Relating Methanogen Community Structure and Anaerobic Digester Function

Much remains unknown about the relationships between microbial community structure and anaerobic digester function. However, knowledge of links between community structure and function, such as specific methanogenic activity (SMA) and COD removal rate, are valuable to improve anaerobic bioprocesses. In this work, quantitative structure–activity relationships (QSARs) were developed using multiple linear regression (MLR) to predict SMA using methanogen community structure descriptors for 49 cultures. Community descriptors were DGGE demeaned standardized band intensities for amplicons of a methanogen functional gene (mcrA). First, predictive accuracy of MLR QSARs was assessed using cross validation with training (n = 30) and test sets (n = 19) for glucose and propionate SMA data. MLR equations correlating band intensities and SMA demonstrated good predictability for glucose (q2 = 0.54) and propionate (q2 = 0.53). Subsequently, data from all 49 cultures were used to develop QSARs to predict SMA values. Higher intensities of two bands were correlated with higher SMA values; high abundance of methanogens associated with these two bands should be encouraged to attain high SMA values. QSARs are helpful tools to identify key microorganisms or to study and improve many bioprocesses. Development of new, more robust QSARs is encouraged for anaerobic digestion or other bioprocesses, including nitrification, nitritation, denitrification, anaerobic ammonium oxidation, and enhanced biological phosphorus removal

THE KYOTO PROTOCOL: ECONOMIC EFFECTS OF ENERGY PRICES ON NORTHERN PLAINS DRYLAND GRAIN PRODUCTION

This study examined possible economic impacts on Northern Plains grain producers of policies that could be undertaken by the United States to comply with the Kyoto Protocol. The paper begins with a discussion of the potential effects of the Kyoto Protocol on prices of energy and inputs used in agricultural production. The next section describes the data and econometric models that were used to develop a field-scale, stochastic simulation model of the crop production system typical of the Northern Plains. This model is based on econometric production models estimated with a spatially referenced, statistically representative sample of farmers in Montana. The simulation analysis shows that the impacts of higher energy prices would tend to discourage the use of fallow, raise variable costs of production by 3 to 13%, and reduce net returns above variable cost by 6 to 18% in the case of spring wheat grown on fallow, Under the higher cost scenarios assumed in an analysis conducted by the Farm Bureau, production costs for spring wheat on fallow would increase by 15 to 27% and net returns would decline by 15 to 24%.Resource /Energy Economics and Policy,

Mineralogy and Geochemistry of Shergottite RBT 04262

This abstract presents mineralogical and geochemical data on newly discovered shergottite RBT 04262 and compares it with other known shergottites

Exploring the Depths: Inquiry to Apply and Deepen Students’ Understanding of Density

This activity is designed to deepen students\u27 understanding of the concept of density through scientific inquiry. Students devise procedures to determine the relative and absolute (qualitative and quantitative) densities of several solutions of salt water, and establish a class consensus on their results. Students then apply their findings to estimate the density of an unknown solution. The targeted grade-level for this activity is 8 grade physical science. However, because we know students at all grade levels struggle to understand density, this activity could also be useful in high school Earth science and chemistry. This activity promotes National Science Education Content Standards A, B, and G, and Iowa Teaching Standards 1, 2, 3, and 4