Microbial monitoring and evaluation of desinfection efficiency in the EDEN-ISS greenhouse in preparation of safe food production in space

Abstract

The EDEN ISS greenhouse, integrated in two joined containers, is a confined mobile test facility in Antarctica for the development and optimization of new plant cultivation techniques for future space programs. The EDEN ISS greenhouse was used successfully from February to November 2018 for fresh food production for the overwintering crew at the Antarctic Neumayer III station. The second mission took place from March 2021 to January 2022. For this season, new cleaning treatments were introduced in order to reduce the bioburden. In the second mission the microbial load (cultivation assays) and diversity (16S rRNA sequencing) in the nutrition solution tanks for the plants and on dedicated surfaces in the greenhouse during the second season were investigated. Furthermore, the results were compared to the microbial bioburden of other confined and monitored environments like the International Space Station (ISS) or the Mars500 habitat. The microbial load is highly dependent on the location and varies from 0 to 4 x 10exp6 CFU/cm². Thereby, the bioburden of two surface areas mostly stayed under the limit required for the ISS surfaces inflight. In general, with the development of human spaceflight, one critical aspect to consider is the food supply for the crewmembers. Producing fresh food from edible plants in the station, instead of packing pre-prepared meals, would not only be more sustainable for long-duration mission, but will also be beneficial for the astronauts’ physical and mental health.