First report of Trypanosoma vivax outbreak in dairy cattle in São Paulo state, Brazil

This is the first description of a Trypanosoma vivax outbreak in the state of São Paulo (municipality of Lins). Fever, jaundice, decreased milk production, weight loss, profuse diarrhea, abortion, anemia, leukocytosis and hyperfibrinogenemia were observed in the affected animals. Thirty-one cows and calves died out of a total of 1080 in the herd. Three cows showed neurological symptoms like dysmetria, ataxia, muscle weakness, ptyalism, lymph node enlargement and submandibular edema. Flagellated hemoparasites were observed in blood smears. The species was diagnosed as T. vivax by means of PCR. This T.vivax strain showed resistance to diaminazene aceturate and the infection spread quickly at the herd. From the ELISA test, 599 serum samples (98.36%) were positive for anti-T.vivax IgG antibodies. This outbreak occurred during a very dry period, which indicates that other factors were involved in the outbreak, such as absence of tabanids and large populations of Haematobia irritans and Stomoxys calcitrans. The increases in these populations may have been due to the use of biosolid waste from sugar and ethanol plants in the sugarcane plantations surrounding the dairy farm.

Cuerpo: efectos escénicos y literarios. Pina Bausch

Programa de doctorado: Literatura y teoría de la literatura

Produzione di bioetanolo da scarti lignocellulosici della canna da zucchero: condizioni di saccarificazione e fermentazione simultanee (SSF) e aspetti ambientali del processo

Il presente studio ha avuto l’obiettivo di indagare la produzione di bioetanolo di seconda generazione a partire dagli scarti lignocellulosici della canna da zucchero (bagassa), facendo riscorso al processo enzimatico. L’attività di ricerca è stata svolta presso il Dipartimento di Ingegneria Chimica dell’Università di Lund (Svezia) all’interno di rapporti scambio con l’Università di Bologna. Il principale scopo è consistito nel valutare la produzione di etanolo in funzione delle condizioni operative con cui è stata condotta la saccarificazione e fermentazione enzimatica (SSF) della bagassa, materia prima che è stata sottoposta al pretrattamento di Steam Explosion (STEX) con aggiunta di SO2 come catalizzatore acido. Successivamente, i dati ottenuti in laboratorio dalla SSF sono stati utilizzati per implementare, in ambiente AspenPlus®, il flowsheet di un impianto che simula tutti gli aspetti della produzione di etanolo, al fine di studiarne il rendimento energetico dell’intero processo. La produzione di combustibili alternativi alle fonti fossili oggigiorno riveste primaria importanza sia nella limitazione dell’effetto serra sia nel minimizzare gli effetti di shock geopolitici sulle forniture strategiche di un Paese. Il settore dei trasporti in continua crescita, consuma nei paesi industrializzati circa un terzo del fabbisogno di fonti fossili. In questo contesto la produzione di bioetanolo può portare benefici per sia per l’ambiente che per l’economia qualora valutazioni del ciclo di vita del combustibile ne certifichino l’efficacia energetica e il potenziale di mitigazione dell’effetto serra. Numerosi studi mettono in risalto i pregi ambientali del bioetanolo, tuttavia è opportuno fare distinzioni sul processo di produzione e sul materiale di partenza utilizzato per comprendere appieno le reali potenzialità del sistema well-to-wheel del biocombustibile. Il bioetanolo di prima generazione ottenuto dalla trasformazione dell’amido (mais) e delle melasse (barbabietola e canna da zucchero) ha mostrato diversi svantaggi: primo, per via della competizione tra l’industria alimentare e dei biocarburanti, in secondo luogo poiché le sole piantagioni non hanno la potenzialità di soddisfare domande crescenti di bioetanolo. In aggiunta sono state mostrate forti perplessità in merito alla efficienza energetica e del ciclo di vita del bioetanolo da mais, da cui si ottiene quasi la metà della produzione di mondiale di etanolo (27 G litri/anno). L’utilizzo di materiali lignocellulosici come scarti agricolturali e dell’industria forestale, rifiuti urbani, softwood e hardwood, al contrario delle precedenti colture, non presentano gli svantaggi sopra menzionati e per tale motivo il bioetanolo prodotto dalla lignocellulosa viene denominato di seconda generazione. Tuttavia i metodi per produrlo risultano più complessi rispetto ai precedenti per via della difficoltà di rendere biodisponibili gli zuccheri contenuti nella lignocellulosa; per tale motivo è richiesto sia un pretrattamento che l’idrolisi enzimatica. La bagassa è un substrato ottimale per la produzione di bioetanolo di seconda generazione in quanto è disponibile in grandi quantità e ha già mostrato buone rese in etanolo se sottoposta a SSF. La bagassa tal quale è stata inizialmente essiccata all’aria e il contenuto d’acqua corretto al 60%; successivamente è stata posta a contatto per 30 minuti col catalizzatore acido SO2 (2%), al termine dei quali è stata pretrattata nel reattore STEX (10L, 200°C e 5 minuti) in 6 lotti da 1.638kg su peso umido. Lo slurry ottenuto è stato sottoposto a SSF batch (35°C e pH 5) utilizzando enzimi cellulolitici per l’idrolisi e lievito di birra ordinario (Saccharomyces cerevisiae) come consorzio microbico per la fermentazione. Un obiettivo della indagine è stato studiare il rendimento della SSF variando il medium di nutrienti, la concentrazione dei solidi (WIS 5%, 7.5%, 10%) e il carico di zuccheri. Dai risultati è emersa sia una buona attività enzimatica di depolimerizzazione della cellulosa che un elevato rendimento di fermentazione, anche per via della bassa concentrazione di inibitori prodotti nello stadio di pretrattamento come acido acetico, furfuraldeide e HMF. Tuttavia la concentrazione di etanolo raggiunta non è stata valutata sufficientemente alta per condurre a scala pilota un eventuale distillazione con bassi costi energetici. Pertanto, sono stati condotti ulteriori esperimenti SSF batch con addizione di melassa da barbabietola (Beta vulgaris), studiandone preventivamente i rendimenti attraverso fermentazioni alle stesse condizioni della SSF. I risultati ottenuti hanno suggerito che con ulteriori accorgimenti si potranno raggiungere gli obiettivi preposti. E’ stato inoltre indagato il rendimento energetico del processo di produzione di bioetanolo mediante SSF di bagassa con aggiunta di melassa in funzione delle variabili più significative. Per la modellazione si è fatto ricorso al software AspenPlus®, conducendo l’analisi di sensitività del mix energetico in uscita dall’impianto al variare del rendimento di SSF e dell’addizione di saccarosio. Dalle simulazioni è emerso che, al netto del fabbisogno entalpico di autosostentamento, l’efficienza energetica del processo varia tra 0.20 e 0.53 a seconda delle condizioni; inoltre, è stata costruita la curva dei costi energetici di distillazione per litro di etanolo prodotto in funzione delle concentrazioni di etanolo in uscita dalla fermentazione. Infine sono già stati individuati fattori su cui è possibile agire per ottenere ulteriori miglioramenti sia in laboratorio che nella modellazione di processo e, di conseguenza, produrre con alta efficienza energetica bioetanolo ad elevato potenziale di mitigazione dell’effetto serra.

