Antimicrobial, antioxidant and anticancer properties of bioactive bacteriocins produced by Lactococcus hircilactis CH4 and Lactobacillus delbrueckii GRIPUMSK isolated from homemade fermented dairy products

Lactic acid bacteria (LAB) are known to produce bacteriocins. In this work, two lactic acid bacterial strains, Lactococcus hircilactis CH4 and Lactobacillus delbrueckii GRIPUMSK were isolated from fermented dairy products. They were tested for their antimicrobial, antioxidant, and anticancer properties. This research aimed to isolate bioactive bacteriocins from these two LAB strains under various conditions and thoroughly examined their molecular structure and physico-chemical properties. The optimal culture conditions for bacteriocin production such as time, temperature, pH, and carbon and nitrogen source supplementation were analyzed. The molecular weight of bacteriocins from Lb. delbrueckii GRIPUMSK and Lc. hircilactis CH4 were detected with the size of 23.8 and 8.9 kDa, respectively. The Fourier transform infrared (FTIR) spectrum of both the bacteriocins from LAB showed, –OH/N-H stretching vibrations, amide II groups and C-N stretch respectively. Proton nuclear magnetic resonance (¹H NMR) spectrum of both the bacteriocins from LAB revealed seven and nine amino acids respectively. The extracted bacteriocins were revealing that bacteriocins from both strains exhibit heat resistance and stability across a wide range of detergents, organic solvents, and pH levels compared to nisin. Furthermore, we discovered that these bacteriocins effectively inhibited (89.00 ± 1.12 % and 86.00 ± 0.67 %) Helicobacter pylori biofilm formation at 100 μg/mL, demonstrated antioxidant capabilities, and showed enhanced selective cytotoxicity with IC₅₀ at 29.87 and 42.52 μg/ml against human colon cancer cells (HT-29). In conclusion, the two isolated bacteriocins serve as safe postbiotic materials in the food and pharmaceutical industries, offering potential benefits to treat cancer and its associated bacterial infections synergistically.