Ethanol production from hardwood spent sulfite liquor using an adapted strain of Pichia stipitis

Conditions have been optimized for fermentation of pretreated hardwood spent sulfite liquor (HSSL) using an adapted strain of Pichia stipitis. The pretreatments, consisting of boiling and overliming with Ca(OH)₂ of HSSL, to partially remove inhibitors, and adaptation of the yeast strain to HSSL, were both critical for a successful fermentation. Ethanol concentration was increased from 6.7 to 20.2 g l⁻¹ using adapted P. stipitis (A) and pretreated HSSL. The maximum ethanol yield (Y _p/s) and productivity (Q _p) were 0.41 g g⁻¹ and 0.44 g l⁻¹ h⁻¹, respectively, at an oxygen transfer rate of 2.0 mmol O₂ l⁻¹ h⁻¹. The optimized results with this strain were compared to those of other xylose-fermenting yeasts and Saccharomyces cerevisiae (SSL-acclimatized) currently used at an industrial plant for the fermentation of spent sulfite liquor. Journal of Industrial Microbiology & Biotechnology (2001) 26, 145–150. Received 23 June 2000/ Accepted in revised form 21 October 2000     

Ultrastructural changes during wood decay by Antrodiella sp. RK1

Southern yellow pine (softwood) and maple (hardwood) wood decayed for 12 weeks by Antrodiella sp. RK1 had average weight losses of 20 and 19%, respectively, and approximately 34 to 35% lignin loss. The ratio of percentage lignin loss to glucose loss was 3.6 and 2.7 for softwood and hardwood, respectively. There was negligible loss of other wood sugars such as xylose, arabinose, galactose and mannose. Scanning electron microscopy revealed the presence of erosion troughs and bore holes in decayed samples of both softwood and hardwood. Secondary walls were void of lignin, middle lamella and cell corners were extensively decayed. Ca²⁺ crystals were abundantly present in the areas of decay. Transmission electron micrographs revealed the presence of hyphal sheath and growth of hyphae directly through the cell corners.R.N. Patel and K.K. Rao are with the Department of Microbiology & Biotechnology Center, Faculty of Science, M.S. University of Baroda, Baroda-390 002, India.     

Linking wood-decay fungal communities to decay rates: Using a long-term experimental manipulation of deadwood and canopy gaps

Decomposition transfers carbon (C) from detrital organic matter to soil and atmospheric pools. In forested ecosystems, deadwood accounts for a large proportion of the detrital C pool and is primarily decomposed by wood-inhabiting fungi (WIF). Deadwood reductions linked to forest harvesting may alter WIF richness and composition, thus indirectly influencing the persistence of deadwood and its contribution to C and nutrient cycling. Forest structure was enhanced via canopy gap creation and coarse woody debris (CWD) addition that mimic natural disturbance by windfall within a deciduous northern hardwood forest (Wisconsin, USA) to examine its effect on deadwood-associated biodiversity and function. Experimental sugar maple (Acer saccharum) logs were sampled, for DNA extraction, ten years after placement to determine the assembly of fungal community composition and its relationship to wood decay rates.Our findings suggest that the WIF community responded to gap disturbance by favoring species able to persist under more extreme microclimates caused by gaps. CWD addition under closed canopy tended to favor a different species assemblage from gap creation treatments and the control, where canopy was undisturbed and CWD was not added. This was presumably due to consistent microclimatic conditions and the abundance of CWD substrates for host specialists. Fungal OTU richness was significantly and inversely related to CWD decay rates, likely due to competition for resources. In contrast, fungal OTU composition was not significantly related to CWD decay rates, canopy openness or CWD addition amounts. Our study site represents a diverse fungal community in which complex interactions among wood-inhabiting organisms and abiotic factors are likely to slow CWD decomposition, which suggests that maintaining a biodiverse and microsite-rich ecosystem may enhance the capacity for C storage within temperate forests.     

