This review summarizes the main results obtained in the fields of general and molecular microbiology and microbial genetics at the Institute of Microbiology of the Academy of Sciences of the Czech Republic (AS CR) [formerly Czechoslovak Academy of Sciences (CAS)] over more than 50 years. Contribution of the founder of the Institute, academician Ivan Málek, to the introduction of these topics into the scientific program of the Institute of Microbiology and to further development of these studies is also included.

• MeSH
• Academies and Institutes history   MeSH
• History, 20th Century MeSH
• Genetics, Microbial history   MeSH
• Molecular Biology history   MeSH
• Check Tag
• History, 20th Century MeSH
• Publication type
• Journal Article MeSH
• Historical Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Geographicals
• Czech Republic MeSH

The effect of temperature on extracellular alpha-amylase synthesis and chromosomal and plasmid DNA replication in Bacillus subtilis A18 carrying plasmid pMI10 was studied. The specific growth rate mu increased with elevated temperature up to 42.5 degrees C, while the activities of alpha-amylase per population dry mass decreased. No obvious quantitative changes of 14C-thymidine incorporation per dry mass increase and no basic differences in plasmid copy number in the range of temperatures from 25 to 40 degrees C were found.

• MeSH
• alpha-Amylases biosynthesis   MeSH
• Bacillus subtilis metabolism   MeSH
• DNA Replication * MeSH
• Temperature MeSH
• Thymidine metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• alpha-Amylases MeSH
• Thymidine MeSH

Vector properties of plasmid pNH602, a higher-copy-number deletion mutant of plasmid R6K, were tested by cloning the 6.5 Mg/mol BamHI pSa fragment carrying determinants of resistance to four antibiotics in the unique BamHI site of pNH602. The resulting in vitro constructed recombinant plasmid pNH606 was found to be stable, conjugative, multicopy (20 copies of pNH606 per E. coli chromosome were estimated) and to ensure the increased expression of different genes responsible for the antibiotic resistance. The pSa fragment inserted in the BamHI site of plasmid pNH602 (located in Tn2660) was proved to be transposable to other replicons. Recombinant plasmid pNH606 was analyzed using restriction enzymes BamHI and EcoRI and its physical and genetic map was constructed.

• MeSH
• Drug Resistance, Microbial MeSH
• Deoxyribonuclease BamHI MeSH
• Deoxyribonuclease EcoRI MeSH
• Escherichia coli genetics   MeSH
• Genetic Vectors * MeSH
• Cloning, Molecular methods   MeSH
• Plasmids * MeSH
• DNA, Recombinant * MeSH
• DNA Restriction Enzymes MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Deoxyribonuclease BamHI MeSH
• Deoxyribonuclease EcoRI MeSH
• DNA, Recombinant * MeSH
• DNA Restriction Enzymes MeSH

Formation of a recombinant plasmid designated pNH603 was observed when two plasmids from incompatibility group X, the multicopy plasmid pNH602 (a higher-copy-number deletion derivative of R6K) and the oligocopy plasmid R485, coexisted in a single Escherichia coli cell. According to its size and its restriction endonuclease cleavage pattern, plasmid pNH603 is a true cointegrate of pNH602 and R485. An insertion-sequence-like element coming from plasmid R485 is supposed to mediate the fusion of both replicons. The pNH603 copy number (1-2 per chromosome) indicates that the mechanism of replication of the low-copy-number plasmid is dominant in this cointegrate. No dissociation of pNH603 to parental plasmids was observed even in E. coli K-12 recA+ cells. On the other hand, deletion derivatives of four size classes originate from pNH603 in both recA+ and recA hosts. A miniplasmid designated pNH604, a representative of the most frequent 7 Mg/mol size class, was found, in a low number of copies per host chromosome.

