Breakdown Of Wood Research Articles

Comparative genome analysis of the freshwater fungus Filosporella fistucella indicates potential for plant-litter degradation at cold temperatures.

Freshwater fungi play an important role in the decomposition of organic matter of leaf litter in rivers and streams. They also possess the necessary mechanisms to endure lower temperatures caused by habitat and weather variations. This includes the production of cold-active enzymes and antifreeze proteins. To better understand the physiological activities of freshwater fungi in their natural environment, different methods are being applied, and genome sequencing is one in the spotlight. In our study, we sequenced the first genome of the freshwater fungus Filosporella fistucella (45.7 Mb) and compared the genome with the evolutionary close-related species Tricladium varicosporioides (48.2 Mb). The genomes were annotated using the carbohydrate-active enzyme database where we then filtered for leaf-litter degradation-related enzymes (cellulase, hemicellulase, laccase, pectinase, cutinase, amylase, xylanase, and xyloglucanase). Those enzymes were analyzed for antifreeze properties using a machine-learning approach. We discovered that F. fistucella has more enzymes to participate in the breakdown of sugar, leaf, and wood than T. varicosporioides (855 and 719, respectively). Filosporella fistucella shows a larger set of enzymes capable of resisting cold temperatures than T. varicosporioides (75 and 66, respectively). Our findings indicate that in comparison with T. varicosporioides, F. fistucella has a greater capacity for aquatic growth, adaptability to freshwater environments, and resistance to low temperatures.

Distribution and relative abundance of three protist genera within the Zootermopsis nevadensis nuttingi hindgut

The termite Zootermopsis nevadensis nuttingi, which inhabits coastal forests of the western United States, plays an important ecological role in the breakdown and digestion of wood. Vital to this role are symbiotic protists residing in the termite’s hindgut. Five protist genera of varying size and morphology make up this gut community, but very little is known about their spatial organization within the hindgut or the number of protist cells per host. To resolve this issue, we used light microscopy and a hemocytometer to determine the distribution of the larger protist genera across hindgut segments. We found that Streblomastix were the most abundant cells in all three segments, but especially in the anterior hindgut. Trichomitopsis cells were significantly more abundant in the posterior hindgut. Trichonympha were the least abundant overall, often reaching their highest abundance in the middle segment but with a more variable distribution. Understanding the distribution of different protists within the hindgut may improve our understanding of the ecological relationships among protists, as well as their individual roles in lignocellulose digestion, contributing to a better understanding of the symbiotic system as a whole.

Breakdown of instream wood in low order forested streams of the Southern Chilean mountain ranges

We analyzed instream wood depletion or breakdown in terms of wood breakage (defined as the reduction in length) and decay (reduction in diameter) on channel segments of three low-order mountain streams located in southern Chile. We used a unique database, composed of 1049 individually tagged logs, which were measured and their position was georeferenced between 2005 and 2014, and re-measured and re-georeferenced after the rainy winter period of 2015. Results showed that median breakdown at the end of the survey ranged between 5 and 27% and between 10 and 25% for median decay, with highest values of 83 and 72% respectively. While median annual breakage ranged between less than 1 and 4 %·year−1 and median annual decay between 1 and 4 %·year−1. According to our results, breakdown of instream wood is influenced by many factors, the most significant being initial log size (both length and diameter), their orientation, residence time and fluvial transport (i.e. displacement length). Wood density and initial tree height at the time of recruitment were also analyzed, aiming to better understand breakage and decay processes. Results showed that in-channel logs were, as expected, less dense than living trees, and very decayed logs significant loose density compared to fresh logs. The differences between initial log size and potential minimum tree height at the time of recruitment ranged between 29 and 64%. We believe that our findings illuminates on wood depletion processes on low order streams in the Chilean mountain ranges, and can be easily extrapolated to other streams with similar conditions; however, the natural heterogeneity among river environments and hydrological conditions during the survey period may influence breakage and decay processes. Therefore, we encourage other researchers to provide data on breakdown of instream wood from different regions.

Natural acetylation impacts carbohydrate recovery during deconstruction of Populus trichocarpa wood

BackgroundSignificant variation in the inherent degree of acetylation naturally exists in the xylem cell walls of Populus trichocarpa. During pretreatment, endogenous acetate hydrolyzes to acetic acid that can subsequently catalyze the breakdown of poplar wood, increasing the efficiency of biomass pretreatment.ResultsPoplar genotypes varying in cell wall composition were pretreated in 0.3% H2SO4 in non-isothermal batch reactors. Acetic acid released from the wood was positively related to sugar release during pretreatment (R ≥ 0.9), and inversely proportional to the lignin content of the poplar wood (R = 0.6).ConclusionThere is significant variation in wood chemistry among P. trichocarpa genotypes. This study elucidated patterns of cell wall deconstruction and clearly links carbohydrate solubilization to acetate release. Tailoring biomass feedstocks for acetate release could enhance pretreatment efficiencies.

