- Volume 133, Issue 2, 1987
Volume 133, Issue 2, 1987
- Physiology And Growth
-
-
-
Synchronous Akinete Germination and Heterocyst Differentiation in Anabaena PCC 7937 and Nostoc PCC 6720
More LessIsolates of the filamentous cyanobacteria Anabaena PCC 7937 and Nostoc PCC 6720 were selected in which the germling extruded from the akinete coat at the single cell stage and in which heterocyst differentiation occurred at the two or three cell stage after germination in the absence of combined nitrogen. The process of heterocyst differentiation of these germinating akinetes was synchronous and highly reproducible, and it resulted in transient yields of mature heterocysts exceeding 35% of the total cell population.
-
-
-
-
The Osmotically Regulated proU Locus of Salmonella typhimurium Encodes a Periplasmic Betaine-binding Protein
More LessThe proU locus of Salmonella typhimurium encodes an osmotically induced betaine transport system. We have identified a 31 kDa periplasmic protein, encoded by proU, whose synthesis is induced by osmotic stress. A specific betaine-binding activity with a K D of about 1 m is also present in the periplasm of osmotically induced cells. This activity is absent in those proU mutants which lack the 31 kDa periplasmic protein. Thus, ProU is a periplasmic binding-protein-dependent transport system.
-
-
-
2-Phenylethylamine Catabolism by Escherichia coli K12
More LessEscherichia coli K12 grows on 2-phenylethylamine as sole carbon and energy source by converting it, via phenylacetaldehyde, to phenylacetic acid. Phenylacetaldehyde was formed by the action of an inducible amine oxidase and catalase activity was increased sixfold, presumably to ensure removal of the H202 that was expected to be a product of the amine oxidation. The phenylacetaldehyde was oxidized to phenylacetic acid by an inducible NAD+-dependent dehydrogenase. Mutants defective in phenylacetaldehyde dehydrogenase cannot grow on 2-phenylethylamine as carbon and energy source but can still use it as a nitrogen source.
-
-
-
Co-adaptation of Escherichia coli and Coliphage λvir in Continuous Culture
More LessPopulations of the bacterium Escherichia coli and of its phage λvir appeared to equilibrate in continuous cultures. The bacterial end-populations were heterogeneous in respect of their resistance to λvir and their ability to utilize maltose. The most competitive of the selected bacteria were mutants which had a reduced rate of synthesis of λ-receptor so as to become highly, but not totally, resistant to the phage. The coexisting phage had an increased affinity for the receptor and an altered antigenic specificity, suggesting adaptation of its adsorption site in response to the evolution of resistance in the bacteria.
-
-
-
Glucose and Penicillin Concentrations in Agar Medium Below Fungal Colonies
More LessThe growth of colonies of Rhizoctonia cerealis and Penicillium chrysogenum on solid media in plate cultures was studied. When grown on defined media containing 10–50 mm-glucose, R. cerealis did not cause a significant reduction in the glucose concentration of the medium in advance of colonization, but did cause the formation of a steep glucose concentration gradient in the substrate below the colony; the medium directly below the centre of a 7 cm diameter colony of R. cerealis was exhausted of glucose even when the fungus was grown on medium containing 50 mm-glucose. Penicillin produced by colonies of P. chrysogenum accumulated in the medium in advance of fungal colonization. For a period up to about 18 d after inoculation, the concentration of penicillin in the medium throughout the plate increased with colony development and thereafter, except at the margins of the plate, decreased.
-
-
-
The Influence of Ammonium Permease Activity and Carbon Source on the Uptake of Ammonium from Simple Defined Media by Saccharomyces cerevisiae
More LessWhen growing under defined conditions, cells of the yeast Saccharomyces cerevisiae absorbed ammonium more rapidly with glucose as carbon source than with maltose. Ammonium pool sizes and permease activity were also higher in the glucose-grown cells and the relationship implies that firstly, the sugar is a primary determinant of ammonium permease activity and, secondly, the activity of the permease largely determines both the rate of ammonium uptake and ammonium pool size in the first part of the fermentation.
-
-
-
An Unusual Hexose-ATP-Kinase with Two Catalytic Sites and a Role in Carbon Catabolite Repression in the Yeast Schwanniomyces occidentalis
More LessThe hexose-ATP-kinase of wild-type Schwanniomyces occidentalis (CBS 819) is, like hexokinase PII of Saccharomyces cerevisiae, associated with carbon catabolite repression and phosphorylates d-glucose and d-fructose. The kinase of Schw. occidentalis repression-resistant (DogR) mutants phosphorylates d-glucose, but not d-fructose. Subjecting the wild-type enzyme to 45 °C for a few minutes appears to alter its activity, specificity and kinetic characteristics to that of the mutant enzyme. Fast protein liquid chromatography, with anion-exchange or gel-filtration columns, gel-electrophoresis, and DNA hybridization with the hexl r mutant of the HXK2 (hexokinase PII) gene of Sacch. cerevisiae, all failed to resolve more than one hexose-ATP-kinase in Schw. occidentalis. Hence Schw. occidentalis appears to have a single hexose-ATP-kinase, M r ∼ 72000, with two catalytic sites, analogous to the aspartate kinase/homoserine dehydrogenase of Escherichia coli. One site is hexokinase-like and associated with catabolite repression and the other is glucokinase-like. Values for apparent K m were 7·2 mm-d-fructose and 0·55 mm-d-glucose (hexokinase site) and 0·078 mm-d-glucose (glucokinase site).
