The SAR11 Group of Alpha-Proteobacteria Is Not Related to the Origin of Mitochondria

Although free living, members of the successful SAR11 group of marine alpha-proteobacteria contain a very small and A+T rich genome, two features that are typical of mitochondria and related obligate intracellular parasites such as the Rickettsiales. Previous phylogenetic analyses have suggested that Candidatus Pelagibacter ubique, the first cultured member of this group, is related to the Rickettsiales+mitochondria clade whereas others disagree with this conclusion. In order to determine the evolutionary position of the SAR11 group and its relationship to the origin of mitochondria, we have performed phylogenetic analyses on the concatenation of 24 proteins from 5 mitochondria and 71 proteobacteria. Our results support that SAR11 group is not the sistergroup of the Rickettsiales+mitochondria clade and confirm that the position of this group in the alpha-proteobacterial tree is strongly affected by tree reconstruction artefacts due to compositional bias. As a consequence, genome reduction and bias toward a high A+T content may have evolved independently in the SAR11 species, which points to a different direction in the quest for the closest relatives to mitochondria and Rickettsiales. In addition, our analyses raise doubts about the monophyly of the newly proposed Pelagibacteraceae family

Going Deeper: Metagenome of a Hadopelagic Microbial Community

The paucity of sequence data from pelagic deep-ocean microbial assemblages has severely restricted molecular exploration of the largest biome on Earth. In this study, an analysis is presented of a large-scale 454-pyrosequencing metagenomic dataset from a hadopelagic environment from 6,000 m depth within the Puerto Rico Trench (PRT). A total of 145 Mbp of assembled sequence data was generated and compared to two pelagic deep ocean metagenomes and two representative surface seawater datasets from the Sargasso Sea. In a number of instances, all three deep metagenomes displayed similar trends, but were most magnified in the PRT, including enrichment in functions for two-component signal transduction mechanisms and transcriptional regulation. Overrepresented transporters in the PRT metagenome included outer membrane porins, diverse cation transporters, and di- and tri-carboxylate transporters that matched well with the prevailing catabolic processes such as butanoate, glyoxylate and dicarboxylate metabolism. A surprisingly high abundance of sulfatases for the degradation of sulfated polysaccharides were also present in the PRT. The most dramatic adaptational feature of the PRT microbes appears to be heavy metal resistance, as reflected in the large numbers of transporters present for their removal. As a complement to the metagenome approach, single-cell genomic techniques were utilized to generate partial whole-genome sequence data from four uncultivated cells from members of the dominant phyla within the PRT, Alphaproteobacteria, Gammaproteobacteria, Bacteroidetes and Planctomycetes. The single-cell sequence data provided genomic context for many of the highly abundant functional attributes identified from the PRT metagenome, as well as recruiting heavily the PRT metagenomic sequence data compared to 172 available reference marine genomes. Through these multifaceted sequence approaches, new insights have been provided into the unique functional attributes present in microbes residing in a deeper layer of the ocean far removed from the more productive sun-drenched zones above

Pathogen germs response to low-dose radiation — medical approach

The side effects of radiation therapy in the case of microbial loading of irradiated organs was considered as phenomenological basis of the experiment carried out on Staphylococcus aureus (ATCC germ) exposed to low X-ray doses. The inoculum was prepared in a liquid culture medium with standard composition, the volumes of 3 ml identical samples (in sterile glass tubes) being irradiated in hospital conditions. Five experimental variants were developed corresponding to irradiation time durations between 25 and 100 minutes. The spectro-colorimetric assay was accomplished at 560 nm and 420 nm, the resulting average values (for three repetitions) being analyzed from the viewpoint of cell density in the irradiated variants compared to control ones. The resistance to antibiotics of the irradiated bacteria was tested on agarized cultures against five antibiotic molecules (ampicillin, cloramphenicol, tetracycline, tobramicin and ofloxacin) by assessing the diameter of inhibition growth areas in each case. The increase of the inhibition area diameter with up to 15% (in the case of tetracycline) was noticed for the lowest irradiation time for all five antibiotics, which is suggesting a weakening of the bacteria resistance to the pharmaceutical agents following the X-ray treatment. This was concordant with the results of the spectro-colorimetric assay of the cell density within the directly irradiated bacteria cultures. The main issue of this study is concerning the optimization of the radiotherapy protocol in patients with potential microbial loading

Chemical composition and in vitro antimicrobial activity of the essential oils of flower heads and leaves of Santolina rosmarinifolia L. form Romania

The essential oils of the flower heads and leaves of Santolina rosmarinifolia L. (Compositae) cultivated in Romania were obtained through hydrodistillation and analysed by GC-MS. Forty-two components were identified, representing 92.3-94.0% of the whole composition of the samples. Their in vitro antimicrobial activity against gram-positive and gram-negative bacteria strains and the fungus Candida albicans was determined using the agar-diffusion method and the broth dilution method

