- Volume 132, Issue 8, 1986
Volume 132, Issue 8, 1986
- Biochemistry
-
-
-
Photoactive Retinal Pigments in Haloalkaliphilic Bacteria
More LessSummary: Light-induced fast transient absorbance changes were detected by time-resolved spectroscopy in 38 of 51 haloalkaliphilic isolates from alkaline salt lakes in Kenya and the Wadi Natrun in Egypt. They indicate the presence of two retinal pigments, Pf and Ps, which undergo cyclic photoreactions with half-times of 2ms and 500ms respectively. Pf absorbs maximally near 580 nm and Ps near 500 nm. The pigments differ in their sensitivity to hydroxylamine and detergent bleaching and the photo reactions of Pf are strongly dependent on chloride concentration. Of the 38 pigment-containing strains, 29 possess both Pf and Ps, 9 possess only Ps. Inhibition of retinal synthesis with nicotine blocks pigment formation and addition of retinal restores it. Hydroxylamine-bleached pigments can be reconstituted with retinal or retinal analogues. Their similarity to the retinal pigments of Halobacterium halobium strongly suggests that they are also rhodopsin-like retinyledene proteins. Pf in all properties tested is almost identical to halorhodopsin, the light-driven chloride pump of H. halobium and may serve the same function in the haloalkaliphiles. Ps has photocycle kinetics similar to sensory rhodopsin and a far-blue-shifted long-lived photocycle intermediate, but its ground state absorption maximum is near 500nm instead of 587nm. We have not found a bacteriorhodopsin-like pigment in the haloalkaliphiles.
-
-
-
-
Effect of Mitochondrial Cytochromes and Haem Content on Cytochrome P450 in Saccharomyces cerevisiae
More LessSummary: It is well established that the mitochondrial and the microsomal cytochromes in Saccharomyces cerevisiae are regulated differently. Mutations affecting the mitochondrial cytochromes aa 3 or c had no effect on the concentration of the microsomal cytochrome P450 even during haem limitation. Moreover, a defect in the cytochrome P450 gene did not affect mitochondrial cytochromes. However, a regulatory mutation present in strain SG1 decreased both mitochondrial and microsomal cytochrome contents. This mutation also affected the intracellular haem concentration. The haem precursor 5-aminolaevulinate increased both mitochondrial and microsomal cytochrome contents. Our results indicate that carbon source and haem concentration are involved in the regulation of cytochrome P450.
-
-
-
Acyltransferase Activity of the Wide Spectrum Amidase of Brevibacterium sp. R312
More LessSummary: The wide spectrum amidase from Brevibacterium sp. R312, which can hydrolyse many amides tothe corresponding acids, was shown to transfer the acyl groups of amides, acids and esters to hydroxylamine. The transfer rates ofthese reactions in cytoplasmic fractions were measured and compared. The K m and V max were determined for different substrates in the presence of hydroxylamine. The enzyme was also shown to transfer the acyl group of the amide analogue N–methylacetamide to hydroxylamide and that of acetamide to the hydroxylamine analogue methylhydroxylamine.
-
-
-
Purification and Characterization of the Secreted Alkaline Phosphatase of Bacillus licheniformis MC14: Identification of a Possible Precursor
More Lesssummary: The most abundantly secreted protein from Bacillus licheniformis MC14 is alkaline phosphatase (APase). A twofold purification yields a homogeneous enzyme. No discernible chemical-physical differences in the secreted APase distinguish this enzyme from the cell-bound APase(s) except a 10-fold higher specific activity. During the growth phase in which the bacterium was secreting APase into the medium an inactive cytosol protein antigenically similar but 3000 Da heavier than the subunit of the mature secreted APase was immunoprecipitated from the cytosol. A pulse-chase experiment showed the kinetics of disappearance of this protein from the cytosol to be correlated with the appearance of the secreted APase in the medium, suggesting that it may be a precursor to the secreted APase.
-
- Development And Structure
-
-
-
Relaxation Motions Induced in Bacillus subtilis Macrofibres by Cleavage of Peptidoglycan
More LessSummary: Bacillus subtilis macrofibres exposed to lysozyme underwent characteristic rotations, termed relaxation motions, in which their twist changed. Intact macrofibres and macrofibre fragments devoid of loop ends responded in the same way. Macrofibre strains for which the helix hand is temperature-dependent and also those of fixed-hand (both left and right) underwent initial relaxation motions towards the right-hand end of the twist spectrum, the only exception being those in which the initial twist state was at or near the right-hand maximum. Often when the initial relaxation motions were completed immediately before structure breakdown the macrofibres underwent one or a few rotations in the opposite direction (towards the left-hand end of the twist spectrum). Crude autolysin extract obtained from wild-type B. subtilis also caused macrofibre relaxation motions at pH 5·6 but at pH 8·0 macrofibre breakdown occurred as a result of septa) cleavage. This resulted in the release of helically shaped individual cellular filaments. These findings suggest that strain in the cell wall associated with helical shape was dependent on the integrity of the glycan backbone rather than peptide cross-bridges. In contrast, cleavage of peptide cross-bridges apparently was instrumental in the cell separation process. Left-and right-hand macrofibres, when exposed to lysozyme, exhibited different rates of relaxation, breakdown of fibre structure and protoplast formation. Similarly, the rate of macrofibre breakdown during the lag between temperature shift and inversion reflected the replacement of septal wall material by that of a new conformation corresponding to the new helix hand. The difference in the rates of protoplast formation indicates asymmetry in the overall rate of cleavage by lysozyme which may reflect the activity of left-twist protein(s).
