Lignocellulosic residues are low-cost abundant feedstocks that can be used for industrial applications. However, their recalcitrance currently makes lignocellulose use limited. In natural ...environments, microbial communities can completely deconstruct lignocellulose by synergistic action of a set of enzymes and proteins. Microbial degradation of lignin by fungi, important lignin degraders in nature, has been intensively studied. More recently, bacteria have also been described as able to break down lignin, and to have a central role in recycling this plant polymer. Nevertheless, bacterial deconstruction of lignin has not been fully elucidated yet. Direct analysis of environmental samples using metagenomics, metatranscriptomics, and metaproteomics approaches is a powerful strategy to describe/discover enzymes, metabolic pathways, and microorganisms involved in lignin breakdown. Indeed, the use of these complementary techniques leads to a better understanding of the composition, function, and dynamics of microbial communities involved in lignin deconstruction. We focus on omics approaches and their contribution to the discovery of new enzymes and reactions that impact the development of lignin-based bioprocesses.
•Train-track-bridge interaction problem with non-linear behavior of track-deck interface.•Track-deck interface behavior is more influenced by temperature than traffic loads.•Plastic incursions at ...track-deck interface were detected under deck temperature variations.•Extension of plastic regions is sensitive to variations of the support’s horizontal stiffness.•Elastic behavior in short spans and plastic behavior in medium/large span bridges.
This article presents an efficient computational methodology for solving the train-track-bridge interaction problem, including track irregularities and considering the non-linear behaviour of the track-deck interface. One of the novelties of the work is the proposal of a specific finite element used to model the track-deck interface, based on an assembly of a friction contact element and a non-linear spring, which is generally not used in non-linear dynamic problems. This element automatically performs changes in the longitudinal resistance of the track, according to the positions of the traffic loads, and takes into account the loading history. The dynamic analyses are performed based on an iterative methodology implemented in AIVE software, which takes advantage of the advanced modeling tools of Abaqus software controlled on Matlab. This software ensures flexibility in the selection of the methods for solving the dynamic problem and allows the incorporation of non-linearities in the vehicle and bridge models, including their interfaces. A parametric study was performed in order to demonstrate the importance of including the non-linear behaviour at the track-deck interface in the evaluation of the dynamic responses of the bridge and vehicle subsystems, under different scenarios of deck temperature, horizontal stiffness of the supports and deck cross-sections. The results show that the responses of the track-deck interface are more influenced by the effects of temperature variations than by the effects of vertical traffic loads, particularly for medium and large span bridges. Significant plastic incursions were detected at the track-deck interface under realistic temperature scenarios, particularly on the side of the mobile support. Under vertical traffic loads, the extension of the regions with plastic behaviour proved to be sensitive to variations in the horizontal stiffness of the support. Additionally, another important achievement of this study was the evaluation of the plastic incursions at the track-deck interface for different bridges typologies. Relevant incursions were detected for medium and large span bridges, where the extension of these regions can reach 25–55% of the bridge span, otherwise, for short span bridges, practically no significant plasticized regions were identified. Non-linear incursions on the track-deck interface cause an overall reduction of the track-bridge stiffness, leading to an increase of the vertical movements of the bridge, and, inherently, of the vehicle’s dynamic responses. The evaluation of the extension of the ballast plastic regions for the different analysis scenarios, which is still a topic shortly addressed in the bibliography, will be particularly useful for upgrading the existing methods for assessment of the dynamic behavior of railway bridges.
Penicillium
species have been studied as producers of plant cell wall degrading enzymes to deconstruct agricultural residues and to be applied in industrial processes. Natural environments containing ...decaying plant matter are ideal places for isolating fungal strains with cellulolytic and xylanolytic activities. In the present study, Cerrado soil samples were used as source of filamentous fungi able to degrade xylan and cellulose.
Penicillium
was the most abundant genus among the obtained xylan and carboxymethylcellulose degraders.
Penicillium polonicum
was one of the best enzyme producers in agar-plate assays. In addition, it secretes CMCase, Avicelase, pectinase, mannanase, and xylanase during growth in liquid media containing sugarcane bagasse as carbon source. The highest value for endo-
β
-1,4-xylanase activity was obtained after 4 days of growth. Xyl
PP
, a 20 kDa endo-
β
-1,4-xylanase, was purified and partially characterized. The purified enzyme presented the remarkable feature of being resistant to the lignin-derived phenolic compounds,
p
-coumaric and trans-ferulic acids. This feature calls for its further use in bioprocesses that use lignocellulose as feedstock. Furthermore, future work should explore its structural features which may contribute to the understanding of the relationship between its structure and resistance to phenolic compounds.