Exposure of wood in floodplains affects its chemical quality and its subsequent breakdown in streams

In stream ecosystems, coarse organic matter from the riparian vegetation, a key food resource, is often retained in the floodplains before reaching the channel. During floodplain exposure, organic matter can be affected by abiotic and biotic processes (“preconditioning”), which alter its quality and affect its subsequent decomposition in streams. We analyzed the effect of floodplain preconditioning on wood quality (lignin, C, N, P, K, among others), and its subsequent aquatic breakdown, paying special attention to microbial activity. We simulated preconditioned standard wooden sticks on one arid stream floodplain for 3 and 4months, and then monitored their breakdown in three different streams, together with control (non-preconditioned) sticks. Preconditioning reduced lignin mass and C:N and lignin:N ratios, caused the leaching of soluble nutrients such as P and K, as well as N immobilization by microbes. These changes enhanced the breakdown of wood in the first week of immersion, but had no effect on breakdown rates after 4months of incubation in the streams, although N immobilization was diminished. Our results suggest that terrestrial preconditioning could alter the role of wood as a long-lasting nutrients and energy source for freshwater ecosystem.

Analysis of Extensive [FeFe] Hydrogenase Gene Diversity Within the Gut Microbiota of Insects Representing Five Families of Dictyoptera

We have designed and utilized degenerate primers in the phylogenetic analysis of [FeFe] hydrogenase gene diversity in the gut ecosystems of roaches and lower termites. H(2) is an important free intermediate in the breakdown of wood by termite gut microbial communities, reaching concentrations in some species exceeding those measured for any other biological system. The primers designed target with specificity the largest group of enzymatic H domain proteins previously identified in a termite gut metagenome. "Family 3" hydrogenase sequences were amplified from the guts of lower termites, Incisitermes minor, Zootermopsis nevadensis, and Reticulitermes hesperus, and two roaches, Cryptocercus punctulatus and Periplaneta americana. Subsequent analyses revealed that all termite and Cryptocercus sequences were phylogenetically distinct from non-termite-associated hydrogenases available from public databases. The abundance of unique sequence operational taxonomic units (as many as 21 from each species) underscores the previously demonstrated physiological importance of H(2) to the gut ecosystems of these wood-feeding insects. The diversity of sequences observed might be reflective of multiple niches that the enzymes have been evolved to accommodate. Sequences cloned from Cryptocercus and the lower termite samples, all of which are wood feeding insects, clustered closely with one another in phylogenetic analyses to the exclusion of alleles from P. americana, an omnivorous cockroach, also cloned during this study. We present primers targeting a family of termite gut [FeFe] hydrogenases and provide results that are consistent with a pivotal role for hydrogen in the termite gut ecosystem and point toward unique evolutionary adaptations to the gut ecosystem.

Genomic Analysis Reveals Multiple [FeFe] Hydrogenases and Hydrogen Sensors Encoded by Treponemes from the H2-Rich Termite Gut

We have completed a bioinformatic analysis of the hydrogenases encoded in the genomes of three termite gut treponeme isolates: hydrogenotrophic, homoacetogenic Treponema primitia strains ZAS-1 and ZAS-2, and the hydrogen-producing, sugar-fermenting Treponema azotonutricium ZAS-9. H(2) is an important free intermediate in the breakdown of wood by termite gut microbial communities, reaching concentrations in some species exceeding those measured for any other biological system. The spirochetes encoded 4, 8, and 5 [FeFe] hydrogenase-like proteins, identified by their H domains, respectively, but no other recognizable hydrogenases. The [FeFe] hydrogenases represented many sequence families previously proposed in an analysis of termite gut metagenomic data. Each strain encoded both putative [FeFe] hydrogenase enzymes and evolutionarily related hydrogen sensor/transducer proteins likely involved in phosphorelay or methylation pathways, and possibly even chemotaxis. A new family of [FeFe] hydrogenases (FDH-Linked) is proposed that may form a multimeric complex with formate dehydrogenase to provide reducing equivalents for reductive acetogenesis in T. primitia. The many and diverse [FeFe] hydrogenase-like proteins encoded within the sequenced genomes of the termite gut treponemes has enabled the discovery of a putative new class of [FeFe] hydrogenase proteins potentially involved in acetogenesis and furthered present understanding of many families, including sensory, of H domain proteins beyond what was possible through the use of fragmentary termite gut metagenome sequence data alone, from which they were initially defined.

