Probiotic efficacy, antioxidant, antimicrobial and anticancer activities of cell free supernatant derived from Weissella confusa isolated from Oreochromis niloticus – An in vitro study

The current study explores the probiotic potential and helps to assess the anti-colon cancer effects of cell-free supernatant (CFS) produced by Weissella confusa isolated from Oreochromis niloticus. By sequencing the 16S rRNA gene, the strain W. confusa , a Gram-positive lactic acid bacterium, was identified. We evaluated their probiotic potential, antimicrobial activity, antibiotic activity, haemolytic activity, antioxidant activity, and anticancer activities. The strain was found to be resistant to high bile salt concentrations (0.3%, 0.7%, and 1%) as well as low pH (acidic), demonstrating its ability to withstand the presence of gastric juice under changing pH conditions. The strain W. confusa showed antimicrobial activity against S. aureus, K. pneumoniae, and Candida albicans and also showed broad resistance to tetracycline, cefotaxime, cefatazidime, gentamicin, linezolid, penicillin, piperacillin, and vancomycin but was sensitive to cefalexin and netilmicin. The DPPH scavenging activity of W. confusa is significantly higher in 100 µg/mL compared to other concentrations (P<0.05), and neglect according to ABTS is observed in 40 µg/mL and 60 µg/mL concentrations. In addition, the IC50 value of 27 ± 1.5 µg/mL indicates that this concentration is required for 50% cell viability inhibition in the MTT assay. AO/EtBr and DAPI staining revealed apoptogenic activity and nuclear fragmentation. According to cell cycle arrest analysis, DNA replication phase distribution related to extract treatment was reduced compared to control, and flow cytometry analysis showed that at higher concentrations of the sample, a maximum of 57.25 percent induced apoptosis in the HT 29 cell line through decreasing Bcl-2 expression and increasing BAX protein expressions. • Weissella confusa strain was isolated from the intestine of fresh fish Oreochromis niloticus (Nile Tilapia) to investigate its probiotic property. • The probiotic potentials such as Bile tolerance, pH tolerance, lysozyme resistance, and the virulency test (haemolytic activity) of W. confusa was determined. • Antimicrobial, antibiotic and anti-oxidant acivities of the strain W. confusa was tested and proved that the strain satisfying all the qualities of probiotics and should be used for further advanced research. • Cell free supernatant separated from W. confusa strain was investigated to explored the in vitro anti-colon cancer activity using HT 29 cell line.