Lactobacillaceae and Cell Adhesion: Genomic and Functional Screening

The analysis of collections of lactic acid bacteria (LAB) from traditional fermented plant foods in tropical countries may enable the detection of LAB with interesting properties. Binding capacity is often the main criterion used to investigate the probiotic characteristics of bacteria. In this study, we focused on a collection of 163 Lactobacillaceace comprising 156 bacteria isolated from traditional amylaceous fermented foods and seven strains taken from a collection and used as controls. The collection had a series of analyses to assess binding potential for the selection of new probiotic candidates. The presence/absence of 14 genes involved in binding to the gastrointestinal tract was assessed. This enabled the detection of all the housekeeping genes (ef-Tu, eno, gap, groEl and srtA) in the entire collection, of some of the other genes (apf, cnb, fpbA, mapA, mub) in 86% to 100% of LAB, and of the other genes (cbsA, gtf, msa, slpA) in 0% to 8% of LAB. Most of the bacteria isolated from traditional fermented foods exhibited a genetic profile favorable for their binding to the gastrointestinal tract. We selected 30 strains with different genetic profiles to test their binding ability to non-mucus (HT29) and mucus secreting (HT29-MTX) cell lines as well as their ability to degrade mucus. Assays on both lines revealed high variability in binding properties among the LAB, depending on the cell model used. Finally, we investigated if their binding ability was linked to tighter cross-talk between bacteria and eukaryotic cells by measuring the expression of bacterial genes and of the eukaryotic MUC2 gene. Results showed that wild LAB from tropical amylaceous fermented food had a much higher binding capacity than the two LAB currently known to be probiotics. However their adhesion was not linked to any particular genetic equipment

Two families of Rep-like genes that probably originated by interspecies recombination are represented in viral, plasmid, bacterial, and parasitic protozoan

Two families of genes related to, and including, rolling circle replication initiator protein (Rep) genes were defined by sequence similarity and by evidence of intergene family recombination. The Rep genes of circoviruses were the best characterized members of the "RecRep1 family." Other members of the RecRep1 family were Rep-like genes found in the genomes of the Canarypox virus, Entamoeba histolytica, and Giardia duodenalis and in a plasmid, p4M, from the Gram-positive bacterium, Bifidobacterium pseudocatenulatum. The "RecRep2 family" comprised some previously identified Rep-like genes from plasmids of phytoplasmas and similar Rep-like genes from the genomes of Lactobacillus acidophilus, Lactococcus lactis, and Phytoplasma asteris. Both RecRep1 and RecRep2 proteins have a nucleotide-binding domain significantly similar to the helicases (2C proteins) of picorna-like viruses. On the N-terminal side of the nucleotide binding domain, RecRep1 proteins have a domain significantly similar to one found in nanovirus Reps, whereas RecRep2 proteins have a domain significantly similar to one in the Reps of pLS1 plasmids. We speculate that RecRep genes have been transferred from viruses or plasmids to parasitic protozoan and bacterial genomes and that Rep proteins were themselves involved in the original recombination events that generated the ancestral RecRep genes

Intrinsic and inducible resistance to hydrogen peroxide in \u3ci\u3eBifidobacterium\u3c/i\u3e species

Interest in, and use of, bifidobacteria as a probiotic delivered in functional foods has increased dramatically in recent years. As a result of their anaerobic nature, oxidative stress can pose a major challenge to maintaining viability of bifidobacteria during functional food storage. To better understand the oxidative stress response in two industrially important bifidobacteria species, we examined the response of three strains of B. longum and three strains of B. animalis subsp. lactis to hydrogen peroxide (H2O2). Each strain was exposed to a range of H2O2 concentrations (0–10 mM) to evaluate and compare intrinsic resistance to H2O2. Next, strains were tested for the presence of an inducible oxidative stress response by exposure to a sublethal H2O2 concentration for 20 or 60 min followed by challenge at a lethal H2O2 concentration. Results showed B. longum subsp. infantis ATCC 15697 had the highest level of intrinsic H2O2 resistance of all strains tested and B. animalis subsp. lactis BL-04 had the highest resistance among B. lactis strains. Inducible H2O2 resistance was detected in four strains, B. longum NCC2705, B. longum D2957, B. lactis RH-1, and B. lactis BL-04. Other strains showed either no difference or increased sensitivity to H2O2 after induction treatments. These data indicate that intrinsic and inducible resistance to hydrogen peroxide is strain specific in B. longum and B. lactis and suggest that for some strains, sublethal H2O2 treatments might help increase cell resistance to oxidative damage during production and storage of probiotic-containing foods