Distribution of [14C]-labeled photosynthates within intensively cultured Populus clones during the establishment year

Seasonal patterns of [¹⁴C]-labeled photosynthate distribution within two intensively cultured Populus clones with contrasting phenology ( P. tristis × P. balsamifera cv. 'Tristis no. 1'; P. × euramericana cv. Eugenei) were investigated during the establishment year. During active shoot elongation upper mature leaves exported ¹⁴C acropetally to the expanding leaves and elongating internodes, and basipetally to the stem. Little ¹⁴C was exported to lower mature leaves or lateral branches. At budset the ¹⁴C export pattern shifted dramatically in the basipetal direction, i.e., to the lower stem, hardwood cutting, and roots. The timing of budset was the primary factor determining the differences between the clones, except that in all cases Tristis exported more ¹⁴C to the roots than Eugenei. After budset lower mature leaves had a similar export pattern to upper leaves, but the quantity of ¹⁴C exported to the roots was slightly higher. The results confirm the importance of autumn foliage for root growth in poplar. Clonal differences in seasonal patterns of photosynthate distribution offer potential for the poplar breeder seeking to match a clone's growth pattern with the specific growing season of the site.     

Denitrification and N<Subscript>2</Subscript>O emission from forested and cultivated alluvial clay soil

Restored forested wetlands reduce N loads in surface discharge through plant uptake and denitrification. While removal of reactive N reduces impact on receiving waters, it is unclear whether enhanced denitrification also enhances emissions of the greenhouse gas N₂O, thus compromising the water-quality benefits of restoration. This study compares denitrification rates and N₂O:N₂ emission ratios from Sharkey clay soil in a mature bottomland forest to those from an adjacent cultivated site in the Lower Mississippi Alluvial Valley. Potential denitrification of forested soil was 2.4 times of cultivated soil. Using intact soil cores, denitrification rates of forested soil were 5.2, 6.6 and 2.0 times those of cultivated soil at 70, 85 and 100% water-filled pore space (WFPS), respectively. When NO₃ was added, N₂O emissions from forested soil were 2.2 times those of cultivated soil at 70% WFPS. At 85 and 100% WFPS, N₂O emissions were not significantly different despite much greater denitrification rates in the forested soil because N₂O:N₂ emission ratios declined more rapidly in forested soil as WFPS increased. These findings suggest that restoration of forested wetlands to reduce NO₃ in surface discharge will not contribute significantly to the atmospheric burden of N₂O.     

Measuring and modelling carbon dioxide and water vapour exchange over a temperate broad-leaved forest during the 1995 summer drought

Forests in the south-eastern United States experienced a prolonged dry spell and above-normal temperatures during the 1995 growing season. During this episode, nearly continuous, eddy covariance measurements of carbon dioxide and water vapour fluxes were acquired over a temperate, hardwood forest. These data are used to examine how environmental factors and accumulating soil moisture deficits affected the diurnal pattern and magnitude of canopy-scale carbon dioxide and water vapour fluxes. The field data are also used to test an integrative leaf-to-canopy scaling model (CANOAK), which uses micrometeorological and physiological theory, to calculate mass and energy fluxes. When soil moisture was ample in the spring, peak rates of net ecosystem CO₂ exchange (N_F) occurred around midday and exceeded 20 μmol m^?2 s^?1. Rates of N_K were near optimal when air temperature ranged between 22 and 25°C. The accumulation of soil moisture deficits and a co-occurrence of high temperatures caused peak rates of daytime carbon dioxide uptake to occur earlier in the morning. High air temperatures and soil moisture deficits were also correlated with a dramatic reduction in the magnitude of N_E. On average, the magnitude of N_E decreased from 20 to 7 μmol m^?2 s^?1 as air temperature increased from 24 to 30°C and the soil dried. The CANAOK model yielded accurate estimates of canopy-scale carbon dioxide and water vapour fluxes when the forest had an ample supply of soil moisture. During the drought and heat spell, a cumulative drought index was needed to adjust the proportionality constant of the stomatal conductance model to yield accurate estimates of canopy CO₂ exchange. The adoption of the drought index also enabled the CANOAK model to give improved estimates of evaporation until midday. On the other hand, the scheme failed to yield accurate estimates of evaporation during the afternoon.     

