Microbiome shifts elicited by ornamental lighting of granite facades identified by MinION sequencing

• Published in: Journal of photochemistry and photobiology. B, Biology Biology, 2024-12, Vol.261, p.113065, Article 113065
• Main Authors: Méndez, Anxo, Maisto, Francesca, Pavlović, Jelena, Rusková, Magdaléna, Pangallo, Domenico, Sanmartín, Patricia
• Format: Article
• Language: English
• Subjects: Archaea - genetics; Archaea - radiation effects; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - radiation effects; Culture-dependent analysis; Fungi - genetics; Granite monuments; Lighting; Microbiota; Monumental illumination; Nanopore Sequencing; Nanopore sequencing technology; Pilot Projects; Silicon Dioxide - chemistry
• ISSN: 1011-1344; 1873-2682; 1873-2682
• DOI: 10.1016/j.jphotobiol.2024.113065

Night-time outdoor illumination in combination with natural sunlight can influence the visible phototrophic colonizers (mainly algae) growing on stone facades; however, the effects on the microbiome (invisible to the naked eye) are not clear. The presence of stone-dwelling microbes, such as bacteria, diatoms, fungi, viruses and archaea, drives further biological colonization, which may exacerbate the biodeterioration of substrates. Considering the microbiome is therefore important for conservation of the built heritage. The impact of the following types of lighting on the relative abundance and diversity of the microbiome on granite ashlars was evaluated in a year-long outdoor pilot study: no lighting; lighting with a metal halide lamp (a traditional lighting system currently used to illuminate monuments); and lighting with a novel LED lamp (an environmentally sound prototype lamp with a biostatic effect, halting biological colonization by phototrophs, currently under trial). Culturable fractions of microbiome and whole-genome sequencing by metabarcoding with Oxford Nanopore Sequencing (MinION) was conducted for bacteria and fungi in order to complement both community characterization strategies. In addition, the possible biodeteriorative profiles of the isolated strains, relative to calcium carbonate precipitation/solubilisation and iron oxidation/reduction, were investigated by plate assays. Alpha and beta diversity indexes were also determined, along with the abundance of biocide and antibiotic resistance genes. Culture-dependent microbiological analysis failed to properly show changes in community composition, for which metagenomic approaches like MinION are better suited. Thus, MinION analysis identified shifts in the granite microbiome elicited by ornamental lighting. The novel LED lamp with the biostatic effect on phototrophs caused an increase in the diversity of bacteria and fungi. In this case, the microbiome was more similar to that in the unlit samples. In the samples illuminated by the metal halide lamp, dominance of bacteria was favoured and the presence of fungi was negligible. [Display omitted] •Microbiome shifts in granite lit by ornamental lighting were identified by MinION.•The LED lamp with a biostatic effect on phototrophs enhanced microbial diversity.•The microbiomes on unlit and LED-lit samples were similar.•43 antibiotic resistance genes (ARGs) were identified in the granite microbiome.