Characterization of dextransucrase from Leuconostoc mesenteroides T3, water kefir grains isolate

Miona Miljkovic,Suzana Dimitrijevic-Brankovic,Slavko Kralj,Slavica Siler-Marinkovic,Mirjana Rajilic-Stojanovic,Sladjana Davidovic

doi:10.2298/hemind160421046m

Miona Miljkovic, Suzana Dimitrijevic-Brankovic + Show 4 more

Open Access

https://doi.org/10.2298/hemind160421046m

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Abstract

The production of dextransucrase (DS) by Leuconostoc mesenteroides T3, novel isolate from water kefir grain, was studied and optimized. Bacterial supernatant reached activity of 3.1 U/ml when the culture was grown at 23 ?C and under static culture condition using classical Tsuchiya medium for DS production. The increase of sucrose concentration to 7% led to an increase of DS activity by 52% compared to the control. Medium with 2% beef extract and 1% yeast extract resulted in 4.52 U/ml, which was 47% higher than in the control (with 2% yeast extract). Finally, the increase of K2HPO4 concentration from 2 to 3% resulted in the increased enzyme activity by 28%. Enzyme purified by polyethylene glycol 400 fractionation displayed maximum activity at 30?C and pH 5.4. Zymogram analysis confirmed the presence of DS of approximately 180 kDa. The addition of divalent cations Ca2+, Mg2+, Fe2+ and Co2+ led to a minor increase of DS activity, while the addition of Mn2+ was the most prominent with 73% increase. These findings classify dextransucrase from Leuconostoc mesenteroides T3 as promising candidate for production of dextran, which has numerous applications in various industries.

Highlights

The production of dextransucrase (DS) by Leuconostoc mesenteroides T3, novel isolate from water kefir grain, was studied and optimized
Dextransucrase (DS) is an extracellular enzyme that belongs to the class of glucosyltransferases [2] and it is mainly produced by microorganisms belonging to the families Lactobacillaceae and Streptococcaceae, especially by the genera Lactobacillus, Leuconostoc and Streptococcus [3]
This study shows a thorough technological characterization of conditions for production of DS using a novel strain L. mesenteroides T3

Summary

Introduction

The production of dextransucrase (DS) by Leuconostoc mesenteroides T3, novel isolate from water kefir grain, was studied and optimized. The enzyme assay was carried out in 450 μl reaction mixture containing 10% sucrose in 20 mM sodium acetate buffer (pH 5.4) and 50 μl cell free supernatant at 30 °C for 15 min. Growth conditions (temperature and aeration) and culture medium composition (sucrose, nitrogen source, K2HPO4 and Tween 80) for enzyme production were screened and optimized.

Results

Conclusion