Characterization of the Extracellular Fructanase FruA in Lactobacillus crispatus and Its Contribution to Fructan Hydrolysis in Breadmaking

J Agric Food Chem. 2020 Aug 12;68(32):8637-8647. doi: 10.1021/acs.jafc.0c02313. Epub 2020 Jul 29.


Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) trigger symptoms of irritable bowel syndrome (IBS). Fructan degradation during bread making reduces FODMAPs in bread while maintaining the content of dietary fiber. This study explored the presence of the fructanases FruA in lactobacilli and characterized its use in bread making. FruA was exclusively present in vertebrate-adapted lactobacilli. In Lactobacillus crispatus DSM29598, FruA was located in cell wall fractions and includes a SLAP domain. FruA hydrolyzed levan or inulin; expression of fruA was not subject to catabolite repression. Fructans in bread were reduced by less than 50% in a straight dough process; conventional sourdough fermentation reduced fructans in bread by 65-70%. Sourdough fermentation with L. crispatus reduced fructans in bread by more than 90%. In conclusion, reduction of FODMAP by sourdough fermentation may improve tolerance in many IBS patients. Fermentation with FruA-expressing L. crispatus DSM29598 produces a low FODMAP bread.

Keywords: FODMAPs; bread; fructan; sourdough; surface layer protein.

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biocatalysis
  • Extracellular Space / enzymology*
  • Extracellular Space / genetics
  • Extracellular Space / metabolism
  • Fructans / metabolism*
  • Glycoside Hydrolases / chemistry*
  • Glycoside Hydrolases / genetics
  • Glycoside Hydrolases / metabolism*
  • Hydrolysis
  • Lactobacillus crispatus / classification
  • Lactobacillus crispatus / enzymology*
  • Lactobacillus crispatus / genetics
  • Lactobacillus crispatus / metabolism
  • Phylogeny
  • Protein Domains


  • Bacterial Proteins
  • Fructans
  • Glycoside Hydrolases
  • levanase