Biomass Gasification - Process analysis and dimensioning aspects for downdraft units and gas cleaning lines

In such territories where food production is mostly scattered in several small / medium size or even domestic farms, a lot of heterogeneous residues are produced yearly, since farmers usually carry out different activities in their properties. The amount and composition of farm residues, therefore, widely change during year, according to the single production process periodically achieved. Coupling high efficiency micro-cogeneration energy units with easy handling biomass conversion equipments, suitable to treat different materials, would provide many important advantages to the farmers and to the community as well, so that the increase in feedstock flexibility of gasification units is nowadays seen as a further paramount step towards their wide spreading in rural areas and as a real necessity for their utilization at small scale. Two main research topics were thought to be of main concern at this purpose, and they were therefore discussed in this work: the investigation of fuels properties impact on gasification process development and the technical feasibility of small scale gasification units integration with cogeneration systems. According to these two main aspects, the present work was thus divided in two main parts. The first one is focused on the biomass gasification process, that was investigated in its theoretical aspects and then analytically modelled in order to simulate thermo-chemical conversion of different biomass fuels, such as wood (park waste wood and softwood), wheat straw, sewage sludge and refuse derived fuels. The main idea is to correlate the results of reactor design procedures with the physical properties of biomasses and the corresponding working conditions of gasifiers (temperature profile, above all), in order to point out the main differences which prevent the use of the same conversion unit for different materials. At this scope, a gasification kinetic free model was initially developed in Excel sheets, considering different values of air to biomass ratio and the downdraft gasification technology as particular examined application. The differences in syngas production and working conditions (process temperatures, above all) among the considered fuels were tried to be connected to some biomass properties, such elementary composition, ash and water contents. The novelty of this analytical approach was the use of kinetic constants ratio in order to determine oxygen distribution among the different oxidation reactions (regarding volatile matter only) while equilibrium of water gas shift reaction was considered in gasification zone, by which the energy and mass balances involved in the process algorithm were linked together, as well. Moreover, the main advantage of this analytical tool is the easiness by which the input data corresponding to the particular biomass materials can be inserted into the model, so that a rapid evaluation on their own thermo-chemical conversion properties is possible to be obtained, mainly based on their chemical composition A good conformity of the model results with the other literature and experimental data was detected for almost all the considered materials (except for refuse derived fuels, because of their unfitting chemical composition with the model assumptions). Successively, a dimensioning procedure for open core downdraft gasifiers was set up, by the analysis on the fundamental thermo-physical and thermo-chemical mechanisms which are supposed to regulate the main solid conversion steps involved in the gasification process. Gasification units were schematically subdivided in four reaction zones, respectively corresponding to biomass heating, solids drying, pyrolysis and char gasification processes, and the time required for the full development of each of these steps was correlated to the kinetics rates (for pyrolysis and char gasification processes only) and to the heat and mass transfer phenomena from gas to solid phase. On the basis of this analysis and according to the kinetic free model results and biomass physical properties (particles size, above all) it was achieved that for all the considered materials char gasification step is kinetically limited and therefore temperature is the main working parameter controlling this step. Solids drying is mainly regulated by heat transfer from bulk gas to the inner layers of particles and the corresponding time especially depends on particle size. Biomass heating is almost totally achieved by the radiative heat transfer from the hot walls of reactor to the bed of material. For pyrolysis, instead, working temperature, particles size and the same nature of biomass (through its own pyrolysis heat) have all comparable weights on the process development, so that the corresponding time can be differently depending on one of these factors according to the particular fuel is gasified and the particular conditions are established inside the gasifier. The same analysis also led to the estimation of reaction zone volumes for each biomass fuel, so as a comparison among the dimensions of the differently fed gasification units was finally accomplished. Each biomass material showed a different volumes distribution, so that any dimensioned gasification unit does not seem to be suitable for more than one biomass species. Nevertheless, since reactors diameters were found out quite similar for all the examined materials, it could be envisaged to design a single units for all of them by adopting the largest diameter and by combining together the maximum heights of each reaction zone, as they were calculated for the different biomasses. A total height of gasifier as around 2400mm