Biological Control of Phototrophic Biofilms in a Show Cave: The Case of Nerja Cave

Abstract

Cyanobacteria and microalgae are usually found in speleothems, rocks and walls of show caves exposed to artificial lighting. These microorganisms develop as biofilms coating the mineral surfaces and producing aesthetic, physical and chemical deterioration. A wide number of physical, chemical and environmental-friendly methods have been used for controlling the biofilms with different results. Natural biological control has been suggested by some authors as a theoretical approach but without direct evidence or application. Here we report the finding of a natural biological control of phototrophic biofilms on the speleothems of Nerja Cave, Malaga, Spain. The formation of plaques or spots where the phototrophic microorganisms disappeared can be assumed on the basis of processes of predation of bacteria, amoebas and some other organisms on the phototrophic biofilms. This study aims at investigating the potentialities of the biological control of phototrophic biofilms in caves, but the originality of these data should be confirmed in future studies with a larger number of biofilm samples in different ecological scenarios.

Prokaryotic communities from a lava tube cave in La Palma Island (Spain) are involved in the biogeochemical cycle of major elements

“…GAL15 was recovered in Pindal Cave, Spain (unpublished results) and Ca. Dadabacteria was observed in Nerja Cave, Spain ( Jurado et al, 2020b ).…”

Colored Microbial Coatings in Show Caves from the Galapagos Islands (Ecuador): First Microbiological Approach

“…This species can be found in caves [55] and can induce calcium carbonate precipitation [56]. Predation of phototrophic biofilms by species of Lysobacter has been reported for Nerja Cave in Spain [43].…”

“…In the coralloid speleothems (Royal 2), the species Paenibacillus selenitireducens and Ammoniphilus resinae were identified, as well as sequences affiliated to the orders Thermosediminibacterales (Thermosediminibacter), Thermoanaerobacteriales (Thermodesulfitimonas), and to the family Syntrophomonadaceae (Dethiobacter). Both aerobic and anaerobic members of Firmicutes are common in caves, although Bacillus dominates [42,43].…”

The Control of Cultural Heritage Microbial Deterioration

“…Recently, a study carried out by Jurado et al [ 101 ] on the speleothems of Nerja Cave (Spain) showed evidence that a form of natural biological control exists in caves, providing a new method to control phototrophic biofilms typical of lithic substrates such as monuments and walls of show caves. By studying the in vivo formation of plaques or spots in the biofilms where the phototrophic microorganisms disappeared, the researchers assumed the presence of predation processes operated by bacteria belonging to the genera Bacillus and Lysobacter , amoebas such as Dactylopodida and Echinamoebida , and insects.…”