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W T Dobrzański

Publications and source records attributed to W T Dobrzański.

At least 19 recordsLinked to original sources
PubMed1985

Bacteriophages of Bacillus polymyxa.

Virulent bacteriophages of colistin--producing Bacillus polymyxa strains were studied. The phages were found to differ in lytic spectrum and were active only against strains of B. polymyxa. They did not attack other strains of the genus Bacillus. The virulent bacteriophages belong to two morphological groups differing in size. The size of the DNA of the bacteriophages of both groups is similar and ranges from 74.9 X 10(6) to 87.8 X 10(6) daltons. The cells of different B. polymyxa strains were also found to carry various defective phages which could be shown after mitomycin C induction of cell cultures. The antibacterial activity of mitomycin C induced cell lysates was not detected. Strains of B. polymyxa most probably devoid of defective bacteriophages (delysogenized) were isolated.

Bacillus↗
PubMed1983

Isolation and preliminary characterization of Streptococcus cremoris (strain 202) bacteriocin.

Ability to produce bacteriocin (lactostrepcin) is demonstrated in Streptococcus cremoris. However, lactostrepcin was found to be produced by only one strain (strain 202) out of the 17 S. cremoris strains tested. This bacteriocin is preliminarily characterized, it differs from other lactic streptococci bacteriocins. The strain 202 bacteriocin acts on many strains of lactic streptococci, strains of Bacillus cereus, and some strains of Leuconostoc and Lactobacillus. It was shown that strain 202 contains some plasmids, but we were not able by preliminary observations to prove the plasmid localization of the determinant(s) for lactostrepcin production by this strain. In persistent lactostrepcin-negative variants of strain 202, in comparison with the parental strain, the plasmid pattern may be changed or unchanged.

Bacteria↗
PubMed1983

Surface-located trypsin-activated Streptococcus sanguis strain Wicky endonuclease.

A new Streptococcus sanguis strain Wicky endonuclease was isolated, purified and partially characterized. This nuclease acts preferentially on thermally denatured DNA, is not inhibited by RNA and is activated 3-5 times by trypsin. This activation is accompanied by the reduction of molecular weight of the enzyme. These features distinguish the new S, sanguis nuclease from the 3 previously described S. sanguis endonucleases. With covalently closed circular plasmid DNA, the enzyme causes first the appearance of a single stranded nick, then the second nick on the opposite DNA strand, resulting in plasmid DNA linearization. This nuclease most likely is located at the cell surface. The possible relationship of the described nuclease with ability of S. sanguis cells to take up DNA in genetic transformation is discussed.

Cell Membrane↗
PubMed1981

Role of Streptococcus sanguis (strain Wicky) cell surface-located deoxyribonucleic acid-binding factor in transformation of a homologous strain.

In a previous report we demonstrated the presence of a factor binding deoxyribonucleic acid (DNA) in vitro (BF) in cell leakage fluids from transformable Streptococcus sanguis strains Wicky, Challis, and Blackburn. BF originating from strain Wicky was purified to homogeneity, and its properties are described. In this work, it was found that BF occurs at the surface of Wicky cells in two forms, loosely bound (LB-BF) and strongly bound to the cell envelope. It was demonstrated that LB-BF formed fast-sedimenting complexes with exogenous DNA at the surface of Wicky cells. About 10-fold-more DNA became associated as a fast-sedimenting complex in competent than in incompetent cells. Thus, LB-BF is a cell receptor for exogenous DNA. However, the comparison of the effects of some agents on the transformation yield and the formation of LB-BF-DNA complexes, showed that the influence of these agents on both observed phenomena is not parallel and may be even opposite. These results are interpreted to mean that the LB-BF-DNA complexes do not take part in transformation. The problem of participation of BF strongly bound with the cell membrane fraction remains to be elucidated.

Carrier Proteins↗
PubMed1980

Purification and properties of deoxyribonucleic acid binding factor isolated from the surface of Streptococcus sanguis cells.