would be obtained in this case. Besides, by arranging air injecting nozzles at different levels along the reactor, gasification zone could be properly set up according to the particular material is in turn gasified. Finally, since gasification and pyrolysis times were found to considerably change according to even short temperature variations, it could be also envisaged to regulate air feeding rate for each gasified material (which process temperatures depend on), so as the available reactor volumes would be suitable for the complete development of solid conversion in each case, without even changing fluid dynamics behaviour of the unit as well as air/biomass ratio in noticeable measure. The second part of this work dealt with the gas cleaning systems to be adopted downstream the gasifiers in order to run high efficiency CHP units (i.e. internal engines and micro-turbines). Especially in the case multi–fuel gasifiers are assumed to be used, weightier gas cleaning lines need to be envisaged in order to reach the standard gas quality degree required to fuel cogeneration units. Indeed, as the more heterogeneous feed to the gasification unit, several contaminant species can simultaneously be present in the exit gas stream and, as a consequence, suitable gas cleaning systems have to be designed. In this work, an overall study on gas cleaning lines assessment is carried out. Differently from the other research efforts carried out in the same field, the main scope is to define general arrangements for gas cleaning lines suitable to remove several contaminants from the gas stream, independently on the feedstock material and the energy plant size The gas contaminant species taken into account in this analysis were: particulate, tars, sulphur (in H2S form), alkali metals, nitrogen (in NH3 form) and acid gases (in HCl form). For each of these species, alternative cleaning devices were designed according to three different plant sizes, respectively corresponding with 8Nm3/h, 125Nm3/h and 350Nm3/h gas flows. Their performances were examined on the basis of their optimal working conditions (efficiency, temperature and pressure drops, above all) and their own consumption of energy and materials. Successively, the designed units were combined together in different overall gas cleaning line arrangements, paths, by following some technical constraints which were mainly determined from the same performance analysis on the cleaning units and from the presumable synergic effects by contaminants on the right working of some of them (filters clogging, catalysts deactivation, etc.). One of the main issues to be stated in paths design accomplishment was the tars removal from the gas stream, preventing filters plugging and/or line pipes clogging At this scope, a catalytic tars cracking unit was envisaged as the only solution to be adopted, and, therefore, a catalytic material which is able to work at relatively low temperatures was chosen. Nevertheless, a rapid drop in tars cracking efficiency was also estimated for this same material, so that an high frequency of catalysts regeneration and a consequent relevant air consumption for this operation were calculated in all of the cases. Other difficulties had to be overcome in the abatement of alkali metals, which condense at temperatures lower than tars, but they also need to be removed in the first sections of gas cleaning line in order to avoid corrosion of materials. In this case a dry scrubber technology was envisaged, by using the same fine particles filter units and by choosing for them corrosion resistant materials, like ceramic ones. Besides these two solutions which seem to be unavoidable in gas cleaning line design, high temperature gas cleaning lines were not possible to be achieved for the two larger plant sizes, as well. Indeed, as the use of temperature control devices was precluded in the adopted design procedure, ammonia partial oxidation units (as the only considered methods for the abatement of ammonia at high temperature) were not suitable for the large scale units, because of the high increase of reactors temperature by the exothermic reactions involved in the process. In spite of these limitations, yet, overall arrangements for each considered plant size were finally designed, so that the possibility to clean the gas up to the required standard degree was technically demonstrated, even in the case several contaminants are simultaneously present in the gas stream. Moreover, all the possible paths defined for the different plant sizes were compared each others on the basis of some defined operational parameters, among which total pressure drops, total energy losses, number of units and secondary materials consumption. On the basis of this analysis, dry gas cleaning methods proved preferable to the ones including water scrubber technology in al of the cases, especially because of the high water consumption provided by water scrubber units in ammonia adsorption process. This result is yet connected to the possibility to use activated carbon units for ammonia removal and Nahcolite adsorber for chloride acid. The very high efficiency of this latter material is also remarkable. Finally, as an estimation of the overall energy loss pertaining the gas cleaning process, the total enthalpy losses estimated for the three plant sizes were compared with the respective gas streams energy contents, these latter obtained on the basis of low heating value of gas only. This overall study on gas cleaning systems is thus proposed as an analytical tool by which different gas cleaning line configurations can be evaluated, according to the particular practical application they are adopted for and the size of cogeneration unit they are connected to.

