Glycoside hydrolases (GHs) have been organized into 114 families in the CAZy database (http://www.cazy.org) based on amino acid sequence similarities. Among these families, glycoside hydrolase family 1 (GH1) enzymes are important members which hydrolyze β-glycosidic linkages. Carbohydrates are the major energy source for Lactic acid bacteria (LABs) and their metabolism utilizes a variety of sugars present in the environment. Carbohydrate uptake mostly occurs through the phosphoenolpyruvate-dependent phosphotranferase system (PEP-PTS). In olive (Olea europea), the glucoside oleuropein is the main phenolic component. Oleuropein is present in leaves as well as in olive fruits and is related to the bitterness of olive oil. Lactobacillus plantarum is a lactic acid bacteria frequently found in the fermentation of plant-derived food products like olives. It has been described that L. plantarum is able to transform oleuropein to hydroxytyrosol, the compound responsible of olive oil healthy properties. In order to identify the enzymes involved in oleuropein transformation, L. plantarum WCFS1 was exposed to oleuropein and the changes in gene expression analyzed. The transcriptomic study revealed the induction of the lp_2777 gene, encoding a putative 6 phospho β-glucosidase. Therefore, the lp_2777 gene was cloned and the recombinant protein was hiperproduced, purified, and biochemically characterized. Substrate specificity was assayed against a library of 4-nitrophenyl synthetic glycosides. The results showed that Lp_2777, in spite that it not exhibited β-glucosidase activity, it was able to hydrolyze 4-nitrophenyl-β-Dglucopyranoside-6-P, and 4-nitrophenyl-β-D-galactopyranoside-6-P. In addition, Lp_2777 protein showed thermal stability. This study constitutes the first characterization of a GH1 glycosidase from Lactobacillus plantarum WCFS1.

Póster presentado a la VII International Conference on Environmental Industrial and Applied Microbiology, celebrada en Madrid (España) del 18 al 20 de octubre de 2017.

This work was supported by grant AGL2014-52911-R (MINEICO).

Peer Reviewed