Fungal diversity differences in the indoor dust microbiome from built environments on earth and in space.

Human occupied built environments are no longer confined to Earth. In fact, there have been humans living and working in low-Earth orbit on the International Space Station (ISS) since November 2000. With NASA's Artemis missions and the age of commercial space stations set to begin, more human-occupied spacecraft than ever will be in Earth's orbit and beyond. On Earth and in the ISS, microbes, especially fungi, can be found in dust and grow when unexpected, elevated moisture conditions occur. However, we do not yet know how indoor microbiomes in Earth-based homes and in the ISS differ due to their unique set of environmental conditions. Here we show that bacterial and fungal communities are different in dust collected from vacuum bags on Earth and the ISS, with Earth-based homes being more diverse (465 fungal OTUs and 237 bacterial ASVs) compared to the ISS (102 fungal OTUs and 102 bacterial ASVs). When dust from these locations were exposed to varying equilibrium relative humidity conditions (ERH), there were also significant fungal community composition changes as ERH and time elevated increased (Bray Curtis: R2 = 0.35, P = 0.001). These findings can inform future spacecraft design to promote healthy indoor microbiomes that support crew health, spacecraft integrity, and planetary protection.

Quantitative evaluation of bioaerosols in different particle size fractions in dust collected on the International Space Station (ISS).

Exposure to bioaerosols can adversely influence human health through respiratory tract, eye, and skin irritation. Bioaerosol composition is unique on the International Space Station (ISS), where the size distribution of particles in the air differs from those on Earth. This is due to the lack of gravitational settling and sources of biological particles. However, we do not understand how microbes are influenced by particle size in this environment. We analyzed two types of samples from the ISS: (1) vacuum bag debris which had been sieved into five different size fractions and (2) passively collected particles on a tape substrate with a passive aerosol sampler. Using quantitative polymerase chain reaction (qPCR), the highest concentration of fungal spores was found in the 106-150 µm-sized sieved dust particles, while the highest concentration of bacterial cells was found in the 150-250 µm-sized sieved dust particles. Illumina MiSeq DNA sequencing revealed that particle size was associated with bacterial and fungal communities and statistically significant (p = 0.035, p = 0.036 respectively). Similar fungal and bacterial species were found within the passive aerosol sample and the sieved dust samples. The most abundant fungal species identified in the aerosol and sieved samples are commonly found in food and plant material. Abundant bacterial species were most associated with the oral microbiome and human upper respiratory tract. One limitation to this study was the suboptimal storage conditions of the sieved samples prior to analysis. Overall, our results indicate that microbial exposure in space may depend on particle size. This has implications for ventilation and filtration system design for future space vehicles and habitats.

Earth observation for public health: Biodiversity change and emerging disease surveillance.

One Health is an emerging concept in the health sciences that approaches human, animal and environmental health from a single framework. This policy approach is grounded in the knowledge that approximately 70 percent of emerging diseases in humans originate from other species, and that this species crossover is precipitated by stresses to environmental systems such as habitat change and biodiversity loss. Remote sensing tools apply well to this approach due to the multitude of variables that can be measured across borders in real-time. This paper explores the challenges and opportunities of using satellite remote sensing to monitor biodiversity loss in real time, with a goal of predictive surveillance for emerging disease events. Key findings include that (1) certain emerging disease events are preceded by biodiversity changes that can be observed from space; (2) refining quantitative assessments of biodiversity loss is a critical next step; and (3) biodiversity loss as observed from space merits inclusion in emerging disease surveillance programs as a complement to in situ and epidemiological surveillance data.