Acid solubilization of lignin and bioconversion of treated newsprint to methane

Newsprint was pretreated with acetic-nitric acid reagent tosolubilize and remove the lignin component and improveits conversion to methane in anaerobic digestion. Aceticacid itself cannot dissolve lignin even at a concentrationas high as 80% at elevated temperature (in a boilingwater bath). In order to effectively dissolve significantamounts of lignin, nitric acid must also be added. At anacetic acid concentration of 35% with 2% nitric acid,about 80% of lignin was removed from newsprint(resulting in a weight loss of about 40%). Hydrochloricacid may partially but not completely replace the nitricacid. The methane yield from treated newsprintbioconversion increased nearly three times over that ofuntreated newsprint in a 60-day test. Treated newsprintgenerated about 75% as much methane as office paper inthe same 60-day test. Acid pretreatment producednewsprint with the same cellulose content (as apercentage of volatile solids) as office paper. Despitethese promising results, however, the cellulose/lignin ratioof newsprint was increased from 1.6 to only 9.9 by acidpretreatment, compared to 22.9 for office paper. Since thelignin was not completely removed, the cellulose-ligninassociation is considered to be the major limiting factoron long-term anaerobic digestion of both untreated andtreated newsprint. An additional limiting factor todevelopment of a practical pretreatment method based onthis approach, efficient recovery of acids following ligninsolubilization, was not pursued in this research.     

Recent advances toward the bioconversion of methane and methanol in synthetic methylotrophs

Abundant natural gas reserves, along with increased biogas production, have prompted recent interest in harnessing methane as an industrial feedstock for the production of liquid fuels and chemicals. Methane can either be used directly for fermentation or first oxidized to methanol via biological or chemical means. Methanol is advantageous due to its liquid state under normal conditions. Methylotrophy, defined as the ability of microorganisms to utilize reduced one-carbon compounds like methane and methanol as sole carbon and energy sources for growth, is widespread in bacterial communities. However, native methylotrophs lack the extensive and well-characterized synthetic biology toolbox of platform microorganisms like Escherichia coli, which results in slow and inefficient design-build-test cycles. If a heterologous production pathway can be engineered, the slow growth and uptake rates of native methylotrophs generally limit their industrial potential. Therefore, much focus has been placed on engineering synthetic methylotrophs, or non-methylotrophic platform microorganisms, like E. coli, that have been engineered with synthetic methanol utilization pathways. These platform hosts allow for rapid design-build-test cycles and are well-suited for industrial application at the current time. In this review, recent progress made toward synthetic methylotrophy (including methanotrophy) is discussed. Specifically, the importance of amino acid metabolism and alternative one-carbon assimilation pathways are detailed. A recent study that has achieved methane bioconversion to liquid chemicals in a synthetic E. coli methanotroph is also briefly discussed. We also discuss strategies for the way forward in order to realize the industrial potential of synthetic methanotrophs and methylotrophs.     

Technologies for the bioconversion of methane into more valuable products

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Coal methanogenesis: a review of the need of complex microbial consortia and culture conditions for the effective bioconversion of coal into methane

Microbial biodegradation of coal into low-molecular-weight compounds such as methane has been extensively researched in the last two decades because of the underlying environmental and industrial applications of this technique as compared to the chemical and physical methods of coal conversions. However, the irregular structure of coal and the need for complex microbial consortia under specific culture conditions do not make this biotransformation an ideal process for the development of anaerobic bioreactors. The most abundant species in a methanogenic culture are acetoclastic and hydrogenotrophic methanogens which utilize acetate and H₂+CO₂, respectively. Medium- to low-rank coals such as high-volatile bituminous, sub-bituminous and lignite are more promising in this bioconversion as compared to semi- and meta-anthracite coals. While covering the details of the ideal culture conditions, this review enlightens the need of research setups to explore the complex microbial consortia and culture conditions for maximum methane production through coal methanogenesis.     

