Classification of a moderately oxygen-tolerant isolate from baby faeces as Bifidobacterium thermophilum

<p>Abstract</p> <p>Background</p> <p>Bifidobacteria are found at varying prevalence in human microbiota and seem to play an important role in the human gastrointestinal tract (GIT). Bifidobacteria are highly adapted to the human GIT which is reflected in the genome sequence of a <it>Bifidobacterim longum </it>isolate. The competitiveness against other bacteria is not fully understood yet but may be related to the production of antimicrobial compounds such as bacteriocins. In a previous study, 34 <it>Bifidobacterium </it>isolates have been isolated from baby faeces among which six showed proteinaceous antilisterial activity against <it>Listeria monocytogenes</it>. In this study, one of these isolates, RBL67, was further identified and characterized.</p> <p>Results</p> <p><it>Bifidobacterium </it>isolate RBL67 was classified and characterized using a polyphasic approach. RBL67 was classified as <it>Bifidobacterium thermophilum </it>based on phenotypic and DNA-DNA hybridization characteristics, although 16S rDNA analyses and partial <it>gro</it>EL sequences showed higher homology with <it>B. thermacidophilum </it>subsp. <it>porcinum </it>and <it>B. thermacidophilum </it>subsp. <it>thermacidophilum</it>, respectively. RBL67 was moderately oxygen-tolerant and was able to grow at pH 4 and at a temperature of 47°C.</p> <p>Conclusion</p> <p>In order to assign RBL67 to a species, a polyphasic approach was used. This resulted in the classification of RBL67 as a <it>Bifidobacterium thermophilum </it>strain. To our knowledge, this is the first report about <it>B. thermophilum </it>isolated from baby faeces since the <it>B. thermophilum </it>strains were related to ruminants and swine faeces before. <it>B. thermophilum </it>was previously only isolated from animal sources and was therefore suggested to be used as differential species between animal and human contamination. Our findings may disapprove this suggestion and further studies are now conducted to determine whether <it>B. thermophilum </it>is distributed broader in human faeces. Furthermore, the postulated differentiation between human and animal strains by growth above 45°C is no longer valid since <it>B. thermophilum </it>is able to grow at 47°C. In our study, 16S rDNA and partial <it>gro</it>EL sequence analysis were not able to clearly assign RBL67 to a species and were contradictory. Our study suggests that partial <it>gro</it>EL sequences may not be reliable as a single tool for species differentiation.</p

New method for selection of hydrogen peroxide adapted bifidobacteria cells using continuous culture and immobilized cell technology

<p>Abstract</p> <p>Background</p> <p>Oxidative stress can severely compromise viability of bifidobacteria. Exposure of <it>Bifidobacterium </it>cells to oxygen causes accumulation of reactive oxygen species, mainly hydrogen peroxide, leading to cell death. In this study, we tested the suitability of continuous culture under increasing selective pressure combined with immobilized cell technology for the selection of hydrogen peroxide adapted <it>Bifidobacterium </it>cells. Cells of <it>B. longum </it>NCC2705 were immobilized in gellan-xanthan gum gel beads and used to continuously ferment MRS medium containing increasing concentration of H₂O₂from 0 to 130 ppm.</p> <p>Results</p> <p>At the beginning of the culture, high cell density of 10¹³CFU per litre of reactor was tested. The continuous culture gradually adapted to increasing H₂O₂concentrations. However, after increasing the H₂O₂concentration to 130 ppm the OD of the culture decreased to 0. Full wash out was prevented by the immobilization of the cells in gel matrix. Hence after stopping the stress, it was possible to re-grow the cells that survived the highest lethal dose of H₂O₂and to select two adapted colonies (HPR1 and HPR2) after plating of the culture effluent. In contrast to HPR1, HPR2 showed stable characteristics over at least 70 generations and exhibited also higher tolerance to O₂than non adapted wild type cells. Preliminary characterization of HPR2 was carried out by global genome expression profile analysis. Two genes coding for a protein with unknown function and possessing trans-membrane domains and an ABC-type transporter protein were overexpressed in HPR2 cells compared to wild type cells.</p> <p>Conclusions</p> <p>Our study showed that continuous culture with cell immobilization is a valid approach for selecting cells adapted to hydrogen peroxide. Elucidation of H₂O₂adaptation mechanisms in HPR2 could be helpful to develop oxygen resistant bifidobacteria.</p

Taking screenshots of the invisible: A study on bacterial contamination of mobile phones from university students of healthcare professions in Rome, Italy

