Extracellular degradative enzymes released by psychrophilic marine bacteria (growing optimally at or below 15 degrees C and maximally at 20 degrees C) typically express activity optima at temperatures well above the upper growth limit of the producing strain. In the present study, we investigated whether or not near-zero Arctic environments contain extracellular enzymes with activity optimized to temperatures lower than previously reported. By applying fluorescently tagged substrate analogues to measure leucine-aminopeptidase and chitobiase activity, the occurrence of extracellular enzymatic activity (EEA) with remarkably low temperature optima (15 degrees C) was documented in sea-ice samples. An extremely psychrophilic bacterial isolate, strain 34H, yielded an extract of cell-free protease with activity optimized at 20 degrees C, the lowest optimum yet reported for cell-free EEA from a pure culture. The use of zymogram gels revealed the presence of three proteolytic bands (between 37 and 45 kDa) in the extract and the release of the greatest quantities of the proteases when the strain was grown at -1 degrees C, suggesting a bacterial strategy for counteracting the effects of very cold temperatures on the catalytic efficiency of released enzymes. The detection of unusually cold-adapted EEA in environmental samples has ramifications not only to polar ecosystems and carbon cycling but also to protein evolution, biotechnology and bioremediation.

Single, thermally thick particles of lodgepole pinewood were pyrolyzed under well-defined conditions of industrial importance. Particle thickness, heating level, moisture content, density, and grain axis relative to one-dimensional heating were varied using a Box-Behnken experimental design. Gross product fractions, as well as components therein, were measured and the batch yields were correlated with second-order polynomials. The empirical equations correlating the batch yields, together with their prediction uncertainties, are presented and are suitable for use in simulations of wood combustion and thermal conversion. Comparison of large particle pyrolysis product distributions to other studies of small-particle pyrolysis yields shows the trends with particle size to be consistent. Tar yield minima depend on both particle size and heating rate. Gas yield is dependent on both particle size and heating intensity. Because some process controllables were found to alter product yields from large particles in a multiplicative way, rather than an additive way, suggestions for future experiments are made.

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