Lignin is an aromatic macromolecule and one of the main constituents of lignocellulosic materials. Kraft lignin is generated as a residual by-product of the lignocellulosic biomass industrial ...process, and it might be used as a feedstock to generate low molecular weight aromatic compounds. In this study, we seek to understand and explore the potential of ruminal bacteria in the degradation of kraft lignin. We established two consortia, KLY and KL, which demonstrated significant lignin-degrading capabilities. Both consortia reached maximum growth after two days, with KLY showing a higher growth and decolorization rate. Additionally, SEM analysis revealed morphological changes in the residual lignin from both consortia, indicating significant degradation. This was further supported by FTIR spectra, which showed new bands corresponding to the C-H vibrations of guaiacyl and syringyl units, suggesting structural transformations of the lignin. Taxonomic analysis showed enrichment of the microbial community with members of the Dickeya genus. Seven metabolic pathways related to lignin metabolism were predicted for the established consortia. Both consortia were capable of consuming aromatic compounds such as 4-hydroxybenzoic acid, syringaldehyde, acetovanillone, and syringic acid, highlighting their capacity to convert aromatic compounds into commercially valuable molecules presenting antifungal activity and used as food preservatives as 4-hydroxyphenylacetic, 3-phenylacetic, and phenylacetic acids. Therefore, the microbial consortia shown in the present work are models for understanding the process of lignin degradation and consumption in bacterial anaerobic communities and developing biological processes to add value to industrial processes based on lignocellulosic biomass as feedstock.
•The bacterial consortia established degrade and consume lignin anaerobically.•Aromatic compounds with commercial interest were produced.•Dickeia is the main genus involved in lignin degradation.
An M6.5-class flare was observed at N12E56 on the solar surface at 16:06 UT on July 8, 2014. In association with the flare, two neutron detectors located at high mountains, Mt. Sierra Negra in Mexico ...and Mt. Chacaltaya in Bolivia, recorded two neutron pulses, separated approximately by 30 min. Moreover, enhancements were also observed by the solar neutron detector onboard the International Space Station. We analyzed these data combined with solar images from
Atmospheric Imaging Assembly
(AIA) onboard the
Solar Dynamics Observatory
. From these we noticed that the production mechanism of neutrons cannot be explained by a single model; at least one of the enhancements may be explained by an electric field generated by the collision of magnetic loops and the other by the shock acceleration mechanism at the front side of the CME.
The Large Aperture GRB Observatory (LAGO) project aims at the detection of high energy photons from Gamma Ray Bursts (GRB) using the single particle technique in ground-based water-Cherenkov ...detectors (WCD). To reach a reasonable sensitivity, high altitude mountain sites have been selected in Mexico (Sierra Negra, 4550
m a.s.l.), Bolivia (Chacaltaya, 5300
m a.s.l.) and Venezuela (Mérida, 4765
m a.s.l.). We report on detector calibration and operation at high altitude, search for bursts in 4 months of preliminary data, as well as search for signal at ground level when satellites report a burst.
We present the results of an ongoing survey on the association between the muon flux variation at ground level (3 m above sea level) registered by the Tupi telescopes (Niteri-Brazil, 22degrees.9S, ...43degreeds.2W, 3 m) and the Earth-directed transient disturbances in the interplanetary medium propagating from the Sun (such as coronal mass ejections (CME), and corotating interaction regions (CIRs)). Identification of interplanetary structures and associated solar activity was based on the nomenclature and definitions given by the satellite observations, including an incomplete list of possible interplanetary shocks observed by the CELIAS/MTOF Proton Monitor on the Solar and Heliospheric Observatory (SOHO) spacecraft. Among 29 experimental events reported in the present analysis, there are 15 possibly associated with the CMEs and sheaths, and 3 events with the CIRs (forward or reverse shocks); the origin of the remaining 11 events has not been determined by the satellite detectors.