• MeSH
• Deoxyribonuclease BamHI MeSH
• Deoxyribonuclease EcoRI MeSH
• DNA, Bacterial analysis   isolation & purification   ultrastructure   MeSH
• Electrophoresis, Polyacrylamide Gel MeSH
• Microscopy, Electron MeSH
• Escherichia coli genetics   MeSH
• Plasmids * MeSH
• Recombination, Genetic MeSH
• DNA Replication MeSH
• DNA Restriction Enzymes MeSH
• DNA Transposable Elements MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Deoxyribonuclease BamHI MeSH
• Deoxyribonuclease EcoRI MeSH
• DNA, Bacterial MeSH
• DNA Restriction Enzymes MeSH
• DNA Transposable Elements MeSH

A stable deletion derivative pNH602 was obtained when the recently described higher-copy-number point mutant pNH601 of plasmid R6K was introduced to a minicells-producing strain of Escherichia coli. The size of plasmid pNH602 is 18.8 Mg/mol as determined by electron microscopy. The 7.2 Mg/mol fragment of R6K genome missing in pNH602 carries the Smr-determinant and the region finO and, according to the results of restriction analysis, it includes one EcoRI site. With its radioisotopically determined 33 copies of pNH602 per E. coli K-12 chromosome (npc), representing a 23% increase of the point mutant pNH601 and 150% enhancement of R6K npc, plasmid pNH602 differs from another closely related R6K deletion derivative pAS3 of the same size which exhibits only 20 npc. Both pNH602 and pAS3 plasmids are conjugative.

• MeSH
• Chromosome Deletion * MeSH
• DNA, Bacterial isolation & purification   MeSH
• Species Specificity MeSH
• Microscopy, Electron MeSH
• Escherichia coli genetics   MeSH
• Genotype MeSH
• Conjugation, Genetic MeSH
• Mutation * MeSH
• Plasmids * MeSH
• DNA Restriction Enzymes MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA, Bacterial MeSH
• DNA Restriction Enzymes MeSH

E. coli strain J53(RP4) was mutagenized with ethyl methanesulfonate and N-methyl-N'-nitro-N-nitrosoguanidine. Clones showing a two-to threefold increase in resistance to ampicillin were produced. This increase was not due to an increased number of RP4 copies per chromosome. The level of penicillinase activity was twice higher in comparison with the parental strain. No detectable changes were found in the region coding for the resistance to ampicillin on the plasmid by restriction analysis.

• MeSH
• Ampicillin pharmacology   MeSH
• Species Specificity MeSH
• Escherichia coli drug effects   genetics   MeSH
• Ethyl Methanesulfonate pharmacology   MeSH
• Mutation * MeSH
• R Factors drug effects   MeSH
• DNA Replication drug effects   MeSH
• DNA Restriction Enzymes MeSH
• Penicillin Resistance MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Ampicillin MeSH
• Ethyl Methanesulfonate MeSH
• DNA Restriction Enzymes MeSH

A stable copy-number mutant (pNH601) of plasmid R6K was isolated by selection for increased resistance to ampicillin determined by this plasmid. The size of the mutant plasmid was found to be unchanged (26 Mg/mol) but it is present in 27 copies of pNH601 per E. coli K-12 chromosome which represents a two-fold increase of R6K copy number value. The following genetic properties of pNH601 are reported and compared with those of R6K: conjugative transfer, fertility inhibition of plasmids belonging to other incompatibility groups, incompatibility with plasmid R485 under both non-selective and selective conditions and the integrative suppression of the dnaA ts mutation. The mutant plasmid pNH601 was found to be different from the original R6K in most of these properties.

• MeSH
• Ampicillin pharmacology   MeSH
• DNA, Bacterial analysis   MeSH
• Escherichia coli analysis   drug effects   genetics   MeSH
• Conjugation, Genetic MeSH
• DNA, Circular analysis   MeSH
• Mutation * MeSH
• R Factors * MeSH
• Streptomycin pharmacology   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Ampicillin MeSH
• DNA, Bacterial MeSH
• DNA, Circular MeSH
• Streptomycin MeSH