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Mugnai G, Borruso L, Wu YL, Gallinaro M, Cappitelli F, Zerboni A, Villa F. Ecological strategies of bacterial communities in prehistoric stone wall paintings across weathering gradients: A case study from the Borana zone in southern Ethiopia. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:168026. [PMID: 37907101 DOI: 10.1016/j.scitotenv.2023.168026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/18/2023] [Accepted: 10/20/2023] [Indexed: 11/02/2023]
Abstract
Rock art paintings represent fragile ecosystems supporting complex microbial communities tuned to the lithic substrate and climatic conditions. The composition and activity of these microbial communities associated with different weathering patterns affecting rock art sites remain unexplored. This study aimed to explore how bacterial communities adapt their ecological strategies based on substrate weathering, while also examining the role of their metabolic pathways in either biodeterioration or bioprotection of the underlying stone. SEM-EDS investigations coupled with 16S rRNA gene sequencing and PICRUSt2 analysis were applied on different weathered surfaces that affect southern Ethiopian rock paintings to investigate the relationships between the current stone microbiome and weathering patterns. The findings revealed that samples experiencing low and high weathering reached a climax stage characterized by stable microenvironments and limited resources. This condition favored K-strategist microorganisms, leading to reduced α-biodiversity and a community with a positive or neutral impact on the substrate. In contrast, moderately-weathered samples displayed diverse microhabitats, resulting in the prevalence of r-strategist bacteria, increased α-biodiversity, and the presence of specialist microorganisms. Moreover, the bacterial communities in moderately-weathered samples demonstrated the highest potential for carbon fixation, stress responses, and complete nitrogen and sulfur cycles. This bacterial community also showed the potential to negatively impact the underlying substrate. This research provided valuable insights into the little-understood ecology of bacterial communities inhabiting deteriorated surfaces, shedding light on the potential role of these microorganisms in the sustainable conservation of rock art.
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Affiliation(s)
- Gianmarco Mugnai
- Department of Agriculture, Food and Environmental Sciences, University of Perugia, Borgo XX Giugno, 74, I-06121 Perugia (PG), IT, Italy.
| | - Luigimaria Borruso
- Free University of Bolzano, Faculty of Agricultural, Environmental and Food Sciences, Piazza Universitá 5, 39100 Bolzano, Italy.
| | - Ying-Li Wu
- Dipartimento di Scienze della Terra "A. Desio", Università degli Studi di Milano, 20133 Milan, Italy.
| | - Marina Gallinaro
- Dipartimento di Scienze dell'Antichità, Università di Roma La Sapienza, 00185 Rome, Italy.
| | - Francesca Cappitelli
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano, 20133 Milan, Italy.
| | - Andrea Zerboni
- Dipartimento di Scienze della Terra "A. Desio", Università degli Studi di Milano, 20133 Milan, Italy.
| | - Federica Villa
- Dipartimento di Scienze per gli Alimenti, la Nutrizione e l'Ambiente, Università degli Studi di Milano, 20133 Milan, Italy.
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Favero-Longo SE, Matteucci E, Voyron S, Iacomussi P, Ruggiero MG. Lithobiontic recolonization following cleaning and preservative treatments on the rock engravings of Valle Camonica, Italy: A 54-months monitoring. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 901:165885. [PMID: 37524193 DOI: 10.1016/j.scitotenv.2023.165885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/03/2023] [Accepted: 07/27/2023] [Indexed: 08/02/2023]
Abstract
Both the indirect control of microclimate conditions and the direct application of preservative products to contrast stone bioreceptivity may contribute to limit lithobiontic recolonization of cultural heritage surfaces after cleaning interventions. However, the priority deserved by these different preventive approaches has still been poorly evaluated, particularly in outdoor environments. This work dealt with the engraved sandstone surfaces of the National Park of Rock Engravings of Naquane (Italy, UNESCO WHS), widely colonized by lichens, mosses and a dark cyanobacterial biofilm, and thus requiring frequent cleaning interventions to preserve their legibility for visitors and scholars. In particular, post-cleaning recolonization by the different lithobionts was seasonally monitored along 54 months in different zones of an engraved outcrop, primarily differing in levels of shading, on parcels exposed to nine different conservative treatments. These included (or not) a pre-cleaning devitalization of lithobionts and the post-cleaning application of biocidal (benzalkonium chloride, plant essential oils, usnic acid) and other restoration products (nanocrystalline anatase, polysiloxane-based water repellent, ethyl-silicate-based consolidant). The combination of surface image analyses, fluorimetric and colorimetric measurements showed that mosses and the cyanobacterial biofilm rapidly recolonized all the parcels in the more shaded zone, irrespective of conservative treatments. In the other areas, recolonization significantly differed depending on the treatment. The post-cleaning application of biocides determined the best results through two vegetative seasons, but only nanocrystalline anatase and the polysiloxane-based water repellent maintained the surfaces lighter than uncleaned controls along the whole monitoring period. Recolonization primarily proceeded by the uncleaned surfaces surrounding the parcels and, at least in the examined case of lichens, did not show substantial shifts in community composition, although some nitrophytic species increased their frequency. In conclusion, the effectiveness of preservative treatments to prevent a rapid recolonization of heritage stone surfaces appeared subordinate to the presence of microenvironmental conditions less favourable to lithobionts.
