Isolation and Characterization of Levoglucosan Metabolizing Bacteria

Bacteria were isolated from wastewater and soil containing charred wood remnants based on their ability to use levoglucosan as a sole carbon source and on their levoglucosan dehydrogenase (LGDH) activity. On the basis of their 16S rRNA gene sequences, these bacteria represented diverse genera of Microbacterium, Paenibacillus , Shinella , and Klebsiella . Genomic sequencing of the isolates verified that two isolates represented novel species, Paenibacillus athensensis MEC069 T and Shinella sumterensis MEC087 T , while the remaining isolates were closely related to either Microbacterium lacusdiani or Klebsiella pneumoniae . The genetic sequence of LGDH, lgdA , was found in the genomes of these four isolates as well as Pseudarthrobacter phenanthrenivorans Sphe3. The identity of the P. phenanthrenivorans LGDH was experimentally verified following recombinant expression in E. coli . Comparison of the putative genes surrounding lgdA in the isolate genomes indicated that several other gene products facilitate the bacterial catabolism of levoglucosan, including a putative sugar isomerase and several transport proteins. Importance Levoglucosan is the most prevalent soluble carbohydrate remaining after high temperature pyrolysis of lignocellulosic biomass, but it is not fermented by typical production microbes such as Escherichia coli and Saccharomyces cerevisiae . A few fungi metabolize levoglucosan via the enzyme levoglucosan kinase, while several bacteria metabolize levoglucosan via levoglucosan dehydrogenase. This study describes the isolation and characterization of four bacterial species which degrade levoglucosan. Each isolate is shown to contain several genes within an operon involved in levoglucosan degradation, furthering our understanding of bacteria which metabolize levoglucosan.

Chemical Characterization of Waterlogged Charred Wood: The Case of a Medieval Shipwreck

In 2008, a medieval wooden shipwreck was discovered at the port of Rhodes, Greece. The shipwreck was party burned, presenting a challenge for conservators, as uncharred, semi-charred and charred waterlogged wood were often encountered on the same piece of timber. In seeking the most appropriate conservation method for this unusual material, its chemical characterization was considered necessary. This study examined the chemistry of the three dominant wood conditions found in the wreck. Fourier transform infrared spectroscopy and X-ray diffraction analysis were implemented in comparison to reference samples. Energy dispersive analysis was also used for assessing the inorganic composition of each condition. Moreover, for charred and semi-charred wood, proximate analysis was undertaken. Results obtained regarding the organic moieties of the waterlogged archaeological material, demonstrated that charred samples were chemically comparable to charcoals, semi-charred material showed similarity to thermally modified wood, whereas uncharred waterlogged wood was proven to have an analogous chemistry to biodeteriorated wood. Elemental analysis results also diversified among the three shipwreck’s conditions. Sulfur, iron, and oxygen decreased in charred areas, whereas carbon increased. Proximate analysis showed that ash and fixed carbon content increased with charring, whereas volatile mater decreased. This work proved major chemical differences among shipwreck timbers’ conditions owing to different degree of charring. These are anticipated to influence not only conservation methods’ efficacy, but also the post-treatment behavior of the material. Further investigation is needed for correlating the chemistry of the archaeological material to its physical properties in order to contribute to practical aspects of conservation.

Durability and Fire Performance of Charred Wood Siding (Shou Sugi Ban)

Shou sugi ban, also known as yakisugi, or just sugi ban, is an aesthetic wood surface treatment that involves charring the surface of dimensional lumber, such as exterior cladding. The goal of this research is to examine the effect of shou sugi ban on the flammability and decay resistance of wood. Several species and variants of commercially available sugi ban were tested. The flammability was examined from the heat release rate curves using the oxygen consumption method and cone calorimeter. Durability was examined with a soil block assay for one white-rot fungus and one brown-rot fungus. The testing showed that the shou sugi ban process did not systematically improve the flammability or durability of the siding

Effect of Weathering on Surface Functional Groups of Charred Norway Spruce Cladding Panels

Norway spruce cladding panels were surface charred with a prototype device utilizing a hot plate method. The panels were used to construct a test wall that was exposed to natural weathering for a period of two years. The changes in functional groups were evaluated with photoacoustic FTIR spectroscopy. The analysis revealed degradation of the thermally modified lignin component, indicating poor stability in weathering. Improvements in the prototype device process conditions, such as increased surface pressure and slower feed speed, and future research needs regarding surface charred wood are discussed.

