The relevance of fungi in astrobiology research – Astromycology

Since the very first steps of space exploration, fungi have been recorded as contaminants, hitchhikers, or as part of missions’ crews and payloads. Because fungi can cause human disease and are highly active decomposers, their presence in a space-linked context has been a source of major concern given their possible detrimental effects on crews and space structures. However, fungi can also be beneficial and be used for many space applications. The exact effects on fungi are not always clear as they possess high adaptability and plasticity, and their phenotypes and genotypes can undergo several changes under the extreme conditions found in space, thus leading to different results than those we would have on Earth. Understanding and analysing these aspects is the subject of astromycology, a research field within astrobiology. The impending situation of a resurgent space race is expected to boost astromycology’s visibility and importance. However, researchers lack both a framework and a solid base of knowledge from which to contextualise their work. This critical review addresses this gap by conceptualising the field of astromycology, covering key research and current questions pertaining to the field, and providing a relevant research instrument for future work

Hypolithic and soil microbial community assembly along an aridity gradient in the Namib Desert

The Namib Dessert is considered the oldest desert in the world and hyperarid for the last 5 million years. However, the environmental buffering provided by quartz and other translucent rocks supports extensive hypolithic microbial communities. In this study, open soil and hypolithic microbial communities have been investigated along an East–West transect characterized by an inverse fog-rainfall gradient. Multivariate analysis showed that structurally different microbial communities occur in soil and in hypolithic zones. Using variation partitioning, we found that hypolithic communities exhibited a fog-related distribution as indicated by the significant East– West clustering. Sodium content was also an important environmental factor affecting the composition of both soil and hypolithic microbial communities. Finally, although null models for patterns in microbial communities were not supported by experimental data, the amount of unexplained variation (68–97 %) suggests that stochastic processes also play a role in the assembly of such communities in the Namib Desert.Web of Scienc

Unveiling metabolic pathways involved in the extreme desiccation tolerance of an Atacama cyanobacterium

Abstract Gloeocapsopsis dulcis strain AAB1 is an extremely xerotolerant cyanobacterium isolated from the Atacama Desert (i.e., the driest and oldest desert on Earth) that holds astrobiological significance due to its ability to biosynthesize compatible solutes at ultra-low water activities. We sequenced and assembled the G. dulcis genome de novo using a combination of long- and short-read sequencing, which resulted in high-quality consensus sequences of the chromosome and two plasmids. We leveraged the G. dulcis genome to generate a genome-scale metabolic model (iGd895) to simulate growth in silico. iGd895 represents, to our knowledge, the first genome-scale metabolic reconstruction developed for an extremely xerotolerant cyanobacterium. The model's predictive capability was assessed by comparing the in silico growth rate with in vitro growth rates of G. dulcis, in addition to the synthesis of trehalose. iGd895 allowed us to explore simulations of key metabolic processes such as essential pathways for water-stress tolerance, and significant alterations to reaction flux distribution and metabolic network reorganization resulting from water limitation. Our study provides insights into the potential metabolic strategies employed by G. dulcis, emphasizing the crucial roles of compatible solutes, metabolic water, energy conservation, and the precise regulation of reaction rates in their adaptation to water stress

Ethical considerations for analogue fieldwork in extreme environments

Recent movements towards decolonizing the university and promoting racial justice and equality in social relations have highlighted and challenged the colonial influences on contemporary science and scientific knowledge production. These colonial legacies have a direct bearing on power relations between the Global North and the Global South, as well as collaborations and partnerships with local scholars and local communities. Astrobiology is one scholarly discipline that often makes use of remote sites in the Global South. Here we examine the ethical implications of carrying out fieldwork that involves accessing and sampling these extreme environments. Experiences of local and international collaborations in these sites have highlighted the importance of co-learning when engaging with diverse communities of scientists and right holders living on and around field sites. We argue that adopting an ethical approach to research in these environments is relevant also to research on other celestial bodies and to the future of space exploration. We propose that understanding space and Earth as interconnected domains, mutually shaped by scientific theories and practices, calls for a new terminology: ‘planetary ethics’, which places attention on this interconnection

Aeolian transport of viable microbial life across the Atacama Desert, Chile: Implications for Mars

Here we inspect whether microbial life may disperse using dust transported by wind in the Atacama Desert in northern Chile, a well-known Mars analog model. By setting a simple experiment across the hyperarid core of the Atacama we found that a number of viable bacteria and fungi are in fact able to traverse the driest and most UV irradiated desert on Earth unscathed using wind-transported dust, particularly in the later afternoon hours. This finding suggests that microbial life on Mars, extant or past, may have similarly benefited from aeolian transport to move across the planet and find suitable habitats to thrive and evolve..A.B. and A.G.F. thank the Project “icyMARS”, funded by the European Research Council, ERC Starting Grant No. 307496. M.P.Z., C.G.S., R.F. and F.J.M.T. thank the funding received from the Dubai Future Foundation through the Guaana.com open research platform (https://www.guaana.com/projects/jeGEimuX6DLCLsbQP)