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Affiliation(s)
- Sergio E Favero-Longo
- Dipartimento di Scienze della Vita e Biologia dei Sistemi, Università degli Studi di Torino, Viale Mattioli 25, 10125 Torino, Italy.
| | - Enrica Matteucci
- Dipartimento di Scienze della Vita e Biologia dei Sistemi, Università degli Studi di Torino, Viale Mattioli 25, 10125 Torino, Italy; Fondazione Centro per la Conservazione e Restauro "La Venaria Reale", via XX settembre 18, 10078 Venaria Reale, TO, Italy
| | - Samuele Voyron
- Dipartimento di Scienze della Vita e Biologia dei Sistemi, Università degli Studi di Torino, Viale Mattioli 25, 10125 Torino, Italy
| | - Paola Iacomussi
- Istituto Nazionale di Ricerca Metrologica, Divisione Ottica, Strada delle Cacce 91, 10135 Torino, Italy
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Martin-Pozas T, Fernandez-Cortes A, Cuezva S, Cañaveras JC, Benavente D, Duarte E, Saiz-Jimenez C, Sanchez-Moral S. New insights into the structure, microbial diversity and ecology of yellow biofilms in a Paleolithic rock art cave (Pindal Cave, Asturias, Spain). THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 897:165218. [PMID: 37419360 DOI: 10.1016/j.scitotenv.2023.165218] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 06/13/2023] [Accepted: 06/28/2023] [Indexed: 07/09/2023]
Abstract
In the absence of sunlight, caves harbor a great diversity of microbial colonies to extensive biofilms with different sizes and colors visible to the naked eye. One of the most widespread and visible types of biofilm are those with yellow hues that can constitute a serious problem for the conservation of cultural heritage in many caves, such as Pindal Cave (Asturias, Spain). This cave, declared a World Heritage Site by UNESCO for its Paleolithic parietal art, shows a high degree of development of yellow biofilms that represents a real threat to the conservation of painted and engraved figures. This study aims to: 1) identify the microbial structures and the most characteristic taxa composing the yellow biofilms, 2) seek the linked microbiome reservoir primarily contributing to their growth; 3) seed light on the driving vectors that contribute to their formation and determine the subsequent proliferation and spatial distribution. To achieve this goal, we used amplicon-based massive sequencing, in combination with other techniques such as microscopy, in situ hybridization and environmental monitoring, to compare the microbial communities of yellow biofilms with those of drip waters, cave sediments and exterior soil. The results revealed microbial structures related to the phylum Actinomycetota and the most characteristic bacteria in yellow biofilms, represented by the genera wb1-P19, Crossiella, Nitrospira, and Arenimonas. Our findings suggest that sediments serve as potential reservoirs and colonization sites for these bacteria that can develop into biofilms under favorable environmental and substrate conditions, with a particular affinity for speleothems and rugged-surfaced rocks found in condensation-prone areas. This study presents an exhaustive study of microbial communities of yellow biofilms in a cave, which could be used as a procedure for the identification of similar biofilms in other caves and to design effective conservation strategies in caves with valuable cultural heritage.
