Enterococcus lactis Q1 and 4CP3 strains from raw shrimps: Potential of antioxidant capacity and anti-biofilm activity against methicillin-resistant Staphylococcus aureus strains

Antibacterial resistance is an increasingly serious threat to global public health. The search for new anti-infection agents from biological antimicrobial systems became a necessity. This study discusses the utilisation of Enterococcus lactis Qi and 4CP3 strains to evaluate the antioxidant and the efficacy potential against the development of biofilms formed by methicillin-resistant Staphylococcus aureus (MRSA) strains. E. lactis Qi and 4CP3 used alone and in combination showed an interesting antioxidant capacity using the in vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ARTS(+)) free radical scavenging assays. The combination C6 (E. lactis Q1 at 40% and E. lactis 4CP3 at 60%) was the most active in the DPPH free radical scavenging test. Furthermore, the anti-biofilm effects of all strains against a reference S. aureus strain and two MRSA strains were evaluated. Our findings showed the potent efficacy of E. lactis Q1 and 4CP3 used alone and their highly synergistic combination against the development of biofilms formed by staphylococcal strains. The film containing 40% of E. lactis Q1 and 60% of E. lactis 4CP3 exhibited substantial anti adhesion properties inhibiting biofilm formation on its surface and considerably reduced formation of biofilms on the surrounding surfaces by all tested strains including antibiotic resistant MRSA.