Assessment of maximum flow and emplacement temperatures reached by PDCs using charred wood fragments

<p>Temperature evaluation of PDCs has been recently performed using optical analysis of charred wood (Reflectance analysis - Ro%) embedded within the pyroclastic deposits.</p><p>The validity of this proxy for the emplacement temperature assessment, has been established in different case studies (Fogo Volcano, Laacher See volcano, Merapi Volcano, Colima Volcano, Doña Juana Volcano, Ercolano-Vesuvius Volcano), resulting comparable with the already well know paleomagnetic analysis (pTRM).</p><p>Due to its not retrograde nature, the process of carbonification records over time the maximum temperatures experienced by the wood fragment/tree trunk/furniture. This peculiarity has great importance in terms of timing of charring events, as the charred wood can record the possible temperature fluctuations in case of multiple pulse events. This allows us to reconstruct the thermal and dynamic of PDCs history at different steps.</p><p>Reflectance analysis (Ro%) results display samples with homogeneous charring temperature (same Ro% values) from rim to core and others with different charring temperatures throughout the sample. Ro% of the latter usually infer higher temperature on the edge of the fragment/tree trunk than in the inner part. This bimodal reflectance distribution can be attributable to multiple temperature exposure, occurred during diachronous events of flow and deposition. Therefore, within the same fragment/tree trunk we can extrapolate PDCs temperature information related not only to equilibrium (emplacement) condition but, more importantly, to dynamic (flow) regime.</p><p>This study constitutes a pioneering attempt for the indirect estimation of the temperature of the PDCs not only for volcanic hazard estimation, but also in the archaeological field. In fact, the numerous remains of charred wooden artefacts found in the archaeological sites of Pompeii, Herculaneum and in the Meurin quarry (Eiffel-Germany), allowed the reconstruction of temperature variation based on the vent distance and the presence of buildings which may have interacted with the depositional processes of pyroclastic flows. This study opens a promising new frontier to evaluate the maximum temperature of the PDCs, based on the degree of carbonization of the organic matter incorporated during volcanic events. Estimating the temperature of the dynamic temperature of the PDC has important implications in terms of volcanic risk assessment.</p>

Identification of archaeological charred wood from Ille site, El Nido, Palawan, Philippines

Seven charred wood fragments from the archaeological site of Ille in El Nido, Palawan were identified as an undetermined monocot and representatives of the families Caesalpiniaceae, Dipterocarpaceae, and Araucariaceae/Podocarpaceae. Though very few pieces were determined, the results gave a glimpse of the types of woody plants most likely present in the vicinity of Ille, 14,000 to around 4,000 years ago. This report also aims to provide taxonomic identification based on the available literature to serve as baseline information for future use.

Charred conifer remains from the Late Oligocene – Early Miocene of Northern Hesse (Germany)

Fire is an important constituent of many modern and fossil ecosystems. During the last decades a large number of studies have dealt with fires in pre-Cenozoic ecosystems. Evidence for the occurrence of Palaeogene and Neogene wildfires (e.g. in the form of pyrogenic inertinites in lignite deposits) is geographically and stratigraphically widespread. However, as compared to earlier periods (i.e. the Permian and Cretaceous), fewer studies have focussed so far on plants burnt (or charred) in wildfires from these periods, even though these periods are of considerable interest for our understanding of the evolution of modern ecosystems. Here we report the occurrence of charred wood remains belonging to different conifer taxa from the base seam of the former Frielendorf opencast lignite mine in Northern Hesse (Germany). These findings are evidence that these conifers, and the types of vegetation they were growing in, were affected by wildfires occurring during the Late Oligocene – Early Miocene in this region.