-
-
-
Production and Activation of an SDS-resistant Alkaline Serine Exoprotease of Vibrio alginolyticus
More LessVibrio alginolyticus produced an extracellular SDS-resistant protease (protease A) with an apparent M r of approximately 54000 when cultured in complex, proteinaceous media. Ca2+ was required for the activation and stability of this protease. Its activity was inhibited by EDTA and a serine protease inhibitor, but was not affected by an inhibitor of trypsin-like enzymes. Optimum protease activity occurred under alkaline conditions. Two SDS-resistant exoproteases, B and C, with apparent M r values of approximately 41000 and 37000 respectively, were also produced in complex proteinaceous media. Dialysis of cell-free supernatant samples, which contained predominantly protease A, against distilled water, resulted in increased B and C activity. Production of protease A, B and C activities was inhibited by o-phenanthroline, quinacrine and lack of aeration.
-
-
-
The Role of Glucose in the pH Regulation of Germ-tube Formation in Candida albicans
More LessIt has been reported that Candida albicans can form germ-tubes only in the narrow pH range of 6–8, and that by changing only the pH one can regulate germ-tube formation. We found that the pH minimum for germ-tube formation could be dramatically lowered by eliminating the glucose present in many induction solutions. Lee’s medium lacking glucose, ethanol, N-acetyl-d-glucosamine, and proline induced germ-tubes at pH values as low as 3 under most conditions. The presence of as little as 1 m-glucose in these induction solutions was sufficient to cause the cells to grow either as yeasts with multiple buds or as pseudohyphae when the pH was 3·7. However, when C. albicans was grown in any of the above induction solutions (with the exception of ethanol), containing 200 mm-glucose buffered at pH 5·8, not only were germ-tubes formed, but their rate of formation and length were also increased. Preincubation of the cells in a solution buffered at pH 3·7 and containing 200 mm-glucose, before exposure to induction solutions lacking glucose at pH 3·7 or at pH 5·8, did not inhibit germ-tube formation. Likewise, addition of glucose after 45 min exposure to an induction solution was without effect. Theophylline and dibutyryl cAMP did not counteract the action of glucose. Other sugars which suppressed germ-tube formation at low pH were fructose, galactose, mannose, xylose, gluconic acid and the nonmetabolizable sugar 3-O-methylglucose. These results indicate that pH does not directly regulate dimorphism in C. albicans, and that glucose or its metabolites may play an important role.
-
-
-
Establishment of the Steady State in Glucose-limited Chemostat Cultures of Klebsiella pneumoniae
More LessTo investigate the relationship between growth rate and concentration of the nutrient that limits growth, ‘Klebsiella aerogenes’ NCTC 418 (K. pneumoniae) was grown in a glucose-limited chemostat. The actual time required to establish a steady-state glucose concentration exceeded that expected theoretically. Apparently, there is a long-term adaptation of the cells to nutrient limitation. As yet, it is not clear whether this has a phenotypic or genetic origin. In the final steady state, the dependence of the growth rate on glucose concentration could be mathematically described equally well by a hyperbolic and by a logarithmic function.
-
- Systematics
-
-
-
Systematic Analysis of the Long-chain Components of Eubacterium lentum
More LessThe cellular long-chain component patterns of 33 strains of Eubacterium lentum were determined by gas chromatography. Two main types of long-chain component patterns were distinguished. The first (26 strains) was characterized by saturated branched-chain fatty acids (brl4:0, br 15:0, br16:0 and br17:0). The second (7 strains) did not contain branched-chain fatty acids and was characterized by saturated straight-chain fatty acids (11:0,12:0, 14:0 and 16:0). Both types contained fatty aldehydes and their respective dimethyl acetals (14ald and 14dma, 16ald and 16dma). brl6dma was only found in the first type. The G + C content of the DNA (T m) of the 33 strains varied between 63·7 and 69·1 mol %. Canonical correlation analysis distinguished three subtypes within the first main type.
-
-
-
-
Taxonomic Studies on Some Gram-negative Methylotrophic Bacteria
More LessOne hundred and fifteen cultures, including obligate, restricted facultative and facultative methylotrophs and members of possibly related taxa, were tested for 135 characters based on morphology, physiology and biochemistry and the results were subjected to computer analysis. The polar lipid composition of all the strains was examined. The isoprenoid quinone composition and the mol% G + C value of the DNA were determined for all the obligate and restricted facultative bacteria, and also for some of the other strains representative of the clusters formed in the numerical taxonomic study. The results indicate that the obligate methanol-utilizing bacteria all exhibit a high phenotypic similarity and are taxonomically distinct from the restricted facultative and the facultative methanol-utilizing bacteria examined and from the pseudomonad reference strains. The results also indicate that the obligate methylotrophs and the restricted facultative methylotrophs represent two distinct taxa of generic status: Methylobacillus and a taxon which can be equated with the organisms currently referred to as ‘Methylophilus’.
-
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)