The microbiome of phosphate-rich deposits in Muierilor Cave, South-Western Carpathians

Muierilor Cave is one of the most important caves in Romania from paleontological, biological, and archaeological points of view. A newly discovered chamber, with unique yellow calcite crystals, fine-grained crusts, and black sediments, is connected to the upper levels that contains fossil bones and a large pile of guano. Samples were taken from this chamber and another passage to investigate the diversity of microorganisms related to the substrates and identify potential pathogenic taxa for humans and animals. Chemical, mineralogical, and whole community 16S rRNA gene-based metabarcoding analyses were undertaken, and the base of the guano deposit was radiocarbon dated. Metabarcoding of the analyzed samples found that ~16% of the identified bacteria are potentially pathogenic to humans. Moreover, more than 87% of the identified genera were not previously reported in caves. We identified bacteria involved in the phosphate cycle that can only originate from the organic deposits inside the cave, such as the bats' guano in the touristic, upper level, or the fossil bones. Our study indicate also the guano deposit as the possible source of potentially pathogenic microorganisms. The results on the microbiome of different deposit types unravel the diversity of microorganisms and indicate the potentially pathogenic taxa for humans and animals

Competition-cooperation in the chemoautotrophic ecosystem of Movile Cave: first metagenomic approach on sediments

Movile Cave (SE Romania) is a chemoautotrophically-based ecosystem fed by hydrogen sulfide-rich groundwater serving as a primary energy source analogous to the deep-sea hydrothermal ecosystems. Our current understanding of Movile Cave microbiology has been confined to the sulfidic water and its proximity, as most studies focused on the water-floating microbial mat and planktonic accumulations likely acting as the primary production powerhouse of this unique subterranean ecosystem. By employing comprehensive genomic-resolved metagenomics, we questioned the spatial variation, chemoautotrophic abilities, ecological interactions and trophic roles of Movile Cave’s microbiome thriving beyond the sulfidic-rich water

Last deglaciation flooding events in the Southern Carpathians as revealed by the study of cave deposits from Muierilor Cave, Romania

Caves often hold valuable palaeoclimate archives including speleothems, fossil remains, and clastic sediments that complement each other. This paper presents a multi-archive interdisciplinary study of an extensive deposit of fossil mammals from the scientific reserve in the Muierilor Cave, Southern Carpathians, Romania. We present two new palaeontological excavations that indicate a high abundance and diversity of MIS 3–2 fossil mammals (carnivores, omnivores and herbivores) synchronous with the early modern humans known from this cave. Using geochronological and sedimentological methods, we present a general reconstruction of the cave evolution between ~120 kyr B.P. and the Holocene. The study is based on a combination of geochronological tools including OSL dating of sediments, U/Th dating of speleothems, and radiocarbon dating of fossil remains, with a total of 54 ages. Based on U/Th dating of speleothems from stratigraphically-relevant positions, we show that the MIS 3 assemblage of fossil mammals were massively reworked and deposited during the post-LGM deglaciation, slightly earlier than previously known for the Southern Carpathians. On the other hand, several young radiocarbon ages of cave bear samples suggest that the Southern Carpathians might have been functioning as a glacial refuge for this species as late as ~22 kyr B.P. •High diversity of MIS 3–2 fauna was recorded in two excavations in Muierilor Cave.•We documented one of the last cave bear population in Eurasia.•Geochronological methods helped to determine key-stages during the last 120 kyr.•The fossil assemblage has been most probably reworked during the last deglaciation.•The deglaciation took place ~2 kyr earlier than for the northern slopes of the region