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

Physiological properties, properties of their lactate dehydrogenases and DNA /DNA relatedness have been determined for strains of streptococci which grow at 10°C but not at 45 °C; these include strains of Streptococcus lactis, Streptococcus cremoris and Streptococcus raffinolactis. The results show that S. lactis and S. cremoris are variants of a single species unrelated to S. raffinolactis and also to a group of strains which cannot be separated from S. lactis on easily determined physiological properties.

Several strains could not be classified but one strain received as Lactobacillus hordniae proved to be a variant of S. lactis by DNA/DNA homology and the properties of its lactate dehydrogenase, although its physiological properties would not indicate that it belongs to that species.

The activity and biomass of soil microorganisms were studied in a nitrogen-fertilized Scots pine forest moor in Sweden. The investigation was made five years after the application of 150, 300 and 600 kg N ha⁻¹ of each of urea and ammonium nitrate, respectively. Soil respiration rate and FDA-active fungal biomass were significantly lower in fertilized plots, the decrease in these levels being proportional to the amount applied. A tendency toward lower bacterial biomass after fertilization was also found. Similar results were obtained both in the organic and the mineral soil. There were no significant differences between the two types of fertilizer. Possible explanations for the results are discussed.

All of 19 different strains of soil bacteria with the ability to utilize chloridazon (5-amino-4-chloro-2-phenyl-3-(2H)-pyridazinone) and antipyrin (2,3-dimethyl-1-phenyl-pyrazolone) as the only carbon source have been shown to harbour plasmid DNA. By agarose gel electrophoresis the presence of at least two different plasmids was demonstrated for all strains, several strains were shown to contain three, four or even six plasmids. Regarding the size of the plasmids considerable variations within the different plasmids of one strain and among the different bacterial strains have been observed. Molecular weights in the range of 8.0 to 300 Md were found.

Evidence is presented for a correlation of degradative capacity and the presence of plasmids: Strains K2 and K3 which are able to utilize antipyrin as their sole carbon source, were found to loose this capacity spontaneously by repeated transfers on antipyrin-free media, giving rise to mutant strains with the phenotypes Phe⁺AP⁻. These mutants were found to be devoid of the first enzyme of the degradation of antipyrin (dioxygenase). No revertants to the wild types were obtained hitherto. Both mutant strains were found to contain only one plasmid of 14.0 Md. The wild types (Phe⁺AP⁺), however, contain two plasmids of 21.5, 14.0 Md (K2) and of 20.2, 14.0 Md (K3). The 14.0 Md plasmid was shown to be identical in strains K2 and K3 (Phe⁺AP⁺ and Phe⁺AP⁻) by restriction endonuclease cleavage and by hybridization experiments. The existence of two pathways for the metabolism of phenylalanine, one assumed to be plasmidborne the other one encoded by chromosomal genes, is discussed.

The methyl esters of the fatty acids of 45 strains of Mycobacterium avium and 40 strains of 20 other species were studied by gas-liquid chromatography. A mean theoretical profile (MTP) was etablished from 32 strains of Mycobacterium avium. All the strains of Mycobacterium avium investigated displayed a profile identical to that of the MTP; no difference was observed between Mycobacterium avium and Mycobacterium scrofulaceum, nor between the different serotypes of Mycobacterium avium. The 12 fatty acids studied in Mycobacterium avium were also found in the other species of Mycobacteria and the analysis of their relative peak heights (excluding that of palmitic acid) enabled their classification into 3 groups. Some of these groups exhibited particular differences, e.g. the presence of differing types of branched chain fatty acid in Mycobacterium kansasii and Mycobacterium gordonae. The existence of some other peaks supplementary to those of the 12 typical fatty acids were also noted. These were defined according to their retention times relative to C16:O with respect to a large number of species, of which Mycobacterium tuberculosis was one. The usefulness of this technique is, however, restricted due to the costs of chromatography involved.

The glyceraldehyde-3-phosphate dehydrogenases from Streptococcus faecalis, Lactobacillus acidophilus and Pediococcus cerevisiae were purified to homogeneity and characterized. The respective enzymes exhibit estimated molecular weights of 135,000, 155,000 and 152,000. The enzymes appear to be composed of four subunits of identical size ranging from a molecular weight of 37,000 to 42,000. Preliminary immunodiffusion experiments with anti P. cerevisiae glyceraldehyde-3-phosphate dehydrogenase serum indicate that the enzymes share some degree of structural homology.

