5:15 PM - 6:45 PM
[AHW22-P16] Lampenflora in the limestone cave generated by LED lighting
Keywords:lampenflora, microbial communities, show cave, amplicon sequencing
Ryugado Cave is a limestone cave designated as a natural monument in Kami City, Kochi Prefecture. Fluorescent lighting has been installed for tourists. Microorganisms have developed in areas illuminated by the lighting, causing the walls to become colorized. The lighting was switched to LED to reduce the quantity of light, but this inadvertently increased the amount of light per unit area due to a narrower angle of light irradiation, further promoting the proliferation of light-related microorganisms. Efforts were made to prevent pigmentation-causing organism growth and adjust the light wavelength to preserve the cave walls. However, specific microorganisms causing pigmentation on the cave walls have not been identified. In this study, the community of pigmented microorganisms proliferated by LED lighting in Ryugado Cave was investigated. Additionally, the effectiveness of UV sterilization lamps against isolated microorganisms was evaluated.
Microorganisms that proliferated on the discolored walls and floors illuminated by lighting in Ryugado Cave were collected using sterilized cotton swabs. DNA was extracted from the tips of the cotton swabs, and community analysis was performed using the clone library method with DNA barcode sequences of bacteria, fungi, and plant species. The major bacteria were isolated by the dilution plate method. In addition, metagenomic analyses of bacteria and fungi with significant coloration were performed on microorganisms collected from cave walls. As a result, bacteria producing blue-purple pigments, photosynthetic bacteria, cyanobacteria, diatoms, and various moss species were detected. Through microbial isolation, it was confirmed that some of the purple-colored attachments were caused by pigment-producing bacteria. From metagenomic analysis, it was found that rhizobia, which symbiotically associates with plants, animals, and cyanobacteria, accounted for approximately 30% to 40% of the total. Additionally, bacteria widely distributed in water and soil, such as the phyla Planctomycetes and Bacteroidetes, were frequently detected. Moss diversity was found to be high along the tourist route, with many species adapted to nutrient-poor environments.
Microorganisms that proliferated on the discolored walls and floors illuminated by lighting in Ryugado Cave were collected using sterilized cotton swabs. DNA was extracted from the tips of the cotton swabs, and community analysis was performed using the clone library method with DNA barcode sequences of bacteria, fungi, and plant species. The major bacteria were isolated by the dilution plate method. In addition, metagenomic analyses of bacteria and fungi with significant coloration were performed on microorganisms collected from cave walls. As a result, bacteria producing blue-purple pigments, photosynthetic bacteria, cyanobacteria, diatoms, and various moss species were detected. Through microbial isolation, it was confirmed that some of the purple-colored attachments were caused by pigment-producing bacteria. From metagenomic analysis, it was found that rhizobia, which symbiotically associates with plants, animals, and cyanobacteria, accounted for approximately 30% to 40% of the total. Additionally, bacteria widely distributed in water and soil, such as the phyla Planctomycetes and Bacteroidetes, were frequently detected. Moss diversity was found to be high along the tourist route, with many species adapted to nutrient-poor environments.