Technological, molecular, and safety characterization of autochthonous lactic acid bacteria in Moroccan Jben cheese: Towards the development of a native starter culture

Abstract

The present study involved the technological, molecular, and safety characterization of lactic acid bacteria isolated from artisanal Moroccan Jben cheese. A total of eighty-nine Gram-positive, catalase-negative isolates were initially assessed for acidifying and proteolytic activity, with positive strains screened for additional traits, including citrate utilization, gas production, lipolytic activity, aroma and diacetyl production, and antibacterial activity. Species identification was achieved via species-specific PCR and partial 16S rRNA gene sequencing. It was revealed that sixty-seven strains (75.3 %) displayed at least two technological properties (acidification and proteolysis) with most classified as Enterococcus (67.2 %), Lactococcus (25.4 %), and, to a lesser extent, Lactiplantibacillus (6 %) and Leuconostoc (1.5 %) species. None of the isolates utilised citrate or exhibited lipolytic activity. Only Leuconostoc mesenteroides produced gas. Pleasing aromas were detected in 62.7 % of strains, while 26.9 % emitted sulphurous notes. Diacetyl production was observed in 79.1 % of the isolates, with Lactiplantibacillus and Enterococcus identified as the primary producers. Only Enterococcus strains (60 %) demonstrated antilisterial activity. For safety purposes, all Enterococcus faecalis strains, as well as some Enterococcus faecium strains that did not exhibit antibacterial activity, were excluded from the collection. The remaining strains (n=25) underwent autolysis and further safety testing. Autolysis patterns varied by strain, with some Lactococcus species exhibiting good autolytic potential. Safety assessments indicated partial haemolysis in some Enterococcus faecium strains, while antibiotic resistance analysis revealed higher resistance in Lactiplantibacillus plantarum and Leuconostoc mesenteroides, primarily of intrinsic origin. This study identified multiple strains of Lactococcus lactis with promising technological and safety profile, suggesting their suitability as effective starters for Jben cheese production.