either orientation at each site. All six plasmids conferred melanin production (the Mel+ phenotype) on their host. As in the S. antibioticus parent, strains of S. lividans carrying the gene specifying tyrosinase synthesis possessed an enzyme activity which was inducible. Most of the tyrosinase activity was secreted during growth of S. antibioticus; in contrast, the majority remained intracellular in the S. lividans clones. The specific activity of the induced tyrosinase activity (intracellular) was higher (up to 36-fold) when the gene was present on the multicopy vector in comparison with its location on the low copy plasmids, pIJ700 or pIJ701, or in S. antibioticus.
Restriction mapping of the tyrosinase fragment in pIJ702 revealed endonuclease cleavage sites for several enzymes, including single sites for Bg/II, SphI and SstI that are absent from the parent vector (pIJ350). Insertion of DNA fragments at any one of these sites abolished the Mel+ phenotype. The results indicate that pIJ702 is a useful cloning vector with insertional inactivation of the Mel+ character as the basis of clone recognition.
-
-
-
-
Enzyme Polymorphism and Genetic Population Structure in Escherichia coli and Shigella
More LessElectrophoretically demonstrable variation in 12 enzymes was studied in more than 1600 isolates of Escherichia coli from human and animal sources and in 123 strains of the four species of Shigella. All 12 enzymes were polymorphic; and the number of allozymes (mobility variants), which were equated with alleles, averaged 9·3 per locus in E. coli. For Shigella species, the mean number of alleles was 2·9 per locus. Some 77% of the allozymes recorded in Shigella were shared with E. coli. A total of 302 unique genotypic combinations of alleles over the 12 loci (electrophoretic types, ETs) was distinguished, of which 279 represented E. coli and 23 were Shigella. Among electrophoretic types, mean allelic diversity per locus was 0·52 for E. coli and 0·29 for Shigella. It was estimated that there are, on the average, about 0·3 detectable codon differences per locus between pairs of strains of E. coli and Shigella, which is roughly equivalent to 1·2 amino acid differences per enzyme. Evidence that the enzyme loci studied are a random sample of the genome is provided by a significant positive correlation between estimates of genetic divergence between pairs of strains obtained by DNA reassociation tests and estimates of genetic distance between the same strains based on electrophoresis.
A principal components analysis of allozyme profiles revealed that the 302 ETs fall into three overlapping clusters, reflecting strong non-random associations of alleles, largely at four loci. Each of the four ETs of E. coli that have been most frequently recovered from natural populations has an allozyme profile that is very similar to, or identical with, the hypothetical modal ET of one of the groups. ETs of Shigella fall into two of the groups. No biological significance can at present be attributed to the genetic structure revealed by multilocus electrophoretic techniques. The electrophoretic data are fully compatible with other molecular and more conventional evidence of a close affinity between E. coli and Shigella, and they raise questions regarding the present assignments of certain strains to species. In support of evidence from DNA reassociation tests and serotyping, the present study suggests that S. sonnei is homogeneous in chromosomal genotype.
-
-
-
Protease Deficiency and Its Association with Defects in Spore Coat Structure, Germination and Resistance Properties in a Mutant of Bacillus subtilis
More LessSpores formed by Bacillus subtilis carrying the mutation ger-36 are lysozyme-sensitive and germination-defective. The coats of these spores lack a number of polypeptides normally found in the spore coat, and four additional polypeptides are present that are not normally found in the coats of wild-type spores. The ger-36 mutation also prevents the synthesis (at about stage V) and the incorporation into the spore outer layers, of an intracellular protease (protease B, approx. mol wt. of monomer 25000). A partial revertant of a strain carrying ger-36 was isolated and this had an additional mutation in a locus distinct from gerE. The suppressing mutation restored the protease activity, but not the germination defect. It partly restored resistance to lysozyme and the spores formed had apparently normal coat protein composition except for the absence of one polypeptide (mol wt. 36000).
