With the advancements in science and technology, we are witnessing the golden era of space exploration. However, we have a lot to learn as we embark on this exciting journey. One of the important things is to understand the effects of space environment on human physiology. Space flight might weaken the human immune response, thereby increasing the risk of microbial infections. Space environment might also alter the microbes, making them more harmful. Hence, it is important to conduct studies investigating the effects of space environment on microbes on spaceflights or under laboratory conditions, simulating the microgravity environment observed in space. Addressing this issue, researchers (Tirumalai et al.), at the University of Houston, recently published a study in npj Microgravity, where they grew the bacteria Escherichia coli (E. coli) under microgravity conditions in the laboratory and showed that these microbes undergo both phenotypic and genomic changes.
For this study, the researchers chose a specific strain of E. coli and grew it for thousand generations in low-shear modeled microgravity (LSMMG) environment in the laboratory, which simulates the microgravity condition found in space. This strain was referred to as the 1000-G strain. Interestingly, they found that in the LSMMG environment, the microgravity-adapted 1000-G strain generated more colonies and showed an adaptive growth advantage of 2.46 fold as compared to the unadapted E. coli strain. In order to assess whether the growth advantage exhibited by the 1000-G strain was due to the temporary phenotypic changes brought about by the exposure to the LSMMG environment or due to the permanent genomic changes to adapt to such an environment, the researchers cultured the 1000-G strain under normal gravity conditions for 10-30 generations before shifting it to the microgravity culture conditions and then measured the number of colonies generated. They observed that the 1000-G strain retained 50% of the adaptive growth advantages. This indicated that culture under microgravity conditions resulted in genomic changes in the 1000-G strain, enabling it to grow better than the unadapted strain.
The researchers also sequenced the genome of the 1000-G E. coli strain and found 16 mutations when compared to the normal E. coli strain. The genes that underwent mutations included the ones regulating bacterial attachment to surfaces and stress response. The researchers speculate that these mutations might help the microbes to adapt to the low gravity environment. Despite these genomic changes, the 1000-G E. coli strain did not show any significant change in its sensitivity against a broad range of antibiotics. However, further studies are required to ensure that the mutations observed in the 1000-G strain specifically developed because of the exposure to the microgravity environment.
Although the microgravity conditions in the laboratory provide an excellent system to study the effects of space conditions on microbial properties, the researchers suggest that similar studies performed on the International Space Station will help to confirm these findings. Such studies will help us better understand the effects of the space conditions on the microbes and their subsequent impact on human physiology. Recently, another group showed the ability of cosmic rays to adversely affect the human cells and increase the risk of cancer. While space exploration is indeed a giant leap for mankind, a deeper understanding of the consequences of the space environment on the human body is critical before embarking on long-term space missions.
Journal reference:
Tirumalai MR, Karouia F, Tran Q, Stepanov VG, Bruce RJ, Mark Ott C, Pierson DL, Fox GE. The adaptation of Escherichia coli cells grown in simulated microgravity for an extended period is both phenotypic and genomic. npj Microgravity (2017) 3:15; doi:10.1038/s41526-017-0020-1
Other references:
https://futurism.com/3-bacteria-shown-to-mutate-in-space/
Featured image source: Pixabay
About the author:
Isha Verma has recently finished her Ph.D. from the Indian Institute of Science, Bangalore. She is currently working as a Research Associate at the same institute. Her research work focusses on the generation of neural cells from stem cells. She also works as a freelance scientific editor and scientific consultant. She loves reading, traveling, and star gazing. She can be reached here.
Edited by: Radhika Raheja
