Bacterial communities forming yellow biofilms in different cave types share a common core.

The walls of different types of caves under diverse geological settings (limestone, gypsum and volcanic) are colonized by biofilms of different colors: white, yellow, pink, grey, green to dark brown, but only a few colored biofilms such as the white, yellow and grey ones have been extensively studied. However, an assessment among the microbial communities originating these biofilms in different lithologies is lacking. Here we compare the yellow biofilms from two caves, Covadura and C3, in the Gypsum Karst of Sorbas in Spain, with those from two Spanish limestone caves (Pindal and Santian), and four volcanic caves in Spain and Italy (Viento, Honda del Bejenado, Grotta del Santo, Grotta di Monte Corruccio).

Gypsum Cave Biofilm Communities are Strongly Influenced by Bat- And Arthropod-Related Fungi.

The Gypsum Karst of Sorbas, Almeria, southeast Spain, includes a few caves whose entrances are open and allow the entry and roosting of numerous bats. Caves are characterized by their diversity of gypsum speleothems, such as stalactites, coralloids, gypsum crusts, etc. Colored biofilms can be observed on the walls of most caves, among which the Covadura and C3 caves were studied.

Microbiological exploration of the Cueva del Viento lava tube system in Tenerife, Canary Islands.

Cueva del Viento, located in the Canary Islands, Spain, is the Earth's sixth-longest lava tube, spanning 18,500 m, and was formed approximately 27,000 years ago. This complex volcanic cave system is characterized by a unique geomorphology, featuring an intricate network of galleries. Despite its geological significance, the geomicrobiology of Cueva del Viento remains largely unexplored.

A Second Fungal Outbreak in Castañar Cave, Spain, Discloses the Fragility of Subsurface Ecosystems.

Castañar is a cave with strict visitor control measures since it was open to public visits in 2003. However, in recent years, the cave suffered two fungal outbreaks, the first in 2008 and controlled by cleaning the contaminated sediments and subsequent closure of the cave until 2014. The cave was reopened but limited to a maximum of 450 visitors/year.