Adhesion of the genome-sequenced <Emphasis Type="Italic">Lactococcus lactis</Emphasis> subsp. <Emphasis Type="Italic">cremoris</Emphasis> IBB477 strain is mediated by specific molecular determinants

Understanding the nature of mucus-microbe interactions will provide important information that can help to elucidate the mechanisms underlying probiotic adhesion. This study focused on the adhesive properties of the Lactococcus lactis subsp. cremoris IBB477 strain, previously shown to persist in the gastrointestinal tract of germ-free rats. The shear flow-induced detachment of L. lactis cells was investigated under laminar flow conditions. Such a dynamic approach demonstrated increased adhesion to bare and mucin-coated polystyrene for IBB477, compared to that observed for the MG1820 control strain. To identify potential genetic determinants giving adhesive properties to IBB477, the improved high-quality draft genome sequence comprising chromosome and five plasmids was obtained and analysed. The number of putative adhesion proteins was determined on the basis of surface/extracellular localisation and/or the presence of adhesion domains. To identify proteins essential for the IBB477 specific adhesion property, nine deletion mutants in chromosomal genes have been constructed and analysed using adhesion tests on bare polystyrene as well as mucin-, fibronectin- or collagen IV-coated polystyrene plates in comparison to the wild-type strain. These experiments demonstrated that gene AJ89_07570 encoding a protein containing DUF285, MucBP and four Big_3 domains is involved in adhesion to bare and mucin-coated polystyrene. To summarise, in the present work, we characterised the adhesion of IBB477 under laminar flow conditions; identified the putative adherence factors present in IBB477, which is the first L. lactis strain exhibiting adhesive and mucoadhesive properties to be sequenced and demonstrated that one of the proteins containing adhesion domains contributes to adhesion.     

Enantiomerization of Allylic Trifluoromethyl Sulfoxides Studied by HPLC Analysis and DFT Calculations

Enantiomerization of allylic trifluoromethyl sulfoxides occurs spontaneously at room temperature through the corresponding allylic trifluoromethanesulfenates via a [2,3]‐sigmatropic rearrangement. Dynamic enantioselective high‐performance liquid chromatography (HPLC) analysis revealed the stereodynamics of these sulfoxides ranging from chromatographic resolution to peak coalescence at temperatures between 5 and 53 °C. The rate constant of enantiomerization and activation parameters were determined and compared with Density Functional Theory (DFT) calculations. Chirality 28:136–142, 2016. © 2015 Wiley Periodicals, Inc.     

Interspecies Comparison of the Bacterial Response to Allicin Reveals Species‐Specific Defense Strategies

Allicin, a broad‐spectrum antimicrobial agent from garlic, disrupts thiol and redox homeostasis, proteostasis, and cell membrane integrity. Since medicine demands antimicrobials with so far unexploited mechanisms, allicin is a promising lead structure. While progress is being made in unraveling its mode of action, little is known on bacterial adaptation strategies. Some isolates of Pseudomonas aeruginosa and Escherichia coli withstand exposure to high allicin concentrations due to as yet unknown mechanisms. To elucidate resistance and sensitivity‐conferring cellular processes, the acute proteomic responses of a resistant P. aeruginosa strain and the sensitive species Bacillus subtilis are compared to the published proteomic response of E. coli to allicin treatment. The cellular defense strategies share functional features: proteins involved in translation and maintenance of protein quality, redox homeostasis, and cell envelope modification are upregulated. In both Gram‐negative species, protein synthesis of the majority of proteins is downregulated while the Gram‐positive B. subtilis responded by upregulation of multiple regulons. A comparison of the B. subtilis proteomic response to a library of responses to antibiotic treatment reveals 30 proteins specifically upregulated by allicin. Upregulated oxidative stress proteins are shared with nitrofurantoin and diamide. Microscopy‐based assays further indicate that in B. subtilis cell wall integrity is impaired.     

A Putative Mechanism for Magnetoreception by Electromagnetic Induction in the Pigeon Inner Ear

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Host genetic requirements for DNA release of lactococcal phage TP901-1

The first step in phage infection is the recognition of, and adsorption to, a receptor located on the host cell surface. This reversible host adsorption step is commonly followed by an irreversible event, which involves phage DNA delivery or release into the bacterial cytoplasm. The molecular components that trigger this latter event are unknown for most phages of Gram-positive bacteria. In the current study, we present a comparative genome analysis of three mutants of Lactococcus cremoris 3107, which are resistant to the P335 group phage TP901-1 due to mutations that affect TP901-1 DNA release. Through genetic complementation and phage infection assays, a predicted lactococcal three-component glycosylation system (TGS) was shown to be required for TP901-1 infection. Major cell wall saccharidic components were analysed, but no differences were found. However, heterologous gene expression experiments indicate that this TGS is involved in the glucosylation of a cell envelope-associated component that triggers TP901-1 DNA release. To date, a saccharide modification has not been implicated in the DNA delivery process of a Gram-positive infecting phage.