-
-
-
Genetic Analysis of A-factor Synthesis in Streptomyces coelicolor A3(2) and Streptomyces griseus
More LessA-factor is a potent pleiotropic effector produced by Streptomyces griseus and is essential for streptomycin production and spore formation in this organism. Its production is widely distributed among various actinomycetes including Streptomyces coelicolor A3(2). Genetic analysis of A-factor production was carried out with S. coelicolor A3(2), and two closely linked loci for A-factor mutations (afsA and B) were identified between cysD and leuB on the chromosomal linkage map. In contrast, genetic crosses of A-factor-negative mutants of S. griseus, using a protoplast fusion technique, failed to give a fixed locus for A-factor gene(s) and suggested involvement of an extrachromosomal or transposable genetic element in A-factor synthesis in this organism.
-
-
-
Altered Mercury Transport in a Mutant of Pseudomonas fluorescens B69
More LessA 34 MDal plasmid harboured by Pseudomonas fluorescens B69 carried a gene coding for the mercuric reductase enzyme, thus promoting mercury resistance in the host strain. Mercury-sensitive variants were isolated when a hypersensitive, cured derivative of strain B69 was exposed to 10 g mercury (II) ml−1. The alteration in mercury transport appeared to be the result of a mutation, since a transconjugant of the mutant, which carried the mercury-resistance plasmid, showed a reduced rate of mercury volatilization compared to the parental resistant strain. In addition, more mercury was tightly bound to the mutant cells. This phenomenon represents a new aspect of bacterial resistance to mercurials.
-
-
-
Transposition of a Gene Encoding OXA-2 β-Lactamase
More LessA bla gene encoding OXA-2 β-lactamase has been transposed from the Salmonella typhimurium R plasmid R1767. This transposable element which was designated Tn2410 encoded sulphonamide and mercury resistance in addition to the bla gene. It had a size of 18·5 kb and appeared to be flanked by small inverted repeats. Restriction enzyme analysis resulted in a detailed map of Tn2410, which showed a high degree of similarity with the published map of Tn2603, a transposon encoding OXA-1 β-lactamase. The ampicillin and sulphonamide resistance genes on Tn2410 were mapped in a cluster on the region between the centre and the right end of the map.
-
- Pathogenicity And Medical Microbiology
-
-
-
Growth Temperature-dependent Variation in the Bacteriophage-inactivating Capacity and Antigenicity of Yersinia enterocolitica Lipopolysaccharide
More LessGrowth temperature affected the structure of Yersinia enterocolitica Ye 3827 lipopolysaccharide (LPS). Although Y. enterocolitica Ye 3827 synthesized smooth LPS when grown at a low temperature (25 °C), partial smooth-rough transition occurred when the bacteria were grown at the physiological temperature (37 °C). The structural alteration was detected by bacteriophage-inactivation assay and chemical and immunological analyses. LPS prepared from bacteria grown at 25 °C inactivated a number of bacteriophages that recognize the O-antigenic polysaccharide portion of LPS, whereas more than 3000 times the amount of LPS from bacteria grown at 37 °C was required for the same degree of inactivation. The antigenic determinant(s) responsible for the major reaction between 25 °C-LPS and anti-25 °C-bacteria was located on the O-antigenic polysaccharide portion of LPS, but those responsible for the major reaction between 37 °C-LPS and anti-37 °C-bacteria were located on the R-core or inner portion of LPS.
-
-
-
-
Serological Evidence that Yersinia enterocolitica Lipopolysaccharide produced during Growth in vivo Resembles that Produced during Growth in vitro at 25 °C
More LessPartial smooth-rough transition was observed in 30 strains of Yersinia enterocolitica O:3 cultivated at 37 °C. Immunodiffusion and haemagglutination inhibition tests with eight patients sera demonstrated that the immunogenicity of the lipopolysaccharide of Yersinia enterocolitica in vivo was similar to that of the bacteria grown in vitro at 25 °C.
-
-
-
The Production of F41 Fimbriae by Piglet Strains of Enterotoxigenic Escherichia coli that Lack K88, K99 and 987P Fimbriae
More LessThe enterotoxigenic Escherichia coli strains 1676, 1706, 1751 and KEC96a, which do not produce fimbrial adhesive antigens of the K88, K99 or 987P antigen type reacted both in vitro and in vivo with antiserum to F41 fimbriae in an indirect immunofluorescent antibody technique. Antiserum used to demonstrate material B, an adhesive antigen thought to mediate the adhesive and mannose-resistant (MR) haemagglutinating properties of E. coli strains 1676, 1706 and 1751, reacted in vitro with an F41+ strain. The antiserum also inhibited the MR haemagglutinating activity of F41 antigen and gave an anionic precipitation line in immunoelectrophoresis experiments with an extract containing F41 antigen.
