Assessment of probiotic intervention for control of biofilm former Escherichia coli isolates of animal-origin foods

Abstract

The study investigates the efficacy of lactic acid bacteria (LAB) strains (Lactobacillus rhamnosus and Lactobacillus casei) in combating Escherichia coli biofilms by determining antibacterial, anti-biofilm activity, auto-aggregation, and co-aggregation assay. The study included 115 E. coli isolates from milk (n = 36), chicken meat (n = 33), and chicken eggs (n = 46). Among 115 E. coli isolates, 22.61% were strong biofilm formers. The LAB strain, L. rhamnosus exhibited a 28.47 mm mean antibacterial inhibition zone, an average reduction of 51.22% in biofilm growth, 55.46% auto-aggregation, and 41.57% co-aggregation with E. coli. Similarly, L. casei demonstrated a 21.55 mm mean antibacterial inhibition zone, an average reduction of 36.74% in biofilm growth, 45.23% auto-aggregation, and 38.74% co-aggregation with E. coli isolates. Both strains individually and in combination demonstrate substantial reductions in biofilm growth, with L. rhamnosus observed to be more effective than L. casei. Scanning electron microscopy provides valuable insights into the structural aspects of the probiotic impact on diminishing E. coli biofilm. Probiotics' ability to auto-aggregate and co-aggregate with pathogenic strains serves as an initial screening method for identifying suitable probiotic bacteria. In conclusion, the results underscore the efficacy of specific LAB strains in combating E. coli biofilm formation. This study provides a basis for future investigations into LAB's capacity to mitigate biofilm-related hurdles and strengthen microbial management protocols within food processing settings or relevant food substrates.