Mycological Assessment of Karfas Beach in Chios, Greece: Focus on Filamentous Fungi in the Sand

Abstract

Among the most interesting habitats for studying microorganisms are coastal beaches, often associated with an arid environment, but which also exhibit rich microbial biodiversity. Karfas, a beach located on the island of Chios in Greece, is a key site for studying filamentous fungi due to its fluctuating geographical location. Beach sands constitute dynamic reservoirs of microbial communities with important ecological and public health implications. The samples were collected on June 3, 2024. This study evaluated the presence and diversity of filamentous fungi and yeasts in sand samples collected from Karfas beach, Chios, Greece. Sand samples were obtained from the dry area of the beach, and 1 gram of sand was spread in triplicate on each of the following plates: Sabouraud dextrose agar (SDA), Rose Bengal agar (RBA), Sabouraud dextrose-chloramphenicol agar (SDCA), Mycosel agar, and Hardy CHROM™ Candida. These were incubated for 7 to 14 days at 25°C and Hardy CHROM ™ Candida samples were incubated at 35°C for 48 hours. Negative and positive controls were prepared for each culture medium. Colony-forming units (CFU) were counted, and the average was calculated for each medium. Species were isolated in tubes containing the same culture medium. They were incubated at the same temperature as the plates. Each isolate was identified microscopically using lactophenol cotton blue. Fungal isolates were identified by macroscopic and microscopic characteristics and chromogenic reactions for yeasts. Eight fungal genus were detected (Aspergillus, Penicillium, Fusarium, Candida, Cladosporium, Ascomycetes, Chaetomium, and Cephalosporium), with Aspergillus being the dominant genus. The most frequently isolated species were A. niger, A. fumigatus, A. terreus, A. flavus, Cladosporium elatum, Penicillium restrictum, P. chrysogenum, Candida albicans and Fusarium oxysporum. The overall mean fungal load was 14 CFU/g, indicating that the sand has an average microbiological quality according to Portuguese and INSA guidelines. The detection of potentially pathogenic species highlights the importance of routine monitoring of beach sand to assess environmental quality and potential health risks, especially in coastal areas with high visitor traffic.