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

The Archaean is commonly defined as the time of procaryotes. From these, eucaryotes are believed to have evolved not earlier than during the middle or upper Proterozoic. Paleontological evidence, however, contradicts this concept. Microfossils resembling fungi and eucaryotic algae occur in Archaean sediments of the non-stromatolitic facies. These findings suggest that the diversification of life into its principial phyla took place in the lower Archaean, possibly prior to 3,800 million years ago.

The distribution of the various cell wall structures and polymers found in the living world fits together very well with Woese's concept, based on 16S ribosomal RNA sequence similarity, that 3 urkingdoms have emerged from a common ancestor. It is assumed that the common ancestor did not contain a rigid cell envelope, whereas the primitive eubacterial ancestor developed a peptidoglycan sacculus, characterized by muramic acid and a sequence of alternating L- and D-amino acids. This so-called murein occurs in two major structural modifications - monomolecular layer (Gram-negatives) or multilayer (Gram-positives) - and more than 100 chemotypes in all Eubacteria except the Mycoplasmatales. Each chemotype is more or less typical of certain taxa of bacteria. Within the Archaebacteria the cell wall is probably of polyphyletic origin, since no common sacculus or envelope polymer is found. Only after the cell wall-lacking primitive archaebacteria had branched into various physiologically different lines were cell walls independently developed within some of the lines. In the Methanobacteriales a peptidoglycan with a chemical structure quite different from that of murein is found, the so-called pseudomurein, which contains talosaminuronic acid instead of muramic acid and in which D-amino acids are missing. The genus Halococcus exhibits a sacculus consisting of a highly sulfated hetero-polysaccharide containing gulosaminuronic acid, whereas the sacculus of Methanosarcina consists of a different heteropolysaccharide lacking sulfate residues and gulosaminuronic acid. The archaebacteria of all the other groups do not possess a rigid sacculus, but an envelope of protein or glycoprotein subunits or a fibrillary protein sheath enclosing short chains of cells. Only Thermoplasma has not developed any kind of cell envelope.

Within the Eucaryotes the cell wall is probably also of polyphyletic origin. Whereas the animals lack a cell wall, plants, fungi and algae are characterized by rigid cell walls consisting of cellulose, chitin and a variety of heteropolysaccharides, respectively. A diagram demonstrating the correlation between the 16S rRNA-relatedness and the distribution of cell wall structures and polymers within the 3 urkingdoms is presented.

Methanobacterium thermoautotrophicum ΔH and M. thermoautotrophicum Marburg have been investigated for DNA relatedness by DNA-DNA hybridization. The two strains proved to be interrelated on the 46% binding level. The relatively low degree of DNA homology correlated with differences in biochemical and physiological characteristics:

• 1.

  The pseudomurein sacculus of the ΔH strain contained glucosamine and talosaminuronic acid as major sugar components, whereas the sacculus of the Marburg strain contained galactosamine and talosominuronic acid.

• 2.

  One of the eight subunits of the DNA dependent RNA polymerase differed considerably with respect to molecular weight.

• 3.

  The membrane fraction of the ΔH strain exhibited high ATPase activity, which could not be detected in the Marburg strain.

• 4.

  The Marburg strain grew more rapidly (td = 1.6 h versus 2.2 h) and to a higher cell density than the ΔH strain.

Cells of Streptococcus lactis No. 21 were coupled to Sepharose 6B and magnetized with ferrofluid. The agglutinating capacity of immobilized and non-immobilized cells was compared. The immobilized cells can be repeatedly used and may be helpful in the production of jellified noodles.

The survival of four strains of different Proteus species and one of Providentia was determined in two different types of sterile soil. The strains were found to belong to the short-lived enterobacteria in soil with a decimal reduction time of 6 d at 18–20°C and of 3.5 d at 4°C and 37°C, respectively. They are not able to multiply in soil. Enrichment of the soil with (NH₄)₂PO₄ had no significant effect on the survival time, whereas casamino acid led to a lag period of 10–30 days before the total count decreased at the same rate as in non-enriched soils.

