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Bacterial Chemotaxis

#2739


Study of the Behavior of Chemotactic Bacteria in Porous Structures and at the Interface of Heterotrophic Media

Tech Area / Field

  • BIO-MIB/Microbiology/Biotechnology
  • OBS-NAT/Natural Resources and Earth Sciences/Other Basic Sciences

Status
3 Approved without Funding

Registration date
18.03.2003

Leading Institute
State Research Center for Applied Microbiology, Russia, Moscow reg., Obolensk

Collaborators

  • University of Virginia / Department of Chemical Engineering, USA, VA, Charlottesville

Project summary

Bacterial chemotaxis has been recently widely used in the following research areas:
· monitoring of the environment
· bioremediation (bioutilization of industrial wastes)
· acclimation, survival and migration of bacterial populations in natural conditions
· dependence between pathogenicity and chemosensoric system
· generation and development of biofilms
· methods of the spread and transmission of infection
· symbiotic relationships between microorganisms, mineral, plant and animal forms
· bacterial chemotaxis–based biosensors

In recent years researchers have shifted from investigations of chemotaxis in liquid media to chemotaxis taking place on the surface and inside porous media. This is associated with that key chemosensoric reactions occur just at the interface rather than free inside convective fluxes. The character of motility of bacteria and porous structures in nature are adequate one another as a result, probably, of million years evolution.

As a rule, on-bench research on bacterial chemotaxis is limited to measuring colony sizes on semi-solid agar and counting bacteria accumulated in a capillary in response to attractant (Adler’s method).

Methods of mathematical modeling applied to description of processes of bacterial migration are of general and abstract character (standard wave equation of mathematical physics). Peculiarities of bacterial chemotaxis itself, which is well studied at molecular and structural levels, are usually ignored.

The objective of the project is to develop a kinetic model of distribution of chemotactic bacterial populations inside porous structures, as well as on boundaries of heterogenic media.

To have full notion of the process of bacterial chemotaxis we shall develop kinetic model of distribution of bacterial populations on the boundary of heterotrophic media, as well as inside porous structures. Our previously developed mathematical model of bacterial chemotaxis and their motility in liquid media will become a basis. The model was used for interpretation of different events associated with bacterial migration (distribution of bacterial fronts and cell orientation in chemotaxis). Unlike other methods, the approach of kinetic modeling of chemotaxis allows integration of microparameters of any inpidual cell (including constants of binding of transmembrane receptors and chemoeffector, and functions of intracellular regulator of rotation of flagella) and macroparameters of bacterial migration in heterogenous chemical media.

Bacterial chemotaxis will be investigated by modified Adler's method, as well as on the surface of semi-solid agar medium. By method implying using Data interpretation will be performed by using kinetic model of chemotaxis.

A densitometric method of investigation will be developed. It will allow one to study experimentally the dynamics of distribution of bacterial fronts and bands of concentrated cells on the boundary of heterotrophic media. Densitometric data obtained will be processed with a computer and used then for testing the mathematical model. They will be also of interest as a species specific map for each strain.

Finally, the procedure, which will make possible to study and fractionate bacterial strains on columns, that are based on a porous carrier due to which gradient of preset form of chemotactically active substance is generated. It is much easier to generate gradients of preset forms and to study them inside porous structures than in free liquids, in which because of convective flows the equilibrium can be rapidly shifted.

Using the kinetic model, we shall describe adequately events taking place on the boundary of reaction media and predict the development of these events, which usually depend on components involved and preset boundary conditions.

Tasks to be pursued:


1. Design a mathematical model of migration of bacteria inside porous structures and on the boundary of heterogenous medial in bacterial chemotaxis.
2. Select bacteria from SRCAM collection, which will be best-suited for chemotaxis-associated model experiments.
3. Develop a densitometric method for investigation chemotactic events, as well as procedures for data processing.
4. Test the densitometric method using columns with porous carriers.


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