SYNTHESIS ORGANOSILICATE SOL-GEL MATERIALS FOR THE DEVELOPMENT OF BIOCATALYSTS ON THE BASIS OF YEAST DEBARYOMYCES HANSENII VKM Y – 2482

Afonina E.L, Kamanina O.A Ponamoreva O.N.

Tula State University, Russia, Tula

In recent years intensively developing methods of obtaining new materials based on sol-gel processes. Common name "sol-gel process" combines a large group of materials preparation methods from solutions, which is an essential element for the formation of one of the stages of the sol, which turns into a gel. These methods are widely used for the development of functional coatings, catalysts, separation membranes and matrices for immobilizing biomolecules, the so-called biohybrid materials, due to the flexibility of the chemical composition of the materials in the preparation of which does not require energy-intensive, expensive equipment. The sol-gel methods are economical and environmentally friendly and allow synthesis in mild conditions, in particular at low temperatures. The starting compounds for the synthesis of polymeric materials (precursors) may be titanium, vanadium, zirconium, but the greatest interest are silicon oxides, usually organosilicon compound (aroksisilany alkoxy and), which are readily hydrolyzed, followed by condensation. On the basis of these compounds obtained organic-inorganic hybrid materials that combine the advantages of both organichskih and inorganic polymer materials and are promising matrices for immobilization of microorganisms, as they provide long-term preservation at a high level of biological activity of the biological material; effective protection against external damaging factors (mechanical, thermal and biological effects); maintaining a constant amount of organosilicate material that provides high-speed diffusion fluxes [1, 2].

Microorganisms immobilizovanye using a sol-gel process, are used as biocatalysts or bioraspoznayuschih elements in biosensors for determination of biochemical oxygen demand (BOD) [3]. One of the most promising microorganisms for BOD biosensor cells are yeast Debaryomyces hansenii.

In this paper we have investigated the possibility of a protective capsule around also organic Debaryomyces hansenii yeast cells in a sol-gel synthesis. As used silane precursor tetraethoxysilane (TEOS, 15 vol.%), Which completely gidralizuetsya and methyltriethoxysilane (MTES, 85 vol.%) That contains non-hydrolysable group, ie is a hydrophobic additive. Synthesis was carried out in the presence of a catalyst - fluoride ion at pH 6,8. Under these conditions, the hydrolysis rate limits the speed of the entire process, resulting in the formation of microparticles and sol gel porous structure. This and the presence of a significant amount of hydrophobic additive provides effective diffusion of substances through the organosilicate matrix formed. In the presence of yeast is observed preferential formation of the sol particles on the cell surface, which leads to the formation of solid capsule around each cell.

Encapsulated yeasts used as bioraspoznayuschego element BOD biosensor. BOD values, determined using a biosensor based on encapsulated yeast and standard methods differ insignificantly. Encapsulated in the organosilicate matrix yeast Debaryomyces hansenii do not lose their activity in the presence of heavy metal ions. When excess of MPC 100 times encapsulated mikroorganimov respiratory activity is reduced by 20% while the yeast activity without silicate coated capsule is reduced by several times. Organosilicate capsule also protects cells from the effects of UV radiation. Analytical and metrological characteristics biochuvstvitelnogo element based on yeast immobilized in a silicone matrix, virtually unchanged compared with unirradiated biochuvstvitelnogo element characteristics, while not encapsulated cells did not show any activity.

The results indicate the specific protective function also organic capsule that forms around yeast that should be considered in the development of BOD biosensor.

Список литератур

1. Sakai-Kato K., Ishikura K. Integration of biomolecules into analytical systems by means of silica sol-gel technology // National Institute of Health Science. ‒ 2005. ‒ V. 6. ‒ P. 70-75.

2. Dickson D., Ely R. Silica sol-gel encapsulation of cyanobacteria: lessons for academic and applied research // Applied Microbiology and Biotechnology. ‒ 2013. ‒ V. 97, I. 5. ‒ P. 1809-1819.

3. Arlyapov, V.A., et al., BOD biosensor based on the yeast Debaryomyces hansenii immobilized in poly(vinyl alcohol) modified by N-vinylpyrrolidone. Enzyme and Microbial Technology, 2013. 53(4): p. 257-262.

The reported study was funded by RFBR according to the research project No. 16-38-00700