Breakdown and invertebrate colonization of dead wood in wetland, upland, and river habitats

Breakdown of woody debris in river and upland habitats as well as the interactions between wood and invertebrates have been well described. Studies of wood in wetlands are rare, and far less is known about breakdown and invertebrate use of wood in these transitional habitats. This study experimentally assessed breakdown and invertebrate colonization of wood in a floodplain wetland and directly related patterns in the wetland to adjacent river and upland habitats. Over a 2.7 year period, we monitored breakdown and invertebrate presence in 10 cm diameter × 150 cm long sweetgum ( Liquidambar styraciflua L.) logs in a floodplain wetland (n = 8), river (n = 5), and upland (n = 4) habitat. Mass loss, decay condition change, and C/N ratios of wetland wood more closely resembled upland than river wood. The overall invertebrate assemblage associated with wetland wood was also more similar to that associated with upland than river wood. Breakdown and invertebrate colonization of wood in the floodplain wetland shared more characteristics with upland than river wood, perhaps because of the seasonal nature of flooding in the wetland. However, the ecology of wood in wetlands also had unique characteristics compared with either the uplands or the river.

Biological breakdown of wood in buildings

A review is given of the role of fungi in nature and in buildings. The major groups of microorganisms are presented, and the living conditions of wood-decaying fungi regarding temperature and moisture are described. Both constructional and chemical methods of wood protection are options when wanting to avoid fungal decay. In Denmark, houses can be insured against fungal decay. Moulds affect both indoor climate and people and can cause a range of different health problems, such as allergies and infections. They produce large numbers of spores as well as volatile organic compounds. Mould growth can be controlled by steam treatment and the use of different disinfectants.

Breakdown rates of wood in streams

The breakdown rates of natural branch wood were studied in 2 streams (lowland and upland), and the current knowledge on breakdown rates of wood in streams was reviewed. The breakdown coefficient of natural alder branches, k 5 0.0650/y, in an unpolluted upland stream cor- responded well to the few published data on breakdown rates of natural wood substrates in streams. Breakdown rates of Scots pine (Pinus sylvestris, k 5 0.0698/y), bark-covered black alder (Alnus gluti- nosa, k 5 0.0859/y), and debarked black alder branches (k 5 0.0717/y) in a nutrient-rich sandy lowland stream indicated that breakdown rates differ among tree species. Data from the present and previous studies on the breakdown of natural wood and commercial wood products (wood veneer, tongue depressors, ice-cream sticks) showed that breakdown is slower for natural wood than for commercial wood products, in part because the commercial wood products used in the studies had high surface to volume ratios. A strong relationship exists between surface to volume ratio of the substrate and breakdown rates. The breakdown rates of wood in streams were associated with several abiotic factors, including the physical and chemical properties of the wood substrates used, dissolved nutrients, and water temperature. Overall, the review of published breakdown rates emphasized that the current knowledge on the breakdown rates of wood in streams, especially the temporal patterns of microbial activities, is very limited, and heterogeneous experimental designs in previous studies prevent general conclusions. Nevertheless, measuring wood breakdown rates could be a promising tool for practical application in assessment of the ecological integrity of streams.

Breakdown of wood in the Agüera stream

SUMMARY 1. Breakdown of wood was compared at three sites of the Agüera catchment (Iberian Peninsula): two oligotrophic first‐order reaches (one under deciduous forest, the other under Eucalyptus globulus plantations) and one third‐order reach under mixed forest, where concentration of dissolved nutrients was higher.2. Branches (diameter = 3 cm, length = 10 cm) of oak (Quercus robur), alder (Alnus glutinosa), pine (Pinus radiata) and eucalyptus, plus prisms (2.5 × 2.5 × 10 cm) of alder heartwood were enclosed in mesh bags (1 cm mesh size) and placed in the streams. Mass loss was determined over 4.5 years, whereas nutrient, lignin and ergosterol were determined over 3 years. In order to describe fungal dynamics, ergosterol was also determined separately on the outer and inner parts of some branches.3. Breakdown rates ranged from 0.0159 to 0.2706 year−1 with the third‐order reach having the highest values whatever the species considered. The most rapid breakdown occurred in alder heartwood and the slowest in pine branches; breakdown rates of oak, eucalyptus and alder branches did not differ significantly.4. The highest nitrogen and phosphorus contents were found in alder, followed by oak, while pine and eucalyptus had low values. During breakdown, all materials rapidly lost phosphorus, but nitrogen content remained constant or slightly increased. Lignin content remained similar.5. Peaks of ergosterol ranged from 0.023 to 0.139 mg g−1 and were higher in alder than in other species in two of the three sites. The third‐order reach generally had the greatest increase in ergosterol, especially in alder branches, eucalyptus and alder heartwood. The overall species/site pattern of fungal biomass was thus consistent with the observed differences in breakdown.6. When compared with leaves of the same species decomposing at these sites, wood breakdown appeared to be less sensitive to the tree species but more sensitive to stream water chemistry. Although wood breakdown is slower and its inputs are lower than those of leaf litter, its higher resistance to downstream transport results in a relatively high standing stock and a significant contribution to the energy flux.

The breakdown of wood in the side arm of a large river: Preliminary investigations

(1991). The breakdown of wood in the side arm of a large river: Preliminary investigations. SIL Proceedings, 1922-2010: Vol. 24, No. 3, pp. 1785-1788.