Transformation Frequency of Escherichia coli HB101 under Low-Shear Modeled Microgravity

Abstract

Viable microorganisms are frequently found in space stations. The unique adaptive ability of bacteria partly depends on horizontal gene transfer among the individual cells. Microgravity, defined as a local environment in a space habitat where gravity seems not to act, is an unexperienced condition for most of Earth’s organisms, and can therefore affect bacterial physiology, gene expression, and gene transfer. The present study evaluates the effect of microgravity on horizontal gene transfer in Escherichia coli. To this end, we compared the transformation frequencies of E. coli under normal gravity and under low-shear modeled microgravity (LSMMG) generated by a high-aspect rotating vessel (HARV). Our results demonstrated that bacterial transformation is not hampered by LSMMG, and the potential risk of bacterial gene transfer during space flight is comparable to that on Earth. Therefore, we should arrest the spread of harmful genes such as toxin-producing and antibiotic resistance genes in crewed space habitats, as well as on the Earth.