-
-
- Genetics And Molecular Biology
-
-
-
Host Plant Effects on Hybrids of Rhizobium leguminosarum Biovars viceae and trifolii
More LessSummary: Rhizobium leguminosarum biovar viceae host-range plasmid pJB5JI was transferred to six R. leguminosarum biovar trifolii strains. Inheritance of pJB5JI enabled the R. leguminosarum biovar trifolii strains to nodulate both peas and clover species. Bacteria were isolated from nodules formed on peas (the ‘correct’ host for R. leguminosarum biovar viceae) and the hosts for R. leguminosarum biovar trifolii (white, red and subterranean clover). Isolates from peas and white clover appeared to have lost or changed the host-range plasmid conferring the ability to nodulate white clover or peas respectively. Isolates from subterranean and red clover could often nodulate all host plants. These results show that the host exerts some form of functional incompatibility when interacting with hybrid Rhizobium strains and that some hosts are more stringent than others.
-
-
-
-
Properties of in vitro Recombinant Derivatives of pJV1, a Multi-copy Plasmid from Streptomyces phaeochromogenes
More LessSummary: The 10·8 kb plasmid pJVl, isolated from Streptomyces phaeochromogenes, has a high copy number (about 150) and a broad host range among Streptomyces spp. Several pJVl derivatives carrying the thiostrepton resistance gene (tsr) of S. azureus were made. One derivative, pWOR191, was shown to promote its own transfer and to mobilize chromosomal markers in S. lividans. Another derivative, pWOR109, was non-transmissible. Deletion in vitro of a segment of pWOR109 gave pWOR120 (5·6 kb), which has single BamHI and BglII sites shown to be capable of accepting ‘foreign’ DNA such as a previously cloned S. antibioticus DNA fragment encoding tyrosinase, giving vectors (pWOR125, pWOR126) with properties resembling the well-established multicopy vector pIJ702. Shuttle vectors capable of functioning in both S. lividans and Escherichia coli were also constructed. The region of pJVl essential for replication and maintenance was localized to a 2·5 kb segment. Stable maintenance of pWOR109 and pWOR12Q was observed in the presence of derivatives ofpIJl0l, the progenitor of pIJ702.
-
-
-
The TraT Protein is able to Normalize the Phenotype of a Plasmid-carried Permeability Mutation of Salmonella typhimurium
More LessSummary: The isolation of different classes of antibiotic-supersensitive outer membrane permeability mutants of Salmonella typhimurium has been described previously ( Sukupolvi et al., 1984 , Journal of Bacteriology 159,704-712). One of these, the SS-A mutation, sensitizes the bacteria to gentian violet and to hydrophobic antibiotics. The phenotype of the SS-A mutant was restored to normal when a cloned fragment of the F plasmid, or the R plasmid R6-5, carrying the genes traS, T and D was introduced on a multicopy plasmid. The introduction of a plasmid carrying only the tra T gene showed thatthis gene was sufficient to restore the phenotype. Only clones with functioning traT (irrespective of copy number) restored the normal antibiotic-resistant phenotype in the SS-A mutant. An incompatibility test using a donor strain which carried transposon Tn10 in the 60 MDa plasmid of S. typhimurium and a recipient in which Tn5 was placed close to the SS-A mutation indicated that the SS-A mutation was located in the 60 MDa virulence plasmid (previously called the cryptic plasmid) of S. typhimurium. The introduction of the large virulence plasmid carrying the SS-A mutant allele into wild-type S. typhimurium or Escherichia coli resulted in strains with a phenotype identical tothat of the original SS-A mutant.
-
-
-
Nuclear Suppressors of the Mitochondrial Mutation oxi1-V25 in Saccharomyces cerevisiae. Genetic Analysis of the Suppressors: Absence of Complementation between Non-allelic Mutants
More LessSummary: Ten informational nuclear suppressors of the oxil − mitochondrial mutation of Saccharomyces cerevisiae are recessive. They are linked to each other, but their allelism is uncertain. Some of them unfavourably affect functions of standard (mit +) mitochondrial genomes. One suppressor severely impairs or entirely prevents mitochondrial functions of the spore clones carrying it. The spectrum of mit − mutations on which these suppressors act is similar to that exhibited by nam3-l. In double heterozygotes nam x/NAM3+, nam3-l the oxil − (and box3-) mutation is suppressed, yet one of our suppressors (R705) and nam3-l show independent segregation in tetrads. This indicates that there may be absence of complementation between non-allelic suppressors.