The MR haemagglutinating properties of an antigen extract containing material B from E. coli strain 1706 was neutralized by antiserum to F41 fimbriae and by OK antisera to E. coli strains that produce both F41 and K99 fimbriae. These sera also gave an anionic precipitation line with the MR haemagglutinin from E. coli strain 1706 and the MR haemagglutinin gave a line of identity with F41 in gel diffusion experiments with antiserum to F41 fimbriae. OK antisera to K99+ F41− bacteria and OK antisera to K88+ bacteria and 987P+ bacteria did not react with this haemagglutinin.
Transmission electron microscopy on the ileum of newborn gnotobiotic piglets infected with E. coli strain 1706 showed irregular, poorly defined filamentous material surrounding some, though not all, bacteria but regular fimbrial structures were not visible. Fine thread-like material was visible surrounding most of the bacteria in ultra thin sections from a piglet infected with an E. coli strain that produces both F41 and K99. Staining with ruthenium red suggested. that this material was associated with polysaccharide.
-
-
-
Antigenic Cross-reactivity of Neisseria Pili: Investigations with Type- and Species-specific Monoclonal Antibodies
More LessMonoclonal antibodies have been produced with both type-specific and broadly cross-reacting properties against the variant pili of Neisseria gonorrhoeae P9. Competitive radioimmunoassays demonstrated that at least three separate epitopes contribute to type-specificity within the strain. ELISA using purified pili from clinical isolates showed that some of the type-specific epitopes are randomly distributed among variants of single strains isolated from different sites in sexual partners. Cross-reacting antibody SMI recognized an epitope present on all gonococcal isolates. This epitope was also present on a large proportion of meningococci and could be directly demonstrated in CSF from a patient with meningococcal meningitis. Commensal Neisseria and other Gram-negative bacteria tested failed to react. The meningococci which lack the epitope recognized by the antibody SMI were nevertheless shown by electron microscopy to be pilated, suggesting that pili from meningococci may be antigenically more diverse than those from gonococci.
-
-
-
Heterogeneity of the Filamentous Haemagglutinin of Bordetella pertussis Studied with Monoclonal Antibodies
More LessThe filamentous haemagglutinin of Bordetella pertussis has been purified from static, liquid culture supernatants and from extracts of cells grown on a solid medium. SDS-PAGE of the purified protein has shown multiple polypeptides with molecular weights ranging from 220000 to about 58000. By transferring the SDS-dissociated polypeptides to nitrocellulose paper and reacting with several monoclonal antibodies, it has been shown that many of the polypeptides are probably fragments of the polypeptide of highest molecular weight.
-
-
-
Adhesion of Coagulase-negative Staphylococci to Biomaterials
More LessThe adhesion of two Staphylococcus epidermidis strains and one Staphylococcus saprophyticus strain on to poly(tetrafluorethylene-co-hexafluorpropylene) (FEP)-fluorocarbon and cellulose acetate was studied in vitro. Both S. epidermidis strains showed a more hydrophobic character than the encapsulated S. saprophyticus as determined by the bacterial affinity towards xylene. Staphylococcus epidermidis showed a significantly higher adhesion on to the hydrophobic FEP than S. saprophyticus. The adhesion of staphylococci on to the more hydrophilic cellulose acetate was always low. Treatment of S. epidermidis with pepsin or extraction with aqueous phenol yielded cells with a decreased hydrophobicity, which resulted in a decreased adhesion on to FEP. Cells with a decreased hydrophobicity showed a lower rate of reaggregation in suspension. The hydrophobicity and the adhesion on to FEP of S. epidermidis were not affected by exposure to a subminimal inhibitory concentration of penicillin. The strong interaction between S. epidermidis and FEP, which appeared not to be influenced by the age or the metabolic stage of the bacteria, is mainly caused by hydrophobic bonding.
