The green algae Chlamydomonas sp. MACC-549 and Chlamydomonas reinhardtii cc124 were investigated for their hydrogen-evolution capability in mixed algal-bacterial cultures. Stable bacterial contaminations were identified during the cultivation of Chlamydomonas sp. 549. The bacterial symbionts belonged to various genera, mostly Brevundimonas, Rhodococcus, and Leifsonia, each of which enhanced the algal hydrogen production. This phenomenon was not limited to natural associations. Increased algal hydrogen evolution was achieved by simple artificial algal-bacterial communities as well.Algal-bacterial cocultures were designed and tested in hydrogen evolution experiments. The highest hydrogen yields were obtained when hydrogenase-deficient Escherichia coli was used as a symbiotic bacterium (Chlamydomonas sp. 549 generated 1196.06 ± 4.42 μL H 2 L −1 , while C. reinhardtii cc124 produced 5800.54 ± 65.73 μL H 2 L −1 ). The results showed that oxygen elimination is the most crucial factor for algal hydrogen production and that efficient bacterial respiration is essential for the activation of algal Fe-hydrogenase. The algae-based hydrogen evolution method described represents a novel combination of fermentative and photolytic hydrogen generation processes. Active photosynthesis was maintained during the entire hydrogen evolution process, which contributes to the sustainability of hydrogen production.

Thermal modification beneficially alters several technological parameters of wood. The changes in the physical parameters are due to the significant alterations of the structure and the chemical composition of wood, which take place during the modification process. These changes are complex and some aspects are still far from being completely understood. Various industrially important hardwoods and softwoods have been treated in an autoclave in N 2 atmosphere. The physical (density, L-value, moisture content, bending strength, MOE) and chemical (pH, hemicellulose-, total phenol-and soluble carbohydrate content) parameters have been measured and evaluated. By establishing linear correlations between physical and chemical parameters the chemical changes affecting the physical properties could be investigated and tracked. Very good correlations have been found for hardwood samples, whereas for softwoods only poor correlations have been established. Results could contribute to a better understanding of the reactions of thermal modification, and could furthermore provide a basis for wood species dependent technology optimization in the future.

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