A new photocatalytic material based on algal cells.

Metallic platinum was deposited at surfaces of intracellular photosynthetic membranes of whole cells of a cyanobacterium (blue-green alga). The deposited platinum particles acted as a catalyst for generation of hydrogen from photosynthetic decomposition of water in the absence of other exogenous electron transfer agents. This technique represents a means of placing metal catalysts in contact with intracellular structures of microorganisms.

Analysis of an algae-based CELSS. Part 1: model development.

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food. O2, the recycle of human waste and trash, H2O, N2, and food production supply. A simple non-iterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.

Analysis of an algae-based CELSS. Part 2: options and weight analysis.

Life support components are evaluated for application to an idealized closed life support system which includes an algal reactor for food production. Weight-based trade studies are reported as "break-even" time for replacing food stores with a regenerative bioreactor. It is concluded that closure of the life support gases (oxygen recovery) depends on the carbon dioxide reduction chemistry and that an algae-based food production can provide an attractive alternative to re-supply for longer duration missions.

Photosynthetic Production of Hydrogen Peroxide by Anacystis nidulans.

A sensitive assay based upon fluorescence of scopoletin allowed continuous recording of H(2)O(2) production in illuminated intact cells of Anacytis nidulans. Onset of illumination was followed by a 5 to 10 second lag, a burst of very rapid production continuing for up to 5 minutes, and finally a slow and continuing steady rate of H(2)O(2) production. Size of the H(2)O(2) burst was decreased by 3-(3,4-dichlorophenyl)-1, 1-dimethylurea, by low O(2), and by certain Calvin cycle intermediates; it was increased by high light intensity, CO(2) depletion, Calvin cycle inhibitors (as iodoacetamide), cold shock, carbonyl cyanide m-chlorophenylhydrazone, and certain organic acids as glycolate). The H(2)O(2) burst was explained by the following hypothesis: a low potential reductant is produced more rapidly than it can be used in the normal pathway to CO(2) reduction and, instead, reacts with oxygen. H(2)O(2) production is regarded as a metabolic defect observable in Anacystis most dramatically during the transition from a very low rate of oxidative dark metabolism to a high rate of photosynthetic metabolism.