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2 Biotechnology and Food Science

2 2017

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Production of co-immobilized dextransucrase and dextranase preparations and their application in isomalto-oligosaccharides synthesis

Sikora B., Kubik C., Bielecki S.

Biotechnology and Food Science

2017

Vol. 81, nr 2

137--147

Dextransucrase (DS) from Leuconostoc mesenteroides and dextranase (DN) from Penicillium funiculosum were co-immobilized by entrapment in calcium alginate and used to produce isomaltooligosaccharides (IMOs) from sucrose. DS convert sucrose into dextran, which is thesubstrate for DN, so that IMOs are products of dextran hydrolysis. Before the co-immobilization DS was cross-linked with glutardialdehyde (GA), while DN was adsorbed on hydroxyapatite (HAp). Cross-linking was essential for the stability of DS and pre-immobilization of DN to prevent enzyme from leaking out of the alginate beads. Operational stability of co-immobilized preparations of DS and DN was estimated based on amounts of isomaltose and isomaltotriose formed during successive 24h processes of IMOs synthesis, carried out at 30oC, pH 5.4 and 200 rpm in 10% (w/v) sucrose solutions. Preparation characterized by the initial DS/DN activities ratio of 1/14 was found to maintain these activities at least 100 h of IMOs synthesis (5 repeated batch reaction).

A comparison of two enzymatic methods of clinical dextran production

Sikora B., Kubik C., Bielecki S.

Biotechnology and Food Science

2017

Vol. 81, nr 2

125--136

The aim of this study was to evaluate and compare of the two enzymatic methods of clinical dextran production were compared. The reactions were performed at 30°C and pH 5.4 in solutions containing different amounts of sucrose, using dextransucrase (DS, in the presence of dextranase (D) (method 1) or acceptor dextrans (method 2). The activity of Leuconostoc mesenteroides L dextransucrase (DS), which converts sucrose to dextran, was 0.4 U ml-1 in both the methods. As much as 53-56% of clinical dextran fractions were obtained for 28 h from 10% sucrose solutions, which contained 1.5% or 2.5% acceptor dextrans with molecular mass of 10 and 15 kDa, respectively. Approximately 50% of these fractions was obtained (also in 28 h) from 10% sucrose solutions by using 0.004 U ml-1 of DN, added to reaction mixtures 5 h later than our experiments indicate that the clinical dextran can be efficiently produced by using both the compared methods, which employ either acceptor dextrans with definite molecular mass, or the dextranase. Because consumption of the latter enzyme is rather small, and it is easily available, thus this method should be attractive for clinical dextran manufacturers.