FLAGELLUMS BACTERIAL

From Big Medical Encyclopedia

FLAGELLUMS BACTERIAL — the thin elastic proteinaceous outgrowths of cytoplasm which are bodies of the movement at bacteria. On existence or lack of flagellums pathogenic bacteriums are subdivided on mobile and motionless. Definition of mobility at bacteria is an important diagnostic character.

Length. depends on a species of microorganism, and also from a growth technique and age of culture and there can be several times more than length of a body of the microbe. Diameter of flagellums is equal to 12 — 30 nanometers and therefore it is not possible to see them at usual ways of microscopy of bacteria. are found only after the pickle causing their swelling and increase in the size.

One species of bacteria have flagellums on the end of a body in the form of a bunch (a lophotrichy, amfitrikh) or the only flagellum (monotrikh). At other types flagellums surround all surface of a cell (peritrikha). Example of a monotrikh is the cholera vibrio, a peritrikha — the causative agent of a typhoid.

Believe that evolution of bacteria concerning flagellums went in the direction polar flagellums — peritrikhialny flagellums — lack of flagellums. The similar nature of variability can be observed in laboratory. Peritrikh can mutate in atrikhialny (aflagellar) bacteria. Reverse mutations are also possible, but with a low frequency.

On the basis of data electronic and microscopic, cytochemical and immunol, researches Zh. on the structural organization of macromolecules are divided into two types: with spiral laying of globular proteinaceous molecules and the fibrillar structural organization.

the Diagrammatic representation of fastening of a flagellum in cytoplasm of bacteria (according to V. I. Biryuzova): 1 — a basal little body; 2 — a basal plate of a flagellum; 3 — the helical structure fixed on the site of a flagellum between a basal little body and a cytoplasmic membrane; 4 — a cytoplasmic membrane; 5 — the analog of a mitochondrion located in close proximity to a basal little body; 6 — a cell wall; 7 — the outside thicker part of a flagellum passing through a cell wall and the capsule; 8 — the capsule.

Assume that flagellums represent the cylinder, hollow at one bacteria and filled with lipids at others. Flagellums begin in cytoplasm, near a cytoplasmic membrane (fig). They are connected with cytoplasm the hook-shaped end — the basal plate concluded in the basal little body which is an analog of a blepharoplast

. consist of low-molecular protein — a flagellin (Latin of flagella a flagellum). Pier. weight of a flagellin 20 000 — 40 000 dalton. It concerns group of sokratitelny proteins, i.e. is similar to proteins of muscle fiber. Amino-acid structure of a flagellin at different types of bacteria various. It forms the basis for the assumption that serol, specificity of flagellums can be defined by amino-acid structure of a flagellin and its molecular organization.

Methods of allocation of flagellums and a flagellin are developed. Receiving the bacteria of flagellums isolated from a body is based on stirring of a suspension of mobile bacteria with the subsequent differential centrifuging. Impurity of fraction of the allocated flagellums is checked in Goryaev's camera at phase-contrast microscopy or calculation of the whole cells at a submicroscopy.

Three methods of receiving a flagellin are known: 1) destruction. to - that and cleaning of a flagellin with differential centrifuging; 2) soda extraction from flagellums; 3) allocation by means of a gelfiltratsionny chromatography. Allocation and cleaning of a flagellin are necessary for studying of an antigenic structure of flagellums, receiving diagnostic N-serums. As showed researches E. S. Stanislavsky, the isolated flagellums and cleared flagellin are not toxic neither for mice, nor for rabbits.

The antigens connected with flagellums are called flagellates, or H - antigens (see. Bacteria, antigens of bacteria ). Preparation of N-antigen of integral cells is based on processing of mobile microbes by the formalin reducing activity of a somatic antigen.

Most in detail N-antigens are studied at bacteria of enterotyphus group. N-antigen defines standard specificity of many enterobakteriya. At salmonellas, e.g., it consists of two phases — specific and nonspecific. The first phase is characteristic only of this look, the second is the group, meeting at other types this group. The genetic analysis shows that the specified antigenic types of flagellums at salmonellas are controlled by the genes bearing alleles of H1 and H2. Flagellar antigens, apparently, do not play an essential role in formation of specific resistance of an organism.

Except flagellums, on a surface of many bacteria there are thinner outgrowths — the fimbrias (a synonym: saw, cilia, fibers) found only at a submicroscopy. Fimbrias differ from flagellums on chemical structure and immunol. to properties. Value of fimbrias is definitely not established. See also Bacteria , Conjugation at bacteria .


Bibliography: Biryuzova V. I. Membrane structures of microorganisms, M., 1973, bibliogr.; Katz L. N. Superficial structures of a bacterial cell, Usp. sovr, biol., t. 76, century 3(6), page 395, 1973, bibliogr.; P e sh to about in M. A. Comparative cytology of blue-green seaweed, bacteria and actinomycetes, M., 1966; Stanislavsky E. S. Bacterial structures and their antigenicity, M., 1971, bibliogr.; Lowy J. a. Spencer M. Structure and function of bacterial flagella, in book: Aspects of cell motility, p. 215, Cambridge, 1968.

E. P. Pashkov.

Яндекс.Метрика