|
Poster Presentation 2-30
Energetics and Biochemical Aspects of the Synthesis Intensification of the Exopolysaccharide Ethapolan on the Mixture of the Growth Substrates
T.P.Pirog and M.A. Kovalenko
Ukrainian Academy of Sciences, Institut of Microbiology and Virology 154 Zabolotny St., 03143, Kiev, Ukraine
Telephone: 380 44 266 99 69; Fax: 380 44 266 23 79; E-mail: tapirog@usuft.kiev.ua
Ethapolan, an exocellular microbial polysaccharide (EPS) produced by a non-pathogenic Acinetobacter sp. strain, has unique physico-chemical properties which are determined by the occurrence of hydrophobic acyl residues in macromolecules. Due to its unique properties, ethapolan can be considered an EPS of multifunctional assignment. Ethapolan is already used in the Russian oil industry to increase oil recovery.
Independently of the growth substrate (glucose, ethanol), the high activities of the key enzymes of C2- and C6-metabolism were determined in the cells of Acinetobacter sp. with the exception of the isocitrate lyase activity under bacteria cultivation on the glucose medium. The inductors of the isocitrate lyase in Acinetobacter sp. were established to be C2-compounds (ethanol or acetate).
The possibility of the synthesis intensification of the EPS under Acinetobacter sp. strain cultivation on the mixture of the energy-unequivalent substrates (ethanol + glucose) was shown.
Based on the theoretical calculations of the energy requirements for the biomass and EPS synthesis on energy-deficit substrate (glucose), the concentration of the energy-excess substrate (ethanol) was determined to allow for compensation for the glucose carbon loss to obtain the energy necessary for constructive metabolism and to increase the carbon conversion efficiency to the EPS.
The ethanol addition to the medium glucose contained in the molar ratio 3,1:1 was accompanied by the simultaneous consumption of the substrates, increasing of the EPS synthesis (1,8-1,9-fold), its yield relative to the biomass (1,4-1,7-fold), and its yield relative to substrates (1,5-2-fold) as compared with monosubstrates.
The data presented are the basis for the new technologies developing which allow for obtaining the practical valuable secondary metabolites on the mixed energy-unequivalent substrates.
|