The influence of nitrogen concentration and precipitation on fertilizer production from urine using a trickling filter.

Planetary habitation requires technology to maintain natural microbial processes, which make nutrients from biowaste available for plant cultivation. This study describes a 646 day experiment, in which trickling filters were monitored for their ability to mineralize nitrogen when loaded with artificial urine solutions of different concentrations (40, 60, 80 and 100% v/v). Former studies have indicated that increasing urine concentrations slow nitrogen conversion rates and induce growing instability. In the current experiment, nitrogen conversion rates, measured as nitrate production/day, did not differ between concentration levels and increasing instability was not observed. Instead, the buffering capacity of the mussel shells added as buffer system (∼75% calcium carbonate) increased with increasing concentrations of synthetic urine possibly due to the higher phosphate content. The intensified precipitation of calcium phosphates seems to promote carbonate dissolution leading to improved buffering. For space applications, the precipitation of calcium phosphates is not desirable as for the phosphate to be available to the plants the precipitate must be treated with hazardous substances. With regard to terrestrial agriculture the process-integrated phosphate precipitation is a possibility to separate the macronutrients nitrogen and phosphate without addition of other chemicals. Thus, the described process offers a simple and cost-effective approach to fertilizer production from biogenic residues like slurry.

Natural microbial populations in a water-based biowaste management system for space life support.

The reutilization of wastewater is a key issue with regard to long-term space missions and planetary habitation. This study reports the design, test runs and microbiological analyses of a fixed bed biofiltration system which applies pumice grain (16-25 mm grain size, 90 m(2)/m(3) active surface) as matrix and calcium carbonate as buffer. For activation, the pumice was inoculated with garden soil known to contain a diverse community of microorganisms, thus enabling the filtration system to potentially degrade all kinds of organic matter. Current experiments over 194 days with diluted synthetic urine (7% and 20%) showed that the 7% filter units produced nitrate slowly but steadily (max. 2191 mg NO3-N/day). In the 20% units nitrate production was slower and less stable (max. 1411 mg NO3-N/day). 84% and 76% of the contained nitrogen was converted into nitrate. The low conversion rate is assumed to be due to the high flow rate, which keeps the biofilm on the pumice thin. At the same time the thin biofilm seems to prevent the activity of denitrifiers implicating the existence of a trade off between rate and the amount of nitrogen loss. Microbiological analyses identified a comparatively low number of species (26 in the filter material, 12 in the filtrate) indicating that urine serves as a strongly selective medium and filter units for the degradation of mixed feedstock have to be pre-conditioned on the intended substrates from the beginning.

Impact of a high magnetic field on the orientation of gravitactic unicellular organisms--a critical consideration about the application of magnetic fields to mimic functional weightlessness.

The gravity-dependent behavior of Paramecium biaurelia and Euglena gracilis have previously been studied on ground and in real microgravity. To validate whether high magnetic field exposure indeed provides a ground-based facility to mimic functional weightlessness, as has been suggested earlier, both cell types were observed during exposure in a strong homogeneous magnetic field (up to 30 T) and a strong magnetic field gradient. While swimming, Paramecium cells were aligned along the magnetic field lines; orientation of Euglena was perpendicular, demonstrating that the magnetic field determines the orientation and thus prevents the organisms from the random swimming known to occur in real microgravity. Exposing Astasia longa, a flagellate that is closely related to Euglena but lacks chloroplasts and the photoreceptor, as well as the chloroplast-free mutant E. gracilis 1F, to a high magnetic field revealed no reorientation to the perpendicular direction as in the case of wild-type E. gracilis, indicating the existence of an anisotropic structure (chloroplasts) that determines the direction of passive orientation. Immobilized Euglena and Paramecium cells could not be levitated even in the highest available magnetic field gradient as sedimentation persisted with little impact of the field on the sedimentation velocities. We conclude that magnetic fields are not suited as a microgravity simulation for gravitactic unicellular organisms due to the strong effect of the magnetic field itself, which masks the effects known from experiments in real microgravity.

Differential gene expression profile and altered cytokine secretion of thyroid cancer cells in space.

This study focuses on the effects of short-term [22 s, parabolic flight campaign (PFC)] and long-term (10 d, Shenzhou 8 space mission) real microgravity on changes in cytokine secretion and gene expression patterns in poorly differentiated thyroid cancer cells. FTC-133 cells were cultured in space and on a random positioning machine (RPM) for 10 d, to evaluate differences between real and simulated microgravity. Multianalyte profiling was used to evaluate 128 secreted cytokines. Microarray analysis revealed 63 significantly regulated transcripts after 22 s of microgravity during a PFC and 2881 after 10 d on the RPM or in space. Genes in several biological processes, including apoptosis (n=182), cytoskeleton (n=80), adhesion/extracellular matrix (n=98), proliferation (n=184), stress response (n=268), migration (n=63), angiogenesis (n=39), and signal transduction (n=429), were differentially expressed. Genes and proteins involved in the regulation of cancer cell proliferation and metastasis, such as IL6, IL8, IL15, OPN, VEGFA, VEGFD, FGF17, MMP2, MMP3, TIMP1, PRKAA, and PRKACA, were similarly regulated under RPM and spaceflight conditions. The resulting effect was mostly antiproliferative. Gene expression during the PFC was often regulated in the opposite direction. In summary, microgravity is an invaluable tool for exploring new targets in anticancer therapy and can be simulated in some aspects in ground-based facilities.

Interleukin-6 expression under gravitational stress due to vibration and hypergravity in follicular thyroid cancer cells.

It is known that exposing cell lines in vitro to parabolic flights changes their gene expression and protein production patterns. Parabolic flights and spaceflight in general are accompanied by transient hypergravity and vibration, which may impact the cells and therefore, have to be considered too. To estimate the possible impact of transient hypergravity and vibration, we investigated the effects of these forces separately using dedicated ground-based facilities. We placed follicular thyroid ML-1 and CGTH W-1 cancer cells in a specific centrifuge (MuSIC Multi Sample Incubator Centrifuge; SAHC Short Arm Human Centrifuge) simulating the hypergravity phases that occur during one (P1) and 31 parabolas (P31) of parabolic flights, respectively. On the Vibraplex device, the same cell lines were treated with vibration waves corresponding to those that occur during a whole parabolic flight lasting for two hours. After the various treatments, cells were harvested and analyzed by quantitative real-time PCR, focusing on the genes involved in forming (ACTB, MYO9, TUBB, VIM, TLN1, and ITGB1) and modulating (EZR, RDX, and MSN) the cytoskeleton, as well as those encoding growth factors (EGF, CTGF, IL6, and IL8) or protein kinases (PRKAA1 and PRKCA). The analysis revealed alterations in several genes in both cell lines; however, fewer genes were affected in ML-1 than CGTH W-1 cells. Interestingly, IL6 was the only gene whose expression was changed in both cell lines by each treatment, while PKCA transcription remained unaffected in all experiments. We conclude that a PKCa-independent mechanism of IL6 gene activation is very sensitive to physical forces in thyroid cells cultured in vitro as monolayers.