Renewable energy from Cyanobacteria: energy production optimization by metabolic pathway engineering

The need to develop and improve sustainable energy resources is of eminent importance due to the finite nature of our fossil fuels. This review paper deals with a third generation renewable energy resource which does not compete with our food resources, cyanobacteria. We discuss the current state of the art in developing different types of bioenergy (ethanol, biodiesel, hydrogen, etc.) from cyanobacteria. The major important biochemical pathways in cyanobacteria are highlighted, and the possibility to influence these pathways to improve the production of specific types of energy forms the major part of this review

Reduction in Local Ozone Levels in Urban São Paulo Due to a Shift from Ethanol to Gasoline Use

It has been proposed that lower NOx emission fuels such as ethanol can mitigate air pollution from vehicles burning oil-based hydrocarbons. Yet, existing modeling and laboratory studies, even those seeking to simulate the same environment, vary in their predictions of how gasoline/ethanol blends affect atmospheric pollutant concentrations, including ozone. Importantly, ambient concentrations have not been evaluated during an actual – as opposed to hypothetical – shift in fuel mix in a real-world environment. Here, we report the first such study, for the subtropical megacity of São Paulo, Brazil. We combine detailed street-hour level data on regulated pollutant concentrations, meteorology, and traffic with fuel shares from a consumer demand model to compare concentrations across subsamples that differ only in the fuel mix but are otherwise similar in meteorology, anthropogenic activity, and biogenic emissions. As the gasoline share of the bi-fuel light-duty vehicle fleet rose by 62 percentage points, we estimate a robust and statistically significant reduction of about 20% in ozone concentrations, and less precise increases in NO and CO concentrations. We propose that our “model-free” analysis potentially accounts for the interaction between anthropogenic and biogenic emissions and caution that successful strategies against ozone pollution require knowledge of the local chemistry and analysis beyond the presently monitored pollutants, most notably fine particles

Pathways of human development and carbon emissions embodied in trade

It has long been assumed that human development depends on economic growth, that national economic expansion in turn requires greater energy use and, therefore, increased greenhouse-gas emissions. These interdependences are the topic of current research. Scarcely explored, however, is the impact of international trade: although some nations develop socio-economically and import high-embodied-carbon products, it is likely that carbon-exporting countries gain significantly fewer benefits. Here, we use new consumption-based measures of national carbon emissions to explore how the relationship between human development and carbon changes when we adjust national emission rates for trade. Without such adjustment of emissions, some nations seem to be getting far better development 'bang' for the carbon 'buck' than others, who are showing scant gains for disproportionate shares of global emissions. Adjusting for the transfer of emissions through trade explains many of these outliers, but shows that further socio-economic benefits are accruing to carbon-importing rather than carbon-exporting countries. We also find that high life expectancies are compatible with low carbon emissions but high incomes are not. Finally, we see that, despite strong international trends, there is no deterministic industrial development trajectory: there is great diversity in pathways, and national histories do not necessarily follow the global trends

Intracellular polyamine pools, oligopeptide-binding protein A expression, and resistance to aminoglycosides in Escherichia coli

The role of intracellular free polyamine (putrescine and spermidine) pools in multiple resistance to aminoglycoside antibiotics was investigated among in vitro selected kanamycin-resistant Escherichia coli J53 mutants expressing diminished oligopeptide-binding protein (OppA) levels and/or defective ornithine decarboxylase (ODC) activity. The results suggest that diminished OppA content, but not defective ODC activity expression, increased the relative concentration of free spermidine as compared to the wild type strain. Moreover, by adding exogenous polyamines or polyamine synthesis inhibitors to cultures with different mutant strains, a direct relationship between the intracellular OppA levels and resistance to kanamycin was revealed. Collectively these results further suggest a complex relation among OppA expression, aminoglycoside resistance and polyamine metabolism

Households’ Coping Dynamics in Response to Large-Scale Land Acquisition for Jatropha Plantations: Evidence from Asante Akim North District of Ghana

The study investigated the implications of large-scale land acquisition for jatropha cultivation on the livelihoods of farming households and the various coping strategies adopted. Three communities namely- Dukusen, Ananekrom and Afrisie in the Asante Akim North District were selected for the study based on their proximity to a large-scale jatropha plantation project and the extent of farming activities in the communities. The study employed the mixed method strategy using a cross-sectional study design. Interviews, focus group discussion and documentary analysis were espoused in gathering data for the study. The simple random sampling procedure was used in selecting 30 farming households whereas the managers of the plantation project and two local chiefs, two District Assemblymen, and the Headmasters of basic schools were purposively selected and interviewed. Correlation and descriptive statistical tools were used to analyze the quantitative data while recursive abstraction was applied in analyzing the qualitative aspects of the data. We found that prior to the large-scale land acquisition by the plantation project, all the respondents (100%) had farming as their livelihood activity and major source of food and income, but this had, however, dropped to 60% after the land acquisition for the jatropha project. The average farm size had also reduced from 3.5 acres per household to about 1.5 acres. These changes have triggered various coping dynamics among farming households within the study communities including all year round cropping, application of fertilizers, and cultivation of high-yielding varieties as well as petty trading activities to support household income and ensure sustainable livelihoods and wellbeing. The paper generally concludes that large-scale land acquisition has higher tendency of pushing farming households into adopting different coping strategies and dynamics. The findings reveal new dimensions of the empirical accounts on households’ coping dynamics in response to large-scale land acquisition.</p