A novel high dextran yielding Weissella cibaria JAG8 for cereal food application

Abstract

A new isolate from apple (Malus domestica) producing dextransucrase and dextran was characterized by morphological, biochemical and 16S rDNA analyses. The bacterium that was identified as Weissella cibaria (GenBank accession number KC110687) was Gram positive, non-motile, short rod, catalase negative, vancomycin resistant. The maximum dextransucrase activity (5.8 U/ml) as well as dextran concentration of 38 mg/ml was observed at 24°C after 12 h of growth under static condition. The polyethylene glycol (PEG)-400 fractionation of partially purified enzyme showed a specific activity of 20.0 U/mg and displayed a single homogenous band of molecular size 177 kDa on sodium dodecyl sulphate-Poly acrylamide gel electrophoresis (SDS-PAGE) (7.5%). The dextran was enzymatically synthesized using dextransucrase and substrate sucrose. Dextran was purified by alcohol precipitation for further characterization. The rheological analysis of dextran elucidated a non-Newtonian pseudoplastic behaviour. ¹H and ¹³C NMR analyses revealed the fact that the dextran contained d-glucose monomer with 93.0% of α(1 → 6) linear and 7.0% of α(1 → 3) branched linkages.

Keywords::

• dextransucrase
• dextran
• Weissella cibaria
• rheometry
• NMR

Declaration of interest : The research work was financially supported by a grant from Indo-Finland joint project from Department of Biotechnology, Ministry of Science and Technology, New Delhi, India to AG. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Notice of CorrectionThe iFirst version of this article published online ahead of print on 18 October 2012 contained an error on pages 1, 3, 4 and in the reference list.On page 1 the sentence “The bacterium that was identified as Weissella cibaria (GenBank accession number AB621969.1) was Gram positive, non-motile, short rod, catalase negative, vancomycin resistant” should have read “The bacterium that was identified as Weissella cibaria (GenBank accession number KC110687) was Gram positive, non-motile, short rod, catalase negative, vancomycin resistant”.On page 3 the sentence “One microlitre of culture was withdrawn from each conical flask at every 4 h interval and centrifuged at 10,500g for 10 min at 4°C” should have read “One millilitre of culture was withdrawn from each conical flask at every 4 h interval and centrifuged at 10,500g for 10 min at 4°C”.On page 4 the sentence “The isolate was identified as W. cibaria JAG8 by BLAST analysis of 645 bp sequence of the 5′-end of 16S rDNA and phylogenetic analysis using neighbour-joining method. The query sequence was subjected to sequence alignment with bacterial genome database and showed 96% similarity with W. cibaria 105 with Genbank accession number AB621969.1 (Figure 1a), whereas the sequence showed common evolutionary relationship with Bifidobacterium PG13 (Figure 1b)” should have read “The isolate was identified as W. cibaria JAG8 by BLAST analysis of 1040 bp sequence of the 5′-end of 16S rDNA and phylogenetic analysis using neighbour-joining method. The query sequence was subjected to sequence alignment with bacterial genome database and showed 96% similarity with W. cibaria 105 with Genbank accession number KC110687 (Figure 1a), whereas the sequence showed common evolutionary relationship with Bifidobacterium PG13 (Figure 1b).”The reference Goyal et al. 1995 has also been removed from the References and text. The corrected version is shown in this issue.