-
-
-
Regulatory Mutations Affecting the Synthesis of Pectate Lyase in Erwinia chrysanthemi
More LessSummary: Erwinia chrysanthemi secretes five isoenzymes of pectate lyase (PLa to PLe), which are involved in the phytopathogenicity of this bacterial species. We describe the isolation and characterization of mutants in the regulatory systems controlling PL synthesis. The regulation of PL synthesis appears to be complex, involving several controls. In one class of mutants, designated cri, the synthesis of various proteins became resistant to catabolite repression. This mutation mainly affected the synthesis of isoenzymes PLb and PLc. In a second class of mutants, designated gpiR, PL synthesis was no longer inducible in the presence of pectin derivatives; the regulatory gene responsible for the induction was evidently inactivated. Moreover gpiR mutations led to synthesis of PL independent of the growth phase, whereas in the wild-type strain PL synthesis increased only at the end of exponential growth. These mutations mainly affected the synthesis of PLa, PLd and PLe. Mutations in kdgR, the regulatory gene controlling 2-keto-3-deoxygluconate catabolism, had the same effects on PL synthesis as gpiR mutations.
-
-
-
Genetic Transformation of Rifampicin Resistance in Lactobacillus acidophilus
More LessSummary: Lactobacillus acidophilus strain 100-33, originally isolated from swine faeces, was transformed to rifampicin resistance with DNA from spontaneous rifampicin-resistant mutants derived from it. Cells of the recipient strain were treated with lysozyme and mutanolysin, mixed with donor DNA and polyethylene glycol and grown on a regeneration medium overnight. After 48 h incubation, the numbers of rifampicin-resistant cells in the populations of regenerated cells were estimated from numbers of colonies. Efficiency of the lysozyme/mutanolysin treatment (the ratio of the number of osmotically fragile cells after the enzyme treatment to the initial cell number) was about 99%. The regeneration frequency of the enzyme-treated cells varied from 5 to 67%. The transformation frequency varied from about 0·2 × 10−8 to 8·0 × 10−8 transformants per regenerated cell per μg DNA. To our knowledge, this method for genetic transformation is the first to be reported for a Lactobacillus strain.
-
-
-
Molecular Cloning of a Gene Coding for a Vibrio cholerae Haemagglutinin
More LessSummary: Recombinant plasmids encoding a Vibrio cholerae haemagglutinin were isolated from the highly virulent V. cholerae strain C5 by cosmid cloning. Both Escherichia coli HB101 containing the recombinant plasmids and V. cholerae C5 were able to agglutinate a variety of erythrocytes from human and animal origin ; this haemagglutination was not inhibited by D-mannose or L-fucose. Subcloning of the recombinant cosmid DNA revealed that a 1·3 kb DNA fragment was sufficient for haemagglutinin production in E. coli HB101. Under direction of this 1·3 kb Vibrio DNA fragment, two proteins were made inE. coli minicells, of 27 and 10 kDa. Haemagglutinin-encoding sequences were not detected in every V. cholerae strain.
-
-
-
Suppression by the ColV, I-K94 Plasmid of a Growth Lesion in ompA Mutants of Escherichia coli
More LessSummary: Organisms of three independently isolated ompA mutants of Escherichia coli failed to form colonies on glucose minimal agar (glucose MA) at 44 °C after growth in glucose minimal salts medium at 37 °C, although all three strains formed colonies on nutrient agar at 44 °C. Supplementation of the glucose MA with individual amino acids including L-methionine and/or L-cysteine did not allow colony formation at 44 °C, although addition of 0·1% Casamino acids was effective; replacement of glucose with other energy sources or ammonium ions with glutamate also did not allow growth at 44 °C. The failure to form colonies at 44 °C was not due to killing of the organisms, because colonies were formed if plates of the ompA mutant initially incubated at 44 °C were shifted to 30 °C after 16 h. Introduction of the ColV, I-K94 plasmid into P678-54 ompA, 1131 ompA or an ompC ompA mutant suppressed the 44 °C growth lesion, but other plasmids (F lac, R483ColIa, RI, ColB-K98, R124) tested in P678-54 ompA did not. Growth of the ColV, I-K94+ derivative at 44 °C was due to a suppressing effect of the plasmid rather than to introduction of the plasmid into a variant with normal or altered OmpA protein. An attempt was made to ascertain which component(s) encoded by ColV, I-K94 was (were) responsible for allowing growth at 44 °C. Transfer components appeared unlikely to be involved and plasmids which conferred individual colicins (plus the corresponding immunity component) did not suppress. The findings that the ColV, I-K94-encoded VmpA protein resembles the OmpA protein (a) immunologically and (b) in being a transmembrane component of the outer membrane suggested that it might be the presence of the VmpA protein which allowed growth at 44 °C. Several experiments were in accord with this possibility.
-
-
-
β-Galactosidase and A1ka1ine Phosphatase Do Not Become Extracellular When Fused to the Amino-terminal Part of Colicin N
More LessSummary: A series of plasmids encoding hybrid proteins comprising various lengths of the NH2-terminal region of colicin N coupled to almost complete β-galactosidase or alkaline phosphatase polypeptides was constructed by transposon mutagenesis of ColN plasmid derivatives. Synthesis of the hybrid proteins, like that of colicin N itself, was regulated by the SOS response. Large quantities of the hybrid proteins accumulated in the cytoplasm (β-galactosidase) or particulate fractions (alkaline phosphatase). When the gene fusions were expressed in cells that were producing colicin E2 and expressing the ColE2 lysis gene, only very low levels of the hybrid proteins were found in the medium. The results suggest that the amino-terminal part ofcolicin N does not contain sufficient biochemical information to promote the release of the hybrid proteins into the medium.
