ABSTRACT
The study describes a small closed ecosystem used to test technologies to be further employed in full-scale manned closed ecosystems. The experimental ecosystem is designed to use a certain portion of human metabolism, which is included in the gas, water, and organic waste loops of the system. In this experimental ecosystem, gas and water loops are fully closed, and the model enables processing of human waste and plant inedible biomass. A physicochemical method is used to remove pollutants from the air in the system. A human takes part in the gas exchange of the system through its respiration loop. This experimental ecosystem can be used for testing and improving new technologies to be further used in the future space stations.
Subject(s)
Ecological Systems, Closed , Life Support Systems , Photosynthesis , Plants/metabolism , Water/metabolism , Biodegradation, Environmental , Biomass , Carbon Dioxide/metabolism , Feces/chemistry , Humans , Manure/analysis , Oxygen/metabolism , Urine/chemistryABSTRACT
Synthesis of polyhydroxyalkanoates (PHAs) by a new strain of Cupriavidus - Cupriavidus eutrophus B-10646 - was investigated under autotrophic growth conditions. Under chemostat, at the specific flow rate D=0.1h(-1), on sole carbon substrate (CO2), with nitrogen, sulfur, phosphorus, potassium, and manganese used as growth limiting elements, the highest poly(3-hydroxybutyrate) [P(3HB)] yields were obtained under nitrogen deficiency. In batch autotrophic culture, in the fermenter with oxygen mass transfer coefficient 0.460 h(-1), P(3HB) yields reached 85% of dry cell weight (DCW) and DCW reached 50 g/l. Concentrations of supplementary PHA precursor substrates (valerate, hexanoate, γ-butyrolactone) and culture conditions were varied to produce, for the first time under autotrophic growth conditions, PHA ter- and tetra-polymers with widely varying major fractions of 3-hydroxybutyrate, 4-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyhexanoate monomer units. Investigation of the high-purity PHA specimens showed significant differences in their physicochemical and physicomechanical properties.
Subject(s)
Carbon Dioxide/chemistry , Clostridium beijerinckii/metabolism , Fermentation , Hydrogen/chemistry , Polyhydroxyalkanoates/chemistry , Polymers , 3-Hydroxybutyric Acid/chemistry , Biodegradation, Environmental , Bioreactors , Carbon/chemistry , Crystallization , Gases , Oxygen/chemistry , Polymers/chemistry , Refuse Disposal/methods , TemperatureABSTRACT
Microbial polyhydroxyalkanoates (PHAs), because of their well studied complex physiology and commercial potential, are vehicles for carbon and potential storage reduction for many microbial species. Even with the wealth of studies about microbial PHAs in the scientific literature, polymer accumulation and degradation are still not comprehensively understood. Poly(3-hydroxybutyrate) (P3HB) granule formation and polymer mobility were studied here in the bacterium Ralstonia eutropha strain B5786 in autotrophic cultures. Electron microscopy studies revealed decreasing cell size concomitant with enlargement of size and number of intracellular granules, and inhibition of cell division during intracellular polymer production. Activities of key P3HB biosynthetic enzymes demonstrated correlations with each other during polymer accumulation, suggesting an intricately regulated P3HB cycle in autotrophically grown R. eutropha cells.
