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The history of Earth is a story of co-evolution of minerals and microbes: not only numerous rocks arisen from life, but the life itself may have formed from rocks. To understand the strong association between microbes and inorganic substrates, we investigated the moonmilk, a speleothem of calcium carbonate of microbial origin, present in the Iron Age Etruscan Necropolis of Tarquinia, in Italy. These tombs present a unique environment where the hypogeal walls of the tombs are covered by this speleothem. To study moonmilk formation, we investigated the bacterial community in the rock in which the tombs are carved: calcarenite and hybrid sandstone. We present the first evidence that moonmilk precipitation is driven by microbes within the rocks and not only on the rock surfaces. We also describe how the moonmilk produced within the rocks contributes to rock formation and evolution. The microbial communities of the calcarenite and hybrid sandstone displayed, at phylum level, the same microbial pattern of the moonmilk sampled from the walls of the hypogeal tombs, pointing out that the moonmilk originates from the metabolism of endolytic bacterial community. The calcite speleothem moonmilk is the only known carbonate speleothem on Earth with undoubted biogenic origin, thus representing a robust and credible biosignature of life. Its presence in the inner parts of rocks adds to its characteristics as a biosignature. [ABSTRACT FROM AUTHOR]

Summary: Earth's microbial biosphere extends down through the crust and much of the subsurface, including those microbial ecosystems located within cave systems. Here, we elucidate the microbial ecosystems within anthropogenic 'caves'; the Iron‐Age, subterranean tombs of central Italy. The interior walls of the rock (calcium‐rich macco) were painted ~2500 years ago and are covered with CaCO3 needles (known as moonmilk). The aims of the current study were to: identify biological/geochemical/biophysical determinants of and characterize bacterial communities involved in CaCO3 precipitation; challenge the maxim that biogenic activity necessarily degrades surfaces; locate the bacterial cells that are the source of the CaCO3 precipitate; and gain insight into the kinetics of moonmilk formation. We reveal that this environment hosts communities that consist primarily of bacteria that are mesophilic for temperature and xerotolerance (including Actinobacteria, Bacteroidetes and Proteobacteria); is populated by photosynthetic Cyanobacteria exhibiting heterotrophic nutrition (Calothrix and Chroococcidiopsis); and has CaCO3 precipitating on the rock surfaces (confirmation that this process is biogenic) that acts to preserve rather than damage the painted surface. We also identified that some community members are psychrotolerant (Polaromonas), acidotolerant or acidophilic (members of the Acidobacteria), or resistant to ionizing radiation (Brevundimonas and Truepera); elucidate the ways in which microbiology impacts mineralogy and vice versa; and reveal that biogenic formation of moonmilk can occur rapidly, that is, over a period of 10 to 56 years. We discuss the paradox that these ecosystems, that are for the most part in the dark and lack primary production, are apparently highly active, biodiverse and biomass‐rich. [ABSTRACT FROM AUTHOR]

Polymerization of 3′,5′ cyclic guanosine monophosphate (3′,5′ cGMP) was previously reported to afford short RNA sequences from a plausible mildly activated prebiotic precursor in a non‐enzymatic and template‐free manner. In the current paper we analyze the reaction with PAGE as well as by infrared micro‐ and nanospectroscopy on time scales not considered before. We provide evidence that a preliminary oligomerization step in dry state allows for a continued synthesis of RNA oligomers even in the presence of subsequently added water. On a longer time scale, the oligomerization yield oscillates in an apparently chaotic fashion hinting at the importance of some non‐reversible phase‐separation processes on the experimentally observed outcome of the polymerization/degradation chemistries. The long‐lasting (hundreds of hours) intrinsic sustainability and resilience of the process gives a robust prebiotic potential to this unique oligomerization reaction, which could lead to the very first oligonucleotide sequences on the primordial Earth. [ABSTRACT FROM AUTHOR]

The 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme of the mevalonate pathway for the synthesis of cholesterol in mammals (ergosterol in fungi), is inhibited by statins, a class of cholesterol lowering drugs. Indeed, statins are in a wide medical use, yet statins treatment could induce side effects as hepatotoxicity and myopathy in patients. We used Saccharomyces cerevisiae as a model to investigate the effects of statins on mitochondria. We demonstrate that statins are active in S.cerevisiae by lowering the ergosterol content in cells and interfering with the attachment of mitochondrial DNA to the inner mitochondrial membrane. Experiments on murine myoblasts confirmed these results in mammals. We propose that the instability of mitochondrial DNA is an early indirect target of statins. [ABSTRACT FROM AUTHOR]

Aims: Hypogeal environments with Cultural Heritage interest pose a real challenge for their preservation and conservation. The ancient Etruscan Necropolis of Tarquinia, Italy, consists of 200 tombs decorated with extraordinary mural paintings, of great artistic and historical value. Since the beginning of the restoration campaign in 2016, a regular microbiological survey has been performed in the Tomba degli Scudi. The aim of this study was to investigate the nature of an expansion of black spots on the pictorial layers recently observed., Methods and Results: To determine the origin of the black spots in the atrium chamber of the Tomba degli Scudi, the fungal community was sampled using various techniques: cellulose discs, swabs and nylon membranes and investigated by a multi-analytical approach. The obtained results suggest that the identified fungal strains (e.g. Gliomastix murorum and Pseudogymnoascus pannorum) are common to many subterranean environments around the world, such as Lascaux cave., Conclusions: The continuous and long-term monitoring made it possible to detect alterations at an early stage and assess the harmfulness of different fungal strains. This work is a demonstration of the effectiveness of prevention and monitoring actions within these fragile and valuable environments., (© The Author(s) 2024. Published by Oxford University Press on behalf of Applied Microbiology International.)