High gamma-aminobutyric acid (GABA) producing Enterococcus malodoratus isolated from protected denomination of origin (PDO) cheese

Four strains of Enterococcus malodoratus were isolated from São Jorge cheese – and showed a high conversion of L-glutamate to GABA, achieving a yield above 50%. These new strains neither fermented lactose nor produced hydrogen sulphide. They produced slow acidification and low amounts of diacetyl, and lacked most enzymatic activities and genes encoding virulence traits. They were sensitive to ampicillin, vancomycin, fluoroquinolones, chloramphenicol and streptogramins, but resistant to penicillin, oxacillin, erytromycin and tetracycline. One strain (SJC62) showed antimicrobial activity against Listeria monocytogenes , Salmonella enterica , Escherichia coli and Pseudomonas aeruginosa ; and antifungal activity against Aspergillus caesiellus and Mucor racemosus . The strains also showed probiotic potential in vitro , as they exhibited good resistance to gastrointestinal conditions, high hydrophobicity and mucin adhesion. The spectrum of favourable technological, antimicrobial and probiotic properties, in combination with their high ability to convert glutamic acid into GABA make these strains relevant for use in novel dairy foods. • Four strains of Enterococcus malodoratus isolated from São Jorge cheese showed a high conversion of L-glutamate to GABA. • Strains did not produce hydrogen sulphide, a characteristic attributed to this species. • Strain SJC62 showed the broadest antibacterial and antifungal spectrum of activity. • The strains have probiotic potential as they are resistant to the conditions in the gut, are highly hydrophobic and adhere to mucin.