Abstract— The paper presents the results of studying quantitative dynamics, changes in the composition and species diversity (Shannon diversity index, SDI) of the cultured microbial community on samples of structural materials during the long-term exposure inside the International space station (space experiment Biorisk). It was found that the total number and species diversity of microorganisms changed in waves but the general trend was downward. In all, over the period of the experiment we detected, after cultivation in nutrient media, 20 bacterial species and 5 species of microscopic fungi grown on the samples of structural materials. Among bacteria, dominating species belonged to the Bacillus genus, and species of the normal cutaneous and mucous microbiota belonged to the Staphylococcus and Micrococcus genera. The Aspergillus and Penicillium genera dominated among fungi. Species diversity of the cultured microbial community was maximal for glass textolite and minimal for polyvinylchloride. SDI was 2.99 and 1.72, respectively. Also, these materials were populated by the largest (11) and least (5) numbers of cultured microorganisms. The low microbial load on all types of materials after different periods of exposure suggests eco-safety of the ISS environment and effectiveness of the respective control measures.
Kharin et al. (2025) studied this question.