L. Acidophilus Research Paper

Lactobacilli are lactic acid bacteria, an anaerobic / microaerophilic, non-sporulation, low in G+C content gram-positive bacteria which belong to the phylum Firmicutes [1]. Lactobacillus colonizes the human gut and confers various health benefits to humans. Lactobacillus acidophilus NCFM (North Carolina Food Microbiology) strain is marketed as probiotic microbe which is routinely used in dietary supplements and fermented dairy products [2]. L. acidophilus is naturally occurring bacteria in human gut, intestines, mouth or female genitals. The clinical applications of L. acidophilus includes prevention of antibiotic associated diarrhea [3], treatment for allergies [4], as an antagonist against Campylobacter jejuni [5] and enteroaggregative Escherichia

to adhere and colonize human intestinal mucosa/ epithelial cells is a major criterion for selection as probiotic or commensal bacteria. Adhesion to the host tissues is a prerequisite first step of bacterial colonization which is generally mediated by cell surface adhesion proteins [10]. Adhesion of probiotic bacteria not only help in persistence of bacteria in gut but also participate in pathogen exclusion by competition and blocking of their binding sites at the mucosa [11]. This adherence to epithelial cells on mucosal surface is modulated by specific binding of microbial adhesins. Lactobacilli adhesins can be broadly classified according to their targets in the intestinal mucosa (i.e. mucus, extracellular matrix), based on their localization in the bacterial surface (i.e. surface layer proteins) and/or to the way how they are anchored to bacterial surface (i.e. sortase-dependent proteins, N/C terminal anchored). Extracellular matrix (ECM) comprises of variety of proteins like collagen, fibronectin, laminin along with mucins. Lactobacillus has an array of proteins which specifically binds with ECM proteins and further mediating adhesion of cells to mucosa layer in

GAPDH is considered as a principal "moonlighting" protein / multifunctional enzyme with additional roles like apoptosis initiation [16], transcription activation [17] and host-pathogen interactions [18]. GAPDH is reported earlier as an anchorless molecule on surface of bacteria involved in adhesion performing non-glycolytic moonlighting function [19-25]. Multiple role of GAPDH was first identified in group A streptococci as a major surface protein with multiple binding activities. This was the first report of protein with multiple role therefore, GAPDHs are considered as the prototype moonlighting bacterial protein with the adhesion ability to bind to host epithelial components like mucin, ECM components (fibronectin, mucin, plasminogen etc.) or directly to Caco-2/ HT29 epithelial cell lines which makes it one of the essential mediators of host-microbe interactions [20, 22, 26]. Earlier report on L. acidophilus GAPDH (Uniprot ID: LBA0698) indicates that it is a secreted or surface associated protein [27] although it lacks any signal sequences, cell wall-anchoring motifs, or hydrophobic membrane-spanning regions that could target it to a secretion pathway and the exact mechanism remains