Fungal Flora on Board the Mir‐Space Station, Identification by Morphological Features and Ribosomal DNA Sequences

Abstract

This report is on the morphological and molecular biological identification, using 18S-and ITSI-rDNA sequences, of the "space fungi" isolated on board the Russian Mir-Space Station as the major constituents of the fungal flora. The six fungal strains were isolated from air by using an air sampler or from condensation. Strains were identified as Penicillium chrysogenum, Aspergillus versicolor, or Penicillium sp, by both methods. The species of space fungi were common saprophytic fungi in our living environment, potential pathogens, and aUergens. This study concluded that the environment on board the space station Mir allows the growth of potentially pathogenic fungi as true in residential areas on the earth. Therefore, to prevent infection or other health disorders caused by these fungi, easy and reliable methods should be established to survey the fungal flora in a space station.Key words: Mir-Space Station, Fungal flora, DNA Sequences, Identification Space science is a new field of study that will inevitably progress in the early part of this century. Several long-term manned space missions have already been scheduled to the International Space Station, of which the completion is expected to be 2006. Humans in space are exposed both to space radiation and microgravity. Moreover, astronauts will face a variety of microorganisms, especially fungi, as partially reported in English abstracts of Russian papers (12)(13)(14) in the cases of Salyut-6 and Mir-Space Stations. It is possible that these fungi can cause unexpected infections or allergic diseases in astronauts whose immune systems are disturbed by radiation effects under the condition of microgravity or another environment of space. These "space fungi" also damaged electronic equipment on the MirSpace Station by biodeterioration. It is therefore important to study space microbiology, especially the field of medical mycology. We report here the morphological and molecular biological identification, using 18S-and ITS I-rONA sequences, of these space fungi isolated on Materials and MethodsSampling fungal strains. Six fungal strains were isolated from air by using an air sampler (Millipore, 21.1 em', 0.45 11m filter; AI-II, AI-21, BI-6, B2-1O, and B2-24), or from condensation (WI-C4) on board the Russian Mir-Space Station (Mission: JIMM, Mir-Station, 2110-3/2, 1997, National Space Development Agency, Japan). The isolation was done at the Department of Microbiology, Gifu University School of Medicine, and strains were delivered to Teikyo University Institute of Medical Mycology. Air samples were cultured with yeast and mold broth (Millipore) at room temperature (20-25 C) for one to two weeks, and condensation was cultured with Sabouraud dextrose agar (SDA; %, w/v; peptone 1, glucose 1, with agar 1.5) at 30 C for two weeks.Morphological observations. The colonial characAbbreviations: EDTA, ethylenediaminetetraacetic acid; ITS, internal transcribed spacer; peR, polymerase chain reaction; rONA, ribosomal DNA; SDA, Sabouraud dextrose agar.

Bacterial Population in Russian Space Station “Mir”

“…We analyzed bacterial and fungal populations from these samples. Data on fungal isolates were previously reported by our co-workers (12), and the results of the bacterial analysis are described in this report. Through this study we discovered six unclassified isolates that were genetically independent from any recognized species and thought to be new species candidates.…”

“…Few reports from Japanese researchers described the inside environment of the space laboratory, but some did recently publish .one report that described fungal flora in space station through the same project with this study (12). The bacterial population inside a space station or spacecraft had been studied by American and Russian researchers in the 1970s (23).…”

“…Furthermore, the laboratory will be used to conduct biological experiments. The accumulation of data on the microbial population in a closed space laboratory is important for monitoring the health conditions of astronauts and designing future biological experiments.Few reports from Japanese researchers described the inside environment of the space laboratory, but some did recently publish .one report that described fungal flora in space station through the same project with this study (12). The bacterial population inside a space station or spacecraft had been studied by American and Russian researchers in the 1970s (23).…”

Development of Safety Culture Tube for Molds and Proposed Procedure for Collecting Conidia or Fixing Strains to Control Fungal Infection and Allergy

“…However, culture-based identification is time-consuming and sometimes dangerous, especially for highly pathogenic fungal strains. To resolve this problem, molecular biological identification systems 6,7 have been reported. DNA was successfully extracted from the culture fixed in the culture tubes, therefore, the manner of fixing described here assures the safe manipulation of such biological agents.…”

“…4 Mycelia were then picked up and processed for DNA extraction 6,7 . The mycelia and the needle were also incubated in sterile tube with 50 ml of potato dextrose broth Difco 3 .…”