-
- Physiology And Growth
-
-
-
Mitochondrial Structure, ATP Concentration and Inorganic Pyrophosphatase Activity in a B Mutant Strain of Schizophyllum commune
More LessIn the tetrapolar basidiomycete Schizophyllum commune a mutation in the B factor impairs the vegetative growth of the hyphae. An ultrastructural study of the hyphae revealed an increased number of vacuoles in the subapical cells and defects in mitochondria in both apical and subapical cells. The ATP concentration in the hyphae and the specific activity of soluble inorganic pyrophosphatase (EC 3.6.1.1) were also observed to be decreased. These changes were interpreted as the result of non-specific hydrolytic activity caused by the mutation in the B factor and originating in the cytoplasm but also affecting the mitochondria. The morphological and biochemical changes recorded in the B mutant hyphae are comparable with those at the beginning of the mating of compatible homokaryons. At that time the breakdown of the cell components may be necessary to abolish the existing homokaryotic information and to control the direction of nuclear migration.
-
-
-
-
Use of Transition Studies in Continuous Cultures of Lipomyces starkeyi, an oleaginous yeast, to Investigate the Physiology of Lipid Accumulation
More LessThe physiological changes that occurred in chemostat cultures of an oleaginous yeast, Lipomyces starkeyi CBS 1809 undergoing transitions from steady-state carbon-limiting to steady-state nitrogen-limiting conditions have been investigated. A sequence of events has been identified initiated by the presentation of excess glucose to the culture and culminating in the accumulation of substantial quantities of intracellular lipid. The intracellular concentrations of adenine nucleotides and citrate have been determined and their possible regulatory significance in the control of catabolic and anabolic pathways is discussed.
-
-
-
Combined Carbon Dioxide Inhibition and Oxygen Limitation of the Growth of Pseudomonas fragi 72 in Batch and Continuous Culture
More LessThe effect of CO2 inhibition and O2 limitation on the growth of Pseudomonas fragi strain 72 was studied in carbon and/or energy limited continuous culture using citric acid as the growth substrate. The influence of different CO2 concentrations on the maximal growth capacity, estimated as the dilution rate at which the culture density begins to fall (D b) or the dilution rate at which biomass output rate is maximal (D m), was demonstrated together with the differences in influence of CO2 inhibition and O2 limitation, on the steady-state characteristics of the culture. The combined effect of CO2 inhibition and O2 limitation was measured. Comparative studies made in batch cultures suggested that continuous culture was more sensitive to change than the batch culture.
The maximum specific growth rate of the organism decreased when the CO2 concentration was increased. However, the results from the continuous cultures revealed a plateau in the curve of D b versus CO2 concentration (between 3·5 % and 12 % CO2). This plateau could not be seen from the μmax determinations (batch).
Unlike O2 limitation the CO2 inhibition did not disturb the regularity of the curves of the steady-state characteristics. Two levels of O2 limitation were indicated from the curve of biomass versus dilution rate, a minor one, slightly reducing the biomass concentration of the culture and a major one, significantly reducing the biomass. An O2 concentration of 5 % of the incoming gas (dissolved oxygen tension in the culture: 3–5 %) had no effect on the steady-state characteristics of the culture, while 0·4 % O2 significantly affected the curve of biomass versus dilution rate (dissolved oxygen tension 0–0·4 %).
The combined effect of oxygen limitation and 12 % CO2, further altered the steady-state characteristics and the biomass curve started to decrease at very low dilution rates. Thus, the two inhibitory agents co-operated and their joint growth restricting effect was considerably stronger than the strongest agent alone. The question whether the restricting effect of the two together should be regarded as ‘synergistic’ or ‘additive’, is still open to discussion even though some evidence was obtained which suggested the former.
