Outdoor climate drives diversity patterns of dominant microbial taxa in caves worldwide.

The cave microbiota is assumed to be shaped by indoor microclimate, biotic and abiotic factors, which are largely dependent from outside environmental conditions; however, this knowledge is available at local or regional scales only. To address this knowledge gap, we reanalyzed over 1050 bacterial and fungal communities of caves worldwide, and found that outdoor temperature and rainfall play a critical role in explaining differences in microbial diversity patterns of global caves, selecting specific dominant taxa across gradients of growing aridity conditions with arid climate leading to a reduction in total cave microbial diversity. Moreover, we found that fungal (from 186 to 1908 taxa) and bacterial (from 467 to 1619 taxa) diversity increased under temperate-tropical and temperate-continental climatic regions, respectively, highlighting an opposite preference for the two microbial compartments.

Positive fungal interactions are key drivers in Antarctic endolithic microcosms at the boundaries for life sustainability.

In the ice-free areas of Victoria Land in continental Antarctica, where the conditions reach the limits for life sustainability, highly adapted and extreme-tolerant microbial communities exploit the last habitable niches inside porous rocks (i.e. cryptoendolithic communities).

Tourism affects microbial assemblages in show caves.

Anthropogenic disturbance on natural ecosystems is growing in frequency and magnitude affecting all ecosystems components. Understanding the response of different types of biocoenosis to human disturbance is urgently needed and it can be achieved by adopting a metacommunity framework. With the aid of advanced molecular techniques, we investigated sediment communities of Fungi, Bacteria and Archaea in four Italian show caves, aiming to disentangle the effects induced by tourism on their diversity and to highlight changes in the driving forces that shape their community composition.

Microbial diversity and proxy species for human impact in Italian karst caves.

To date, the highly adapted cave microbial communities are challenged by the expanding anthropization of these subterranean habitats. Although recent advances in characterizing show-caves microbiome composition and functionality, the anthropic effect on promoting the establishment, or reducing the presence of specific microbial guilds has never been studied in detail. This work aims to investigate the whole microbiome (Fungi, Algae, Bacteria and Archaea) of four Italian show-caves, displaying different environmental and geo-morphological conditions and one recently discovered natural cave to highlight potential human-induced microbial traits alterations.

Endolithic microbial composition in Helliwell Hills, a newly investigated Mars-like area in Antarctica.

The diversity and composition of Antarctic cryptoendolithic microbial communities in the Mars-analogue site of Helliwell Hills (Northern Victoria Land, Continental Antarctica) are investigated, for the first time, applying both culture-dependent and high-throughput sequencing approaches. The study includes all the domains of the tree of life: Eukaryotes, Bacteria and Archaea to give a complete overview of biodiversity and community structure. Furthermore, to explore the geographic distribution of endoliths throughout the Victoria Land (Continental Antarctica), we compared the fungal and bacterial community composition and structure of endolithically colonized rocks, collected in >30 sites in 10 years of Italian Antarctic Expeditions.