Effects of spaceflight and simulated microgravity on microbial growth and secondary metabolism

Bing Huang,Dian-Geng Li,Ying Huang,Chang-Ting Liu

doi:10.1186/s40779-018-0162-9

Abstract

Spaceflight and ground-based microgravity analog experiments have suggested that microgravity can affect microbial growth and metabolism. Although the effects of microgravity and its analogs on microorganisms have been studied for more than 50 years, plausible conflicting and diverse results have frequently been reported in different experiments, especially regarding microbial growth and secondary metabolism. Until now, only the responses of a few typical microbes to microgravity have been investigated; systematic studies of the genetic and phenotypic responses of these microorganisms to microgravity in space are still insufficient due to technological and logistical hurdles. The use of different test strains and secondary metabolites in these studies appears to have caused diverse and conflicting results. Moreover, subtle changes in the extracellular microenvironments around microbial cells play a key role in the diverse responses of microbial growth and secondary metabolisms. Therefore, “indirect” effects represent a reasonable pathway to explain the occurrence of these phenomena in microorganisms. This review summarizes current knowledge on the changes in microbial growth and secondary metabolism in response to spaceflight and its analogs and discusses the diverse and conflicting results. In addition, recommendations are given for future studies on the effects of microgravity in space on microbial growth and secondary metabolism.

Highlights

Microbes are highly evolved [1] and can survive in many extreme environments [2, 3], including outer space [4, 5]
The progress of spaceflight and ground-based simulated microgravity technology has promoted our understanding of the effects of microgravity in space on microbes
There may be major influencing factors other than microgravity that can affect the growth and metabolisms of microorganisms during spaceflight, such as cosmic radiation and the vibrations generated by the rocket and acceleration during the launch and landing of the spacecraft [4]

Summary

Introduction

Microbes are highly evolved [1] and can survive in many extreme environments [2, 3], including outer space [4, 5]. Other experiments performed under simulated microgravity conditions on the ground using RWVs, RWBs, HARVs, RCCSs and diamagnetic levitation indicated that the growth rate of E. coli was increased [56, 62, 65, 66, 71, 78].

Results

Conclusion