Diamagnetic levitation enhances growth of liquid bacterial cultures by increasing oxygen availability

Abstract

Diamagnetic levitation is a technique that uses a strong, spatially varying magnetic field to reproduce aspects of weightlessness, on the Earth. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 h, to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture and reduces the sedimentation rate of the cells. Further experiments and microarray gene analysis show that the increase in growth rate is owing to enhanced oxygen availability. We also demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause convection during the aerobic phases of bacterial growth. We propose that this convection enhances oxygen availability by transporting oxygen around the liquid culture. Since this process results from the strong magnetic field, it is not present in other weightless environments, e.g. in Earth orbit. Hence, these results are of significance and timely to researchers considering the use of diamagnetic levitation to explore effects of weightlessness on living organisms and on physical phenomena.

Evaporation Rate of Water as a Function of a Magnetic Field and Field Gradient

“…The resulting relationship between position and surface area is similar to previously reported results [13]. This relationship convinces us that the magnetization force affects the amount of evaporated water, because evaporation is proportional to the evaporating surface area.…”

Ground-Based Facilities for Simulation of Microgravity: Organism-Specific Recommendations for Their Use, and Recommended Terminology

“…These were followed by studies of levitating yeast (Coleman et al, 2007), swimming paramecia in gadolinium solution (Guevorkian and Valles, 2006b), E. coli (Dijkstra et al, 2011), cell cultures (Babbick et al, 2007;Hammer et al, 2009;Qian et al, 2009), a mouse , and Drosophila melanogaster Hill et al, 2012).…”

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

“…Various biological systems have been exposed to magnetic levitation ranging from cell cultures (e.g., Babbick et al, 2007;Hammer et al, 2009), bacteria (Dijkstra et al, 2011;Liu et al, 2011), and yeast (Coleman et al, 2007) to more complex systems, such as plants (Arabidopsis) and insects (Drosophila melanogaster) (Herranz et al, 2012), frog eggs (Valles et al, 1997), frogs (Berry and Geim, 1997), and mice (Liu et al, 2010).…”