Oral use of Lactobacillus rhamnosus GR-1 and L. fermentum RC-14 significantly alters vaginal flora: Randomized, placebo-controlled trial in 64 healthy women

The composition of vaginal bifidoflora in 56 clinically healthy women of reproductive age was studied. The study revealed that four species of bifidobacteria, viz. Bifidobacterium bifidum, B. breve, B. adolescentis 2 and B. longum, dominated in the composition of this bifidobacterial population. Nine out of 11 isolated strains were found to be capable of inhibiting indicator microorganisms Staphylococcus aureus and Enterococcus faecalis when tested in vitro; in addition, strains B. adolescentis 2 F1, B. bifidum G1, B. breve P2 and B. longum Z4 inhibited Klebsiella ozaenae, Pseudomonas aeruginosa, Escherichia coli and were also active acid producers. Three of these 4 bifidobacterial strains were capable of adhesion to vaginal epitheliocytes, while B. bifidum G1 was practically incapable of adherence to these cells, similarly to B. bifidum strain 791 of intestinal origin. In addition, the spectra of antibiotic susceptibility varied from strain to strain, but all bifidobacterial strains were susceptible to benzylpenicillin and resistant to lomefloxacin, most of them being also resistant to cyprofloxacin and gentamicin. Thus the data presented in this work are indicative of the possibility and advantages of using bifidobacterial strains belonging to this ecological niche as probiotics for the correction of the microflora of the urogenital tract in females

Comparative High-Density Microarray Analysis of Gene Expression during Growth of Lactobacillus helveticus in Milk versus Rich Culture Medium

Lactobacillus helveticus CNRZ32 is used by the dairy industry to modulate cheese flavor. The compilation of a draft genome sequence for this strain allowed us to identify and completely sequence 168 genes potentially important for the growth of this organism in milk or for cheese flavor development. The primary aim of this study was to investigate the expression of these genes during growth in milk and MRS medium by using microarrays. Oligonucleotide probes against each of the completely sequenced genes were compiled on maskless photolithography-based DNA microarrays. Additionally, the entire draft genome sequence was used to produce tiled microarrays in which noninterrupted sequence contigs were covered by consecutive 24-mer probes and associated mismatch probe sets. Total RNA isolated from cells grown in skim milk or in MRS to mid-log phase was used as a template to synthesize cDNA, followed by Cy3 labeling and hybridization. An analysis of data from annotated gene probes identified 42 genes that were upregulated during the growth of CNRZ32 in milk (P < 0.05), and 25 of these genes showed upregulation after applying Bonferroni's adjustment. The tiled microarrays identified numerous additional genes that were upregulated in milk versus MRS. Collectively, array data showed the growth of CNRZ32 in milk-induced genes encoding cell-envelope proteinases, oligopeptide transporters, and endopeptidases as well as enzymes for lactose and cysteine pathways, de novo synthesis, and/or salvage pathways for purines and pyrimidines and other functions. Genes for a hypothetical phosphoserine utilization pathway were also differentially expressed. Preliminary experiments indicate that cheese-derived, phosphoserine-containing peptides increase growth rates of CNRZ32 in a chemically defined medium. These results suggest that phosphoserine is used as an energy source during the growth of L. helveticus CNRZ32

Strains, isolated from the same children in different time points.

<p>Horizontal axis represent the age of the subject, rows represent the children, labels in the cells correspond to the isolated strains. Dotted lines connect similar strains.</p

Whole genome alignment of complete genome sequences using Mauve.

<p>Colored boxes, linear collinear blocks (LCB). White gaps, insertions and deletions. Position atop or below the horizontal line represents the direction of LCB.</p