Deoxyribonucleic acid (DNA) binding factor (BF) was found in surface fluids from competent and noncompetent cells of Streptococcus sanguis strains Challis, Wicky, and Blackburn. Fluids from noncompetent cells exhibited about 10% BF activity compared with extracts from competent cells. BF from competent Wicky cells was purified to homogeneity by electrophoresis and immunodiffusion. Purified BF preparations exhibited slight endonucleolytic activity, directed mainly against single-stranded DNA. Nucleolytic and DNA binding activities present in purified BF could be separated by polyacrylamide gel electrophoresis. Purified BF was sensitive to proteolytic enzymes and to phospholipase D, and its activity was stimulated in the presence of low Triton X-100 concentrations. The protein component of BF is a single, monomeric polypeptide with a molecular weight of 56,000 and an isoelectric point of pH 5.8. Binding of purified BF to DNA was a very rapid process at the optimum temperature, pH, and ionic strength and led to the formation of fast-sedimenting complexes. Purified BF was tested for several properties. It exhibited higher affinity to single- than to double-stranded DNA. It bound poorly to glucosylated phage T4 and single-stranded, synthetic polydeoxyribonucleotides and did not bind to RNA. It protected single-stranded DNA against nuclease S(1) action but did not protect native DNA against deoxyribonuclease I action. No evidence was found for unwinding activity, using double-stranded DNA as a substrate.

Bacterial Proteins↗
PubMed1980

Deoxyribonucleases of Streptococcus sanguis.

Three DNases, designated 1, 2 and 3 have been isolated from lysates of old (incompetent in genetic transformation) and logarithmic phase (competent) Streptococcus sanguis strain Challis cells. These DNases have different electrophoretic mobilities and immunological properties. Influence of some activators and inhibitors on their activity was determined. Molecular weights of 3 DNases are in the range of 52,000--57,000. All these enzymes are endonucleases which degrade native DNA; thermally denatured DNA is a poor substrate. The enzymes described in this paper differ from the previously known DNases of Streptococcus pyogenes and Streptococcus pneumoniae. Nucleases similar or identical to the Challis strain enzymes have been found in two other S. sanguis strains--Wicky and Blackburn.

Animals↗
PubMed1978

Lactostrepcins--acid bacteriocins produced by lactic streptococci.

All 47 non-nisin producing strains of Streptococcus lactis and 12/13 strains of Str. lactis subsp. diacetylactis examined produced bacteriocins, for which the term lactostrepcins is suggested. Seven strains of Str. cremoris examined produced no bacteriocins active against 3 lactic streptococci strains used as indicators. The strains examined were divided into 3 groups: I, those producing lactostrepcins active against only one streptomycin resistant mutant of Str. lactis 60 indicator strain; II, those producing lactostrepcins active against all 3 indicator strains; III, those not producing lactostrepcins active against the indicator strains employed. The lactostrepcins were sensitive to various proteolytic enzymes and to phospholipase D, but retained full or partial activity after dialysis. Most of the bacteriocins studied were fully active only within the pH range 4.2--5.0 and were reversibly inactivated at pH 7.0 or 8.0. Results suggested occurrence of 4 different lactostrepcins. The lactostrepcins produced by all group I strains were the same, but there were differences among the lactostrepcins produced by group II strains. Lactostrepcins killed some beta-haemolytic streptococci and some strains of Lactobacillus helveticus. One of the lactostrepcins was also active against certain Leuconostoc strains, but not against other Leuconostoc strains, nor against L. helveticus or other Gram-positive bacteria.

Bacteriocins↗
PubMed1978

Enchancement of streptococcal transformation yield by proteolytic enzymes.

