-
Volume 141,
Issue 6,
1995
Volume 141, Issue 6, 1995
- Physiology And Growth
-
-
-
Erwinia chrysanthemi at high osmolarity: influence of osmoprotectants on growth and pectate lyase production
The mechanism of osmotic stress adaptation was investigated in the phytopathogen Erwinia chrysanthemi. Growth of the bacterium was inhibited by elevated medium osmolarity, and exogenous glycine betaine, proline, ectoine or pipecolate permitted recovery of growth at inhibitory osmolarity. Osmoprotectants were taken up by transporters induced by elevated osmolarity, and their level of accumulation within the cell was dependent on the osmolarity of the growth medium. The influence of osmolarity and osmoprotectants on the production of pectate lyases (PLs) was investigated. Increased medium osmolarity resulted first in an induction of PL activity, followed by a shift to the basal level at higher osmolyte concentrations. This induction was reversed by osmoprotectants in the medium. The increased PL activity was attributed in part to the induced transcription of the main PL gene, pelE, and all the osmoprotectants that were analysed were found to prevent pelE induction. PL activity was partially inhibited in vitro by high ionic strength but not by elevated concentrations of sugars, and the addition of osmoprotectants at 1 mM had no effect on PL activity in vitro.
-
-
-
-
The effect of NaCl on the growth of a Halomonas species: accumulation and utilization of compatible solutes
More LessThe effect of NaCl on growth and compatible solute utilization was investigated in a Halomonas species. Growth of Halomonas was observed in medium of low osmolarity (high water activity) when only 01 mM Na+ was present. However, lowering the water activity, by addition of KCl or sucrose, inhibited growth in this low-Na+ medium, but growth could be restored by the addition of NaCl. The bacterium could grow on glucose as the sole carbon source in up to 355 M NaCl and was shown also to metabolize glycine betaine. However NaCl concentrations greater than 2 M inhibited growth when glycine betaine was the sole carbon source. Glycine betaine was transported into the cells by a process stimulated by NaCl irrespective of whether the carbon source was glucose or glycine betaine. Cytoplasmic levels of glycine betaine were monitored throughout the growth cycle in 2 M NaCl medium with glycine betaine as sole carbon source. As the culture aged, glycine betaine was increasingly replaced by the tetrahydropyrimidine ectoine as the major cytoplasmic solute. The increased sensitivity to high NaCl concentrations when grown on glycine betaine may be due to the glycine betaine catabolic pathway enzymes being inhibited by the increasing external solute concentration.
-
- Systematics
-
-
-
Heterogeneity among 16S-23S rRNA intergenic spacers of species within the ‘Streptococcus milleri group’
More LessThe 16S-23S rRNA intergenic spacer has been suggested as a suitable region of the bacterial genome from which to derive useful taxonomic information, particularly with regard to identification at the species level. To investigate this approach as an aid to the identification of the three species comprising the ‘Streptococcus milleri group’ (SMG), the spacers of isolates of Streptococcus intermedius, Streptococcus anginosus and Streptococcus constellatus were amplified by PCR and length polymorphisms determined by agarose gel electrophoresis. Phenotypically atypical isolates which had been identified presumptively as belonging to these three species were also included. Spacers from two representatives of each spacer length found within the three SMG species were sequenced. 16S-23S rRNA intergenic spacer length polymorphisms allowed discrimination between S. anginosus (350 bp or 450 bp amplification product) and S. constellatus (380 bp amplification product), species that are difficult to differentiate phenotypically. S. intermedius (330 bp or 450 bp amplification product) and S. anginosus (350 bp or 450 bp amplification product) were not reliably distinguished by this method but are phenotypically distinct. Sequencing data demonstrated that the spacers had a central region of highly variable length flanked by conserved regions which included a single tRNAAla gene. Polymorphism in the length of the 16S-23S spacer determined by PCR provides a rapid and useful adjunct to strain identification for S. anginosus and S. constellatus, which are not readily differentiated phenotypically.
-
-
-
-
Paracoccus thiocyanatus sp. nov., a new species of thiocyanate-utilizing facultative chemolithotroph, and transfer of Thiobacillus versutus to the genus Paracoccus as Paracoccus versutus comb. nov. with emendation of the genus
More LessA facultatively chemolithotrophic thiocyanate-degrading bacterium, strain THI 011T, which was previously isolated from activated sludge and tentatively named Thiobacillus sp., was studied taxonomically and phylogenetically. This bacterium utilizes thiocyanate as sole energy source and the specific growth rate for chemolithoautotrophic growth with thiocyanate was 0059 h-1. Molecular phylogenetic relationships of strain THI 011T to Thiobacillus versutus and members of the genus Paracoccus were elucidated by comparing 16S rRNA gene sequences. Binary sequence comparisons showed that strain THI 011T was most related to Paracoccus aminophilus, at a similarity level of 970%, and T. versutus was most similar to Paracoccus denitrificans, at a level of 991%. A neighbour-joining phylogenetic tree showed that strain THI 011T formed a cluster together with T. versutus and known species of the genus Paracoccus within the α-3 subclass of the Proteobacteria. DNA-DNA hybridization assays and phenotypic studies indicated that strain THI 011T differed from T. versutus and known species of the genus Paracoccus. On the basis of these results, we propose to classify strain THI 011T into a new species of the genus Paracoccus with the name Paracoccus thiocyanatus sp. nov. We also propose to transfer T. versutus to the genus Paracoccus and present an emended description of the genus.
-
-
-
Molecular systematics of the genus Pleurotus: analysis of restriction polymorphisms in ribosomal DNA
More LessPart of the nuclear ribosomal DNA unit of Pleurotus cornucopiae, including most of the intergenic sequences, was used as a probe to hybridize with DNA from eleven Pleurotus taxa (29 isolates), digested with nine restriction endonucleases. For all digests, a high level of rDNA heterogeneity between and within species was detected, which is in agreement with the phenetic variability already reported in previous studies on Pleurotus taxa. Numerical analysis of the results, performed by use of two different tree-making methods, clearly distinguished among well-defined species, i.e. P. dryinus, P. eryngii and P. flabellatus, which presented large phenetic distances with the rest of the taxa tested. P. abalonus, despite morphological similarity and interfertility with P. cystidiosus, appears to be a discrete taxon. Although they showed relative affinity, P. cornucopiae, P. columbinus and P. ostreatus presented large distances among their representative isolates, supporting the idea that they correspond to distinct taxa. All strains of P. pulmonarius, P. sajor-caju and P. sapidus having small phenetic distances were closely positioned on dendrograms; in relation to results from recent interfertility and isozyme studies, these results support the common genetic background of P. pulmonarius and P. sajor-caju; the position of P. sapidus remains controversial. Furthermore, the rDNA analysis identified ten fragments suitable for species identification: eight allowed the characterization of five taxa (P. cornucopiae. P. ostreatus, P. sajor-caju, P. abalonus and P. columbinus) and two distinguished among clusters including related taxa. By a combination of just two restriction enzymes, the rDNA probe used seems to be the appropriate tool for both varietal characterization and protection of commercially valuable strains.
-
Volumes and issues
-
Volume 171 (2025)
-
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)
Most Read This Month
