Microbial Growth Kinetics Under Conditions of Microgravity (Biokin-4) - 07.15.14
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Science Objectives for Everyone Microbial Growth Kinetics Under Conditions of Microgravity-4 (Biokin-4) will test the development of biological air filter to clean-up contaminated air in manned space vehicles.
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Bioclear Environmental Biotechnology, Groningen, , Netherlands
Kayser Italia Srl., Livorno, , Italy
Sponsoring Space Agency
European Space Agency (ESA)
ISS Expedition Duration
October 2007 - April 2008
Previous ISS Missions
- Microbial Growth Kinetics Under Conditions of Microgravity-4 (Biokin-4) will determine the characteristics of bacterial growth kinetics under microgravity conditions to develop a system for the removal and complete oxidation of gaseous and airborne contaminants originating in confined atmospheres with the use of microorganisms in order to purify and recycle air in manned space aircraft.
Water and air are essential raw materials for manned space missions. Recycling of these materials is one of the biggest challenges in the further space exploration. The application of biotechnological techniques with as ultimate goal a fully closed ecological life support system is seen as the only solution.
The principle of the Biological Air Filter (BAF-system) is based on a support/sorbant membrane material colonized by selected micro-organisms in a near resting state, oxidizing the various contaminants. Two experimental BAF modules have already been designed, constructed and successfully tested. Laboratory experiments with the experimental models showed a high efficiency for the removal of the selected contaminants and demonstrated a good potential for space application.
Main objective of the presented work is the determination of the influence of the space environment on the growth-kinetics of the biodegradation of the air-contaminant 1,2-dichloroethane by micro-organisms at the degradation of organic volatile contaminants. The overall growth rate that the bacterial cells can reach depend on 1) the prevalent substrate concentration(s), 2) a cascade of biochemical reactions involved in the metabolism of the substrate, including the uptake and transport of the substrates, and 3) the kinetic properties of the enzymes involved in these reactions, and 4) the prevalent environmental conditions, such as temperature, pH and for instance the absence or presence of gravity. In space where sedimentation of the bacterial cells is absent, it is thought that concentrations of physiologically important cellular metabolites will leak out of the bacterial cells. In the absence of gravity the cells will remain in close proximity to these excreted or diffused metabolites, leading to little energetic loss. In the presence of gravity (1 g) the cells will sediment away from these metabolites leading to energy loss. Therefore it is hypothesized that bacterial cells modify their micro-environment in such a way resulting in (i) increased maximum specific growth rates/ substrate degradation rates in space as compared to growth on Earth, (ii) increased substrate affinities in space as compared to growth on Earth, (iii) increased molar cell yields in space as compared to growth on Earth and (iv) higher concentrations of excreted (by) products or metabolites on Earth as compared to growth in space.
In the current presentation results will be shown of base-line data collection to demonstrate the bacterial growth kinetics for the degradation of 1,2-dichloroethane under conditions of gravity (1 g). In addition, the experimental set-up will be shown for the study of the bacterial growth kinetics for 1,2-dichloroethane that will be performed under microgravity conditions.
Experiment containers supplied by Kaiser Italia, Livorno, Italy. A membrane system keeps separates the culture medium from an internal airspace, simulating the function of a biological airfilter. The containers are loaded at the investigators lab in Groningen, then transported refrigerated until integration into a KUBIK incubator placed in the Soyuz vehicle. The KUBIK incubator maintains the samples at +6 degrees C until experiment activation approximately two days after launch, when the incubator temperature is raised to +28 degrees C. The experiment is run at +28 degrees C for two days, after which the substrate is automatically added to the culture followed by fixative. Following fixation the KUBIK incubator is switched to +6 degrees C to refrigerate the samples until download.
Biokin hardwae, image courtesy of ESA.
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