Biodegradation of acidolysis lignins from Chilean hardwoods by the ascomycete Chrysonilia sitophila

The biodegradability of five lignins extracted from Chilean hardwoods in Chrysonilia sitophila cultures was evaluated. All lignins showed an increase in their molecular weight after 12 days of culture. Infrared analysis of the degraded lignins indicated the formation of new substructures containing carbonyl, as well as CO cleavage reactions. A random behaviour was observed between the methoxyl/phenolic hydroxyl ratio of lignins and the extent of biodegradation.     

Effects of VA-mycorrhizal fungi on growth and nutrient uptake of cuttings ofRosa multiflora in two container media with three levels of fertilizer application

Rooted cuttings ofRosa multiflora ‘Brooks 56’ were grown in a medium of 1 mineral soil: 1 sand (v/v) or bark: 1 sand (v/v) inoculated with the VA-mycorrhizal (VAM) fungiGlomus mosseae (Nicol. and Gerd.) Gerd. and Trappe andG. fasciculatum (Thaxt. sensu Gerd.) Gerd. and Trappe or left as noninoculated controls. The slow release fertilizer osmocote was applied at rates of either 0, 1.2, or 4.2 kg/m³ (18N-6P-12K) and incorporated into the container medium. After 180 days plants were evaluated for growth, development and chemical leaf analysis. Greatest growth responses occurred after the highest fertilizer application of 4.2 kg/m³, and the poorest one after 0 kg/m³. Combination bark: sand medium was superior to mineral soil: sand medium for growth of mycorrhizal plants. At 0 kg/m³, mycorrhizal plants in bark: sand medium had longer shoots than other treatments. At 1.2 kg/m³, VAM plants compared to nonmycorrhizal plants in park:sand medium had greater effect on growth parameters. At the highest fertilizer application of 4.2 kg/m³, greatest growth responses occurred with VAM plants in bark:sand medium. Mycorrhizal plants compared to nonmycorrhizal plants in bark:sand medium had greater K and Zn uptake at 0 kg/m³, and greater K, Ca, S, Mn and Zn uptake at 1.2 kg/m³. Texas Agr. Expt. Sta. Journal Series No. TA-22264.     

Effects of Natural Barriers and Habitat on the Western Spread of Raccoon Rabies in Alabama

Abstract: Although domestic animal transmission of rabies has largely been mitigated, the disease remains a concern in both Europe and North America where wildlife transmission has caused epizootics. Raccoon (Procyon lotor) rabies was established in Alabama, USA, in 1975, primarily in the southeastern corner of the state. However, with the exception of isolated events, rabies has not continued to spread westward across the Alabama River. We monitored movements of 100 radiocollared raccoons on 2 sites within hardwood and agriculture habitats in a rabies enzootic area east of the Alabama River, in managed pine habitat area west of the river where rabies sporadically occurs, and in a mixed pine hardwood area outside of the known rabies enzootic area to determine if raccoon movements and habitat use in certain habitat types and the presence of a river may serve as natural barriers preventing the western spread of rabies in Alabama. We also examined raccoon contact rates to determine if they influence disease transmission through static and dynamic interactions. Raccoons in mixed pine-hardwood forest habitats had smaller home ranges and less overlap of ranges compared to the other 3 habitats. However, static interactions between habitats in the use of overlap areas did not differ (F_11,129 = 1.63, P = 0.09). Rabies antibody titers were highest in the managed pine habitat (28%) even prior to oral vaccine bait distributions in spring of 2004 and 2005. Biomarker data from radiocollared and additional raccoons captured after the bait distribution west of the Alabama River demonstrated a low efficacy of the vaccine reaching the small southern raccoons. The combination of the river as a partial barrier, the high percentage of pine forested habitat west of the river, and limited spatial movements of raccoons within these forested habitats appears to have reduced the likelihood of rabies establishing west of the river. Understanding different host-habitat- disease systems is important for successful management of diseases. Based on our results, we recommend that the oral vaccine program continue to use the Alabama River as a partial barrier and baiting be concentrated in the fragmented bottomland hardwood forests and around larger bodies of water where raccoon densities are highest. Success of baiting strategies designed to take advantage of northern raccoon dynamics and habitat use may not be applicable to southern populations.