Metagenomic Analysis of the Dynamic Changes in the Gut Microbiome of the Participants of the MARS-500 Experiment, Simulating Long Term Space Flight

Abstract

A metagenomic analysis of the dynamic changes of the composition of the intestinal microbiome of five participants of the MARS-500 experiment was performed. DNA samples were isolated from the feces of the participants taken just before the experiment, upon 14, 30, 210, 363 and 510 days of isolation in the experimental module, and two weeks upon completion of the experiment. The taxonomic composition of the microbiome was analyzed by pyrosequencing of 16S rRNA gene fragments. Both the taxonomic and functional gene content of the microbiome of one participant were analyzed by whole metagenome sequencing using the SOLiD technique. Each participant had a specific microbiome that could be assigned to one of three recognized enterotypes. Two participants had enterotype I microbiomes characterized by the prevalence of Bacteroides, while the microbiomes of two others, assigned to type II, were dominated by Prevotella. One participant had a microbiome of mixed type. It was found that (1) changes in the taxonimic composition of the microbiomes occurred in the course of the experiment, but the enterotypes remained the same; (2) significant changes in the compositions of the microbiomes occurred just 14-30 days after the beginning of the experiment, presumably indicating the influence of stress factors in the first stage of the experiment; (3) a tendency toward a reversion of the microbiomes to their initial composition was observed two weeks after the end of the experiment, but complete recovery was not achieved. The metagenomic analysis of the microbiome of one of the participants showed that in spite of variations in the taxonomic compositions of microbiomes, the “functional” genetic composition was much more stable for most of the functional gene categories. Probably in the course of the experiment the taxonomic composition of the gut microbiome was adaptively changed to reflect the individual response to the experimental conditions. A new, balanced taxonomic composition of the microbiome was formed to ensure a stable gene content of the community as a whole without negative consequences for the health of the participants.

Temporal dynamics of the gut microbiota in people sharing a confined environment, a 520-day ground-based space simulation, MARS500

“…The MARS500 project allowed us to evaluate, for the first time, the impact of long-lasting isolated confinement conditions, with lack of social interaction, reduced contact with the environment, restricted resources, and mostly tinned food, ready or semi-ready for consumption, on the temporal variability of the intestinal microbiota. It should be mentioned that another study has recently attempted to characterize the faecal microbiota of MARS500 participants, but only seven time points and five subjects were taken into consideration [14], making it impossible to actually observe the ecological dynamics of the gut microbiota under strictly controlled conditions.…”

Whole-genome sequencing targets drug-resistant bacterial infections

“…Herein, we showed that WGS may be well poised to make a decisive impact on the study and control of MDR in pathogenic bacteria (Table 1 ) [ 126 ]. However, although not reviewed here, studies have shown that WGS can also contribute to the investigation of various pathogenic and beneficial resistant microorganisms: bacteria [ 70 , 155 ], fungi ( Candida spp., Cryptococcus neoformans , Pneumocystis spp., and Aspergillus spp.) [ 208 ], and viruses (HIV virus, hepatitis B, hepatitis C, influenza, herpes viruses) [ 144 , 255 ].…”

The theory and application of space microbiology: China's experiences in space experiments and beyond

“…These changes may result in an imbalance in the intestinal flora. Significant changes in the compositions of microbiomes were observed 14-30 days after the beginning of the MARS-500 experiment, presumably indicating the effect of stress factors in the first stage of the experiment, and complete recovery was not achieved 2 weeks after the end of the experiment (Mardanov et al, 2013). However, direct evidence that space flight results in an imbalance in the intestinal flora is insufficient because human space activities are limited.…”