Zentralblatt für Bakteriologie: I. Abt. Originale C: Allgemeine, angewandte und ?kologische Mikrobiologie最新文献

A bacterium capable of utilizing 4-chlorobenzoic acid as its sole carbon source was isolated from soil and tentatively identified as a species of Pseudomonas. The organism is also able to grow on the 4-chloro- and 4-bromo-derivatives of benzoate, phenylacetate, and phenylalanine.

During growth on 4-chlorobenzoic acid, 4-hydroxybenzoate and protocatechuate were accumulated in the culture medium. Protocatechuate was broken down by ortho-fission and further metabolized via the β-ketoadipate pathway. In extracts of 4-chlorobenzoategrown cells, the enzymes responsible for the degradation of 4-chlorobenzoic acid were detected. 4-Chlorobenzoic acid proved to be the only inducer of the dehalogenating enzyme, of 4-hydroxybenzoate 3-hydroxylase and of protocatechuate 3,4-dioxygenase.

Polynucleotide sequence relatedness reactions were carried out to determine the extent of DNA divergence between labelled DNA of Klebsiella pneumoniae and Enterobacter cloacae and unlabelled DNA of E. aerogenes and K. oxytoca. DNA homology between 14 strains of E. aerogenes and one strain of K. pneumoniae and one strain of E. cloacae was 53% ± 3 and 39% ± 4 respectively. Similarly, unlabelled DNA from 11 strains of K. oxytoca exhibited 55% ± 4 and 40% ± 3 DNA relatedness with labelled DNA of K. pneumoniae and E. cloacae respectively. It is concluded that E. aerogenes should be classified in the genus Klebsiella with the denomination of Klebsiella mobilis as previously proposed by Bascomb et al. (1971).

Strain PeH₂20 of leaf nodule bacteria has been identified as a member of Erwinia herbicola subsp. herbicola by the computer-assisted clustering of 60 phenotypic data, by DNA: rRNA hybridizations with ¹⁴C-rRNA from Escherichia coli, Pseudomonas fluorescens and P. acidovorans, and by percent GC determinations. The phenotypical features of the strain have been described.

The numbers of total and actively respiring bacteria were determined in samples of waste-contaminated Baltic sea and lake water. Both parameters were monitored by means of a new simultaneous direct count technique with the aid of a fluorescence microscope. The numbers of total and actively respiring bacteria were consistently higher in polluted samples. The total bacteria numbers were 10² to 10⁴ times greater than plate counts. In addition, the total bacteria numbers showed lower variations from high polluted to low polluted samples than did plate counts. These observations also applied to the actively respiring bacteria. Smaller numbers of these bacteria were always registered for sea water than for lake water. The tendencies described above were better illustrated by the calculated biomass than by the corresponding detected number of bacteria.

A catechol 2.3-dioxygenase, isolated from Nocardia sp. DSM 43251 (Rhodococcus rubrus) after induction with unpolar substituted phenols e.g. 4-(methylthio)-phenol or 4-methoxyphenol, was purified 79-fold by ammonium sulfate precipitation, acetone precipitation, and sephadex G 200 gel filtration. The molecular weight, as determined by gel filtration, was 125,000. SDS-polyacrylamide gel electrophoresis revealed three non-identical subunits with molecular weights from 40,000 to 50,000. Highest activity was obtained at pH 7.5 to 8.5. The enzyme was stable in the presence of oxygen, reducing and oxidizing agents, and at high temperatures with an optimum temperature of 60 °C. Atomic absorption spectrometry proved one atom of iron per molecule of enzyme which could not be removed by dialysis. The ring cleavage reaction was inhibited by metal ions like Ag⁺, Hg⁺⁺ and Cu⁺⁺ (10⁻⁶–10⁻⁵ M), and by 2,2′-bipyridyl (10⁻³ M).

Catechol 2,3-dioxygenase from Nocardia sp. DSM 43251 showed a strict specificity for catechols with a substituent at C-4. Maximum reaction velocity was strongly influenced by the electronegativity of these substituents. Additional methyl groups at C-3 or C-5 decreased the affinity of the enzyme for the substrate as well as the reaction velocity. The structure of the reaction product and linear correlation of the reaction velocity with the tfp-values of the different catechols tested clearly indicate a 2,3-cleavage-mechanism.