-
-
-
Tolerance of Nectria haematococca MP VI to the Phytoalexin Pisatin in the Absence of Detoxification
More LessMost isolates of Nectria haematococca mating population (MP) VI detoxify pisatin, the major phytoalexin produced by pea. However, there is evidence of another pisatin tolerance mechanism that does not depend on pisatin degradation. To facilitate further studies on nondegradative tolerance, a bioassay was developed in which culture turbidity was used as a measure of mycelial growth. Under conditions of this assay, four N. haematococca MP VI isolates degraded 0·4 mm-pisatin within 15 h, but two other isolates required more than 24 h. A remaining group of four isolates did not degrade pisatin. These three groups were typified by the isolates 126–71. T-77 and 126–80, respectively. Regardless of their ability to degrade pisatin, however, all 10 isolates grew equally well after addition of 0·4 mm-pisatin, suggesting that detoxification may not be needed for pisatin tolerance during the short time interval of this assay. The existence of a nondegradative tolerance in isolate 126–71 was confirmed when additional experiments showed that growth could occur (i) before degradation had reduced pisatin below initially noninhibitory levels, and (ii) when pisatin degradation was inhibited by 2 % ethanol. When tested in growth medium, pretreatment with a noninhibitory concentration of pisatin for 3 h enhanced equally the ability of isolates 126–71 and 126–80 to tolerate pisatin. After cultures were pretreated with pisatin while temporarily suspended in buffer, isolates 126–71 and T-77 were stimulated to degrade pisatin, and they grew better than did isolate 126–80. Again, however, growth began before there was significant detoxification, especially for isolate T-77. Thus, these three isolates all appeared to have an inducible, nondegradative tolerance to pisatin. Nectria haematococca MP I isolate T-145 lacked an adaptive tolerance to pisatin and was more sensitive to pisatin than any of the MP VI isolates.
-
-
-
Characterization of an Inducible, Nondegradative Tolerance of Nectria haematococca MP VI to Phytoalexins
More LessIsolates of Nectria haematococca mating population (MP) VI were found previously to possess an inducible tolerance to pisatin, a pea phytoalexin, regardless of their ability to detoxify this compound. Nondegradative tolerance to pisatin was further characterized by studying MP VI isolate 126-80, a strain that does not degrade pisatin. Tolerance was maximally induced in growth medium at 28 °C by a 3 h treatment with 0.1 mM-pisatin. Shorter time intervals or lower pisatin concentrations reduced the degree of induction. Adaptation to pisatin was inhibited if mycelium was temporarily suspended in buffer during the induction period. Enhanced tolerance in growth medium was lost completely within 4 h at 28 °C after pisatin was removed from the medium. However, incubation at 1 °C prevented both the induction and the loss of enhanced pisatin tolerance. These results suggest that the induction of tolerance requires an active metabolic response, and that the expression of tolerance is tightly controlled. Of six isoflavonoid derivatives tested that were structurally related to pisatin, only four were good inducers of pisatin tolerance. Cyanide and the polyene antibiotic amphotericin B also induced some pisatin tolerance. However, tolerance was not a general stress response, because three other antimicrobial compounds failed to induce tolerance. Besides inducing tolerance to itself, pisatin simultaneously induced nondegradative tolerance to the structurally related isoflavonoid phytoalexins medicarpin and phaseollin. A partial tolerance was also induced to the isoflavone biochanin A. Of the non-isoflavonoid toxicants tested, only amphotericin B was tolerated as a result of pisatin pretreatment. Tolerance to amphotericin B was expressed both as the ability to grow and as the decreased leakage of cellular constituents after treatment with normally inhibitory concentrations of amphotericin B. We suggest that the plasma membrane is modified during the induced adaptation to pisatin, and that such modifications could be involved in nondegradative tolerance to phytoalexins.
-
-
-
Natural-abundance 13C Nuclear Magnetic Resonance Studies on the Internal Solutes of Xerophilic Fungi
More LessNatural-abundance 13C nuclear magnetic resonance spectroscopy was used to study the patterns of accumulation of osmotically active internal solutes in five different fungi. Four xerophilic fungi (Penicillium janczewskii, Eurotium chevalieri, Xeromyces bisporus and Wallemia sebi), and one non-xerophilic fungal species (P. digitatum) were grown at three different water activities (a w) on media containing sorbitol, glucose/fructose or NaCl as the controlling solute. Under all conditions studied, the major internal solutes detected in aqueous ethanol extracts of these fungi were simple polyhydric alcohols: glycerol, erythritol, arabitol and mannitol. The most important osmoregulatory solute accumulated by all species was glycerol. On the sorbitol and the glucose/fructose media, all five fungi were able to accumulate glycerol. However, when NaCl was used to control a w, only one species, W. sebi, was able to accumulate glycerol below 0.92 a w. Significant quantities of the controlling solutes were also present in the extracts.
