Co-production of hydrogen and ethanol from glucose in Escherichia coli by activation of pentose-phosphate pathway through deletion of phosphoglucose isomerase (pgi) and overexpression of glucose-6-phosphate dehydrogenase (zwf) and 6-phosphogluconate dehydrogenase (gnd)

Background: Biologically, hydrogen (H-2) can be produced through dark fermentation and photofermentation. Dark fermentation is fast in rate and simple in reactor design, but H-2 production yield is unsatisfactorily low as < 4 mol H-2/ mol glucose. To address this challenge, simultaneous production of H-2 and ethanol has been suggested. Co-production of ethanol andH(2) requires enhanced formation of NAD(P) H during catabolism of glucose, which can be accomplished by diversion of glycolytic flux from the Embden-Meyerh-of-Parnas (EMP) pathway to the pentose-phosphate (PP) pathway in Escherichia coli. However, the disruption of pgi (phosphoglucose isomerase) for complete diversion of carbon flux to the PP pathway made E. coli unable to grow on glucose under anaerobic condition. Results: Here, we demonstrate that, when glucose-6-phosphate dehydrogenase (Zwf) and 6-phosphogluconate dehydrogenase (Gnd), two major enzymes of the PP pathway, are homologously overexpressed, E. coli.pgi can recover its anaerobic growth capability on glucose. Further, with additional deletions of Delta hycA,Delta hyaAB,Delta hybBC,Delta ldhA, and Delta frdAB, the recombinant.pgi mutant could produce 1.69 mol H-2 and 1.50 mol ethanol from 1 mol glucose. However, acetate was produced at 0.18 mol mol(-1) glucose, indicating that some carbon is metabolized through the Entner-Doudoroff (ED) pathway. To further improve the flux via the PP pathway, heterologous zwf and gnd from Leuconostoc mesenteroides and Gluconobacter oxydans, respectively, which are less inhibited by NADPH, were overexpressed. The new recombinant produced more ethanol at 1.62 mol mol(-1) glucose along with 1.74 mol H-2 mol(-1) glucose, which are close to the theoretically maximal yields, 1.67 mol mol(-1) each for ethanol andH(2). However, the attempt to delete the ED pathway in the.pgi mutant to operate the PP pathway as the sole glycolytic route, was unsuccessful. Conclusions: By deletion of pgi and overexpression of heterologous zwf and gnd in E. coli Delta hycA Delta hyaAB Delta hybBC Delta ldhA Delta frdAB, two important biofuels, ethanol andH(2), could be successfully co-produced at high yields close to their theoretical maximums. The strains developed in this study should be applicable for the production of other biofuels and biochemicals, which requires supply of excessive reducing power under anaerobic conditions

Global patterns and drivers of ecosystem functioning in rivers and riparian zones

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.peerReviewe

Telepsychiatry for Neurocognitive Testing in Older Rural Latino Adults

As the population of older Latinos in the U.S. increases, availability of culturally-adapted geriatric psychiatry services is becoming a growing concern. This issue is exacerbated for rural Latino populations. In this study, we assessed whether neurocognitive assessment via telepsychiatry (TP) using a Spanish-language battery would be comparable to in-person (IP) testing using the same battery in a sample of Spanish-speaking older adults in a rural setting. Patients (N=22) received IP and TP testing 2 weeks apart. The order of IP and TP test administrations in individual subjects was determined randomly. Comparison of scores indicated that there were no significant differences between IP and TP test performance though both groups scored non-significantly higher at the second visit. This study demonstrates feasibility and utility of neurocognitive testing in Spanish using TP among older rural Latinos

Factors affecting prevalence of obesity among primary school students in Turkey

Obesity is an energy metabolism disorder which results in the excessive storage of fat and may also lead to physical and psychological problems. Since the 1980s, obesity has drastically increased across all age and socio-economic groups around the world. Objectives: The purpose of the study was to investigate the risk factors affecting obesity in students in the age group of 6-15 years. Patients and Methods: This was a population-based cross-sectional study on 868 students in Bahçelievler elementary school in Zonguldak, Turkey from March to April in 2010. Data was collected using demographic questionary forms and weight-length measurements. Results: The median age was 10.3 ± 2.1; 47.6% of the children were female and 52.4% of them were male. About 70.2% of the students consumed fast food. It was identified that 67.1% of the students in the 6-10-year age group and 32.9% in 11-15-year age group were obese (P = 0.000). The obesity prevalence of children with one or two siblings was higher than the ones with more than two siblings (P = 0.001). Conclusions: The study concluded that there were certain criteria related to development of obesity during a specific period of childhood and taking certain precautions could be effective in preventing it