A group of seven strains of heterofermentative lactobacilli including the reference strain of Reuter's Lactobacillus fermentum Biotype II (F275 = DSM 20016) isolated from faeces were found to differ from L. fermentum and the other species of the heterofermentative lactobacilli with respect to several phenotypical and genetical characters. These strains are considered as representative of the new species L. reuteri sp. nov., with DSM 20016 being the type strain.

The DNA-dependent RNA polymerase from Methanooacterium thermoautotrophicum was purified to homogeneity under the exclusion of oxygen. The subunit composition formula of the enzyme is: O: (96000)₁; A: (74000)₁; B: (59000)₁; C: (50000)₁; D: (33000)₁; E: (24500)₁; F: (10500)₁; G: (6500)₆. This results in a molecular weight of about 390000 for the complete enzyme. An incomplete particle lacking subunit O and demonstrating a five-fold lower specific activity can be isolated in addition to the complete enzyme by heparin cellulose chromatography. Maximal RNA synthesis is obtained in the presence of about 10 mM MgCl₂ and 200 mM KCl at 50 or 60°C, depending on the template. As are the other archaebacterial RNA polymerases, this enzyme is insensitive to rifampicin and streptolydigin. The spacing of the heavy subunits and the existence of a fragment particle lacking the heaviest subunit are reminiscent of the halobacterial RNA polymerase.

This enzyme is therefore clearly different from eubacterial RNA polymerases but it is similar to other archaebacterial RNA polymerases, thus supporting the theory of Carl Woese concerning the existence of two kingdoms of procaryotes.

A selective medium was developed for isolating coagulase-positive and coagulase-negative staphylococci. The selective agents employed were sodium azide, potassium thiocyanate, lithium chloride and glycine. Addition of lithium chloride and glycine is only necessary if high counts of streptococci are expected. All type strains of the various staphylococcal species and other staphylococci tested revealed good growth on this new medium. S. intermedius was the only exception since its recovery was significantly lower than on control medium. However, normal growth of S. intermedius is possible at a lower sodium azide concentration (15–20 mg/litre). Growth of all micrococci and other bacteria such as various bacilli, arthrobacters, lactobacilli, streptococci, Escherichia coli, Enterobacter cloacae and Proteus mirabilis is inhibited: these organisms do not grow at all or at most as pinpoint-sized colonies. Addition of egg yolk or pork plasma to the medium may provide a basis for distinguishing S. aureus from coagulase-negative staphylococci. The new medium is not only useful for the selective isolation of staphylococci but also represents a new routine method für the separation of staphylococci from micrococci. The great specificity of this new medium could be demonstrated in detecting staphylococci in various foods at levels as low as 100/g.

The “classical” and biochemical characters and the DNA-DNA homology of 37 strains of Lactobacillus acidophilus were determined. Two main homology groups, subdivided into 5 and 2 subgroups, respectively, were established. The subdivision into two main groups was found to correlate with the electrophoretic type of the L-lactic acid dehydrogenase and several features of the cell wall chemistry, whereas no phenotypical characters were found to distinguish the homology subgroups from each other. Therefore the subgroups were not named, although the homology among them was 50% or less, thus justifying their separation into distinct species. At present, only the two main homology groups are considered to constitute named species. The group which contains the type strain of L. acidophilus retains the epithet acidophilus, whereas the other group was recently described as the new species L. gasseri. The implications of the distinct heterogeneity of “L. acidophilus” for intestine bacteriology is discussed.

A chloridazone-degrading bacterium strain E incubated with trans-cinnamic acid accumulated cis-2.3-dihydro-2.3-dihydroxy-trans-cinnamic acid in the culture medium. A chloridazone-degrading bacterium strain N incubated with trans-cinnamic acid, accumulated 2.3-dihydroxy-trans-cinnamic acid in the culture medium. Each metabolite was isolated in crystalline form and identified by a variety of conventional chemical techniques-Catechol-2.3-dioxygenase prepared from the strain E converted 2.3-dihydroxy-trans-cinnamic acid to the meta cleavage product. Cell extracts converted the yellow ring fission product. The production of fumaric acid could be detected with high performance liquid chromatography and with fumarase.