Einfluss der Habitatfragmentierung durch Überflutung auf Laufkäferpopulationen (Coleoptera; Carabidae)

Innerhalb dieser Dissertation wurde zwischen den Jahren 2002 und 2005 mit Hilfe von Barberfallen die Laufkäferfauna der Auwälder am nördlichen Oberrhein zwischen Mainz und Bingen erfasst. Dabei dienten verschiedene Rheininseln und ufernahe Festlandgebiete als Probeflächen. Fünf der typischen Bewohner dieser Flächen (Agonum afrum, Nebria brevicollis, Oxypselaphus obscurus, Platynus assimilis, Pterostichus anthracinus) dienten weiterhin als Modellarten für die Untersuchung der genetischen Diversität zwischen den einzelnen Populationen mittels RAPD-Analysen. Alles in allem konnten im Untersuchungsgebiet über 20.000 Individuen aus 101 Carabidenarten gefangen werden. Die häufigsten Vertreter waren Platynus assimilis, Pterostichus melanarius und Agonum afrum. Hohe Diversitäts- und Dominanzindices auf allen Flächen sprechen für die Dynamik des Lebensraumes und somit die Intaktheit der untersuchten Auwälder. Einen weiteren Hinweis auf die ständig wechselnden Lebensbedingungen durch immer wiederkehrende Überflutungen zeigt das Auftreten verschiedener ökologischer Gruppen. Überall dominierten deutlich die Arten, die mit gewissen Störungen des Habitates auskommen oder durch ihr hohes Ausbreitungspotential davor fliehen können. Das sind die Imaginalüberwinterer, makropteren, hygrophilen und kleinen Spezies. Auch das Geschlechterverhältnis weist auf deutliche Anzeichen für regelmäßige Beeinträchtigungen der Flächen hin. Knapp die Hälfte der beobachteten Arten im Untersuchungsgebiet steht auf einer der Roten Listen von Deutschland, Rheinland-Pfalz oder Hessen. Somit besteht für das gesamte Gebiet ein hoher Schutzbedarf. Das Hauptaugenmerk dieser Arbeit lag bei den Einflüssen der Hochwasserstände auf die Artenzusammensetzungen und die genetischen Diversitäten der Laufkäferpopulationen. Deshalb untersuchte man auch die Wirkung derjenigen Faktoren, die ihrerseits unmittelbar von den Extremwasserständen beeinflusst werden. Hier sind vor allem der Auentyp (Weichholz/Hartholz) und die Lage der Flächen auf Insel oder Festland zu nennen, die die deutlichsten Unterschiede in Artendiversität und Genetik der einzelnen Populationen zeigten. Aber auch weitere Faktoren, wie Wasserstandsdynamik, Auwaldbreite, Entfernung vom Fluss und Lage zum Damm weisen Zusammenhänge mit bestimmten ökologischen Gruppen auf. Lediglich die Habitatgröße scheint keinen Einfluss auf die Diversitäten zu nehmen. Abschließend konnten auch für das Jahr 2003, in dem extrem heiße und trockene Bedingungen herrschten, negative Effekte auf die Laufkäfergemeinschaften gezeigt werden.

Idrolisi diretta di cellulosa e lignocellulosa in catalisi eterogenea

This work deals with a comparison of the catalytic behavior of several heterogeneous acid catalysts in the direct hydrolysis of an untreated softwood dust. Amongst the various catalysts investigated, some were characterized by relatively high yield to monosaccharides, such as a Zirconium phosphate and the reference Amberlyst 15. Conversely, some catalyst types, ie, Sn/W mixed oxide and Zirconia-grafted trifluoromethanesulphonic acid, were selective into glucose, since sugars derived from hemicellulose dissolution and hydrolysis were rapidly degraded. A detailed analysis of the reactivity of Zr/P/O was pursued, in the hydrolysis of both untreated and ball-milled microcrystalline cellulose; at 150°C and 3h reaction time, the catalyst gave high selectivity to glucose, with negligible formation of 5-hydroxymethylfurfural, and moderate cellulose conversion. After ball-milling of the cellulose, a remarkable increase of conversion was achieved, still with a high selectivity to glucose and very low formation of degradation compounds. The catalyst showed high affinity for β-1,4-glucans, as demonstrated by the activity in cellobiose hydrolysis into glucose.