When intact mycelia of P. janczewskii were examined by NMR, resonances of all the major internal solutes were clearly discernible, although they were not as well resolved as those from the fungal extracts. Relaxation measurements showed that the solutes were relatively mobile inside the cells.
-
-
-
Association of Intracellular Low-density Vesicles with Plasma Membranes from Saccharomyces cerevisiae NCYC 366
More LessFractionation on sucrose density gradients of spheroplast lysates from Saccharomyces cerevisiae NCYC 366 yielded a fraction with a peak density of 1·05 g ml−1, intermediate between that of membranes and intracellular low-density vesicles. Electron microscopy showed the fraction to consist of membranes associated with intracellular vesicles. Evidence for the presence of plasma membranes in the association fraction was obtained by using 125I-labelled spheroplasts. The fraction was free from detectable amounts of cytochromes and DNA. Fractionation on sucrose density gradients of incubation mixtures containing isolated crude plasma-membranes and vesicles gave rise to a visible intermediate-density band, which electron microscopy showed to contain membranes associated with vesicles. Evidence for the presence of plasma membranes in the in vitro intermediate-density band came from incubating mixtures containing 125I-labelled crude plasma-membranes, and evidence for the presence of vesicles came from using 125I-labelled vesicles. Supplementing incubation mixtures with calcium chloride sharply increased the size of the intermediate-density band. Cycloheximide and methylbenzimidazol-2-yl-carbamate had no effect on its formation. Purified plasma-membranes failed to form an intermediate-density band when incubated with vesicles. Supplementing these incubation mixtures with calcium chloride did not produce an intermediate-density band, but caused extensive association of vesicles with plasma membranes that pelleted in gradients. Isolated vesicles were not osmotically active; their polyphosphate content was 1·61 μmol orthophosphate equivalent (mg vesicle protein)−1. They had diameters in the range 0·45-0·65 μm, as measured on electron micrographs of thin sections. The data reported provide further evidence for a role for intracellular low-density vesicles in envelope growth in S. cerevisiae.
-
- Short Communication
-
-
-
Detection of Heterotrophic Contaminants in Cultures of Thiobacillus ferrooxidans and Their Elimination by Subculturing in Media Containing Copper Sulphate
More LessOf the four cultures of Thiobacillus ferrooxidans held by the National Collections of Industrial and Marine Bacteria, U.K., two were found to be contaminated with acidophilic heterotrophic bacteria. One of the contaminated cultures was the type strain (NC1B 8455) of T. ferrooxidans; the equivalent culture from the American Type Culture Collection (ATCC 23270) was found not to be contaminated. Heterotrophic contaminants could be subcultured along with T. ferrooxidans in media containing ferrous iron, but devoid of organic material, and remained viable in mixed cultures for periods of at least one year. Subculturing in media containing high concentrations of copper ions resulted in the elimination of the heterotrophic bacteria.
-
-
- Taxonomy
-
-
-
Fermentation Enzymes in Strictly Aerobic Bacteria: Comparative Studies on Strains of the Genus Alcaligenes and on Nocardia opaca and Xanthobacter autotrophicus
More LessNocardia opaca, Xanthobacter autotrophicus and 18 representative strains of the genus Alcaligenes were examined for the presence of NAD-dependent dehydrogenases for lactate, ethanol or 2,3-butanediol after the cells had been transiently cultivated under conditions of oxygen deficiency. Formation of these enzymes was derepressed in all strains except Nocardia opaca and Alcaligenes latus. The protein patterns of Alcaligenes hydrogenophilus and Alcaligenes eutrophus type strain and strains N9A, H16, B19, H1 and H20 obtained by PAGE were similar. The purified lactate dehydrogenases from these strains were strongly inhibited by 1 to 5 μm-oxaloacetate, had a broad substrate specificity and a high affinity for MatrexTM Gel Green A. Alcaligenes faecalis shared the properties of the lactate dehydrogenase but differed greatly with respect to its protein pattern. In A. eutrophus strain A7 a high activity of lactate dehydrogenase was detected, but the enzyme was not sensitive to oxaloacetate.
