Highlights ► Substantial progress has been made in the development of CBP. ► Production of ethanol at high yield and titer using ‘native strategy’. ► Production of CBHI and CBHII in yeast at levels ...sufficient for industrial process. ► Economic benefits of CBP result from more-effective biomass solubilization.
Biologically mediated processes seem promising for energy conversion, in particular for the conversion of lignocellulosic biomass into fuels. Although processes featuring a step dedicated to the ...production of cellulase enzymes have been the focus of most research efforts to date, consolidated bioprocessing (CBP) – featuring cellulase production, cellulose hydrolysis and fermentation in one step – is an alternative approach with outstanding potential. Progress in developing CBP-enabling microorganisms is being made through two strategies: engineering naturally occurring cellulolytic microorganisms to improve product-related properties, such as yield and titer, and engineering non-cellulolytic organisms that exhibit high product yields and titers to express a heterologous cellulase system enabling cellulose utilization. Recent studies of the fundamental principles of microbial cellulose utilization support the feasibility of CBP.
Recent efforts to understand the contribution of low-molecular weight compounds to carbon dynamics in soil ecosystems has resulted in a frame-work that suggests that low-molecular weight, labile ...carbon compounds can be directly assimilated by microbial biomass before being stabilized on soil colloids. However, this model primarily focuses on dissolved organic matter inputs and overlooks the potential importance of volatile organic compounds (VOCs). Here we determined the effects of two VOCs commonly emitted from soil and decomposing leaf litter (methanol, and acetone) on soil respiratory dynamics during a 28-day lab experiment. At the end of the experiment we quantified carbon and nitrogen concentrations in dissolved organic matter, microbial biomass, particulate organic matter, mineral associated organic matter, the labile carbon pool, and we quantified nitrifying microorganism abundance. Our results demonstrate that VOCs (i.e. methanol and acetone) increase soil respiration, contribute to labile soil C, and inhibit nitrification. Our VOC additions resulted in respiration spikes 4.1–5.5-fold greater than the control for acetone and methanol, respectively, though respiration returned back to control levels within 144 h after additions. Our VOC additions resulted in a 1.6–1.7-fold increase in labile soil carbon, suggesting that litter-derived VOCs could enter soil C pools following microbial metabolism. Additionally, soils exposed to VOCs contained ~ 2.25-fold less total dissolved nitrogen, and ~ 34–220-fold less nitrate. Ammonia oxidizing archaea were ~ 1.5 fold less abundant in VOC treated soils than in the control. After VOC additions were ceased, nitrate levels increased at approximately the same rate in all treatments, suggesting an inhibitory effect of methanol and acetone on nitrifying microorganisms. These results indicate that common decomposition derived VOCs play an important yet under-recognized role in driving the formation of soil organic matter as well as increasing the immobilization of nitrogen in soil ecosystems.
Since September 11, 2001, there has been the recognition of a plausible threat from acts of terrorism, including radiological or nuclear attacks. A network of Centers for Medical Countermeasures ...against Radiation (CMCRs) has been established across the U.S.; one of the missions of this network is to identify and develop mitigating agents that can be used to treat the civilian population after a radiological event. The development of such agents requires comparison of data from many sources and accumulation of information consistent with the “Animal Rule” from the Food and Drug Administration (FDA). Given the necessity for a consensus on appropriate animal model use across the network to allow for comparative studies to be performed across institutions, and to identify pivotal studies and facilitate FDA approval, in early 2008, investigators from each of the CMCRs organized and met for an Animal Models Workshop. Working groups deliberated and discussed the wide range of animal models available for assessing agent efficacy in a number of relevant tissues and organs, including the immune and hematopoietic systems, gastrointestinal tract, lung, kidney and skin. Discussions covered the most appropriate species and strains available as well as other factors that may affect differential findings between groups and institutions. This report provides the workshop findings.
Stone, H. B., Moulder, J. E., Coleman, C. N., Ang, K. K., Anscher, M. S., Barcellos-Hoff, M. H., Dynan, W. S., Fike, J. R., Grdina, D. J., Greenberger, J. S., Hauer-Jensen, M., Hill, R. P., ...Kolesnick, R. N., MacVittie, T. J., Marks, C., McBride, W. H., Metting, N., Pellmar, T., Purucker, M., Robbins, M. E., Schiestl, R. H., Seed, T. M., Tomaszewski, J., Travis, E. L., Wallner, P. E., Wolpert, M. and Zaharevitz, D. Models for Evaluating Agents Intended for the Prophylaxis, Mitigation and Treatment of Radiation Injuries. Report of an NCI Workshop, December 3–4, 2003. Radiat. Res. 162, 711–728 (2004). To develop approaches to prophylaxis/protection, mitigation and treatment of radiation injuries, appropriate models are needed that integrate the complex events that occur in the radiation-exposed organism. While the spectrum of agents in clinical use or preclinical development is limited, new research findings promise improvements in survival after whole-body irradiation and reductions in the risk of adverse effects of radiotherapy. Approaches include agents that act on the initial radiochemical events, agents that prevent or reduce progression of radiation damage, and agents that facilitate recovery from radiation injuries. While the mechanisms of action for most of the agents with known efficacy are yet to be fully determined, many seem to be operating at the tissue, organ or whole animal level as well as the cellular level. Thus research on prophylaxis/protection, mitigation and treatment of radiation injuries will require studies in whole animal models. Discovery, development and delivery of effective radiation modulators will also require collaboration among researchers in diverse fields such as radiation biology, inflammation, physiology, toxicology, immunology, tissue injury, drug development and radiation oncology. Additional investment in training more scientists in radiation biology and in the research portfolio addressing radiological and nuclear terrorism would benefit the general population in case of a radiological terrorism event or a large-scale accidental event as well as benefit patients treated with radiation.