A contribution of hydrogenotrophic methanogenesis to the biogenic coal bed methane reserves of Southern Qinshui Basin,China

The activity of methanogens and related bacteria which inhabit the coal beds is essential for stimulating new biogenic coal bed methane (CBM) production from the coal matrix. In this study, the microbial community structure and methanogenesis were investigated in Southern Qinshui Basin in China, and the composition and stable isotopic ratios of CBM were also determined. Although geochemical analysis suggested a mainly thermogenic origin for CBM, the microbial community structure and activities strongly implied the presence of methanogens in situ. 454 pyrosequencing analysis combined with methyl coenzyme-M reductase (mcrA) gene clone library analysis revealed that the archaeal communities in the water samples from both coal seams were similar, with the dominance of hydrogenotrophic methanogen Methanobacterium. The activity and potential of these populations to produce methane were confirmed by the observation of methane production in enrichments supplemented with H₂ + CO₂ and formate, and the only archaea successfully propagated in the tested water samples was from the genus Methanobacterium. 454 pyrosequencing analysis also recovered the diverse bacterial communities in the water samples, which have the potential to play a role in the coal biodegradation fueling methanogens. These results suggest that the biogenic CBM was generated by coal degradation via the hydrogenotrophic methanogens and related bacteria, which also contribute to the huge CBM reserves in Southern Qinshui Basin, China.     

Meteorologically Driven Simulations of Dengue Epidemics in San Juan,PR

Meteorological factors influence dengue virus ecology by modulating vector mosquito population dynamics, viral replication, and transmission. Dynamic modeling techniques can be used to examine how interactions among meteorological variables, vectors and the dengue virus influence transmission. We developed a dengue fever simulation model by coupling a dynamic simulation model for Aedes aegypti, the primary mosquito vector for dengue, with a basic epidemiological Susceptible-Exposed-Infectious-Recovered (SEIR) model. Employing a Monte Carlo approach, we simulated dengue transmission during the period of 2010–2013 in San Juan, PR, where dengue fever is endemic. The results of 9600 simulations using varied model parameters were evaluated by statistical comparison (r²) with surveillance data of dengue cases reported to the Centers for Disease Control and Prevention. To identify the most influential parameters associated with dengue virus transmission for each period the top 1% of best-fit model simulations were retained and compared. Using the top simulations, dengue cases were simulated well for 2010 (r² = 0.90, p = 0.03), 2011 (r² = 0.83, p = 0.05), and 2012 (r² = 0.94, p = 0.01); however, simulations were weaker for 2013 (r² = 0.25, p = 0.25) and the entire four-year period (r² = 0.44, p = 0.002). Analysis of parameter values from retained simulations revealed that rain dependent container habitats were more prevalent in best-fitting simulations during the wetter 2010 and 2011 years, while human managed (i.e. manually filled) container habitats were more prevalent in best-fitting simulations during the drier 2012 and 2013 years. The simulations further indicate that rainfall strongly modulates the timing of dengue (e.g., epidemics occurred earlier during rainy years) while temperature modulates the annual number of dengue fever cases. Our results suggest that meteorological factors have a time-variable influence on dengue transmission relative to other important environmental and human factors.     

Methylotrophic methanogenesis governs the biogenic coal bed methane formation in Eastern Ordos Basin, China

To identify the methanogenic pathways present in a deep coal bed methane (CBM) reservoir associated with Eastern Ordos Basin in China, a series of geochemical and microbiological studies was performed using gas and water samples produced from the Liulin CBM reservoir. The composition and stable isotopic ratios of CBM implied a mixed biogenic and thermogenic origin of the methane. Archaeal 16S rRNA gene analysis revealed the dominance of the methylotrophic methanogen Methanolobus in the water produced. The high potential of methane production by methylotrophic methanogens was found in the enrichments using the water samples amended with methanol and incubated at 25 and 35?°C. Methylotrophic methanogens were the dominant archaea in both enrichments as shown by polymerase chain reaction (PCR)–denaturing gradient gel electrophoresis (DGGE). Bacterial 16S rRNA gene analysis revealed that fermentative, sulfate-reducing, and nitrate-reducing bacteria inhabiting the water produced were a factor in coal biodegradation to fuel methanogens. These results suggested that past and ongoing biodegradation of coal by methylotrophic methanogens and syntrophic bacteria, as well as thermogenic CBM production, contributed to the Liulin CBM reserves associated with the Eastern Ordos Basin.     

