Study on disinfection using wet wipes and UV irradiation for areas prone to condensate accumulation in the Chinese Space Station

Introduction Condensate water is one of the environmental niches aboard space stations that is most prone to microbial growth. This study reports one of the first applications of a detailed characterization of the microbial composition of condensate water collected from inside the China Space Station during flight, as well as an evaluation of effective cleaning and disinfection strategies for microbial control. Methods To maximize the recovery of microorganisms from the condensate-water environment, we developed a custom high-throughput microbial isolation and cultivation device (cChip) based on the isolation chip method (iChip) and used it for high-throughput cultivation of microorganisms from onboard areas of the China Space Station that are susceptible to microbial proliferation. In addition, to evaluate on the ground the decontamination efficacy of four disinfection methods already used in orbit (wiping with pure-water wipes, 75% alcohol wipes, quaternary ammonium salt wipes, and ultraviolet irradiation), we constructed a microbial contamination model on authentic textile flight materials using the isolated strains in proportions determined from high-throughput sequencing data. The efficacy of these four disinfection approaches against the contamination model was then assessed using contact plates, PMA-qPCR, and qPCR. Results In total, 14 bacterial strains and 9 fungal strains were obtained. Notably, members of the genera Oceanobacillus , Rhodococcus , and Fusarium were not recovered by conventional isolation methods and could be isolated only with the cChip, demonstrating the strong potential of the cChip for recovering previously uncultivable microorganisms. Among the tested methods, alcohol wipes showed the highest bactericidal efficacy against bacteria in the contamination model, achieving a inactivation efficiency of 99.97%, whereas ultraviolet irradiation showed the highest fungicidal efficacy against fungi, achieving a inactivation efficiency of 99.98%.