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Affiliation(s)
- Tamara Martin-Pozas
- Department of Geology, National Museum of Natural Sciences (MNCN-CSIC), 28006 Madrid, Spain.
| | | | - Soledad Cuezva
- Department of Geology, Geography and Environment, University of Alcala, Campus Cientifico-Tecnologico, 28802 Alcala de Henares, Spain.
| | - Juan Carlos Cañaveras
- Department of Environmental and Earth Sciences, University of Alicante, Campus San Vicente del Raspeig, 03690 Alicante, Spain.
| | - David Benavente
- Department of Environmental and Earth Sciences, University of Alicante, Campus San Vicente del Raspeig, 03690 Alicante, Spain.
| | - Elsa Duarte
- Department of History, University of Oviedo, 33011 Oviedo, Spain.
| | - Cesareo Saiz-Jimenez
- Department of Agrochemistry, Environmental Microbiology and Soil and Water Protection, Institute of Natural Resources and Agricultural Biology (IRNAS-CSIC), 41012 Seville, Spain.
| | - Sergio Sanchez-Moral
- Department of Geology, National Museum of Natural Sciences (MNCN-CSIC), 28006 Madrid, Spain.
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Gallego-Cartagena E, Morillas H, Morgado-Gamero W, Fuentes-Gandara F, Vacca-Jimeno V, Salcedo I, Madariaga JM, Maguregui M. Elemental imaging approach to assess the ability of subaerial biofilms growing on constructions located in tropical climates as potential biomonitors of atmospheric heavy metals pollution. CHEMOSPHERE 2022; 309:136743. [PMID: 36209867 DOI: 10.1016/j.chemosphere.2022.136743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/30/2022] [Accepted: 10/01/2022] [Indexed: 06/16/2023]
Abstract
Over the last decades, the concern about air pollution has increased significantly, especially in urban areas. Active sampling of air pollutants requires specific instrumentation not always available in all the laboratories. Passive sampling has a lower cost than active alternatives but still requires efforts to cover extensive areas. The use of biological systems as passive samplers might be a solution that provides information about air pollution to assist decision-makers in environmental health and urban planning. This study aims to employ subaerial biofilms (SABs) growing naturally on façades of historical and recent constructions as natural passive biomonitors of atmospheric heavy metals pollution. Concretely, SABs spontaneously growing on constructions located in a tropical climate, like the one of the city of Barranquilla (Colombia), have been used to develop the methodological approach here presented as an alternative to SABS grown under laboratory conditions. After a proper identification of the biocolonizers in the SAB through taxonomic and morphological observations, the study of the particulate matter accumulated on the SABs of five constructions was conducted under a multi-analytical approach based mainly on elemental imaging studies by micro Energy Dispersive X-ray fluorescence spectrometry (μ-EDXRF) and Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectrometry (SEM-EDS) techniques, trying to reduce the time needed and associated costs. This methodology allowed to discriminate metals that are part of the original structure of the SABs, from those coming from the anthropogenic emissions. The whole methodology applied assisted the identification of the main metallic particles that could be associated with nearby anthropogenic sources of emission such as Zn, Fe, Mn, Ni and Ti by SEM-EDS and by μ-EDXRF Ba, Sb, Sn, Cl and Br apart others; revealing that it could be used as a good alternative for a rapid screening of the atmospheric heavy metals pollution.
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Affiliation(s)
- Euler Gallego-Cartagena
- Department of Civil and Environmental, Universidad de la Costa, Calle 58 #55-66, 080002, Barranquilla, Colombia; Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, P.O. Box 644, 48080, Bilbao, Basque Country, Spain.
| | - Héctor Morillas
- Department of Didactic of Mathematics, Experimental and Social Sciences, Faculty of Education and Sport, University of the Basque Country UPV/EHU, 01006, Vitoria-Gasteiz, Basque Country, Spain
| | - Wendy Morgado-Gamero
- Department of Exact and Natural Sciences, Universidad de la Costa, Calle 58 #55-66, 080002, Barranquilla, Colombia
| | - Fabio Fuentes-Gandara
- Department of Exact and Natural Sciences, Universidad de la Costa, Calle 58 #55-66, 080002, Barranquilla, Colombia
| | - Víctor Vacca-Jimeno
- Faculty of Basic Sciences, Universidad Del Atlántico, Km5 Vía Puerto Colombia, 081007, Atlántico, Colombia
| | - Isabel Salcedo
- Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country UPV/EHU, P.O. Box 644, 48080, Bilbao, Basque Country, Spain
| | - Juan Manuel Madariaga
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, P.O. Box 644, 48080, Bilbao, Basque Country, Spain
| | - Maite Maguregui
- Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country UPV/EHU, P.O. Box 450, 01080, Vitoria-Gasteiz, Basque Country, Spain
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