-
-
-
A Detailed Study of gerJ Mutants of Bacillus subtilis
More LessSummary: A total of nine gerJ mutants have now been isolated in Bacillus subtilis. All are defective in their spore germination properties, being blocked at an intermediate (phase grey) stage. The dormant spores are sensitive to heating at 90°C and two of the mutants (generated by transposon insertion) produce spores sensitive at 80°C. The spores of these two more extreme mutants had a visibly defective cortex when studied by electron microscopy, as did some of the other mutants. During sporulation, the acquisition of spore resistance properties and the appearance of the sporulation-specific penicillin-binding protein PBP5* were delayed. A strain probably carrying a lacZ fusion to the gerJ promoter demonstrated increased expression between t 2 and t 4. We propose that the gerJ locus is involved in the control of one or more sporulation-specific genes.
-
-
-
Enhanced Nitrogen Fixation and Competitiveness for Nodulation of Lotus pedunculatus by a Plasmid-cured Derivative of Rhizobium loti
More LessSummary: A plasmid-cured derivative of Rhizobium loti strain NZP2037, strain PN4010, was significantly more effective in N2 fixation and showed an improved capacity to compete with other root nodule bacteria for nodulation of Lotus pedunculatus, relative to that of strain NZP2037. Reintroduction of the plasmid pRlo2037 into PN4010 resulted in a return to the NZP2037 level of symbiotic effectiveness and competitiveness. The enhanced effectiveness and competitiveness of PN4010 for L. pedunculatus was associated with its increased capacity to form nodules. Strain PN4010 did not differ from NZP2037 in its growth characteristics in pure culture, in its resistance to L. pedunculatus root flavolan or in its ability to multiply in the L. pedunculatus rhizosphere in the presence of a competing strain of R. loti. An examination of 35 R. loti strains (including 25 field isolates) revealed two strains (NZP2014 and NZP2042) that did not contain a single large indigenous plasmid; both were significantly more effective in N2 fixation with L. pedunculatus than was NZP2037 or two other Nod+ Fix+ plasmid-containing strains of R. loti. Transfer of pRlo2037 into NZP2014 and NZP2042 reduced their effectiveness for L. pedunculatus.
-
-
-
Molecular Cloning and Nucleotide Sequence of the Alkaline Cellulase Gene from the Alkalophilic Bacillus sp. Strain 1139
More LessSummary: The cellulase gene from the alkalophilic Bacillus sp. strain 1139 was cloned in Escherichia coli using pBR322. Plasmid pFK1 was isolated from transformants producing cellulase, and the cloned cellulase gene was found to be in a 4.6 kb HindIII fragment. The cellulase gene was subcloned in a functional state on a 2.9 kb DNA fragment and its nucleotide sequence was determined. The coding sequence showed an open reading frame encoding 800 amino acids. The pFK1-encoded cellulase had the same enzymic properties as the extracellular cellulase produced by the alkalophilic Bacillus sp. strain 1139, but its M r was slightly higher.
-
-
-
Cloning and Expression of the pepD Gene of Escherichia coli
More LessPeptidase D of Escherichia coli, cleaving the unusual dipeptide carnosine, was found to be encoded by the ColE1 hybrid plasmid pLC44-11. From this plasmid the pepD gene was subcloned into small vectors. As shown by successive reduction of the flanking sequences of genomic DNA, the order of genes in the region at 6 min of the E. coli K12 map is phoE, pepD, in the clockwise orientation. Insertional inactivation of the pepD gene and expression of recombinant plasmids in maxicells allowed the identification of the pepD product as a 52 kDa protein. Comparison with the 100 kDa protein molecular mass determined by gel filtration suggests that active peptidase D is probably a dimer.
-
- Pathogenicity And Medical Microbiology
-
-
-
Cord Factor is Associated with the Maintenance of the Chronic Inflammatory Reaction Caused by Mycobacteria
More LessSummary: The distribution of an aqueous suspension of cord factor (CF) from Mycobacterium bovis BCG in several mouse organs was examined after intravenous injection, and the correlation between evolution of the inflammatory granulomatous reaction and the presence of CF in these organs was determined. CF was preferentially deposited in the lungs and liver, and the kinetics of the pulmonary and hepatic inflammatory reaction, evaluated by determining the indices for these organs, showed a gradual increase on day 2 after injection, reached a peak around the fifth day, and declined thereafter. Histological analysis showed that on day 5 both the lungs and the liver were diffusely damaged by a mononuclear inflammatory infiltrate arranged in a granulomatous manner and consisting predominantly of histiocytes. CF elimination was more marked in the liver than in the lungs: 2 d after injection 76% of the material deposited in the liver had been eliminated. Little or no CF was detected in the liver and lungs by day 16, when the inflammatory reaction was also substantially decreased. A second CF dose administered 8 d after the first exacerbated the inflammatory process in both the lungs and the liver, indicating that the intensity of this process depends on CF concentration in the lesion site.
