An investigation into the probiotic, anti-bacterial, anti-biofilm, and safety properties of Lactococcus lactis NJ414

Abstract

Probiotics are live microorganisms that positively influence the host’s gut by modifying and enhancing its microbial equilibrium. The study aimed to investigate the probiotic, anti-bacterial, anti-biofilm, and safety properties of Lactococcus lactis NJ414. L. lactis NJ414 exhibited strong resistance to acidity, gut conditions, and bile salts. The strain exhibited notable characteristics, with percentages for hydrophobicity (44.30%), auto-aggregation (35.50%), co-aggregation (18.30%), antioxidant activity (48.80%), and cholesterol reduction (46.90%). L. lactis NJ414 demonstrated effectiveness in competing with, displacing, and hindering the adhesion of L. monocytogenes at rates of 37.80%, 24.50%, and 33.40%, respectively. Moreover, it displayed a 9.10% adhesion rate to epithelial cells, susceptibility to most antibiotics, and no DNase or hemolytic activity. The strain exhibited potent anti-microbial activity against L. monocytogenes, with inhibition zones of 11.20 mm in disk diffusion agar (DDA) and 11.75 mm in well diffusion agar (WDA), while Escherichia coli showed the lowest susceptibility, with inhibition zones of 3.25 mm in DDA and 3.40 mm in WDA. The cell-free supernatant of the strain demonstrated effectiveness in inhibiting and eradicating biofilm formation by L. monocytogenes, with respective rates of 43.40 ± 0.58% and 38.90 ± 0.46%. Overall, these findings support the notion that L. lactis NJ414 holds probiotic potential.