title: Factors driving epilithic algal colonization in show caves and new insights into combating biofilm development with UV-C treatments.
abstract: The proliferation of epilithic algae that form biofilms in subterranean environments, such as show caves, is a major problem for conservators. In an effort to reduce the use of chemical cleansers when addressing this problem, we proposed investigating the effects of UV-C on combating algal biofilm expansion in a cave located in northeastern France (Moidons Cave). First, the biofilms and cavity were studied in terms of their algal growth-influencing factors to understand the dynamics of colonization in these very harsh environments. Next, colorimetric measurements were used both to diagnose the initial colonization state and monitor the UV-C-treated biofilms for several months after irradiation. The results indicated that passive dispersal vectors of the viable spores and cells were the primary factors involved in the cave's algae repartition. The illumination time during visits appeared to be responsible for greater colonization in some parts of the cave. We also showed that colorimetric measurements could be used for the detection of both thin and thick biofilms, regardless of the type of colonized surface. Finally, our results showed that UV-C treatment led to bleaching of the treated biofilm due to chlorophyll degradation even one year after UV-C treatment. However, a re-colonization phenomenon was colorimetrically and visually detected 16months later, suggesting that the colonization dynamics had not been fully halted.
authors.affiliation: Laboratoire Chrono-Environnement (LCE), UMR CNRS 6249, Université de Franche-Comté, Place Leclerc, F-25030 Besançon, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Borderie
authors.affiliation: Laboratoire Chrono-Environnement (LCE), UMR CNRS 6249, Université de Franche-Comté, Place Leclerc, F-25030 Besançon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tête
authors.affiliation: Laboratoire Environnement, Dynamique et Territoires de Montagne (EDYTEM), UMR CNRS 5204, Université de Savoie, F-73376 Le Bourget du Lac, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Cailhol
authors.affiliation: Laboratoire Chrono-Environnement (LCE), UMR CNRS 6249, Université de Franche-Comté, Place Leclerc, F-25030 Besançon, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Alaoui-Sehmer
authors.affiliation: Laboratoire de Recherche des Monuments Historiques (LRMH), USR 3224, 29 rue de Paris, F-77420 Champs-sur-Marne, France.
authors.forename: Faisl
authors.initials: F
authors.lastname: Bousta
authors.affiliation: Laboratoire Chrono-Environnement (LCE), UMR CNRS 6249, Université de Franche-Comté, Place Leclerc, F-25030 Besançon, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Rieffel
authors.affiliation: Laboratoire Chrono-Environnement (LCE), UMR CNRS 6249, Université de Franche-Comté, Place Leclerc, F-25030 Besançon, France. Electronic address: lotfi.aleya@univ-fcomte.fr.
authors.forename: Lotfi
authors.initials: L
authors.lastname: Aleya
authors.affiliation: Laboratoire Chrono-Environnement (LCE), UMR CNRS 6249, Université de Franche-Comté, Place Leclerc, F-25030 Besançon, France.
authors.forename: Badr
authors.initials: B
authors.lastname: Alaoui-Sossé
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D059552:Caves; D004203:Disinfection / Q000379:methods*; D005602:France; D006664:History; D058086:Microalgae / Q000254:growth & development*; D014466:Ultraviolet Rays
keywords: Biofilms; Cave; Colorimetric measurements; Epilithic algae; Growth-influencing factors; UV-C treatment