Alcohol dehydrogenase and 2,3-butanediol dehydrogenase were even more widely distributed than lactate dehydrogenase among the strains studied. In many cases the electrophoretic mobilities of both alcohol dehydrogenases were identical. The study results in the following taxonomical conclusions. Alcaligenes eutrophus type strain and strains N9A, H16, B19, H1 and H20 are almost identical with respect to protein and enzyme patterns as well as the presence of a derepressible L(+)-lactate dehydrogenase sensitive to oxaloacetate. The strains CH34, 707, A7 and JMP134 differ greatly from this core group and from each other and have to be considered as aberrant strains of A. eutrophus.
-
-
-
-
Identification of Clostridium butyricum and Clostridium beijerinckii by Gas-Liquid Chromatography and Sugar Fermentation: Correlation with DNA Homologies and Electrophoretic Patterns
More LessSixty-five strains of Clostridia of the butyricum group were studied by DNA-DNA hybridization, electrophoresis of cell proteins, gas-liquid chromatography, and fermentation of glycerol, inositol and ribose. The DNA-DNA hybridization results confirmed that strains of this group belong to two main species, Clostridium butyricum and C. beijerinckii. Five strains did not hybridize with the reference strains of these two species. Most of the strains could be identified by quantitative gas-liquid chromatographic analysis combined with fermentation patterns. The other strains could be identified by their protein electrophoretic patterns.
-
-
-
Thiosphaera pantotropha gen. nov. sp. nov., a Facultatively Anaerobic, Facultatively Autotrophic Sulphur Bacterium
More LessDuring studies on a desulphurizing, denitrifying effluent-treatment system, an organism which is able to grow aerobically and anaerobically on reduced sulphur compounds and hydrogen, while fixing carbon dioxide, was isolated. The new isolate is also capable of mixotrophic and heterotrophic growth on a wide range of substrates, and is therefore a facultatively aerobic, facultative autotroph. Comparisons with two similar species, Thiobacillus A2 and Paracoccus denitrificans, showed that the new isolate is significantly different from the other two, and merits separate classification. In view of its ability to oxidize reduced sulphur compounds, and because it is a chain-forming coccus rather than a rod, the new isolate has been given the generic name of Thiosphaera, and the species name pantotropha in recognition of its wide range of possible substrates.
-
-
-
Serotaxonomical Analyses of Some Streptomyces and Related Organisms
More LessFifteen strains of Streptomyces, two of Streptoverticillium and one of Nocardia mediterranea were studied by the immunodiffusion technique and the results were compared with those of a previous phenetic study. Both the serological and phenetic analyses demonstrated that Nocardia mediterranea was different from strains of Streptomyces and Streptoverticillium. The latter two genera were phenetically distinguishable but demonstrated a comparatively close serological relationship. Those strains of Streptomyces and Streptoverticillium which shared a high number of precipitinogens also belonged to the same phenetic cluster, while strains which were less serologically related usually fell into different clusters. Thus there was good evidence of a general congruence between serological and phenetic similarity. The immunological results also supported the phenetic evidence in suggesting that many species in the genus Streptomyces should be combined. Similar evidence was obtained for the genus Streptoverticillium.
