A novel dextransucrase is produced by Leuconostoc citreum strain B/110-1-2: an isolate used for the industrial production of dextran and dextran derivatives

Abstract

The industrial Leuconostoc strain B/110-1-2 producing dextran and dextran derivatives was taxonomically identified by 16S rRNA as L. citreum. Its dextransucrase enzymes were characterized according to their cellular location and reaction specificity. In the presence of sucrose, the strain B/110-1-2 produced two cell-associated dextransucrases (31.54% of the total glucosyltransferase activity) with molecular weights of 160 and 240 kDa and a soluble dextransucrase (68.46%) at 160-180 kDa. Two open reading frames (ORF) coding for L. citreum strain B/110-1-2 dextransucrases were identified. One of them shared a 52% identity with the alternansucrase ASR of L. citreum NRRL B-1355 and with a putative annotated alternansucrase sequence found in the genome of L. citreum KM20. The structural analysis (HPAEC-PAD, HPSEC, and (13)C-NMR) of the polymer and oligodextrans produced by the B/110-1-2 dextransucrases suggest this novel glucansucrase has specificity similar to a dextransucrase but not to an alternansucrase, producing a soluble linear dextran with glucose molecules linked mainly in α-1,6 and α-1,3 with α-1,4 branches. These results enhance the understanding of this industrially significant strain and will aid in distinguishing between physiologically similar Leuconostoc spp. strains.

Characterization of glucansucrase and dextran from Weissella sp. TN610 with potential as safe food additives

“…The latter were selected for further screening for extracellular glycosyltransferase activity in liquid MRS-S. A pear-derived isolate, termed TN610, was noted to represent the best EPS-producing strain, and was, therefore, retained for subsequent analyses. The culture supernatant from this strain was observed to exhibit a maximum soluble glycosyltransferase activity of about 0.7 U/ml, which is in agreement with the extracellular localization previously reported for most glycosyltransferase activities produced by LAB [8,[11][12][13]. The TN610 isolate was identified as a Weissella sp.…”

“…GS use sucrose to naturally catalyze the synthesis of a variety of ␣-d-glucans. These include dextrans (mainly produced by GS from Leuconostoc and Weissella strains) which are characterized by a linear backbone containing ␣-(1→6) linkages, or predominant ␣-(1→6) linkages together with ␣-(1→3), ␣-(1→2), and/or ␣-(1→4)-linked branches [8,[10][11][12][13]. They also include mutans (mainly found in Streptococcus strains) that have more than 50% of ␣-(1→3) linkages in the linear backbone with ␣-(1→6)-liked branches [14].…”

Structure–function relationships of family GH70 glucansucrase and 4,6-α-glucanotransferase enzymes, and their evolutionary relationships with family GH13 enzymes

“…Recently, more α-glucan-producing Leuconostoc bacteria and corresponding GSs have been isolated from various sources. An isolate from sugarcane juice was identified as Leuconostoc citreum B/110-1-2 encoding a novel dextransucrase (DSRF) [ 41 ]. DSRF synthesizes a dextran with 93 % (α1 → 6) linkages, 6 % (α1 → 3) linkages and 1 % (α1 → 4) linkages (Table 1 ) [ 42 ].…”

Construction of a Novel Chimeric Dextransucrase Fused to the Carbohydrate-Binding Module CBM2a

“…The Cuban Research Institute on Sugarcane By-products (ICIDCA) has a collection of LAB strains isolated from sugarcane and sugarcane derivatives. Some of them have already been characterized to some extent [19][20][21]. In the present study, a chimeric dextransucrase fused to the carbohydrate-binding module (CBM2a) of the exoglucanase/xylanase Cex (Xyn10A) of Cellulomonas fimi ATCC 484 was obtained.…”