Abstract
BackgroundDiamagnetic levitation is a technique that uses a strong, spatially varying magnetic field to simulate an altered gravity environment, as in space. In this study, using Streptomyces avermitilis as the test organism, we investigate whether changes in magnetic field and altered gravity induce changes in morphology and secondary metabolism. We find that a strong magnetic field (12T) inhibit the morphological development of S. avermitilis in solid culture, and increase the production of secondary metabolites.Methodology/Principal Findings S. avermitilis on solid medium was levitated at 0 g*, 1 g* and 2 g* in an altered gravity environment simulated by diamagnetic levitation and under a strong magnetic field, denoted by the asterix. The morphology was obtained by electromicroscopy. The production of the secondary metabolite, avermectin, was determined by OD245 nm. The results showed that diamagnetic levitation could induce a physiological response in S. avermitilis. The difference between 1 g* and the control group grown without the strong magnetic field (1 g), showed that the magnetic field was a more dominant factor influencing changes in morphology and secondary metabolite production, than altered gravity.Conclusion/SignificanceWe have discovered that magnetic field, rather than altered gravity, is the dominant factor in altered gravity simulated by diamagnetic levitation, therefore care should to be taken in the interpretation of results when using diamagnetic levitation as a technique to simulate altered gravity. Hence, these results are significant, and timely to researchers considering the use of diamagnetic levitation to explore effects of weightlessness on living organisms and on physical phenomena.
Highlights
Understanding how the space ‘condition’ influences bacterial behaviour is important, for the immediate health of astronauts, and for the long-term future of space exploration
Conclusion/Significance: We have discovered that magnetic field, rather than altered gravity, is the dominant factor in altered gravity simulated by diamagnetic levitation, care should to be taken in the interpretation of results when using diamagnetic levitation as a technique to simulate altered gravity
Increasing the gravitational force did not significantly affect the morphology of PE1, but could compensate the negative effect of magnetic field in part. These results demonstrated that we could isolate and quantitate a direct effect of the high magnetic field and of gravity on the morphology of S. avermitilis strain PE1
Summary
Understanding how the space ‘condition’ influences bacterial behaviour is important, for the immediate health of astronauts, and for the long-term future of space exploration. To overcome issues with experiments in space, and in accordance with the hypothesis that ‘‘sensing no weight’’ would have comparable effects to those of weightlessness [3], several forms of ground-based simulated setups that simulate weightlessness have been developed. Many of these experiments have used rotation to time-average the gravity vector to zero, this can introduce artifacts owing to the rotating reference frame (clinostats, random positioning machine) [4]. We find that a strong magnetic field (12T) inhibit the morphological development of S. avermitilis in solid culture, and increase the production of secondary metabolites
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