Stochastic chain termination in bacterial pilus assembly.

Adhesive type 1 pili from uropathogenic Escherichia coli strains are filamentous, supramolecular protein complexes consisting of a short tip fibrillum and a long, helical rod formed by up to several thousand copies of the major pilus subunit FimA. Here, we reconstituted the entire type 1 pilus rod assembly reaction in vitro, using all constituent protein subunits in the presence of the assembly platform FimD, and identified the so-far uncharacterized subunit FimI as an irreversible assembly terminator. We provide a complete, quantitative model of pilus rod assembly kinetics based on the measured rate constants of FimD-catalyzed subunit incorporation.

Electrooptical Analysis of Microbial Cell Suspensions forDetermination of Antibiotic Resistance.

The effects of ampicillin; kanamycin, chloramphenicol, and tetracycline on electrophysical characteristics of cells of sensitive (ampicillin; kanamycin, chloramphenicol) and resistant (ampicillin; kanamycin, chloramphenicol, tetracycline) Escherichia coli strains were studied. Under the action of antibiotics sensitive and resistant E. coli strains acquire different electro-optical properties.

Electrooptical Assay for Record of Antibiotic Action on Microbial Cells.

Development of rapid and sensitive procedures for determination of microbial resistance to antibiotics is one of the most urgent trends in microbiology. The problem is shown to be solved by using electrooptical assay based on change of the electrophysical properties of suspended bacterial cells exposed to antibiotics with different mechanisms of action. Possible determination of the microbial cell susceptibility to antibiotics and their antibacterial activity is demonstrated.

[Immunodetection of bacteriophages by a piezoelectric resonator with lateral electric field].

It has been demonstrated that electroacoustic analysis with polyclonal antibodies can be used for bacteriophage detection. The frequency dependences of the real and imaginary parts of electrical impedance of a resonator with a viral suspension with antibodies were shown to be essentially different from the dependences of a resonator with control viral suspension without antibodies. It was shown that ΦAl-Sp59b bacteriophages were detected with the use of antibodies in the presence of foreign virus particles.

[Change of Electrophysical Properties of Escherichia coli Cells Due to Levomycetin and Tetracycline Action].

The effect of chloramphenicol and tetracycline, as inhibitors of protein synthesis, on electrophysical properties of Escherichia coli K-12 cells was investigated. Significant changes in the orientation spectra (OS) of the cell suspensions incubated with various concentrations of chloramphenicol were observed only at the first five frequencies of the electric field (10-1000 kHz). When the cells were exposed to chloramphenicol (1.