Hyper glucansucrase, glucan and oligosaccharide producing novel Weissella cibaria RBA12 isolated from Pummelo (Citrus maxima)

Weissella cibaria RBA12 (GenBank accession no: KF515952) producing glucansucrase and glucan was isolated from pulp of Pummelo (Citrus maxima). The isolate RBA12 was characterized and identified on the basis of morphological, biochemical properties and 16S rRNA gene sequence analysis, and gave maximum glucansucrase activity of 7.2 U/mL at 20 degrees C and 180 rpm. The molecular mass of crude glucansucrase was approximately 180 kDa as determined by SDS-PAGE analysis and was confirmed as glucansucrase by periodic acid-Schiff staining using sucrose as substrate. Maximum glucan concentration of 8.3 mg/mL with an efficiency of glucan production of 83 % was observed in the cell-free supernatant under optimized conditions of growth of W. cibaria RBA12. The production of oligosaccharides by W. cibaria RBA12 was carried out by supplementing fermentation medium with maltose as an acceptor molecule. The time-dependent analysis of the acceptor reaction in the medium by TLC and ESI-TOF-MS revealed that W. cibaria RBA12 produced oligosaccharides ranging from trisaccharides to homologous penta-saccharides.