Processes influencing the nitrate concentration in an aquifer for drinking water production in Bremen-Nord - Northern Germany

Groundwater represents the most important raw material. Germany struggles to maintain the best water quality possible by providing advanced monitoring systems and legal measures to prevent further pollution. In areas involved in the intensive growing of plantations, one of the major contamination factors derives from nitrate. The aim of this master thesis is the characterisation of the Water Protection Area of Bremen (Germany). Denitrification is a natural process, representing the best means of natural reduction of the hazardous nitrate ion, which is dangerous both for human health and for the development of eutrophication. The study has been possible thanks to the collaboration with the University of Bremen, the Geological Service of Bremen (GDfB) and Peter Spiedt (Water Supply Company of Bremen). It will be defined whether nitrate amounts in the groundwater still overcome the threshold legally imposed, and state if the denitrification process takes place, thanks to new samples collected in 2015 and their integration with historical data. Gas samples have been gathered to test them with the “N2/Ar method”, which is able to estimate the denitrification rate quantitatively. Analyses stated the effective occurrence of the reaction, nevertheless showing that it only affects the chemical of the deep aquifers and not shallow ones. Temporal trends concentrations of nitrate have shown that no real improvement took place in the past years. It will be commented that despite the denitrification being responsible for an efficacious lowering in the nitrate ion, it needs reactive materials to take place. Since the latter are finite elements, it is not an endless process. It is thus believed that is clearly necessary to adopt a better attitude in order to maintain the best chemical qualities possible in such an important area, providing drinking water.

Patches of Bare Ground as a Staple Commodity for Declining Ground-Foraging Insectivorous Farmland Birds

Conceived to combat widescale biodiversity erosion in farmland, agri-environment schemes have largely failed to deliver their promises despite massive financial support. While several common species have shown to react positively to existing measures, rare species have continued to decline in most European countries. Of particular concern is the status of insectivorous farmland birds that forage on the ground. We modelled the foraging habitat preferences of four declining insectivorous bird species (hoopoe, wryneck, woodlark, common redstart) inhabiting fruit tree plantations, orchards and vineyards. All species preferred foraging in habitat mosaics consisting of patches of grass and bare ground, with an optimal, species-specific bare ground coverage of 30–70% at the foraging patch scale. In the study areas, birds thrived in intensively cultivated farmland where such ground vegetation mosaics existed. Not promoted by conventional agri-environment schemes until now, patches of bare ground should be implemented throughout grassland in order to prevent further decline of insectivorous farmland birds.

Indigenous fodder trees can increase grazing accessibility for landless and mobile pastoralists in northern Pakistan

Degraded hillsides in Northern Pakistan are rehabilitated through social forestry campaigns using fast growing exotic trees. These plantations on former scrublands curtail access by livestock owned by landless pastoralists and create social tension. This study proposes an alternative strategy of planting indigenous fodder trees and shrubs that are well-suited to the local socio-ecological characteristics and can benefit all social segments. The choice of fodder tree species, their nutritional value and distribution within the complex socio-ecological system is explained. This study also explores the suitability of these trees at different elevations, sites and transhumant routes. Providing mobile herders with adequate fodder trees could relax social tensions and complement food security.

