Izolacija, biokemijske značajke i identifikacija termotolerantnih i celulolitičkih bakterija Paenibacillus lactis i Bacillus licheniformis

Research background. Cellulose is an ingredient of waste materials that can be converted to other valuable substances. This is possible provided that the polymer molecule is degraded to smaller particles and used as a carbon source by microorganisms. Because of the frequently applied methods of pretreatment of lignocellulosic materials, the cellulases derived from thermophilic microorganisms are particularly desirable. Experimental approach. We were looking for cellulolytic microorganisms able to grow at 50 °C and we described their morphological features and biochemical characteristics based on carboxymethyl cellulase (CMCase) activity and the API® ZYM system. The growth curves during incubation at 50 °C were examined using the BioLector® microbioreactor. Results and conclusions. Forty bacterial strains were isolated from fermenting hay, geothermal karst spring, hot spring and geothermal pond at 50 °C. The vast majority of the bacteria were Gram-positive and rod-shaped with the maximum growth temperature of at least 50 °C. We also demonstrated a large diversity of biochemical characteristics among the microorganisms. The CMCase activity was confirmed in 27 strains. Hydrolysis capacities were significant in bacterial strains: BBLN1, BSO6, BSO10, BSO13 and BSO14, and reached 2.74, 1.62, 1.30, 1.38 and 8.02 respectively. Rapid and stable growth was observed, among others, for BBLN1, BSO10, BSO13 and BSO14. The strains fulfilled the selection conditions and were identified based on the 16S rDNA sequences. BBLN1, BSO10, BSO13 were classified as Bacillus licheniformis, whereas BSO14 as Paenibacillus lactis. Novelty and scientific contribution. We described cellulolytic activity and biochemical characteristics of many bacteria isolated from hot environments. We are also the first to report the cellulolytic activity of thermotolerant P. lactis. Described strains can be a source of new thermostable cellulases, which are extremely desirable in various branches of circular bioeconomy.Pozadina istraživanja. Celuloza je sastojak otpadnih tvari koji se može preraditi u korisne spojeve. To je moguće ako se molekule polimera razgrade na manje čestice koje mikroorganizmi mogu iskoristiti kao izvor ugljika. Celulaze proizvedene s pomoću termofilnih mikroorganizama su naročito zanimljive zbog njihove učestale primjene u prethodnoj obradi lignoceluloznog materijala. Eksperimentalni pristup. Istražili smo celulolitičke mikroorganizme koji rastu na 50 °C te opisali njihove morfološke i biokemijske značajke na osnovi aktivnosti karboksimetil celulaze i ostalih enzima ispitanih sustavom API® ZYM. Krivulje rasta tijekom inkubacije pri 50 °C ispitane su uzgojem bakterija u mikrobioreaktoru BioLector®. Rezultati i zaključci. Četrdeset sojeva bakterija izolirano je iz fermentirane slame, geotermičkog izvora u kršu, termalnog vrela i geotermalnog jezera s temperaturom od 50 °C. Većina bakterija bile su Gram-pozitivne i štapićastog oblika, a najviša temperatura pri kojoj su rasle je iznosila najmanje 50 °C. Također smo potvrdili veliku raznolikost biokemijskih značajki među ispitanim mikroorganizmima. Aktivnost karboksimetil celulaze potvrđena je u 27 sojeva. Sojevi bakterija sa značajnim hidrolitičkim kapacitetom bili su: BBLN1 s 2,74; BSO6 s 1,62; BSO10 s 1,30; BSO13 s 1.38 i BSO14 s kapacitetom od 8,02. Sojevi BBLN1, BSO10, BSO13 i BSO14 rasli su brzo i stabilno. Ispunjavali su odabrane preduvjete pa su identificirani 16S rDNA sekvenciranjem. Sojevi BBLN1, BSO10 i BSO13 klasificirani su kao sojevi bakterije Bacillus licheniformis, dok je soj BSO14 potvrđen kao soj Paenibacillus lactis. Novina i znanstveni doprinos. Opisali smo celulolitičku aktivnost i biokemijska svojstva velikog broja bakterija izoliranih iz lokacija gdje vladaju velike vrućine. Prvi smo izvijestili o celulolitičkoj aktivnosti termotolerantne bakterije P. lactis. Opisani bi sojevi mogli biti izvor novih termički stabilnih celulaza, što je izuzetno poželjno u različitim granama cirkularne bioekonomije

