Utilization of agro-industrial by-products as substrates for dextransucrase production by Leuconostoc mesenteroides T3: Process optimization using response surface methodology

Miona Miljkovic,Mirjana Rajilic-Stojanovic,Sladjana Davidovic,Milica Simovic,Aleksandra Djukic-Vukovic,Suzana Dimitrijevic-Brankovic,Mila Ilic

doi:10.2298/hemind200710015m

Abstract

Dextransucrase (DS) is a glucosyltransferase (E. C. 2.4.1.5) that catalyzes the transfer of glucosyl residues from sucrose to dextran polymer and liberates fructose. This enzyme isassociated with a wide application range of dextran and oligosaccharides. DS production by Leuconostoc mesenteroidesT3 was optimized using a Central Composite Design under the Response Surface Methodology. Three variables were chosen for optimization: distillery stillage, sucrose and manganese concentration. The results showed that sucrose and manganese concentrations had a positive linear effect on DS production while all variable interactions (stillage-manganese, stillage-sucrose, and sucrose-manganese) had significant influences on the DS production. The maximal DS yield of 3.391?0.131 U cm-3, was obtained in the medium with 64.33 % distillery stillage concentration, 5.30% sucrose concentration and 0.022 % manganese concentration. Our study revealed the potential of distillery stillage combined with sugar beet molasses, supplemented with sucrose and manganese to be employed as a valuable medium growth for lactic acid bacteria and production of DS. Also, taking into consideration the origin of the substrates, utilization of industrial by-products in this way has a great environmental relevance and is in accordance with circular economy.

Highlights

C. 2.4.1.5) that catalyzes the transfer of glucosyl residues from sucrose to dextran polymer and liberates fructose
The results showed that sucrose and manganese concentrations had a positive linear effect on DS production while all variable interactions had significant influences on the DS production
Our study revealed the potential of distillery stillage combined with sugar beet molasses, supplemented with sucrose and manganese to be employed as a valuable medium growth for lactic acid bacteria and production of DS

Summary

Introduction

C. 2.4.1.5) that catalyzes the transfer of glucosyl residues from sucrose to dextran polymer and liberates fructose [1]. This enzyme catalyzes the so-called acceptor reaction, where in the presence of suitable low molecular weight molecules, for example maltose, the transfer of glucosyl units is redirected from dextran to oligosaccharide synthesis [2]. DS is an extracellular enzyme produced by several species belonging to the genera Lactobacillus, Leuconostoc and Streptococcus [3]. DS is commercially employed in dextran production. Dextrans and their derivatives have been profusely used in food, clinical, pharmaceutical, fine chemicals, cosmetics and agricultural industries [6, 7].

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