Effects of Sub-Lethal High Pressure Homogenization Treatment on the Adhesion Mechanisms and Stress Response Genes in Lactobacillus acidophilus 08

Abstract

Cell surface hydrophobicity (CSH) and adhesion are very important phenotypical traits for probiotics that confer them a competitive advantage for the resilience in the human gastrointestinal tract. This study was aimed to understand the effects over time of a 50 MPa hyperbaric treatment on the surface properties of <i>Lactobacillus acidophilus</i> 08 including CSH, autoaggregation, and <i>in vitro</i> adhesion (mucin layer and Caco-2 cells). Moreover, a link between the hurdle applied and the expression of genes involved in the general stress response (<i>groEL</i> and <i>clpP</i>) and adhesion processes (<i>efTu</i> and <i>slpA</i>) was evaluated. High pressure homogenization (HPH) at 50 MPa significantly increased the CSH percentage (H%), autoaggregation and <i>in vitro</i> adhesion on mucin of <i>L. acidophilus</i> 08 cells compared with the untreated cells. Moreover, the hyperbaric hurdle induced an upregulation of the stress response genes <i>groEL</i> and <i>ef-TU</i> together with a down regulation of the <i>clpP</i> and <i>S-layer slpA</i> genes. Looking at the protein profile, HPH-treatment showed an increase in the number or intensity of protein bands at high and low molecular weights.