Nanlou Respiratory Diseases Department, Chinese PLA General Hospital/Chinese PLA Postgraduate Medical School, Beijing, 100853, China.
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
Mil Med Res. 2018 May 14;5(1):18. doi: 10.1186/s40779-018-0162-9.
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.
航天飞行和地面微重力模拟实验表明，微重力会影响微生物的生长和代谢。尽管人们对微重力及其模拟物影响微生物的研究已经超过 50 年，但在不同的实验中经常报告了一些似乎相互矛盾和多样化的结果，特别是在微生物生长和次生代谢方面。到目前为止，只有少数几种典型微生物对微重力的反应得到了研究；由于技术和后勤方面的障碍，对这些微生物在太空中对微重力的遗传和表型反应进行系统研究仍然不足。在这些研究中使用不同的测试菌株和次生代谢物似乎导致了多样化和相互矛盾的结果。此外，微生物细胞周围细胞外微环境的细微变化在微生物生长和次生代谢多样化反应中起着关键作用。因此，“间接”效应是解释这些现象在微生物中发生的合理途径。本综述总结了目前关于微生物生长和次生代谢对航天飞行及其模拟物的反应的知识，并讨论了多样化和相互矛盾的结果。此外，还为未来研究微重力对太空微生物生长和次生代谢的影响提出了建议。
