Enterococcus faecalis strains from food, environmental, and clinical origin produce ACE-inhibitory peptides and other bioactive peptides during growth in bovine skim milk

Enterococcus faecalis isolates from food and environmental origin were evaluated for their angiotensin-converting enzyme (ACE)-inhibitory activity (ACE-IA) after growth in bovine skim milk (BSM). Most (90% active) but not all (10% inactive) E. faecalis strains produced BSM-derived hydrolysates with high ACE-IA. Known ACE-inhibitory peptides (ACE-IP) and an antioxidant peptide were identified in the E. faecalis hydrolysates by reversed-phase high-performance liquid chromatography-tandem mass spectrometry (RP-HPLC-MS/MS). Antimicrobial activity against Pediococcus damnosus CECT4797 and Listeria ivanovii CECT913 was also observed in the E. faecalis hydrolysates. The incidence of virulence factors in the E. faecalis strains with ACE-IA and producers of ACE-IP was variable but less virulence factors were observed in the food and environmental strains than in the clinical reference strains. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) based analysis demonstrated that food and environmental E. faecalis strains were genetically different from those of clinical origin. When evaluated, most E. faecalis strains of clinical origin also originated BSM-derived hydrolysates with high ACE-IA due to the production of ACE-IP. Accordingly, the results of this work suggest that most E. faecalis strains of food, environmental and clinical origin produce BSM-derived bioactive peptides with human health connotations and potential biotechnological applications. © 2013 Elsevier B.V.This work was partially supported by project AGL2012-34829 from the Ministerio de Economía y Competitividad (MINECO), by projects AGL2009-08348 and AGL2011-24643 from the Ministerio de Ciencia e Innovación (MICINN), and by the CENIT project (2006–2009) from the MITC-CDTI. Funding by grants GR35-10A from the BSCH-UCM and S2009/AGR-1489 from the Comunidad de Madrid (CAM) are also acknowledged. L. Gútiez holds a fellowship (FPU) from the Ministerio de Educación y Ciencia (MEC), Spain.Peer Reviewe