Field and laboratory studies for evaluating the toxicity of the insecticide Reldan on soil fungi

The response of soil fungi to the insecticide Reldan (chlorpyrifos-methyl) was studied under field and laboratory conditions. The colony forming units (CFU) of fungi were determined by means of serial dilution technique after 1 day, 7, 14, and 28 days of the insecticide application in soil. The plate count data indicated that the insecticide affected the number of fungi in treated soil compared with the untreated soil; the developed colonies decreased after 1–7 days of insecticide application and then increased with increasing application time. The effect of different concentrations of insecticide on the morphological features and sporogenesis of Aspergillus flavus, Fusarium culumorum, and Drechslera biseptata was studied. Relative conidiospore formation was sharply decreased and the conidiophores were deformed in A. flavus, while F. culumorum and D. biseptata failed to produce conidiospores, although chlamydospores were formed in large numbers when cultivated on the growth medium containing insecticide.     

Thigmomorphogenesis: Field and laboratory studies of Abies fraseri in response to wind or mechanical perturbation

Field- and greenhouse-grown Abies fraseri (Pursh) Poir. (Fraser fir) were analyzed for wind- or mechanically-induced flexure changes. These changes included inhibition of stem and needle elongation, reinforcement of branch bases around the stem, and increased radial growth in the direction of the mechanical perturbation (MP). Mature trees exposed to high wind conditions were severely flag-formed. These modified tree crowns had a lower drag than crowns of non-flag formed trees in wind-tunnel tests. In both field-grown and greenhouse-grown A. fraseri , MP induced a decrease in flexibility and increased elasticity of the stems. The increased radial growth of the stems overrode the increase in elasticity, resulting in the overall decrease in flexibility. The increase in radial growth caused by wind or mechanical flexure was due to greater cell divisions of the vascular cambium, resulting in increased numbers of tracheids. The decrease in stem elongation in these trees was due, at least in part, to a decrease in tracheid length. The potential biological and mechanical significance of these induced growth changes in trees are addressed. The data support the thigmomorphogenetic theory, which states that plants respond to wind and other mechanical perturbations in a way that is favorable to the plant for continued survival in windy environments.     

Optimization studies for the bioconversion of Jerusalem artichoke tubers to ethanol and microbial biomass

Summary A total of 8 yeast and microbial cultures have been grown in the extract derived from the tubers of Jerusalem artichoke (Helianthus tuberosus) and screened according to the following optimization criteria: rates and yields of ethanol production, rates and yields of biomass production, and % of original sugars utilized during fermentation. Batch growth kinetic parameters were also determined for the cultures studied.     

Small Theropod Teeth from the Late Cretaceous of the San Juan Basin,Northwestern New Mexico and Their Implications for Understanding Latest Cretaceous Dinosaur Evolution

Studying the evolution and biogeographic distribution of dinosaurs during the latest Cretaceous is critical for better understanding the end-Cretaceous extinction event that killed off all non-avian dinosaurs. Western North America contains among the best records of Late Cretaceous terrestrial vertebrates in the world, but is biased against small-bodied dinosaurs. Isolated teeth are the primary evidence for understanding the diversity and evolution of small-bodied theropod dinosaurs during the Late Cretaceous, but few such specimens have been well documented from outside of the northern Rockies, making it difficult to assess Late Cretaceous dinosaur diversity and biogeographic patterns. We describe small theropod teeth from the San Juan Basin of northwestern New Mexico. These specimens were collected from strata spanning Santonian – Maastrichtian. We grouped isolated theropod teeth into several morphotypes, which we assigned to higher-level theropod clades based on possession of phylogenetic synapomorphies. We then used principal components analysis and discriminant function analyses to gauge whether the San Juan Basin teeth overlap with, or are quantitatively distinct from, similar tooth morphotypes from other geographic areas. The San Juan Basin contains a diverse record of small theropods. Late Campanian assemblages differ from approximately co-eval assemblages of the northern Rockies in being less diverse with only rare representatives of troodontids and a Dromaeosaurus-like taxon. We also provide evidence that erect and recurved morphs of a Richardoestesia-like taxon represent a single heterodont species. A late Maastrichtian assemblage is dominated by a distinct troodontid. The differences between northern and southern faunas based on isolated theropod teeth provide evidence for provinciality in the late Campanian and the late Maastrichtian of North America. However, there is no indication that major components of small-bodied theropod diversity were lost during the Maastrichtian in New Mexico. The same pattern seen in northern faunas, which may provide evidence for an abrupt dinosaur extinction.     

