Université de Lorraine, LIBio, Laboratoire d'Ingénierie des Biomolécules, 2 av de la Forêt de Haye, TSA 40602, F-54518 Vandoeuvre lès Nancy, France. Electronic address:
Published: October 2015
AI Article Synopsis
Article Abstract
Probiotic bacteria are routinely incorporated into dairy foods because of the health benefits they can provide when consumed. In this work, the marked pH-dependence of the pili/EPS organization at the outer surface of Lactobacillus rhamnosus GG is characterized in detail by Single Cell Force Microscopy and cell electrophoretic mobility measurements analyzed according to formalisms for nanomechanical contact and soft particle electrokinetics, respectively. At pH 6.8, LGG pili are easily accessible by AFM tips functionalized with whey proteins for specific binding, while at pH 4.8 the collapsed EPS surface layer significantly immobilized the LGG pili. This resulted in their reduced accessibility to the specific whey-coated AFM tip, and to stronger whey protein-pili rupture forces. Thus, pili interactions with whey proteins are screened to an extent that depends on the pH-mediated embedment of the pili within the EPS layer.
To advance probiotic research, a comprehensive understanding of bacterial interactions with human physiology at the molecular and cellular levels is fundamental. LGG is a bacterial strain that has long been recognized for its beneficial effects on human health. Probiotic effector molecules derived from LGG, including secreted proteins, surface-anchored proteins, polysaccharides, and lipoteichoic acids, which interact with host physiological processes have been identified.
Laboratory of Chemical Biology and State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China.
Pyroptosis has garnered increasing attention in cancer immunotherapy. Moreover, increasing plasma membrane damage by reactive oxygen species (ROS) is considered an effective strategy for promoting pyroptosis. However, the current tactics for enhancing membrane rupture in pyroptosis are limited by the inherent drawbacks of ROS and the immunosuppressive tumor microenvironment.
Lactic acid bacteria (LAB) have been studied for several decades to understand and determine their mechanism and interaction within the matrix into which they are introduced. This study aimed to determine the spatial distribution of GG (LGG) in a dairy matrix and to decipher its behaviour towards milk components, especially fat globules. Two strains of this widely studied bacterium with expected probiotic effects were used: LGG WT with pili on the cell surface and its pili-depleted mutant-LGG Δ-in order to determine the involvement of these filamentous proteins.
Many studies have established the functional properties of Lacticaseibacillus rhamnosus GG, previously known as Lactobacillus rhamnosus GG, marketed worldwide as a probiotic. The extraordinary capacity of L. rhamnosus GG to bind to human mucus and influence the immune system especially stand out.
Pili are polymeric proteins located at the cell surface of bacteria. These filamentous proteins play a pivotal role in bacterial adhesion with the surrounding environment. They are found both in Gram-negative and Gram-positive bacteria but differ in their structural organization.
