Safety and technological properties of bacteriocinogenic enterococci isolates from Tunisia

Abstract

Aims: To investigate the safety and technological traits of previously isolated bacteriocinogenic enterococci strains for potential use as starter/adjunct cultures in foods. Methods and Results: Fifty-five bacteriocinogenic enterococci strains previously isolated from different origins in Tunisia were screened for safety. Twenty-two strains did not harbour the genes coding for virulence traits, were susceptible to relevant antibiotics such as vancomycin, and tested negative for haemolysis, histamine production, gelatinase activity and DNase activity. These strains were further assessed for some technological properties, demonstrating low milk-acidifying ability, low proteolytic activity, high peptidolytic activity and diacetyl production in milk. Conclusions: This study revealed that 22 bacteriocinogenic enteroccoci strains did not present virulence features and could be safely applied in food preservation. Some strains also showed good technological potential as adjunct/protective cultures in milk fermentation and cheese production. Significance and Impact of the Study: This is one of very few studies that identified safe Enterococcus strains capable of producing a wide variety of enterocins against different spoilage and pathogenic micro-organisms that have good potential for application as adjunct/protective cultures in foods.