Factors affecting denitrification rates in experimental wetlands: Field and laboratory studies

To identify the conditions that promote high rates of denitrification we systematically investigated the interactions of wetland age, water temperature, organic carbon, macrophytic type and density, hydraulic conditions on denitrification rates in field and laboratory experiments. In the field, nitrate removal was consistently greater in a shallow, young, well-mixed constructed wetland, regardless of temperature and despite lower sediment denitrification potential (DNP), than in mature, more diverse, less well-mixed wetlands. We believe the presence of a benthic mesh, which supported a dense periphytic biofilm, to be partly responsible for the unexpectedly high observed rates. We measured the DNP of wetland sediments and periphyton in the laboratory with the acetylene block method under different temperatures, nitrate concentrations, and carbon sources. The overall DNP of periphyton was greater than the corresponding sediment samples on a per cell basis. We hypothesize that the organic carbon produced by the periphytic algae is readily degradable and promoted the higher denitrification rates. We found a positive relationship between DNP and biodegradable organic carbon concentration and identified chemical markers illustrating that biodegradability is promoted by a combination of polyhydroxyaromatic and polysaccharide parent structures. These findings highlight the importance of organic quality and the role of periphyton in accelerating the rates of denitrification in wetlands.     

Field and laboratory studies of social organization in Bushbabies (Galago senegalensis)

During the course of a one year field study of the Lesser Bushbaby (Galago senegalensis moholi), using a technique of direct observation with red light, it was discovered that family groups which slept together during the daytime split up at night, with each member spending most of the time alone. During the night individuals would come into contact with one another or with members of adjacent groups and the resulting social behaviour varied considerably. An interpretation has been made of more than 120 interactions observed in the field based on the behaviour of bushbabies introduced to one another under controlled semi-natural conditions.     

Palm Community Structure and Land Cover Changes in the San Juan Biological Corridor, Costa Rica

Biological corridors connect forest fragments, minimize the isolation of remaining habitats, and reduce the negative impact of fragmentation. Important studies in a corridor include documentation of land cover and the relationships between the plant community and land cover changes. In this study, density, species richness, and species diversity of palms of different life stages and growth forms were documented in forty 10 × 10 m census plots in the San Juan Biological Corridor (SJBC), Costa Rica. Changes in the percent cover of agricultural, partially forested, and forested lands from 1979 to 2001 were quantified based on existing land classifications. Associations between these palm community characteristics and the reduction in forest cover in 200-m and 1000-m annuli surrounding the census plots were investigated. These palm community characteristics were spatially interpolated to examine their distributions in SJBC. The community characteristics of palms of all growth forms varied among census plots. Forested lands in SJBC decreased from 88 percent to 26 percent during 1979–2001, while the percentage cover of agricultural and partially forested lands increased. The annual deforestation rate was 0.8 percent from 1979 to 1992, 4.3 percent from 1992 to 1997, and 7.5 percent from 1997 to 2001. Overall, palm community characteristics of small-canopy palms, dwarf palms, and cotyledonous seedlings had lower values with a lower percentage forest cover. The spatially interpolated palm community characteristics were consistently greatest within or adjacent to protected areas. This study demonstrates the complexity of the landscape and the effect of loss of adjacent forests on the palm community.     

Field and laboratory studies of the susceptibility of the green treefrog (Hyla cinerea) to Batrachochytrium dendrobatidis infection

Amphibians worldwide are experiencing devastating declines, some of which are due to the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd). Populations in the southeastern United States, however, have not been noticeably affected by the pathogen. The green treefrog (Hyla cinerea) is abundant and widespread in the southeastern United States, but has not been documented to harbor Bd infection. This study examined the susceptibility of H. cinerea to two strains of Bd in the lab and the prevalence of infection in wild populations of this species in southeastern Louisiana. Although we were able to infect H. cinerea with Bd in the lab, we did not observe any clinical signs of chytridiomycosis. Furthermore, infection by Bd does not appear to negatively affect body condition or growth rate of post-metamorphic individuals. We found no evidence of infection in surveys of wild H. cinerea. Our results suggest that H. cinerea is not susceptible to chytridiomycosis post-metamorphosis and probably is not an important carrier of the fungal pathogen Bd in the southeastern United States, although susceptibility at the larval stage remains unknown.