Lignocellulosic material is an alternative, renewable and cheaper source of molecules to be applied in greener industrial processes. Its utilization for this purpose requests steps of pre-treatment ...and hydrolysis. Filamentous fungi are receiving attention as source of plant cell wall degrading enzymes to apply in lignocellulosic biomass hydrolysis. In the present study, a strain of
Penicillium chrysogenum
CCDCA10756 isolated from Brazilian Cerrado soil (Savannah like biome) was evaluated as a producer of plant cell wall degrading enzymes aiming industrial application. The fungus cultivated in the presence of corn straw as sole carbon source secreted cellulases (endo-β-1,4-glucanases, cellobiohydrolases, β-glucosidases), endo-β-1,4-xylanases, and pectinases. Endo-β-1,4-xylanases and pectinases presented earlier production reaching maximum values after 3 days of growth in comparison to cellulolytic activities mostly produced after 5 days. Cellobiohydrolases and endo-β-1,4-glucanases present maximal activity in acid pH (3 and 4) and at 50 °C, whereas β-glucosidase presents maximal activity at pH 5.0 and 60 °C. Pectinases showed maximum activity in pH 8 at 50 °C. Furthermore, endo-β-1,4-glucanases and cellobiohydrolases displayed remarkable thermostability at 40 °C. Lignin-derived compounds, trans-ferulic acid, 4-hydroxybenzoic and syringaldehyde inhibited cellobiohydrolases. Pectinolytic activity, instead, was improved in the presence of
p
-coumaric acid, trans-ferulic acid, and syringaldehyde.
Lignocellulosic residues daily generated as a by-product of economic activities worldwide, stand out as potential feedstock to biorefineries. Industrial processes based on their use still face a ...challenge in the development of low-cost enzymatic mixtures resistant to inhibitors produced during pre-treatment step and efficient in the complete deconstruction of different lignocellulosic wastes. In the present work,
Paenibacillus barengoltzii
A1_50L2 isolated from bovine rumen was studied as a source of plant cell wall degrading enzymes. In addition, the natural produced enzymatic cocktail was characterized and applied to the hydrolysis of lignocellulosic substrates.
P. barengoltzii
grew in liquid media containing cellulose, sugarcane bagasse and wheat bran, as carbon source producing endo-1,4-β-xylanases, pectinases, mannanases, endo-1,4-β-glucanases, exo-1,4-β-glucanases and β-glucosidases, with highest values of endo-1,4-β-xylanase activity. Six isoforms of endo-1,4-β-xylanase (45 to 116 kDa), three of endo-1,4-β-glucanase (40 to 66 kDa) and a single band of mannanase (62 kDa) were secreted by the bacterium during growth on wheat bran, all enzymes presented maximal activity in pH ranging from 4 up to 8 and temperature from 45 up to 60 °C. Endo-1,4-β-xylanases, endo-1,4-β-glucanases, exo-1,4-β-glucanases, pectinases, mannanases and β-glucosidases produced by
P. barengoltzii
are tolerant to lignin-derived compounds showing a minimal residual activity of 61%. Ferulic, gallic, tannic and cinnamic acids enhanced activities of endo-1,4-β-glucanases/endo-1,4-β-xylanases, mannanase and pectinase, respectively.
P. barengoltzii
enzymatic cocktail (PbEC) hydrolyzes sugarcane bagasse, banana stem and corncob with hydrolysis values comparable to those obtained for the commercial blend Viscozyme®. The addition of PbEC to Viscozyme® increases the hydrolysis rate of sugarcane bagasse, banana stem and corncob in three to four times.
Graphic Abstract
Strong signals of neutral emissions were detected in association with a solar flare that occurred on 2005 September 7. They were produced by both relativistic ions and electrons. In particular, ...relativistic neutrons were observed with the solar neutron telescopes (SNTs) located at Mount Chacaltaya in Bolivia and Mount Sierra Negra in Mexico and with neutron monitors (NMs) at Chacaltaya and Mexico City with high statistical significances. At the same time, hard X-rays and g-rays, which were predominantly emitted by high-energy electrons, were detected by the Geotail and the INTEGRAL satellites. We found that a model of the impulsive neutron emission at the time of the X-ray/g-ray peak can explain the main peaks of all the detected neutron signals, but failed to explain the long tailed decaying phase. An alternative model, in which the neutron emission follows the X-ray/g-ray profile, also failed to explain the long tail. These results indicate that the acceleration of ions began at the same time as the electrons but that ions were continuously accelerated or trapped longer than the electrons in the emission site. We also demonstrate that the neutron data observed by multienergy channels of SNTs put constraints on the neutron spectrum.
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