Volatile constituents and antimicrobial activity of tilia tomentosa moench and tilia cordata miller oils

The essential oils of bracts and inflorescences of cultivated Tilia tomentosa and T. cordata from Greece and Romania, respectively, were investigated. Essential oils were obtained by hydrodistilation and analyzed using GC and GC/MS. The oils of from the inflorescences of T. tomentosa and T. cordata were characterized by a high percentage of hydrocarbons (32.3% and 60.4%, respectively) with tricosane being the main component (21.5% and 31.3%). Isocyclocitral (15.3%) and hotrienol (11.5%) were characterized as the main oxygenated monoterpenes of T. tomentosa and T. cordata inflorescences oils, respectively. Linalool (13.1%) and hexahydrofarnesyl acetone (17.7%) were the major constituents in bract oil of T. tomentosa, whereas the bract oil of T. cordata was characterized by the predominance of hydrocarbons (87.4%) with tricosane (32.2%) being the main constituent. © 2007, Taylor & Francis Group, LLC. All rights reserved

Газовая плазма для стерилизации поверхностей

University Grigore T. Popa, Faculty of Pharmacy, Iasi, Romania, University Ion Ionescu dela Brad, Biophysics Department, Iasi, Romania, University Alexandru Ioan Cuza, Faculty of Physics, Iasi, Romania, Conferința științifico-practică cu participare internațională Centrul de Sănătate Publică din municipiul Chișinău – 70 de ani la straja sănătăţii 23 octombrie 2014Interacţiunea plasmei gazoase cu culturi bacteriene a fost studiată ca aplicaţie practică a plasmei reci la sterilizarea obiectelor mici pentru utilizare medicală. Zonele de inhibiţie a creşterii microbiene au fost măsurate în jurul spotului de impact cu jetul de plasmă pentru un jet de 3.5 cm lungime şi pentru unul de 2.5 cm, pentru acelaşi timp de expunere de 50 secunde. Efectul evident de distrugere a bacteriilor recomandă această metodă pentru sterilizarea unor ustensile medicale ce sunt sensibile la temperatură sau la reactivi chimici, ea fi ind de asemenea susţinută de relativa accesibilitate şi costurile mici.Взаимодействие газообразной плазмы с культурами бактерий было исследовано с точки зрения практического применения холодной плазмы для стерилизации малых предметов медицинского пользования. Зоны подавления микробного роста были измерены вокруг места воздействия струй плазмы для струи с длиной 3,5 см, а также с длиной 2,5 см при одинаковом времени воздействия равной 35 сек. Благодаря очевидному эффекту уничтожения бактерий, этот метод рекомендуется использовать для стерилизации некоторых медицинских принадлежностей, чувствительных к температуре или химическим реактивам, метод будучи удобным также благодаря относительной доступности и малой стоимости

Migration of seismic activity associated with phreatic eruption at Merapi volcano, Indonesia

Phreatic activity of Merapi started after nearly 2 years of quiescence following the October-November 2010 eruption which was the largest in more than 100 years. A dozen eruptions identified by visual andior seismic observations took place between August 2012 and April 2014. We present in this work the results of a detailed analysis of the April 20, 2014 phreatic eruption. We attempted to reconstruct the eruptive process, which lasted for over 30 min. To this end, we determined the wavefield composition by polarization analysis, located high-frequency earthquakes occurring in the initial part of the eruption process and then determined the seismic source migration of low-frequency part of the tremor-like signal [0.3-3 Hz] over time. Source depth of low-frequency signal was obtained by comparing the slowness vector calculated using 3 stations of the seismic antenna with a slowness vector model obtained by ray tracing in the structure, taking into account the topography and a 1D velocity model obtained by spatial auto-correlation analysis. The results allow to distinguish 3 different phases: 1) High-frequency transients interpreted as the result of a sudden decompression caused by the transition of the volcanic fluid to a gaseous phase that occurred approximately 1.5 km deep. This decompression process in the hydrothermal system generated a migration of the low-frequency seismic source from 900 m to 1800 m above sea level: 2) A second decompression process revealed by high-frequency micro-seismicity and associated to the migration of the low-frequency tremor source which is marked first by a descent phase, followed by a sharp ascent until reaching the surface. The evolution of the back-azimuth during the migration process indicates a slight inclination of the conduit, presumably in the orientation of the dome fracture, in the NW-SE direction. This direction is consistent with the alignment of regional tectonic structures and with the directivity of eruption deposits. 3) The seismic source then remains positioned at the altitude of the dome for over 10 min. This phase probably corresponds to the ash emission process. The average migration speed of the low-frequency seismic source from the starting eruptive process to ash emission is about 5 m/s