Dextransucrase(EC.2.4.5.1)is a kind ofα-transglucosyltransferase.It is mainly produced by lactic acid bacteria such as Leuconostoc,and Lactobacillus.Dextransucrase is an important tool in the biosynthesis of dextran ...Dextransucrase(EC.2.4.5.1)is a kind ofα-transglucosyltransferase.It is mainly produced by lactic acid bacteria such as Leuconostoc,and Lactobacillus.Dextransucrase is an important tool in the biosynthesis of dextran due to its diverse structure and catalytic mechanisms.Microorganisms producing extracellular dextransucrase were fermented in de Man-RogosaSharpe(MRS)medium with sucrose as the only carbon source.It was purified by using the supernatant of the fermentation solution as a crude enzyme solution.The results showed that the optimum concentration of ammonium sulfate precipitation crude enzyme was 55%.When an anion exchange chromatography system was used to purify the target protein,the optimal pH value of the elution system was 5.0,and CH_(3)COO^(-)exhibited the strongest elution capacity.展开更多
The influence of medium ingredients on extracellular dextransucrase production by a new bacterial strain Weissella confusa Cab3 (Genbank Accession Number JX649223) was evaluated using fractional factorial design of Ta...The influence of medium ingredients on extracellular dextransucrase production by a new bacterial strain Weissella confusa Cab3 (Genbank Accession Number JX649223) was evaluated using fractional factorial design of Taguchi's orthogonal array. Four metabolism influencing factors viz. sucrose, yeast extract, K2HPO4 and Tween80 were selected to optimize dextransucrase production by W. confusa Cab3 using fractional factorial design of Taguchi methodology. Based on the influence of interaction components of fermentation, least significant factors of individual level have higher interaction severity index and vice versa for enzyme production from Weissella confusa Cab3. Sucrose and yeast extract were found to be the most significant factors which positively influenced the dextransucrase production. The optimized medium composition consisted of sucrose—5%;yeast extract—2%;K2HPO4—1.0%;Tween80—0.5%, based on Taguchi orthogonal array method. The optimized composition gave an experimental value of dextransucrase activity of 17.9 U/ml at shake flask level which corresponded well with the predicted value of 17.54 U/ml by the model. The optimized medium by Taguchi method gave significant (3 fold) enhancement of dextransucrase activity as compared to unoptimised enzyme activity of 6.0 U/ml. The dextransucrase production was scaled up in lab scale bioreactor resulting in further enhancement of enzyme activity (22.0 U/ml).展开更多
文摘Dextransucrase(EC.2.4.5.1)is a kind ofα-transglucosyltransferase.It is mainly produced by lactic acid bacteria such as Leuconostoc,and Lactobacillus.Dextransucrase is an important tool in the biosynthesis of dextran due to its diverse structure and catalytic mechanisms.Microorganisms producing extracellular dextransucrase were fermented in de Man-RogosaSharpe(MRS)medium with sucrose as the only carbon source.It was purified by using the supernatant of the fermentation solution as a crude enzyme solution.The results showed that the optimum concentration of ammonium sulfate precipitation crude enzyme was 55%.When an anion exchange chromatography system was used to purify the target protein,the optimal pH value of the elution system was 5.0,and CH_(3)COO^(-)exhibited the strongest elution capacity.
文摘The influence of medium ingredients on extracellular dextransucrase production by a new bacterial strain Weissella confusa Cab3 (Genbank Accession Number JX649223) was evaluated using fractional factorial design of Taguchi's orthogonal array. Four metabolism influencing factors viz. sucrose, yeast extract, K2HPO4 and Tween80 were selected to optimize dextransucrase production by W. confusa Cab3 using fractional factorial design of Taguchi methodology. Based on the influence of interaction components of fermentation, least significant factors of individual level have higher interaction severity index and vice versa for enzyme production from Weissella confusa Cab3. Sucrose and yeast extract were found to be the most significant factors which positively influenced the dextransucrase production. The optimized medium composition consisted of sucrose—5%;yeast extract—2%;K2HPO4—1.0%;Tween80—0.5%, based on Taguchi orthogonal array method. The optimized composition gave an experimental value of dextransucrase activity of 17.9 U/ml at shake flask level which corresponded well with the predicted value of 17.54 U/ml by the model. The optimized medium by Taguchi method gave significant (3 fold) enhancement of dextransucrase activity as compared to unoptimised enzyme activity of 6.0 U/ml. The dextransucrase production was scaled up in lab scale bioreactor resulting in further enhancement of enzyme activity (22.0 U/ml).
