Crewmember microbiome may influence microbial composition of ISS habitable surfaces

Abstract

The International Space Station (ISS) is a complex built environment physically isolated from Earth. Assessing the interplay between the microbial community of the ISS and its crew is important for preventing biomedical and structural complications for long term human spaceflight missions. In this study, we describe one crewmember's microbial profile from body swabs of mouth, nose, ear, skin and saliva that were collected at eight different time points pre-, during and post-flight. Additionally, environmental surface samples from eight different habitable locations in the ISS were collected from two flights. Environmental samples from one flight were collected by the crewmember and samples from the next flight were collected after the crewmember departed. The microbial composition in both environment and crewmember samples was measured using shotgun metagenomic sequencing and processed using the Livermore Metagenomics Analysis Toolkit. Ordination of sample to sample distances showed that of the eight crew body sites analyzed, skin, nostril, and ear samples are more similar in microbial composition to the ISS surfaces than mouth and saliva samples; and that the microbial composition of the crewmember's skin samples are more closely related to the ISS surface samples collected by the crewmember on the same flight than ISS surface samples collected by other crewmembers on different flights. In these collections, species alpha diversity in saliva samples appears to decrease during flight and rebound after returning to Earth. This is the first study to compare the ISS microbiome to a crewmember's microbiome via shotgun metagenomic sequencing. We observed that the microbiome of the surfaces inside the ISS resemble those of the crew's skin. These data support future crew and ISS microbial surveillance efforts and the design of preventive measures to maintain crew habitat onboard spacecraft destined for long term space travel.

Microbiome dynamics during the HI-SEAS IV mission, and implications for future crewed missions beyond Earth

“…Moreover, baselines of the microbiome inside the habitat, its crew and post sampling events would greatly improve evaluations of the impact of con nement on the crew and habitat surfaces. Most comparable studies, either ground-based like Mars500 [41,105] or in space aboard the ISS [24,89,106], showed a similar picture of longitudinal homogenization, composition and diversity of microbiomes.…”

Microbiome dynamics during the HI-SEAS IV mission, and implications for future crewed missions beyond Earth

“…Moreover, baselines of the microbiome inside the habitat, its crew and post sampling events would greatly improve evaluations of the impact of confinement on the crew and habitat surfaces. Most comparable studies, either ground-based like Mars500 [41,105] or in space aboard the ISS [24,89,106], showed a similar picture of longitudinal homogenization, composition and diversity of microbiomes.…”

Assessing the Risk of Transfer of Microorganisms at the International Space Station Due to Cargo Delivery by Commercial Resupply Vehicles

“…Sampling kits were assembled as detailed in our previous ISS studies ( Singh et al, 2018 ; Checinska Sielaff et al, 2019 ; Avila-Herrera et al, 2020 ) to facilitate comparisons between these datasets. Briefly, each polyester wipe (9″ × 9″; ITW Texwipe, Mahwah, NJ, United States) was soaked in 15 mL of sterile molecular grade water (Sigma-Aldrich, St. Louis, MO, United States) for 30 min followed by transfer to a sterile zip lock bag ( Venkateswaran et al, 2012 ).…”

“…Samples from CRV were processed in the same way as ISS samples from our previous studies ( Singh et al, 2018 ; Checinska Sielaff et al, 2019 ; Avila-Herrera et al, 2020 ). Briefly, each wipe was transferred to an individual 500 mL bottle containing 200 mL of sterile phosphate-buffered saline (PBS; Sigma-Aldrich, St. Louis, MO, United States) and vigorously hand shaken for 2 min.…”

“…Utmost care is taken by personal entering these facilities, as they are required to put on face masks, gloves, bodysuits, shoe covers, cleanroom boots, and cover hair and beards with nets (Benardini et al, 2014). These precautionary measures are a part of routine exercises, because humans are the primary source of microbial contamination (Moissl-Eichinger et al, 2015;Checinska Sielaff et al, 2019;Avila-Herrera et al, 2020). On average, humans shed 1.5 million skin cells an hour which carry approximately 15 million bacterial cells, thus becoming a significant source of the indoor microbiome (Jaffal et al, 1997;Lax et al, 2014).…”