Acta microbiologica Polonica. Series A: Microbiologia generalis最新文献

The paper presents studies on the respiratory activity of the soil from two habitats of the Botanical Garden: the steppe and the dune. The abundance of bacteria and fungi in the soils was also estimated. Respiration in the rhizosphere soil was found to be more intense than in the non-rhizosphere soil. Our observations have shown that soil respiration depends largely on the abundance of microorganisms. Under various habitat conditions, however, the microorganisms populations are characterized by some peculiarities of their metabolic activities. These manifest themselves in differences in respiratory activity of various soils independent of additional easily available energetic material introduced into the soil.

In Haemophilus influenzae strains only the type 1 of the restriction endonucleases have an in vivo effect on phage and bacterial transforming DNA. The type 2 of restriction endonucleases which act very efficiently in vitro are completely inactive in vivo. The reasons for this inactivity is unknown.

Lambda bacteriophage adsorbs on the chromosome-less small bodies (minicells) produced by aberrant cell division of Escherichia coli P678-54. The plasmid-less minicells, as well as the minicells harbouring the colicinogenic factor E1, reveal a considerable inhibition of total RNA synthesis after phage adsorption. Both kinds of minicells synthesize RNA hybridizable to lambda DNA, but in the plasmid-harbouring minicells lambda RNA synthesis is much more intensive.

The following stages of mating reaction were analysed in electron micrographs: initial contact of the conjugating cells, formation of a tube-like structure between the mating partners, nuclear fusion and formation of first diploid bud. Nuclear fusion was observed to take place within the conjugation tube, the fusion nucleus, however, was often localised in one of the initial conjugants. The stage of fusion nucleus, preceding the first diploid bud formation, is of longest duration in the mating process. The second longest stage is the formation of a tube-like structure. The whole conjugation process lasts at 25 degrees approximately 60 min. According to the autoradiographic data, DNA synthesis begins after nucelar fusion and proceeds during formation of the first diploid bud.

The fermentative properties of recombinants obtained after conjugation between E. coli K12 HfeC and S. flexneri la Lac Phe mutant were investigated. The recombinants showed the antigenic structure of S. flexneri but their biochemical characteristics differed from the properties typical for this genus. The recombinants were found to acquire the ability to ferment several carbohydrates not degraded by the S. flexneri recipient strain.

The nature of plasmid born resistance of Staphylococcus aureus to cadmium ions has been investigated. Plasmid harbouring strain was significantly more resistant than its plasmid negative variant, both in growth tests and in manometric experiments. Radioisotopic studies have revealed that the resistant organism did not take up 115mCdCl2 at concentrations 10-4M--10-6M, which were also harmless to its respiration. In contrast to this, plasmid negative variant was permeable to all concentrations used (10-3M--10-6M), and the uptake of 115mCd2+ ions always resulted in inhibition of respiration. These findings suggest that the cadmium resistance could be due to the impermeability barrier controlled by plasmid genes. This barrier, however, could be broken through, since at 10-3M some marked uptake of radioactive cadmium by resistant strain was observed, which was accompanied by partial inhibition of respiration. Binding of Cd2+ ions to the sensitive cells was irreversible and temperature dependent (took place at 37 degrees, but did not occur at 2-4 degrees). The bound molecules could not be removed either by extensive washing with water or by cysteine treatment, although cells pretreated with this amino acid were protected against the uptake of 115mCdCl2.

The effect of normal human, rabbit and cow sera, SP50 phage antiserum and the albumin and globulin fractions of normal rabbit serum on transfection of Bacillus subtilis 168 ind was studied. All the sera reduced to varying degrees the efficiency of the process within 60 min. from infection of the culture. None of the sera, except for the antiphage serum, influenced the further course of the process. The albumin fraction of normal rabbit serum otherwise than the globulin fraction, was found to stimulate transfection. The effect of the sera on transfection was influenced by the composition of the media.

A deoxyribonucleoprotein (DNP) complex has been isolated from Escherichia coli cells by chromatography on Sephadex G-200. The DNP complex contains phosphoproteins and the content of phosphorus bound to the DNP protein is 3 times higher than in cytoplasmic proteins not bound to DNA. These results have been confirmed by in vivo (32-P-KH2PO4) and in vitro (32-P-ATP) phosphorylation of E. coli DNA-binding proteins isolated by chromatography on DNA--cellulose.

Further investigations of the instability of restriction and modification properties of H. influenzae Rd strain were carried out. It has been shown that the instable properties of hsd Hind1 system are maintained even after transfer of this system to another H. influenzae strain. The expression of hsd Hind1 system is very sensitive to various physiological changes which do not influence the other hsd systems present in the same Rd strain. The instability of hsd Hind1 system is postulated to be connected with some regulator gene(s).

Comparison was made of the lethal and mutagenic efficiency of 35S yields 35Cl transmutation of incorporated 35S in cells of Escherichia coli strain WP-2 and WP-2S (UV-sensitive). Bacteria were stored at minus 196 degrees. 35S yields 35Cl transmutation induced a higher lethal effect in strain WP-2 than in the UV-sensitive strain WP-2S. Reversions try yields try+ were induced with an approximately similar efficiency in both strains compared.