Characterization of a novel dextransucrase from Weissella confusa isolated from sourdough

Abstract

Weissella confusa and Weissella cibaria isolated from wheat sourdoughs produce, from sucrose, linear dextrans due to a single soluble dextransucrase. In this study, the first complete gene sequence encoding dextransucrase from a W. confusa strain (LBAE C39-2) along with the one from a W. cibaria strain (LBAE K39) were reported. Corresponding gene cloning was achieved using specific primers designed on the basis of the draft genome sequence of these species. Deduced amino acid sequence of W. confusa and W. cibaria dextransucrase revealed common structural features of the glycoside hydrolase family 70. Notably, the regions located in the vicinity of the catalytic triad (D, E, D) are highly conserved. However, comparison analysis also revealed that Weissella dextransucrases form a distinct phylogenetic group within glucansucrases of other lactic acid bacteria. We then cloned the W. confusa C39-2 dextransucrase gene and successfully expressed the mature corresponding enzyme in Escherichia coli. The purified recombinant enzyme rDSRC39-2 catalyzed dextran synthesis from sucrose with a K m of 8.6 mM and a V max of 20 μmol/mg/min. According to (1)H and (13)C NMR analysis, the polymer is a linear class 1 dextran with 97.2 % α-(1→6) linkages and 2.8 % α-(1→3) branch linkages, similar to the one produced by W. confusa C39-2 strain. The enzyme exhibited optimum catalytic activity for temperatures ranging from 35 to 40 °C and a pH of 5.4 in 20 mM sodium acetate buffer. This novel dextransucrase is responsible for production of dextran with predominant α-(1→6) linkages that could find applications as food hydrocolloids.

Genomics of Weissella cibaria with an examination of its metabolic traits

“…Our aim was to provide a genomic overview of this lesserknown genus of lactic acid bacteria LAB, with particular emphasis on W. cibaria due to high levels of dextran production by this species, which has been increasingly studied and applied in a number of food-related applications in recent years (Amari et al, 2013;Galle et al, 2010;Katina et al, 2009;Lynch et al, 2014;Zannini et al, 2013).…”

Screening and characterization of extracellular polysaccharides produced by Leuconostoc kimchii isolated from traditional fermented pulque beverage

“…AW strain) Fructan Inuline-like structure with β-(2→1) glycosidic linkages produced by a cell-associated fructosyltransferase ( L. citreum ) Pozol (maize fermented dough) (Olivares-Illana et al 2002 ) Dextran a Dextran type I containing α-(1→2) D-Glc p and α-(1→3) linked branches ( L. citreum VTT E-93497 strain). Malting process (Maina et al 2008 ) Dextran type I containing few α-(1→3) linked branches ( W. confusa VTT E-90392 strain) Soured carrot mash Dextran Dextran type I linked mainly in α-(1→6) D-Glc p with few α-(1→3) linked branches produced by soluble GTF (Several L. mesenteroides and Weissella spp isolates) Traditional French wheat sourdough (Bounaix et al 2009 ) Dextran type I linked mainly in α-(1→6) D-Glc p with α-(1→2) linked branches produced by soluble GTF (several L. mesenteroides and L. citreum isolates) Dextran type I linked mainly in α-(1→6) D-Glc p with high α-(1→3) linked branches produced by soluble GTF (Several L. citreum isolates) Dextran/levan mixture Dextran type I linked mainly in α-(1→6) D-Glc p with high α-(1→3) linked branches produced by soluble and cell-associated GTF mixed with a levan (several L. mesenteroides isolates) Traditional French wheat sourdough (Bounaix et al 2009 ) Dextran Dextran type I linked mainly in α-(1→6) D-Glc p with few α-(1→2) linked branches ( W. confusa LBAE C39-2) Traditional French wheat sourdough (Amari et al 2012 ) Dextran a Linear backbone linked mainly in α-(1→6) D-Glc p ( Lactobacillus curvatus 69B2 strain and Leuconostoc lactis 95A strain) Wheat sourdough (Palomba et al 2012 ) ...…”

“…A wide diversity of EPS and genes encoding biosynthetic enzymes from naturally occurring LAB in traditional fermented foods and beverages have been extensively studied for their role in the physicochemical and sensorial characteristics of final fermented products (viscosifying, stabilizing or water-binding agents). This has led to the discovery of a remarkable structural diversity of EPS produced by LAB, particularly of the genus Leuconostoc and Weissella (Chellapandian et al 1998 ; Uzochukwu et al 2001 ; Olivares-Illana et al 2002 ; Uzochukwu et al 2002 ; van Hijum et al 2006 ; Eom et al 2007 ; Van der Meulen et al 2007 ; Bauer et al 2009 ; Bounaix et al 2009 ; Bounaix et al 2010 ; Amari et al 2012 ; Vasileva et al 2012 ). EPS have received additional attention as valuable products because of their potential economic applications that include natural, safe-food additives or natural functional food ingredients for their properties as soluble fiber and prebiotics, and the possibility that they can replace or reduce the use of hydrocolloids (Giraffa 2004 ; Tieking et al 2005 ; Vu et al 2009 ; Leemhuis et al 2013 ).…”

Insights into the Microbiological Safety of Wooden Cutting Boards Used for Meat Processing in Hong Kong’s Wet Markets: A Focus on Food-Contact Surfaces, Cross-Contamination and the Efficacy of Traditional Hygiene Practices

“…The nutrients that were trapped on the porous surfaces of the wooden cutting board might have been utilised by W. hellenica for its growth requirements given its ubiquity and the ability to breakdown complex polysaccharides [30]. In addition, this microorganism belongs to the phylum Firmicutes [31,32].…”