Trypsin and other proteolytic enzymes, added together with transforming DNA or during cell-DNA contact to competent cultures of several streptococcal strains, enchanced (10 to 600%) the yield of genetic transformation (stimulation). With few exceptions, the level of stimulation was high (over 100%) when competence was low (below 2%). Stimulation was caused by the action of an enzyme on competent cells and not on any other component of transformation mixture. The phenomenon occurred when the enzyme was added to the culture not earlier than 7 min before and not later than 5 min after the period of cell-DNA contact. The presence of trypsin during cell-DNA contact caused: (i) the alterations at cell surface, demonstrated by electron microscopy, increased release of 3H-amino acid-labeled material, and higher cell susceptibility to autolysis; (ii) the increase of both total and irreversible binding of DNA by the cells; and (iii) the decrease of early nucleolytic degradation of DNA by cells. These and other data point to the importance of a delicate balance of recipient cell's surface nuclease activities in the effectiveness of transformation process. It is also possible that trypsin eliminates an unknown cellular factor which obstructs DNA-cell receptors interaction.

DNA, Bacterial↗
PubMed1978

Competence-related increased enzyme release from Streptococcus sanguis (Wicky) cells.

The ablity of competent and noncompetent Streptococcus sanguis (strain Wicky) cells to release enzymes to the environment was studied. Both competent and noncompetent cells leaked the enzymes tested (aldolase, phosphatase and deoxyribonuclease), but the activities liberated from the competent cells were always roughly 2-fold higher than those released from noncompetent cells. This increased enzyme leakage from competent cells occured in all kinds of media and procedures employed. The leakage of enzymes followed a time-dependent kinetics (different for aldolase and phosphatase), was temperature sensitive and had a pH optimum. The increased enzyme release was most likely not due to cell disruption, but seemed to be rather a consequence of alteration in cell barrier permeability. These results strongly support the "unmasking" model proposed for explanation of competence development in bacteria.

Deoxyribonucleases↗
PubMed1977

Growth requirements and the effect of organic components of the synthetic medium on the biosynthesis of the antibiotic nisin in Streptococcus lactis strain.

A synthetic medium SM-3 has been elaborated for growth of Streptococcus lactis strain 51, which contains the minimal number of organic components required for the growth of this strain and nisin production. This medium contains 9 amino acids, 4 vitamins from B group, glucose and mineral salts. Addition of biotin to the medium stimulated the growth of the strain, while the addition of purines and/or pyrimidines had no effect. Hitherto biotin has been considered to be necessary for the growth of S. lactis and purines and pyrimidines were believed to stimulate the growth of these bacteria. In strain 51 the minimal requirements for growth were also the minimal requirements for nisin biosynthesis. Strain 51 produced 3-4 times less nisin in medium SM-3 than in a complex medium. The addition of one of four amino acids (serine, proline, cysteine or cystine) to SM-3 medium increased the amount of antibiotic produced. The addition of all four amino acids simultaneously, caused formation of nisin amounts similar to those produced in complex medium.

Amino Acids↗
PubMed1975

Nuclease content of group H Streptococcus strain Challis cell surface extracts inactivating transforming deoxyribonucleic acid.

Besides the competence factor (cpf), the activity of nuclease present in cell surface extracts (iF) is most likely necessary for the occurrence of competence in transformation of Challis strain and other group H streptococci. Very small amounts of iF activity were available. For this reason there were no data on nucleases occurring in iF preparations. In our previous studies, three deoxyribonucleases (endonucleases) were isolated and partly purified from stationary Challis strain cells. In the present work, due to the application of stationary-phase cell endonucleases, gel electrophoresis, and the immunological method, we found that two of these nucleases occur in Challis strain iF preparations. These two nucleases are present in larger amounts at the cell surface only in cells originating from the early-logarithmic-phase culture. Only in this phase does competence occur in the Challis strain. Antibodies against the three endonucleases of the Challis strain do not block the occurrence of competence. We suggest that an increase in the permeability of the cell membrane for intracellular nucleases independent of cpf activity is a stage in the maturation of competence.

Bacterial Proteins↗