Mobile phones (MPs) are commonly used both in the personal and professional life. We assessed microbiological contamination of MPs from 108 students in healthcare professions (HPs), in relation to their demographic characteristics and MPs handling habits, collected by means of a questionnaire. Cultural and biochemical tests were performed, and statistical analyses were carried out. Staphylococci were present in 85% of MPs, Enterococci in 37%, Coliforms in 6.5%; E. coli was never detected. Staphylococcus epidermidis was the most frequently isolated staphylococcal species (72% of MPs), followed by S. capitis (14%), S. saprophyticus, S. warneri, S. xylosus (6%), and by S. aureus (4%). Heterotrophic Plate Counts (HPC) at 37◦C, ranged from 0 to 1.2 × 104 CFU/dm2 (mean = 362 CFU/dm2). In univariate analysis, the male gender only was significantly associated with higher HPCs and enterococcal contamination. Multiple linear regression models explained only 17% and 16% of the HPC 37◦C and staphylococcal load variability, respectively. Developing specific guidelines for a hygienic use of MPs in clinical settings, for preventing cross-infection risks, is advisable, as well as introducing specific training programs to HP students. MPs decontamination procedures could also be implemented in the community

Performance of the Electromagnetic Calorimeter of the HERMES Experiment

The performance of the electromagnetic calorimeter of the HERMES experiment is described. The calorimeter consists of 840 radiation resistant F101 lead-glass counters. The response to positrons up to 27.5 GeV, the comparison between the measured energy and the momentum reconstructed from tracking, long-term stability, hadron rejection and neutral meson invariant mass reconstruction are shown.Comment: 22 pages, 13 figures, LaTeX, accepted by NI

Relationship Between Physical Activity and Risk of Falls in Elderly of West Marin

Background: Fall injury is a leading cause of death and disability among older adults (Alamgir, 2012). Fall injury may result in fractures, infection and fear of movement. By reinforcing engagement in muscles used during balance and walking, seniors may avoid unnecessary falls within their homes and the community. Setting/Target Population: West Marin is the largest rural area of Marin County, California and includes seven unincorporated communities. A large percentage of the elderly population who reside in West Marin live alone--thus suffering from isolation. Within the rural, isolated communities of West Marin, the rate of falls among the elderly are increasing. Improvement Project: At the Community Center in Point Reyes, a seated Zumba class is offered to seniors. This class is offered only once per week, yet there is great value in encouraging seniors to utilize their muscles, develop core strength, and improve balance while having fun and being engaged. Twelve Dominican Nursing Students propose to make a video of the seated Zumba class and distribute the DVDs to the patrons of the Senior Luncheons in Point Reyes and San Geronimo Valley (approximately 150 people). Prior to the DVD distribution, the Nursing Students will perform a health presentation to the seniors on the benefits of exercise to encourage their desire to participate. Objectives: 1) increase the number of days per week that West Marin seniors perform the seated Zumba exercises from one day per week to most days of the week; 2) increase strength, mobility, and balance among West Marin seniors who participate in the seated Zumba project; 3) reduce risk of falls among West Marin seniors participating in the seated Zumba project; 4) increase exercise-related endorphins and reduce depression among West Marin seniors participating in the seated Zumba project. Outcomes/Lessons Learned: To be completed at end of project and presented at conference

Occurrence of Legionella in showers at recreational facilities.

Critical environments, including water systems in recreational settings, represent an important source of Legionella pneumophila infection in humans. In order to assess the potential risk for legionellosis, we analyzed Legionella contamination of water distribution systems in 36 recreational facilities equipped with swimming pools. One hundred and sixty water samples were analyzed from shower heads or taps located in locker rooms or in bathrooms. By culture method and polymerase chain reaction, 41/160 samples were positive for Legionella from 12/36 recreational centers. Hotels (57.1%) and sports centers (41.2%) were the most contaminated. L. pneumophila serotypes 2–14 (25/41) were more frequently found than serotype 1 (10/41). Samples at temperature ≥30 °C were more frequently positive than samples at temperature &lt;30 °C (n = 39 vs n = 2, p &lt; 0.00001). The presence of L. pneumophila was investigated by comparison with heterotrophic plate count (HPC), an indicator of water quality. The presence of L. pneumophila was associated more frequently with high and intermediate HPC load at 37 °C, therefore should be considered a potential source when HPC at 37 °C is &gt;10 CFU/mL. Maintenance, good hygiene practices, interventions on the hydraulic system and regular controls must be implemented to minimize exposure to L. pneumophila infection risk