| Popis: |
Bacterial sucrose phosphorylase (sucrose:phosphate α-D-glucosyltransferase ; EC 2.4.1.7) is thoroughly characterized enzyme that catalyses regioselective transglucosylation reactions in which e.g. sucrose may serve as a glucosyl donor while glycerol may be a glucosyl acceptor. Product of this particular reaction, α-D-glucosylglycerol (GG), is a very important and widely applied commercial compound. Heterofermentative lactic acid bacterium Leuconostoc mesenteroides posseses a gene encoding sucrose phosphorylase and in our investigation this bacterium was selected as a whole cell biocatalyst to perform above described reaction. Ultrasound treatment (37 kHz, 90 W, 29±1.0℃) of freshly pregrown L. mesenteroides suspension and addition of a non- ionic detergent Tween-80 (0.4% and 0.6%) to the suspension were chosen as rather mild procedures for permeabilization of bacterial cell membrane. The transglucosylation reaction was carried out in a semi-defined medium enriched by 0.8 M sucrose and 2.0 M glycerol in shaking flasks (200 rpm, up to 50 mL of working volume) at 29±1.0C and not maintained pH value. Conversion of sucrose by permeabilized bacterial cells to lactic acid and acetic acid under described conditions was followed by HPLC method. A new peak eluted from ion-exchange column that do not corresponds to any other compound in the reaction mixture, indicates possible formation of GG. Since GG standard is not available, additional cromatographic separation and NMR analysis of apparently formed GG is under its way in order to undoubtedly identify the compound. |