-
Volumes and issues
-
Volume 170 (2024)
-
Volume 169 (2023)
-
Volume 168 (2022)
-
Volume 167 (2021)
-
Volume 166 (2020)
-
Volume 165 (2019)
-
Volume 164 (2018)
-
Volume 163 (2017)
-
Volume 162 (2016)
-
Volume 161 (2015)
-
Volume 160 (2014)
-
Volume 159 (2013)
-
Volume 158 (2012)
-
Volume 157 (2011)
-
Volume 156 (2010)
-
Volume 155 (2009)
-
Volume 154 (2008)
-
Volume 153 (2007)
-
Volume 152 (2006)
-
Volume 151 (2005)
-
Volume 150 (2004)
-
Volume 149 (2003)
-
Volume 148 (2002)
-
Volume 147 (2001)
-
Volume 146 (2000)
-
Volume 145 (1999)
-
Volume 144 (1998)
-
Volume 143 (1997)
-
Volume 142 (1996)
-
Volume 141 (1995)
-
Volume 140 (1994)
-
Volume 139 (1993)
-
Volume 138 (1992)
-
Volume 137 (1991)
-
Volume 136 (1990)
-
Volume 135 (1989)
-
Volume 134 (1988)
-
Volume 133 (1987)
-
Volume 132 (1986)
-
Volume 131 (1985)
-
Volume 130 (1984)
-
Volume 129 (1983)
-
Volume 128 (1982)
-
Volume 127 (1981)
-
Volume 126 (1981)
-
Volume 125 (1981)
-
Volume 124 (1981)
-
Volume 123 (1981)
-
Volume 122 (1981)
-
Volume 121 (1980)
-
Volume 120 (1980)
-
Volume 119 (1980)
-
Volume 118 (1980)
-
Volume 117 (1980)
-
Volume 116 (1980)
-
Volume 115 (1979)
-
Volume 114 (1979)
-
Volume 113 (1979)
-
Volume 112 (1979)
-
Volume 111 (1979)
-
Volume 110 (1979)
-
Volume 109 (1978)
-
Volume 108 (1978)
-
Volume 107 (1978)
-
Volume 106 (1978)
-
Volume 105 (1978)
-
Volume 104 (1978)
-
Volume 103 (1977)
-
Volume 102 (1977)
-
Volume 101 (1977)
-
Volume 100 (1977)
-
Volume 99 (1977)
-
Volume 98 (1977)
-
Volume 97 (1976)
-
Volume 96 (1976)
-
Volume 95 (1976)
-
Volume 94 (1976)
-
Volume 93 (1976)
-
Volume 92 (1976)
-
Volume 91 (1975)
-
Volume 90 (1975)
-
Volume 89 (1975)
-
Volume 88 (1975)
-
Volume 87 (1975)
-
Volume 86 (1975)
-
Volume 85 (1974)
-
Volume 84 (1974)
-
Volume 83 (1974)
-
Volume 82 (1974)
-
Volume 81 (1974)
-
Volume 80 (1974)
-
Volume 79 (1973)
-
Volume 78 (1973)
-
Volume 77 (1973)
-
Volume 76 (1973)
-
Volume 75 (1973)
-
Volume 74 (1973)
-
Volume 73 (1972)
-
Volume 72 (1972)
-
Volume 71 (1972)
-
Volume 70 (1972)
-
Volume 69 (1971)
-
Volume 68 (1971)
-
Volume 67 (1971)
-
Volume 66 (1971)
-
Volume 65 (1971)
-
Volume 64 (1970)
-
Volume 63 (1970)
-
Volume 62 (1970)
-
Volume 61 (1970)
-
Volume 60 (1970)
-
Volume 59 (1969)
-
Volume 58 (1969)
-
Volume 57 (1969)
-
Volume 56 (1969)
-
Volume 55 (1969)
-
Volume 54 (1968)
-
Volume 53 (1968)
-
Volume 52 (1968)
-
Volume 51 (1968)
-
Volume 50 (1968)
-
Volume 49 (1967)
-
Volume 48 (1967)
-
Volume 47 (1967)
-
Volume 46 (1967)
-
Volume 45 (1966)
-
Volume 44 (1966)
-
Volume 43 (1966)
-
Volume 42 (1966)
-
Volume 41 (1965)
-
Volume 40 (1965)
-
Volume 39 (1965)
-
Volume 38 (1965)
-
Volume 37 (1964)
-
Volume 36 (1964)
-
Volume 35 (1964)
-
Volume 34 (1964)
-
Volume 33 (1963)
-
Volume 32 (1963)
-
Volume 31 (1963)
-
Volume 30 (1963)
-
Volume 29 (1962)
-
Volume 28 (1962)
-
Volume 27 (1962)
-
Volume 26 (1961)
-
Volume 25 (1961)
-
Volume 24 (1961)
-
Volume 23 (1960)
-
Volume 22 (1960)
-
Volume 21 (1959)
-
Volume 20 (1959)
-
Volume 19 (1958)
-
Volume 18 (1958)
-
Volume 17 (1957)
-
Volume 16 (1957)
-
Volume 15 (1956)
-
Volume 14 (1956)
-
Volume 13 (1955)
-
Volume 12 (1955)
-
Volume 11 (1954)
-
Volume 10 (1954)
-
Volume 9 (1953)
-
Volume 8 (1953)
-
Volume 7 (1952)
-
Volume 6 (1952)
-
Volume 5 (1951)
-
Volume 4 (1950)
-
Volume 3 (1949)
-
Volume 2 (1948)
-
Volume 1 (1947)