Antimicrobial properties of Bifidobacterium animalis subsp. lactis Bb-12 paraprobiotic obtained using ohmic heating against Salmonella enterica: A metabolomic approach.

Abstract

This study aimed to obtain paraprobiotics from Bifidobacterium animalis subsp. lactis Bb-12 (BB) presenting optimized antimicrobial activity against Salmonella enterica (SE). The paraprobiotics of BB (BBP) were obtained using ohmic heating (OH) under different conditions, and their effects on critical features of Salmonella, such as bacterial growth, biofilm formation, and adherence to Caco-2 cells, were studied. In addition, a metabolomic analysis was performed using ¹H NMR spectroscopy to identify the metabolites involved in antimicrobial activity against SE. Through an optimization approach, it was found that the linear model demonstrated the highest predictive potential for the antimicrobial activity (AMA) of BBP among the fitted models. In contrast, the quadratic model was more predictive for the antibiofilm activity (ABA) and anti-adherence activity (AAA). The highest effects on the AMA, ABA, and AAA of BBP were associated with the variables electric field (EF), OH time, and OH temperature, respectively. Glycerol (37.6 μmol/g), ethanol (22.6 μmol/g), and lactate (9.8 μmol/g) were measured as the main metabolites in BB, while glycerol (47.8 μmol/g), acetate (34.0 μmol/g), and lactate (24.6 μmol/g) were the main metabolites in BBP. All the anti-SE characteristics of BBP obtained under the optimal conditions of the OH process were higher than those of BB (the untreated sample), which could be related to the higher levels of detected metabolites. The OH process, EF of 8.7 V/cm, OH temperature of 88 °C, cell concentration of 8.7 log CFU/mL, and OH time of 3.6 min, was the best OH condition for obtaining a BBP effective against SE.