Optimization of ethanol production by yeasts from lignocellulosic feedstocks

Ethanol from lignocellulosic feedstocks is not currently competitive with corn-based ethanol in terms of yields and commercial feasibility. Through optimization of the pretreatment and fermentation steps this could change. The overall goal of this study was to evaluate, characterize, and optimize ethanol production from lignocellulosic feedstocks by the yeasts Saccharomyces cerevisiae (strain Ethanol Red, ER) and Pichia stipitis CBS 6054. Through a series of fermentations and growth studies, P. stipitis CBS 6054 and S. cerevisiae (ER) were evaluated on their ability to produce ethanol from both single substrate (xylose and glucose) and mixed substrate (five sugars present in hemicellulose) fermentations. The yeasts were also evaluated on their ability to produce ethanol from dilute acid pretreated hydrolysate and enzymatic hydrolysate. Hardwood (aspen), softwood (balsam), and herbaceous (switchgrass) hydrolysates were also tested to determine the effect of the source of the feedstock. P. stipitis produced ethanol from 66-98% of the theoretical yield throughout the fermentation studies completed over the course of this work. S. cerevisiae (ER) was determined to not be ideal for dilute acid pretreated lignocellulose because it was not able to utilize all the sugars found in hemicellulose. S. cerevisiae (ER) was instead used to optimize enzymatic pretreated lignocellulose that contained only glucose monomers. It was able to produce ethanol from enzymatically pretreated hydrolysate but the sugar level was so low (>3 g/L) that it would not be commercially feasible. Two lignocellulosic degradation products, furfural and acetic acid, were evaluated for whether or not they had an inhibitory effect on biomass production, substrate utilization, and ethanol production by P. stipitis and S. cerevisiae (ER). It was determined that inhibition is directly related to the concentration of the inhibitor and the organism. The final phase for this thesis focused on adapting P. stipitis CBS 6054 to toxic compounds present in dilute acid pretreated hydrolysate through directed evolution. Cultures were transferred to increasing concentrations of dilute acid pretreated hydrolysate in the fermentation media. The adapted strains’ fermentation capabilities were tested against the unadapted parent strain at each hydrolysate concentration. The fermentation capabilities of the adapted strain were significantly improved over the unadapted parentstrain. On media containing 60% hydrolysate the adapted strain yielded 0.30 g_ethanol/g_sugar ± 0.033 (g/g) and the unadapted parent strain yielded 0.11 g/g ±0.028. The culture has been successfully adapted to growth on media containing 65%, 70%, 75%, and 80% hydrolysate but with below optimal ethanol yields (0.14-0.19 g/g). Cell recycle could be a viable option for improving ethanol yields in these cases. A study was conducted to determine the optimal media for production of ethanol from xylose and mixed substrate fermentations by P. stipitis. Growth, substrate utilization, and ethanol production were the three factors used to evaluate the media. The three media tested were Yeast Peptone (YP), Yeast Nitrogen Base (YNB), and Corn Steep Liquor (CSL). The ethanol yields (g/g) for each medium are as follows: YP - 0.40-0.42, YNB -0.28-.030, and CSL - 0.44-.051. The results show that media containing CSL result in slightly higher ethanol yields then other fermentation media. P. stipitis was successfully adapted to dilute acid pretreated aspen hydrolysate in increasing concentrations in order to produce higher ethanol yields compared to the unadapted parent strain. S. cerevisiae (ER) produced ethanol from enzymatic pretreated cellulose containing low concentrations of glucose (1-3g/L). These results show that fermentations of lignocellulosic feedstocks can be optimized based on the substrate and organism for increased ethanol yields.

The growth response of planted red pine (Pinus resinosa Ait.) to alternative thinning regimes

Red pine (Pinus resinosa Ait.) plantations have been established in Michigan with expectations of mixed final product goals: pulpwood, boltwood and possibly sawlogs. The effects of alternative treatments on tree and stand attributes were examined in: the Atlantic Mine trial, thinned in spring 2006 with three alternatives: (1) every fifth row removal plus crown thinning, (2) every third row removal plus crown thinning and (3) every third row removal plus thinning from below; the Crane Lake trial, thinned in fall 2004 with two alternatives: (1) every third row removal and (2) every third row removal plus thinning from above; the Middle Branch East trial, thinned in fall 2004 with two alternatives: (1) every third row removal plus one in three remaining trees and (2) every third row removal plus one in five remaining trees. All trials included control plots where no thinning was applied. The trials were established in the field as a randomized complete block experiments, in which individual trees were measured in 3-4 fixed-area plots located within each treatment unit. Growth responses of diameter at breast height, height, live crown length, stand basal area and stand volume were examined along with their increments. The Tukey multiple comparison test was used to detect significant differences between treatments in their effect on tree growth response. The results showed that diameter increment increased with increasing thinning intensity and was significantly larger in thinned plots compared to unthinned. Treatments did not substantially affect average tree height increment. Stand basal area increment was significantly larger in the control plot only the year after the harvest. Volume increment was significantly larger in controls, but did not differ considerably among remaining treatments. However, the ratio of volume increment to standing volume was significantly smaller in unthinned plots compared to thinned. Since thinning treatments in all trials hardly ever differed significantly in their effect on stand growth response, mainly due to the relatively short time of the evaluation, heavier thinnings should be favored due to higher volume increment rates and shorter time needed to reach desirable diameters. Nevertheless, economic evaluation based on obtained results will be conducted in the future in order to make final decisions about the most profitable treatment.