-
-
-
-
Composition and Immunochemical Properties of the Cell Surface Proteins of Vibrio cholerae
More LessSummary: The composition and immunochemical properties of cell surface proteins of Vibrio cholerae belonging to both the biotypes (classical and El Tor) and the serotypes (Ogawa and Inaba) were investigated. Proteins were isolated by extraction with EDTA/NaCl. When the extract was further treated with sodium deoxycholate, a product significantly enriched with the major protein was obtained. The surface localization of these proteins was confirmed by immunoelectron microscopy using protein A-colloidal gold particles as probes. Antisera to these proteins (a) possessed complement-mediated bactericidal activities towards V. cholerae strains belonging to both the biotypes and the serotypes, and (b) upon crossed immunoelectro-phoresis produced several immunoprecipitation reactions towards whole-cell sonicates belonging to all types of V. cholerae. These proteins were immunogenic in the rabbit intestine, as antibodies of two classes (IgG and IgA) were detected in the intestinal fluids. The intestinal immune response was greatly enhanced when cell surface proteins were administered with liposomes. These results suggest that cell surface proteins represent common antigens of V. cholerae and can be explored as vaccine candidates against cholera.
-
- Physiology And Growth
-
-
-
Buoyancy Regulation in a Strain of Aphaniz.omenon flos-aquae (Cyanophyceae): the Importance of Carbohydrate Accumulation and Gas Vesicle Collapse
More LessSummary: Buoyancy regulation in light-limited continuous cultures of Aphanizomenon flos-aquae was studied. Gas vesicle collapse did not occur during growth under a light-dark cycle. Only cultures with growth rates less than 20% of the maximal growth rate were positively buoyant. The loss of buoyancy at higher growth rates was due to a lower gas vesicle content in the cells. Carbohydrate accumulation was the main factor which caused buoyancy loss if the cells were shifted from low to high photon flux densities. In these experiments turgor-induced gas vesicle collapse occurred only in cultures adapted to long light periods, and several hours after the cells had lost buoyancy due to ballast increase. The results are discussed in relation to adaptation patterns in photosynthesis and carbon metabolism caused by intermittent light.
-
-
-
-
Characterization of Cell Cycle Events in the Dark in Anacystis nidulans
More LessSummary: Anacystis nidulans (Synechococcus PCC 6301) is an obligate phototrophic cyanobacterium. When light-grown cultures of Anacystis are transferred to the dark, the on going cell cycles are aborted. To characterize the fates of cell cycle events in the dark, synchronized cultures of A. nidulans,taken at various phases of growth, were placed in the dark and the macromolecular contents and cell numbers were determined. Cell number did not increase in any culture in the dark. Protein and RNA contents remained the same. However, cultures in the last hour of their respective synthesis periods showed detectable increases in protein and RNA contents. In cultures in the early stages of DNA synthesis, no sustained increase in DNA was observed, indicating that DNA replication was not completed in the dark by these cultures. However, incorporation of 32P in the DNA fraction in the dark suggested that DNA replication was completed for cultures in the last stages of DNA synthesis. These results suggest that macromolecular synthesis and cell septum formation were curtailed (with the exceptions indicated above) and further progress in the cell cycle stopped in the dark.
-
-
-
Photosynthesis, Carbon Flows and Growth of Oscillatoria agardhii Gomont in Environments with a. Periodic Supply of Light
More LessSummary: The cyanobacterium Oscillatoria agardhii was grown in continuous cultures with light periods of various duration at a constant irradiance. Growth at shorter light periods led to light-limited cultures. P max was the only photosynthetic parameter that reflected increastng pigment contents at shorter light periods; α and q O 2, were maximal with light periods of8 h and less. The dynamics of the carbohydrate pool with light/dark cycles are described in a concept ofthree maxima: a maximum accumulation rate, a maximum content and a maximum consumption rate. With shorter light periods the growth yield on carbon increased as did yield values for dark growth on carbohydrate. Rates ofprotein synthesis were equal in the light and dark for light periods >8 h; with shorter light periods the rates of protein synthesis in the dark showed a severe drop. From the response of O. agardhii to changes in light/dark cycle we distinguished four ranges in which regulation ofgrowth differed. The central role ofthe photosynthetic apparatus in the different responses to changes in either irradiance or light period is stressed.
-
-
-
Transport and Excretion of L-Lysine in Corynebacterium glutamicum
More LessSummary: L-Lysine transport in Corynebacterium glutamicum was investigated. The bacterium was shown to possess a highly specific, energy-dependent system of active lysine transport. The system transferred lysine into the cells and exchanged intra-and extracellular lysine. Mutations in the transport system did not lead to overproduction ofthe amino acid. Resting cells ofthe parent strain, or of its lysine-producer derivatives with a defective transport system, failed to excrete lysine into the medium. An efflux ofintracellular lysine could be induced by a hyperosmotic shock, and by different membrane-active substances. It has been suggested that C. glutamicum cells are equipped with channels (pores) for excreting lysine from the cytoplasm. These channels appeared to open in response to an increase in the intracellular lysine concentration. The channel permeability also depends on the membrane structure.
-
-
-
Transport and Hydrolysis of Peptides in Saccharomyces cerevisiae
More Lesssummary: The transport and hydrolysis of several radioactive di- and tripeptides in Saccharomyces cerevisiae was studied. A peptide-transport-deficient mutant isolated on the basis of its resistance to nikkomycin Z lost most of its capacity to take up di- and tripeptides. The transport kinetics of [14C]methionylglycine, [14C]methionylsarcosine and [3H]nikkomycin Z indicated that peptide transport is not dependent on intracellular hydrolysis. Intact cells had some peptidase activity towards methionylsarcosine but not towards nikkomycin Z. The relationship between this activity and peptide transport is discussed.
