Safety assessment and functional properties of four enterococci strains isolated from regional Argentinean cheese

MARTINO, GABRIELA P.; ESPARIZ, MARTÍN; GALLINA NIZO, GABRIEL; ESTEBAN, LUIS; BLANCATO, VÍCTOR S.; MAGNI, CHRISTIAN

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

ELSEVIER SCIENCE BV

Año: 2018 vol. 277 p. 1 - 9

0168-1605

The membersof the Enterococcus genus are widely distributed in nature. Its strains havebeen extensively reported to be present in plant surfaces, soil, water andfood. In an attempt to assess their potential application in food industry,four Enterococcus faeciumgroup-strains recently isolated from Argentinean regional cheese products wereevaluated using a combination of whole genome analyses and in vivo assays. Inorder to identify these microorganisms at species level, in silico analysesusing their newly reported sequences were conducted. The average nucleotideidentity (ANI), in silico DNA-DNA hybridization, and phylogenomic treesconstructed using core genome data allowed IQ110, GM70 and GM75 strains to beclassified as E. faecium while IQ23strain was identified as E. durans.Besides their common origin, the strains showed differences in their geneticstructure and mobile genetic element content. Furthermore, it was possible todetermine the absence or presence of specific features related to growth inmilk, cheese ripening, probiotic capability and gut adaptation including sugar,amino acid, and peptides utilization, flavor compound production, bile salttolerance as well as biogenic amine production. Remarkably, all strains encodedfor peptide permeases, maltose utilization, bile salt tolerance, diacetyl andtyramine production genes. On the other hand, some variability was observedregarding citrate and lactose utilization, esterase, and cell wall-associatedproteinase. In addition, while strains were predicted to be non-human pathogensby the in silico inspection ofpathogenicity and virulence factors, only the GM70 strain proved to benon-virulent in Galleria mellonellamodel. In conclusion, we propose that, in order to improve the rationalselection of strains for industrial applications, a holistic approach involvinga comparative genomic analysis of positive and negative features as well as invivo evaluation of virulence behavior should be performed.