Takashi Yamazaki

Abstract The control of microbes in manned spaceflight is essential to reducing the risk of infection and maintaining crew health. The primary issue is ensuring the safety of a potable water system, where simultaneous monitoring of microbial abundance and community structure is needed. In this paper, we develop a flow cytometry-based counting protocol targeting cellular flavin autofluorescence as a tool for rapid monitoring of bacterial cells in water. This was successfully applied to estimate the bacterial bioburden in the potable water collected from the International Space Station. We also demonstrate the efficacy of the MinION nanopore sequencer in rapidly characterizing bacterial community structure and identifying the dominant species. These monitoring protocols' rapidity and cost effectiveness would contribute to developing sustainable real-time surveillance of potable water in spaceflight.

The International Space Station (ISS) is a completely closed environment that offers a long-term microgravity environment. It is a unique environment where microbes can fly and attach themselves to devices or humans, especially the exposed parts of the body and head. The ongoing monitoring and analysis of microbes and their movement inside the Japanese Experiment Module (named “Kibo”) of the ISS are intended to study the effects of microbes on humans and prevent health hazards caused by microbes during a long-term space mission. This paper describes the current status and future plan of Japanese microbiological experiments to monitor microbial dynamics in Kibo. It also describes the future prospective and prioritized microbiological research areas based on the “Kibo utilization scenario towards 2020 in the field of life science.” Given the microbial research in space being actively conducted by the USA, NASA and international activities are also reported.