-
-
-
The Specific Uptake of Manganese in the YeastCandida utilis
More LessSummary: Uptake of 54Mn from 10 nM-Mn2+ was shown to be both energy-and pH-dependent. Analysis of the uptake kinetics revealed an apparent half-saturation constant, K t of 16·4 nM-Mn2+ and a maximal rate of transport, V max,of l·01 nmol Mn2+ (g dry wt)−1 min−1 Mn2+ uptake was highly specific, being unaffected by 100-fold molar excess of Mg2+, zn2+, Ca2+, Co2+, Ni2+ and Cu2+; however, uptake was inhibited 30 to 40% by 1000-fold molar excess of Mg2+, Zn2+, Ca2+, Co2+ and Ni2+. Zn2+ competitively inhibited Mn2+ uptake, theK i value being approximately 500-fold greater than the Kt for Mn2+. Efflux studies indicated that metabolic exchange of 54Mn occurred to a small extent. Cellular Mn2+ contents remained relatively constant during growth in batch culture. The Mn2+ transport system observed appears to be analogous to the specific metal transport systems reported in bacteria.
-
-
-
A Comparative Study of Acquired Amidase Activity in Pseudomonas Species
More LessPseudomonas putida PP3 carrying dehalogenases I and II and Pseudomonas aeruginosa PAU3 carrying dehalogenase I coded for by plasmid pUU2 were able to grow on 2-monochloropropionic acid (2MCPA). Neither strain utilized 2-chloropropionamide (2CPA) as a carbon or nitrogen source for growth. Mutations in both strains to 2Cpa+ phenotypes (designated P. putida PPW3 and P. aeruginosa PAU5, respectively) involved the expression of an acquired 2CPA-amidase activity. The amidase followed by dehalogenase reactions in these strains constituted a novel metabolic pathway for growth on 2CPA. P. putida PPW3 synthesized a constitutive amidase of molecular mass 59 kDa consisting of two identical subunits of 29 kDa. For those amides tested this acquired enzyme was most active against chlorinated aliphatic amides, although substrate affinities (K m) and maximum rates of activity (V max) were poor. P. aeruginosa PAU5 acquired a 2Cpa+ phenotype by overproducing the A-amidase normally used by this species to hydrolyse aliphatic amides. The A-amidase had only slight activity towards 2CPA. However, with constitutive synthesis the mutant grew on the chlorinated substrates. Chloroacetamide (CAA) was a toxic substrate analogue for these Pseudomonas strains. A strain resistant to CAA was isolated from P. aeruginosa PAU5 when exposed to 1–10 mM-CAA. This mutant, P. aeruginosa PAU6, synthesized an inducible A-amidase. CAA-resistance depended upon the simultaneous expression of CAA-inducible amidase and dehalogenase activities.
-
-
-
Adaptation of Pseudomonas putida mt-2 to Growth on Aromatic Amines
More LessSummary: Pseudomonas putida mt-2 (ATCC 33015) carrying the TOL plasmid pWW0 could adapt to growth on the aromatic amines aniline and m-and p-toluidine. In strain UCC2, a derivative adapted to rapid growth on these compounds, they were oxidatively deaminated to catechol or 4-methylcatechol, which in turn were dissimilated by a meta-cleavage pathway. The aniline/toluidine oxygenase and the meta-cleavage pathway enzymes were inducible by aromatic amines. Evidence is presented that in strain UCC2, plasmid pWWO has undergone deletion of its catabolic genes, and that it is a novel plasmid, pTDNl, which is involved in the catabolism of aniline and m-and p-toluidine. The meta-cleavage pathway genes which are carried by pTDN 1 were shown not to have originated in pWW0.
-
-
-
Isolation and Characterization of Siderophores from Azospirillum lipoferum D-2
More LessSummary: Azospirillum Lipoferum strain D-2 produces the phenolate siderophores 2,3-dihydroxybenzoic acid, 3,5-dihydroxy benzoic acid and salicylic acid under iron-starved conditions. Lysine and leucine were identified as the amino acid conjugates of the siderophores. The concentration of siderophores in the culture supernatant was maximal after 20 h growth. Iron-binding proteins were present in membranes of cultures grown under iron starvation. Iron uptake was enhanced in the presence of each of the siderophores.
-
-
-
Enzyme Activity and Electrophoretic Profile of Extracellular Protein Induced in Trichoderma spp. by Cell Walls of Rhizoctonia solani
More LessSummary: 1,3-β-D-Glucanase and chitinase activities were induced in Trichoderma harzianum when glucose or cell walls of Rhizoctonia solani (anastomosis group AG2) were used as sole carbon source. Electrophoresis showed that more proteins were induced by cell walls than by glucose. The composition, as revealed by electrophoresis, of the T. harzianum extracellular proteins was similar when grown on R. solani AG2 and AG4 cell walls but different for R. solani AG1 cell walls. Several major proteins were induced in all strains of T. harzianum but there were strain differences in the number and intensity of other proteins. The number of induced proteins was less for four strains of T. viride and their composition was different from those of five strains of T. harzianum. The results indicate that chitinase, 1,3-β-D-glucanase and a large number of other extracellular proteins may be involved in the degradation of R. solani cell walls.