Kinetic characterization for pretreatment of timber varieties and switchgrass using diluted acid hydrolysis

In recent years, growing attention has been devoted to the use of lignocellulosic biomass as a feedstock to produce renewable carbohydrates as a source of energy products, including liquid alternatives to fossil fuels. The benefits of developing woody biomass to ethanol technology are to increase the long-term national energy security, reduce fossil energy consumption, lower greenhouse gas emissions, use renewable rather than depletable resources, and create local jobs. Currently, research is driven by the need to reduce the cost of biomass-ethanol production. One of the preferred methods is to thermochemically pretreat the biomass material and subsequently, enzymatically hydrolyze the pretreated material to fermentable sugars that can then be converted to ethanol using specialized microorganisms. The goals of pretreatment are to remove the hemicellulose fraction from other biomass components, reduce bioconversion time, enhance enzymatic conversion of the cellulose fraction, and, hopefully, obtain a higher ethanol yield. The primary goal of this research is to obtain kinetic detailed data for dilute acid hydrolysis for several timber species from the Upper Peninsula of Michigan and switchgrass. These results will be used to identify optimum reaction conditions to maximize production of fermentable sugars and minimize production of non-fermentable byproducts. The structural carbohydrate analysis of the biomass species used in this project was performed using the procedure proposed by National Renewable Energy Laboratory (NREL). Subsequently, dilute acid-catalyzed hydrolysis of biomass, including aspen, basswood, balsam, red maple, and switchgrass, was studied at various temperatures, acid concentrations, and particle sizes in a 1-L well-mixed batch reactor (Parr Instruments, ii Model 4571). 25 g of biomass and 500 mL of diluted acid solution were added into a 1-L glass liner, and then put into the reactor. During the experiment, 5 mL samples were taken starting at 100°C at 3 min intervals until reaching the targeted temperature (160, 175, or 190°C), followed by 4 samples after achieving the desired temperature. The collected samples were then cooled in an ice bath immediately to stop the reaction. The cooled samples were filtered using 0.2 μm MILLIPORE membrane filter to remove suspended solids. The filtered samples were then analyzed using High Performance Liquid Chromatography (HPLC) with a Bio-Rad Aminex HPX-87P column, and refractive index detection to measure monomeric and polymeric sugars plus degradation byproducts. A first order reaction model was assumed and the kinetic parameters such as activation energy and pre-exponential factor from Arrhenius equation were obtained from a match between the model and experimental data. The reaction temperature increases linearly after 40 minutes during experiments. Xylose and other sugars were formed from hemicellulose hydrolysis over this heat up period until a maximum concentration was reached at the time near when the targeted temperature was reached. However, negligible amount of xylose byproducts and small concentrations of other soluble sugars, such as mannose, arabinose, and galactose were detected during this initial heat up period. Very little cellulose hydrolysis yielding glucose was observed during the initial heat up period. On the other hand, later in the reaction during the constant temperature period xylose was degraded to furfural. Glucose production from cellulose was increased during this constant temperature period at later time points in the reaction. The kinetic coefficient governing the generation of xylose from hemicellulose and the generation of furfural from xylose presented a coherent dependence on both temperature and acid concentration. However, no effect was observed in the particle size. There were three types of biomass used in this project; hardwood (aspen, basswood, and red maple), softwood (balsam), and a herbaceous crop (switchgrass). The activation energies and the pre-exponential factors of the timber species and switchgrass were in a range of 49 - 180 kJ/mol and from 7.5x104 - 2.6x1020 min-1, respectively, for the xylose formation model. In addition, for xylose degradation, the activation energies and the preexponential factors ranged from 130 - 170 kJ/mol and from 6.8x1013 - 3.7x1017 min-1, respectively. The results compare favorably with the literature values given by Ranganathan et al, 1985. Overall, up to 92 % of the xylose was able to generate from the dilute acid hydrolysis in this project.

Biochemical Conversions of Lignocellulosic Biomass for Sustainable Fuel-Ethanol Production in the Upper Midwest

Biofuels are an increasingly important component of worldwide energy supply. This research aims to understand the pathways and impacts of biofuels production, and to improve these processes to make them more efficient. In Chapter 2, a life cycle assessment (LCA) is presented for cellulosic ethanol production from five potential feedstocks of regional importance to the upper Midwest - hybrid poplar, hybrid willow, switchgrass, diverse prairie grasses, and logging residues - according to the requirements of Renewable Fuel Standard (RFS). Direct land use change emissions are included for the conversion of abandoned agricultural land to feedstock production, and computer models of the conversion process are used in order to determine the effect of varying biomass composition on overall life cycle impacts. All scenarios analyzed here result in greater than 60% reduction in greenhouse gas emissions relative to petroleum gasoline. Land use change effects were found to contribute significantly to the overall emissions for the first 20 years after plantation establishment. Chapter 3 is an investigation of the effects of biomass mixtures on overall sugar recovery from the combined processes of dilute acid pretreatment and enzymatic hydrolysis. Biomass mixtures studied were aspen, a hardwood species well suited to biochemical processing; balsam, a high-lignin softwood species, and switchgrass, an herbaceous energy crop with high ash content. A matrix of three different dilute acid pretreatment severities and three different enzyme loading levels was used to characterize interactions between pretreatment and enzymatic hydrolysis. Maximum glucose yield for any species was 70% oftheoretical for switchgrass, and maximum xylose yield was 99.7% of theoretical for aspen. Supplemental β-glucosidase increased glucose yield from enzymatic hydrolysis by an average of 15%, and total sugar recoveries for mixtures could be predicted to within 4% by linear interpolation of the pure species results. Chapter 4 is an evaluation of the potential for producing Trichoderma reesei cellulose hydrolases in the Kluyveromyces lactis yeast expression system. The exoglucanases Cel6A and Cel7A, and the endoglucanase Cel7B were inserted separately into the K. lactis and the enzymes were analyzed for activity on various substrates. Recombinant Cel7B was found to be active on carboxymethyl cellulose and Avicel powdered cellulose substrates. Recombinant Cel6A was also found to be active on Avicel. Recombinant Cel7A was produced, but no enzymatic activity was detected on any substrate. Chapter 5 presents a new method for enzyme improvement studies using enzyme co-expression and yeast growth rate measurements as a potential high-throughput expression and screening system in K. lactis yeast. Two different K. lactis strains were evaluated for their usefulness in growth screening studies, one wild-type strain and one strain which has had the main galactose metabolic pathway disabled. Sequential transformation and co-expression of the exoglucanase Cel6A and endoglucanase Cel7B was performed, and improved hydrolysis rates on Avicel were detectable in the cell culture supernatant. Future work should focus on hydrolysis of natural substrates, developing the growth screening method, and utilizing the K. lactis expression system for directed evolution of enzymes.

