Microbiological characteristics of Kumis, a traditional fermented Colombian milk, with particular emphasis on enterococci population

Kumis is a traditional fermented cow milk produced and consumed in South West Colombia. The mainobjective of this research was to studied the enterococcal population, present in 13 kumis samplestraditionally manufactured, for their role as beneficial organisms or opportunistic pathogens. Themolecular identification of 72 isolates evidenced that Enterococcus faecalis and E. faecium were thedominant species. The genes gelE, esp, asa1, cyl and hyl, all associated with virulence factors in enterococci,were detected in 30 isolates, while 42 were free of virulence determinants. Skim milk media werefermented by all the different isolates and further tested for proteolysis (free NH3 groups), Angiotensin-IConverting Enzyme (ACE) inhibitory activity and biogenic amines production. Nine E. faecalis and twoE. faecium strains produced fermented milk with ACE-inhibitory activity values ranging from 39.7% to84.35% .The digestion of fermented milk samples by pepsin and pancreatin evidenced an increase in ACEinhibitory activity, with E. faecalis KE09 as the best producer (IC50 ¼ 14.25 mg ml1). Moreover, thestrains showed a very low tyrosine decarboxylase activity and did not produce histamine during 48 hfermentation in milk. This study underlines the that Colombian kumis is a good source of not virulententerococci able to produce fermented milks with ACE-inhibitory activity.[...]