-
-
-
Production of Bacteriolytic Enzymes and Degradation of Bacteria by Filamentous Fungi
More Lesssummury: Of 33 filamentous fungi, representing five taxonomicsubdivisions, 31 were able to grow on heat-killed Bacillus subtilis cells as sole C,N and P source. Two types of decomposition were observed: cytolysis, in which the bacterial cytoplasm was rapidly degraded, leaving apparently empty cell walls, and bacteriolysis, in which the entire bacterial cell gradually disintegrated. Supernatants of cultures in which the latter type of attack occurred contained enzymes capable of dissolving bacterial cell walls. Most of these enzymes were glycosidases with pH optima of 2·0-3·9.Two were peptidases and/or amidases with pH optima of7·8–8·3.
-
-
-
Phenotypic Characteristics of a Slow-growing, Nongerminating Variant of Candida albicans
More LessSummary: Some of the phenotypic characteristics of a slow-growing, nongerminating variant of a commonly studied strain of Candida albicans are described. The variant arose as a chance isolate. The rate of occurrence was about 0·1% and the reversion rate was about 1 per 106 cells. The colony size was typically smaller than that of the parent and the yeast cells tended not to separate from one another so that catenulate strands of cells (pseudohyphae) were formed. Under standard conditions the generation time of the small-colony variant in liquid shake cultures was about twice that of the parental strain. Growth of the variant was suppressed by antimycin A, indicating that the small colony form was not the consequence of a defect in the cytochrome system. The colony size of the variant was not influenced by chlorobenzotriazole, which suggested that adenine metabolism was not involved in the small-colony phenotype. The pseudohyphal growth pattern was not relieved by high concentrations of utilizable carbohydrates, which means the catenulate microscopic appearance of the yeast cells was not simply an exaggeration of the normal growth pattern of isolates of C. albicans but more probably represented the growth of a cell-cycle mutant defective at the cell separation step. The cytoplasmic proteins of the variant and the parent were very similar though some unique peptides were displayed by each.
-
-
-
Dimorphism-associated Variations in the Lipid Composition of Candida albicans
More LessSummary: Yeast and mycelial forms of Candida albicans ATCC 10231, growing together in 12 h and in 96 h cultures, were separated and their lipids were extracted and characterized. The total lipid content of the yeast forms was always lower than that of the mycelial forms. In 12 h cultures the lipids from the two morphological forms consisted mainly of polar compounds, viz. phospholipids and glycolipids. In 96 h cultures both the yeast and mycelial forms accumulated substantial amounts of apolar compounds, mainly steryl esters and triacylglycerols. The mycelial forms were more active than the yeast forms in this respect. Major differences in the lipid composition between the two morphological forms involved the contents of sterols and complex lipids that contain sterols. As a rule, the yeast lipids contained much larger proportions of free sterols than the mycelial lipids. However, the mycelial lipids contained several times more sterols than the yeast forms but bound as steryl glycosides, esterified steryl glycosides and steryl esters. Steryl glycosides and esterified steryl glycosides occurred in yeast lipids only in traces, if at all. The major steryl glycoside in the mycelial forms was unequivocally identified as cholesteryl mannoside. At both phases of growth the apolar and polar lipid fractions from the mycelial forms contained higher levels of polyunsaturated fatty acids (18:2 and 18:3) but lower levels of oleic acid (18:1) than the corresponding fractions from the yeast forms. The lipid content and composition of 12 h and 96 h yeast and mycelial forms of C. albicans KCCC 14172, a clinical isolate, were almost identical with those of C. albicans ATCC 10231.
-
- Systematics
-
-
-
Phenotypic and Genotypic Diversity of Pseudomonas tolaasii and White Line Reacting Organisms Isolated from Cultivated Mushrooms
More LessSummary: We compared 21 bacterial strains isolated in Belgium from cultivated Agaricus bisporus, Pleurotus ostreatus and Psalliota edulis showing typical brown blotch symptoms, with 12 culture collection strains of Pseudomonas tolaasii, nine P. agarici strains causing drippy gill, four ‘P. gingeri’ strains causing ginger blotch, three Pseudomonas strains responsible for mummy disease, three saprophytic P. fluorescens, four P. aeruginosa and three ‘P. gingeri’ strains. All strains were characterized by 147 auxanographic API tests (API 50CH, API 50AO, API 50AA) and by 128 (for 14 strains, 55) additional biochemical, serological and phytopathological features. The results were analysed by numerical methods. Taking into account also results obtained by gel electrophoresis of soluble proteins and by DNA:DNA hybridizations, we were able to differentiate seven groups, corresponding respectively to P. aeruginosa (phenon I), P. fluorescens biovar II (phenon II), (phenon III), P. tolaasii, including nine of our own isolates (phenon IV), the so-called white line reacting organisms, containing 11 of our own isolates (phenon V), two mummy disease isolates (phenon VI) and P. agarici (phenon VII). P. tolaasii formed a homogeneous group, containing both virulent and avirulent strains. The saprophytic white line reacting organisms of phenon V were, despite their phenotypic similarity, heterogeneous genotypically and in their gel electrophoresis patterns. A determinative scheme for the differentiation of P. tolaasii, the white line reacting organisms and the other Pseudomonas species occurring on mushrooms is proposed.