Richness of Lichen Species, Especially of Threatened Ones, Is Promoted by Management Methods Furthering Stand Continuity

Lichens are a key component of forest biodiversity. However, a comprehensive study analyzing lichen species richness in relation to several management types, extending over different regions and forest stages and including information on site conditions is missing for temperate European forests. In three German regions (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin), the so-called Biodiversity Exploratories, we studied lichen species richness in 631 forest plots of 400 m2 comprising different management types (unmanaged, selection cutting, deciduous and coniferous age-class forests resulting from clear cutting or shelterwood logging), various stand ages, and site conditions, typical for large parts of temperate Europe. We analyzed how lichen species richness responds to management and habitat variables (standing biomass, cover of deadwood, cover of rocks). We found strong regional differences with highest lichen species richness in the Schwäbische Alb, probably driven by regional differences in former air pollution, and in precipitation and habitat variables. Overall, unmanaged forests harbored 22% more threatened lichen species than managed age-class forests. In general, total, corticolous, and threatened lichen species richness did not differ among management types of deciduous forests. However, in the Schwäbische-Alb region, deciduous forests had 61% more lichen species than coniferous forests and they had 279% more threatened and 76% more corticolous lichen species. Old deciduous age classes were richer in corticolous lichen species than young ones, while old coniferous age-classes were poorer than young ones. Overall, our findings highlight the importance of stand continuity for conservation. To increase total and threatened lichen species richness we suggest (1) conserving unmanaged forests, (2) promoting silvicultural methods assuring stand continuity, (3) conserving old trees in managed forests, (4) promoting stands of native deciduous tree species instead of coniferous plantations, and (5) increasing the amount of deadwood in forests.

Tree species and diversity effects on soil water seepage in a tropical plantation

Plant diversity has been shown to influence the water cycle of forest ecosystems by differences in water consumption and the associated effects on groundwater recharge. However, the effects of biodiversity on soil water fluxes remain poorly understood for native tree species plantations in the tropics. Therefore, we estimated soil water fluxes and assessed the effects of tree species and diversity on these fluxes in an experimental native tree species plantation in Sardinilla (Panama). The study was conducted during the wet season 2008 on plots of monocultures and mixtures of three or six tree species. Rainfall and soil water content were measured and evapotranspiration was estimated with the Penman-Monteith equation. Soil water fluxes were estimated using a simple soil water budget model considering water input, output, and soil water and groundwater storage changes and in addition, were simulated using the physically based one-dimensional water flow model Hydrus-1D. In general, the Hydrus simulation did not reflect the observed pressure heads, in that modeled pressure heads were higher compared to measured ones. On the other hand, the results of the water balance equation (WBE) reproduced observed water use patterns well. In monocultures, the downward fluxes through the 200 cm-depth plane were highest below Hura crepitans (6.13 mm day−1) and lowest below Luehea seemannii (5.18 mm day−1). The average seepage rate in monocultures (±SE) was 5.66 ± 0.18 mm day−1, and therefore, significantly higher than below six-species mixtures (5.49 ± 0.04 mm day−1) according to overyielding analyses. The three-species mixtures had an average seepage rate of 5.63 ± 0.12 mm day−1 and their values did not differ significantly from the average values of the corresponding species in monocultures. Seepage rates were driven by the transpiration of the varying biomass among the plots (r = 0.61, p = 0.017). Thus, a mixture of trees with different growth rates resulted in moderate seepage rates compared to monocultures of either fast growing or slow growing tree species. Our results demonstrate that tree-species specific biomass production and tree diversity are important controls of seepage rates in the Sardinilla plantation during the wet season.