Consolidated bioprocessing (CBP) of lignocellulose to bioethanol refers to the combining of the four
biological events required for this conversion process (production of saccharolytic enzymes, ...hydrolysis
of the polysaccharides present in pretreated biomass, fermentation of hexose sugars, and fermentation of
pentose sugars) in one reactor. CBP is gaining increasing recognition as a potential breakthrough
for low-cost biomass processing. Although no natural microorganism exhibits all the features desired for
CBP, a number of microorganisms, both bacteria and fungi, possess some of the desirable properties.
This review focuses on progress made toward the development of baker's yeast (Saccharomyces
cerevisiae) for CBP. The current status of saccharolytic enzyme (cellulases and hemicellulases)
expression in S. cerevisiae to complement its natural fermentative
ability is highlighted. Attention is also devoted to the challenges ahead to integrate all required enzymatic
activities in an industrial S. cerevisiae strain(s) and the need
for molecular and selection strategies pursuant to developing a yeast capable of CBP.
To investigate the possible use of
Saccharomyces cerevisiae as a candidate for consolidated bioprocessing (CBP) of cellulose to ethanol, four fungal cellobiohydrolase (CBH) encoding genes (
...Trichoderma reesei cbh1 and
cbh2,
Aspergillus niger cbhB and
Phanerochaete chrysosporium cbh1–
4) were expressed in this yeast. All four CBHs were successfully expressed and similar extracellular activity was demonstrated on phosphoric acid swollen cellulose (PASC) and bacterial microcrystalline cellulose (BMCC) using a modified affinity digestion procedure. Our results suggest that although heterologous CBHs can be produced in
S. cerevisiae the titers of functionally secreted CBH are relatively low. However, the specific activity of recombinant CBH1 on PASC and BMCC, determined by a sensitive ELISA-based technique, was found not to differ significantly from that of the native
T. reesei enzyme. Given this similarity in specific activity, but the disparity between current levels of CBH expression relative to expression levels required to enable growth on crystalline cellulosic substrates with concomitant ethanol production, future studies should aim to increase the expression levels of CBHs.
Remotely piloted aircraft (RPA) are in frequent use by the U.S. Air Force to engage in combat operations from remote locations. RPA operations involve remote killing, which can lead to significant ...emotional responses. This study addresses a gap in research by examining the association of existential and spiritual health with post-traumatic stress disorder (PTSD) symptoms in RPA and intelligence personnel.
Three hundred and five U.S. Air Force RPA and intelligence personnel completed the Spiritual Well-Being Scale (SWBS) and PTSD Checklist-Military Version. Correlational analyses were used to examine the association between SWBS score and PTSD symptoms.
There was a negative correlation between the SWBS and PTSD Checklist-Military Version scores (Pearson correlation coefficient = -0.49, p < 0.0001). Higher spiritual and existential well-being were associated with lower PTSD symptoms. Further, spiritual and existential scores in this sample were comparable with a number of SWBS norms, suggesting that levels of existential distress may not be high among remote warfare operators.
In this sample of U.S. Air Force personnel involved in remote warfare, higher spiritual and existential well-being were associated with less endorsement of mental health symptoms on a PTSD symptom measure. Additionally, levels of spiritual and existential well-being in this sample were comparable with norms used in a number of samples within the general population. Although there are ongoing concerns regarding the psychological impact remote warfare has on RPA operators, the bulk of current research has indicated that operational stressors such as workload, rotating shifts, organizational and leadership concerns, and balancing work and domestic tasks rather than the job duties themselves (i.e., involvement in killing) likely contribute more to reported emotional distress levels.
Historical fecundity estimates of American Shad Alosa sapidissima used a determinate method that estimated annual fecundity as the standing stock of oocytes at a single point of time prior to ...spawning. Such fecundity estimates have been (1) reported for populations from the Canadian Maritimes to Florida, (2) applied to hypothesis tests of life history evolution, and (3) used in demographic models to advise management policy. However, American Shad have asynchronous development of yolked oocyte clutches, which suggests that new oocytes could arise after spawning commences, biasing the results of a determinate fecundity method downward. If so, annual fecundity should be a product of batch size and the number of batches—an indeterminate fecundity method. We investigated oocyte recruitment, atresia, and spawning intervals using gonad histology of females from the Mattaponi River, Virginia. Batch size (i.e., the number of hydrated oocytes prior to a spawning event) was estimated using a gravimetric method. Spawning duration was obtained from an independent acoustic tagging study. A size hiatus between primary and secondary oocytes was only evident in some individuals during spawning, so we conclude that an indeterminate fecundity method is necessary for this population of American Shad. Atresia was evident during spawning but was low at the end of the 2002 spawning season. Females spawned every 2.2–2.9 d, releasing 11–17 batches per season. Batch fecundity (range: 12,700–81,400) was 23% higher for repeat versus virgin spawners. A bootstrapped estimate of potential annual fecundity for a virgin female—as calculated with an indeterminate fecundity method—was 478,000–544,000 eggs (95% confidence interval), about double the previous (determinate) estimates from this river system (260,000 and 288,000). Until more comparisons are done with other populations, we urge caution in using the many published determinate fecundity estimates of American Shad and other Alosa species. Received June 3, 2013; accepted October 25, 2013
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