-
-
-
-
Separation of Mycobacterium gadium from Other Rapidly Growing Mycobacteria on the Basis of DNA Homology and Restriction Endonuclease Analysis
More LessSummary: DNA was isolated from Mycobacterium gadium with high purity. Its G + C content was between 64 and 67 mol%. The homology of M. gadium DNA with DNA from three other rapidly growing mycobacteria was less than 22%, which indicates that M. gadium is a discrete genomic species. Analysis of the DNAs with restriction endonucleases supported this finding.
-
-
-
KM1, a Bacteriophage of Clostridium butyricum
More LessSummary: Characteristics of bacteriophage KM1, which infects Clostridium butyricum, are described, and several important properties are compared with those of phage 5, which infects the same species. Phage KM1 has a hexagonal head and a tail with a contractile sheath. Agarose gel electrophoresis patterns of BglII, EcoRI and HindIII fragments of the two phage DNAs differed greatly. The G+C contents were 30·5 mol% for phage KM1 and 35·4 mol% for phage 5. Among the 32 strains of clostridia tested, phage KM1 infected only C. butyricum MII588. Other properties of phage KM1 are also discussed.
-
-
-
Physiological and Genetic Characterization of a Diazotrophic Pseudomonad
More LessSummary: A soil isolate, 4B, which had been previously assigned to the genus Pseudomonas and shown to be capable of reducing C2H2 with simple phenolic compounds as sole carbon source, was further characterized in comparison with two other diazotrophs which were identified as pseudomonads. The DNA base composition of 4B was 60·2 mol% G + C. Plasmid DNA was not detected in alkaline SDS lysates of 4B by agarose gel electrophoresis. Comparable maximum C2H2 reduction activities in 4B were observed under microaerobic conditions (pO2 about 0·003 atm) with either 28 mM-glucose or 5 mM-protocatechuate as carbon source. N2 fixation was confirmed by the cellular incorporation of 15N2 in cultures of 4B grown in N-free medium. Extensive biochemical tests, including the carbon utilization pattern, demonstrated that 4B was closely related to Pseudomonas delafieldii (ATCC 17505) although the latter did not fix N2. 4B had metabolic patterns different from the two other strains reported to be diazotrophic pseudomonads; all three contained DNA homologous to the nifHDK genes of Klebsiella pneumoniae M5A1.
-
-
-
Fatty Acid Composition as a Guide to the Classification of Selected Genera of Yeasts Belonging to the Endomycetales
More LessSummary: Gas chromatography was used to determine the long-chain fatty acid composition of 33 strains representing 17 genera of the Saccharomycetaceae, Endomycetaceae, Metschnikowiaceae and Saccharomycodaceae. The similarities between the strains were calculated on the basis of fatty acid composition, resulting in three groups. Group I strains contained oleic acid (C18 : 1) as the major fatty acid, while group II strains had substantial proportions of both oleic acid and linoleic acid (C18 : 2). Strains of group III were characterized by a high percentage of palmitoleic acid (C16 : 1). The one strain of Metschnikowia reukaufii studied fell within the range of variation of group II, but it contained a slightly higher proportion of palmitoleic acid than the other strains in this group.
-
- Short Communication
-
-
-
The Long-chain Fatty Acid Compositions of Species Representing the Genera Saccharomyces, Schwanniomyces and Lipomyces
More LessSummary: The cellular long-chain fatty acid composition of 31 yeast strains representing species of Saccharomyces, Schwanniomyces and Lipomyces was determined by gas chromatography of fatty acid methyl esters. The fatty acid profiles of the strains representingthe three genera were distinguishable from each other. The Saccharomyces and Lipomyces strains were characterized mainly by the presence of palmitic (C16 : 0), palmitoleic (C16 : l), stearic (C18 : 0) and oleic (Cl8 : 1) acid as the major fatty acids. The Schwanniomyces strains were characterized by the presence of palmitic, palmitoleic, oleic, linoleic (C18 : 2) and linolenic (C18 : 3) acid. The 31 strains were divided into three groups on the basis of their fatty acidcontent. The first group was characterized by a higher concentration of linoleic and linolenic acid, the second group by the absence of linolenic acid, and the third group by the absence of both linoleic and linolenic acid.
-
-
-
-
Isolation of a Mycelial Mutant of Candida albicans
More LessSummary: A mutant of Candida albicans strain MEN, which was unable to produce mycelia in SSV medium and in horse serum at 37 °C, was isolated by a physical separation procedure. The mutant was shown to be derived from the parental strain by growth and morphology studies, sugar uptake and fermentation patterns, and the presence of genetic markers.
-
-
-
Phagocytosis of Campylobacter jejuni and C. coli by Peritoneal Macrophages
More LessSummary: Guinea-pig resident peritoneal macrophages had no activity against freshly isolated Campylobacter jejuni, whilst C. coli was phagocytosed and killed. The number of bacteria killed by macrophages always exceeded the number of those ingested, suggesting an extracellular mechanism of killing.
-
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)