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Innovative strategies for identifying and grouping chemicals, nanomaterials and materials to improve their safety of use

To enhance the safety of chemicals, nanomaterials, and materials, innovative identification and grouping strategies are urgently needed. There are various methods which can improve hazard assessment, reduce testing burdens, and support regulatory decisions. This study explores cutting-edge approaches to enable more efficient and accurate safety evaluations, ensuring sustainable and safer use, as part of an European-wide project. Considering the Chemicals Sustainability Strategy (CSS) and the challenges it addresses regarding the production and use of chemicals to meet societal needs and protect people and ecosystems, two key research and innovation actions are being undertaken, namely 1) Strategic Research and Innovation Agenda and 2) implementation of Safe and Sustainable by Design concept. To address these needs, the CheMatSustain project aims to develop new research methods or improve existing ones to enhance the safety and sustainability assessments of chemicals and materials. The project uses photoelectron spectra to identify chemicals, nanomaterials and materials (CNMs), and alternatively, transcriptome and proteome profiles of EA.hy926 cells exposed to contact with the tested CNMs. In the latter alternative case, the cells serve as selective biosensors that repeatedly and specifically recognize the stress factor resulting from contact with artificial surfaces. Identifying similarities and differences in photoelectron spectra and transcriptome and proteome profiles are crucial. All tested samples of CNMs are also used in in vitro biological studies to assess cytotoxicity and genotoxicity, the impact on the processes of free radicals' formation, apoptosis, repair of damaged DNA, and to assess ecological effects in vivo in relation to aquatic organisms. The collected data are stored in a database and utilized to develop computational QSAR models for predicting CNMs' activity in various toxicological and ecotoxicological endpoints (in silico risk assessment). Data obtained within the CheMatSustain project also will allow the combined use of CNMs risk assessment and life cycle assessment to estimate the environmental impacts and human health risks at each stage of the life cycle of the CNMs studied

The ATLAS fast tracKer system

The ATLAS Fast TracKer (FTK) was designed to provide full tracking for the ATLAS high-level trigger by using pattern recognition based on Associative Memory (AM) chips and fitting in high-speed field programmable gate arrays. The tracks found by the FTK are based on inputs from all modules of the pixel and silicon microstrip trackers. The as-built FTK system and components are described, as is the online software used to control them while running in the ATLAS data acquisition system. Also described is the simulation of the FTK hardware and the optimization of the AM pattern banks. An optimization for long-lived particles with large impact parameter values is included. A test of the FTK system with the data playback facility that allowed the FTK to be commissioned during the shutdown between Run 2 and Run 3 of the LHC is reported. The resulting tracks from part of the FTK system covering a limited η-ϕ region of the detector are compared with the output from the FTK simulation. It is shown that FTK performance is in good agreement with the simulation. © The ATLAS collaboratio

The ATLAS Fast TracKer system

The ATLAS Fast TracKer (FTK) was designed to provide full tracking for the ATLAS high-level trigger by using pattern recognition based on Associative Memory (AM) chips and fitting in high-speed field programmable gate arrays. The tracks found by the FTK are based on inputs from all modules of the pixel and silicon microstrip trackers. The as-built FTK system and components are described, as is the online software used to control them while running in the ATLAS data acquisition system. Also described is the simulation of the FTK hardware and the optimization of the AM pattern banks. An optimization for long-lived particles with large impact parameter values is included. A test of the FTK system with the data playback facility that allowed the FTK to be commissioned during the shutdown between Run 2 and Run 3 of the LHC is reported. The resulting tracks from part of the FTK system covering a limited η-ϕ region of the detector are compared with the output from the FTK simulation. It is shown that FTK performance is in good agreement with the simulation