Biology subjects

Zucconi, L.

Publications and source records attributed to Zucconi, L..

3 recordsLinked to original sources

bioRxiv2024

Unravelling the ancient fungal DNA from the Iceman's gut

Here, we explore the possible ancient fungal species in the gut of Otzi, the Iceman, a naturally mummified human found in the Tyrolean Alps (border between Italy and Austria). While ancient DNA (aDNA) has been extensively used to study human, animal, and plant evolution, this research focuses on ancient microbial diversity, specifically fungi. Fungal DNA is often underestimated in metagenomic samples, however here we hypothesise the possibility of retrieving ancient fungal sequences from Otzis gut. A robust bioinformatic pipeline has been developed to detect and authenticate fungal aDNA from stomach, small intestine, and large intestine samples. We revealed the presence of Pseudogymnoascus genus, with P. destructans and P. verrucosus as possible species, that were particularly abundant in the stomach and small intestine. We suggest that Otzi may have consumed these fungi accidentally, likely in association with other elements of his diet, and they thrived in his gut after his death due to their adaptability to harsh and cold environments. This research provides insight into the coexistence of ancient humans with specific fungal species and proposes and validates a conservative bioinformatic approach for detecting fungal aDNA in historical metagenomic samples. Significance statementDespite their essential interactions with all kingdoms of life, limited molecular studies have focused on ancient fungi. Here, we developed a thorough bioinformatic pipeline that allowed us to detect the presence of ancient DNA likely belonging to Pseudogymnoascus destructans and P. verrucosus in the gut of Otzi, a human naturally mummified over 3,000 years ago in the Tyrolean Alps. Both species can survive harsh environmental conditions, and P. destructans is known for its pathogenicity, suggesting that Otzi may have accidentally ingested them and providing valuable insights into how ancient humans coexisted with specific fungal species. We propose a highly reliable methodology for detecting ancient fungal DNA in metagenomic studies of historical samples that can have broader applications to understand ancient ecosystems and their interactions.

microbiology↗

bioRxiv2019

Sampling strategies to assess microbial diversity of Antarctic cryptoendolithic communities.

Describing the total biodiversity of an environmental metacommunity is challenging due to the presence of cryptic and rare species and incompletely described taxonomy. How many samples to collect is a common issue faces ecologists when designing fieldwork sampling: collecting many samples may indeed capture the whole metacommunity structure, but can be prohibitively costly and lead to an enormous amount of data to analyse. Conversely, too few samples may yield inadequate and incomplete data which can prohibit complete assessment of community diversity. High-throughput sequencing allows examination of large numbers of samples enabling comprehensive biodiversity assessments. In this study, we sought to estimate how the scale of sampling affects accuracy of community diversity description in order to develop strategies to exhaustively describe the microbial diversity of cryptoendolithic communities in the McMurdo Dry Valleys in Antarctica accounted as the closest Martian analogue on Earth, exhibiting extreme conditions such as low temperatures, wide thermal fluctuations, low nutrient availability and high UV radiation. We found that sampling effort, based on accumulation curves analysis, had a considerable impact on assessing species richness and composition in these ecosystems, confirming that a sampling as large as nine rock specimens was necessary to detect almost all fungal species present, but was not sufficient to capture whole bacterial assemblage.

microbiology↗

bioRxiv2019

Sun exposure drives Antarctic cryptoendolithic community structure and composition.

The harsh environmental conditions of the ice-free regions of Continental Antarctica are considered one of the closest Martian analogues on Earth. There, rocks play a pivotal role as substratum for life and endolithism represents a primary habitat for microorganisms when external environmental conditions become incompatible with active life on rock surfaces. Due to the thermal inertia of rock, the internal airspace of lithic substratum is where microbiota find a protected and buffered microenvironment, allowing life to spread throughout these regions with extreme temperatures and low water availability. The high degree of adaptation and specialization of the endolithic communities makes them highly resistant but scarsely resilient to any external perturbation and thus, any shifts in microbial community composition may serve as early-alarm systems of environmental perturbation, including climate change.\n\nPrevious research concluded that altitude and distance from sea do not play as driving factors in shaping microbial abundance and diversity, while sun exposure was hypothesized as significant parameter influencing endolithic settlement and development. This study aims to explore our hypothesis that changes in sun exposure translate to shifts in community composition and abundances of main biological compartments (fungi, algae and bacteria) in the Antarctic cryptoendolithic communities. We performed a preliminary molecular survey, based on DGGE and qPCR tecniques, of 48 rocks with varying sun exposure, collected in Victoria Land along an altitudinal transect from 834 to 3100 m a.s.l.\n\nOur findings demonstrate that differences in sun radiation between north and south exposure influence temperature of rocks surface, availability of water and metabolic activity and also have significant impact on community composition and microbial abundance.

microbiology↗