Most of the species of the two largest groups of archaebacteria - halobacteria (9 strains) and methanogens (10 strains) - were tested by the agar diffusion test for their sensitivity to 28 well-known antibiotics including typical inhibitors of membrane function and the synthesis of cell wall polymers, protein or RNA. Archaebacteria were found to be insensitive to many antibiotics acting against eubacteria and eucaryotes, e.g. those inhibiting the synthesis or cross-linkage of the peptide subunit of murein or the synthesis of RNA. They are, however, sensitive towards inhibitors of the lipid cycle of the biosynthesis of cell wall polymers, to the protein inhibitor chloramphenicol, and to the feed additives lasalocid and monensin, which interfere with the membrane function. It remains to be shown, whether this insensitivity to many of the antibiotics is due to the impermeability of the cytoplasmic membrane or to the inactivation of the antibiotic by the cell rather than to the lack of a particular target for the antibiotic. It is pointed out that the very characteristic sensitivity pattern of archaebacteria may serve as a guideline in the search for further biochemical and molecular differences between archaebacteria, eubacteria, and eucaryotes, and that it may also be helpful in designing selective media for the enrichment and isolation of new types of archaebacteria or in controlling mixed populations of eubacteria, archaebacteria, and eucaryotes, e.g. in the rumen and in biogas plants.

The growth of five strains of Vibrio alginolyticus, using standard inoculum cells in the late logarithmic growth phase, was tested in Trypticase-Soy-broth with 0.5, 3, and 6% sodium chloride concentration (0.5, 3, 6 TSB) adjusted at pH values ranging from 4.5 to 12 in 0.5 unit. The individual growth as well as the mean growth levels for the five strains were recorded after 2, 4, 7, and 14 days incubated at 5, 10, 20, 37, and 42 °C, respectively.

V. alginolyticus strains showed most favourable growth rate in a 3% NaCl solution, while the growth in a 6% solution was lower and the lowest growth was found in the 0.5% solution. Testing the influence of low temperature the strains showed that at 10 °C and 5 °C, respectively four days and seven days elapsed before signs of growth appeared, while high temperature (42 °C) produced regular growth (except with 0.5 TSB). Under favourable temperature and salt concentration V. alginolyticus showed acceptable growth at pH values ranging from 4.5–5 to 10.5–11. After two weeks incubation at 5 °C growth could be registered. The marine strain gave sharp and accurate results in contrast to the international type cultures.

The interrelation between methanogenic and desulfuricating bacteria was investigated in the anaerobic sediment of the impounded Saar river during a period of 18 months. This interrelation was mainly determined by the water discharge. The carbon and electron flow, normally observed in the river, was altered by high water, which introduced sulfate into the sediment and thus stimulated sulfate reduction and inhibited methanogenesis. On the other hand, low water prevented sulfate from penetrating into deeper sediment layers and thus favoured methanogenesis. Since methanogenic bacteria kept the partial pressure of hydrogen low, sulfate-reducing bacteria were allowed to release hydrogen and thus to remain metabolically active.

The inhibition of methanogenic bacteria by sulfate was overcome by the addition of organic substrates. According to these laboratory experiments, the available organic substrates were limiting and responsible for the observed competition. The same was particularly true in deeper layers of the sediment. Acetate accounted for only 4–13 % of the methane formed in the sediments. The turnover rate of acetate (0,052 μmol · g⁻¹h⁻¹) was comparatively low with respect to other methanogenic environments. Acetate was consumed by sulfate-reducing bacteria as indicated by high colony counts, obtained on acetate medium. In the sediments the major proportion of the methane formed (81–96 %) arose from the reduction of carbon dioxide by hydrogen.

A rapid membrane filter method employing ECD agar for the direct enumeration of Escherichia coli type 1 in water is described. After a preincubation period of 4 h at 37 °C on trypticase soy agar the membrane is transferred to ECD agar for an additional 12–24 h incubation at 44 °C. E. coli colonies are identified by a positive indole test performed directly on the membrane.

E. coli colonies are easily recognized within a few minutes by their red color and a red halo surrounding the colony. The positively evaluated colonies from natural samples were confirmed to indeed be comprised of E. coli to an extent of 98%.

No difference in E. coli recovery from natural samples was obtained by these means when compared with tests utilizing either M-FC medium or tergitol 7 agar. Regarding specificity, however, the described method was found to be superior to both the M-FC and the tergitol 7 procedures.

In this communication we report on the taxonomic position of strains previously alloted to group F by numerical phenotypic analysis (Gavini et al., 1976b) according to DNA-DNA hybridization studies. This group comprising 28 strains isolated from drinking water and soil is related to the genus Citrobacter on the basis of the IMViC tests. It differs from this taxon with respect to the numerical analysis of its phenotype and also in its G + C mol % of DNA (Ferragut et al., 1978a).

DNA reassociation obtained with labeled reference DNA from strain F44 = CUETM 77-167 showed that 60% of the F-strains constitute a genetically homogenous group with a relative binding rate higher than 82%. The other strains of this group showed a lower DNA-DNA relatedness (32 to 66%). The experiments carried out with species of the family Enterobacteraceae revealed moderate (35–43%) and low (4–35%) levels of relatedness.

The phenotypical and genotypical data allow us to propose a new genus Buttiauxella gen. nov. for F-strains with a relative DNA relatedness higher than 80%. A new species designated Buttiauxella agrestis sp. nov., with strain CIP 80-31 (= CUETM 77-167) as the type strain, is described.