The DNAs of seven bacterial strains belonging to Pedomicrobium ferrugineum and P. manganicum were investigated by buoyant density centrifugation and thermal denaturation experiments. The DNA base composition was calculated to range from 66.3 to 67.3% GC in CsCl gradients and from 64.8 to 65.7% GC in thermal transition profiles. The correlation of both methods was T_mo.issc = 428.5 (ϱ — 1.533) under our experimental conditions. Analysis of the DNA nucleotide distributions revealed a homogeneous group characterized by Gaussian distribution with a mean width of 9.19 ± 0.14% GC (uncorrected) and an average degree of asymmetry of 1.16 ± 0.04.

The number of thiobacilli and the thiosulfate oxidation potency were determined in the water and in the sediment of the river Saar in order to study the aerobic part of the sulfur cycle. Samples were taken along the entire course of the river between summer 1978 and spring 1981, i.e. before the lower part of the river was canalized.

In the water samples, a close correlation was observed between the total number of thiobacilli and the thiosulfate oxidation potency. In the sediment of the middle part of the river, which is canalized, the observed concentration and metabolic activity of the thiobacilli, the presence of sulfide and the diminished concentration of sulfate indicated that both oxidation and reduction of sulfur occurred in this reach.

Highest concentrations (numbers) and activities of thiobacilli, both in the water and in the sediment, were observed at low waters in August 1978; 10³ cells/ml water and 10⁵ cells/g sediment were detected. Lowest concentrations and activities were measured during high waters in February 1980. In a longitudinal study of the river the following species were enumerated in water and sediment by means of selective media: T. thioparus, T. neapolitanus, T. denitrificans, T. thiooxidans and T. ferrooxidans.

Downstream from the source, the number of all these species increased, but in case of T. thioparus and T. neapolitanus maximum concentrations were already observed in the upper part of the river, which is not canalized and not polluted by industrial wastes. The remaining three species increased in number along the entire river. The concentrations of the individual species were considerably higher in the sediments than in the overlaying water. In general, the detected numbers were about 10³-times higher in the sediment samples, regardless whether selective or non-selective media were used.

An anaerobic coccus so far classified as P. saccharolyticus is considered to form an anaerobic species of the genus Staphylococcus. Taxonomic studies including cell wall analysis, DNA-rRNA and DNA-DNA hybridization, 16S rRNA analysis and biochemical studies have shown that P. saccharolyticus has to be regarded as a member of the genus Staphylococcus. On the other hand P. saccharolyticus proved to be not generically related to other species of the genus Peptococcus. P. saccharolyticus is described as Staphylococcus saccharolyticus. The type strain of the species is S. saccharolyticus ATCC 14953.

Four strains of the fish pathogen Vibrio anguillarum have been isolated from rainbow trout (Salmo trutta), salmon (Salmo salar), coalfish (Gadus virens) and eel (Anguilla anguilla) kept captive at water temperatures of 1–4°C for aquaculture or other purposes in the vicinity of Tromsø, Norway.

Biochemically, they all closely resemble a reference strain, V. anguillarum NCMB 6. The only important exception was that our strains have lower cardinal temperatures for growth, namely 0°C (minimum), 15–18°C (optimum) and below 30°C (maximum), as opposed to an optimum of 30°C and a maximum of 30–40°C, respectively, for the reference strain.

The 4 isolates grew optimally in media containing 2% NaCl, with outer limits for growth at 0.5% and 5% NaCl. The viability was quickly lost in nutrient media without inorganic salt, in membrane-filtered seawater and by freezing or freeze-drying. The outer pH limits for growth were 5 and 9, respectively. Our strains showed enhanced anaerobic growth yields in the presence of trimethylamine oxide (TMAO).

When examined with immunochemical methods all the strains, including the reference strain, showed serological cross-reaction, but they clearly differed in antigenic structure.