Prebiotic mechanisms, functions and applications - A review

In October 2012, a group of scientists met at the 10th Meeting of the International Scientific Association of Probiotics and Prebiotics (ISAPP) in Cork, Ireland to discuss issues surrounding prebiotics and their development. This article summarises outputs from the meeting. Various prebiotic definitions were discussed and how the concept has...

Towards understanding molecular modes of probiotic action

The possibility that certain microorganisms might be beneficial to human health is highlighted by the numerous consumer products containing probiotic bacteria. Probiotics are typically administered in food that, following entry into the gastro-intestinal tract, results in measurable health-promoting effects. Although there is a growing list of...

Cell surface hydrophobicity is conveyed by S-layer proteins - A study in recombinant lactobacilli

Cell surface hydrophobicity is one of the most important factors controlling adhesion of microorganisms to surfaces. In this paper, cell surface properties of lactobacilli and recombinant lactobacilli with and without a surface layer protein (SLP) associated with cell surface hydrophobicity were determined, including water contact angles, zeta...

Structural and functional analysis of the S-layer protein crystallisation domain of Lactobacillus acidophilus ATCC 4356 : evidence for protein : protein interaction of two subdomains

The structure of the crystallisation domain, SAN, of the S A-protein of Lactobacillus acidophilus ATCC 4356 was analysed by insertion and deletion mutagenesis, and by proteolytic treatment. Mutant S A-protein synthesised in Escherichia coli with 7-13 amino acid insertions near the N terminus or within regions of sequence variation in SAN (amino...

One repeat of the cell wall binding domain is sufficient for anchoring the Lactobacillus acidophilus surface layer protein

The N-terminal repeat (SAC1) of the S-protein of Lactobacillus acidophilus bound efficiently and specifically to cell wall fragments (CWFs) when fused to green fluorescent protein, whereas the C-terminal repeat (SAC2) did not. Treatment of CWFs with hydrofluoric acid, but not phenol, prevented binding. Apparently, SAC1 is necessary and...

The S-layer protein of Lactobacillus acidophilus ATCC 4356: Identification and characterisation of domains responsible for S-protein assembly and cell wall binding

Lactobacillus acidophilus, like many other bacteria, harbors a surface layer consisting of a protein (SA-protein) of 43 kDa. SA-protein could be readily extracted and crystallized in vitro into large crystalline patches on lipid monolayers with a net negative charge but not on lipids with a net neutral charge. Reconstruction of the S-layer from...

Effects of a milk product, fermented by Lactobacillus acidophilus and with fructo-oligosaccharides added, on blood lipids in male volunteers

Objective: To investigate in adult male volunteers the effect of a new fermented milk product, fermented by Lactobacillus acidophilus and with fructo-oligosaccharides added, on blood lipids. Design: Randomized placebo-controlled double-blind two-way cross over trial with two treatment periods of three weeks, separated by a wash-out period of one...

The Lactobacillus acidophilus S-layer protein gene expression site comprises two consensus promoter sequences, one of which directs transcription of stable mRNA

S-proteins are proteins which form a regular structure (S-layer) on the outside of the cell walls of many bacteria. Two S-protein-encoding genes are located in opposite directions on a 6.0-kb segment of the chromosome of Lactobacillus acidophilus ATCC 4356 bacteria. Inversion of this chromosomal segment occurs through recombination between two...

Interchange of the active and silent S-layer protein genes of Lactobacillus acidophilus by inversion of the chromosomal sip segment

The most-dominant surface-exposed protein in many bacterial species is the S-protein. This protein crystallises into a regular monolayer on the outside surface of the bacteria: the S-layer. Lactobacillus acidophilus harbours two S-protein-encoding genes, slpA and slpB, only one of which (slpA) is expressed. In this study, we show by polymerase...

The presence of two S-layer-protein-encoding genes is conserved among species related to Lactobacillus acidophilus

Previously we have shown that the type strain of Lactobacillus acidophilus possesses two S-protein-encoding genes, one of which is silent, on a chromosomal segment of 6 kb. The S-protein-encoding gene in the expression site can be exchanged for the silent S-protein-encoding gene by inversion of this slp segment. In this study the presence of S...

Genetic analysis of acidocin B: A novel bacteriocin produced by Lactobacillus acidophilus

The genes encoding the production of acidocin B, a bacteriocin produced by Lactobacillus acidophilus strain M46 which is active against Listeria monocytogenes, Clostridium sporogenes, Brochothrix thermosphacta, Lactobacillus fermentum and Lactobacillus delbrueckii subsp. bulgaricus, but inactive against most other Lactobacillus species, were...