Study of the Fungal Community in the Sand of Bocagrande Beach, Cartagena, Colombia

Abstract

Colombia is the fifth most attractive tourist destination in South America. As such, it is highly visited by tourists year-round, but especially during the summer. Many tourists tend to get sick, which can be due to exposure to wind carrying sand particles or direct contact. This study collected samples of dry sand at three equidistant points along the beach. The samples were collected on January 3, 2024. The main objective of this research was to identify the colony-forming unit (CFU) and species of filamentous fungi and Candida species present in the sand of Bocagrande beach in Cartagena, Colombia. The aim was to determine if the fungi and yeasts found are pathogenic to public health and to assess the quality of the sand. Positive and negative controls were prepared, and then one gram of sand was transferred to each of the following culture media: Mycosel, SDA, RBA, and HardyCHROM™ Candida. The samples were prepared in triplicate and incubated for 7 to 14 days at 25°C. Hardy CHROM ™ Candida samples were incubated at 35°C for 48 hours. Colony counts (CFU) were performed, the average was calculated, and the species were isolated in tubes of each medium and incubated at the same temperature. To identify the fungi, a small amount of sample was transferred to a slide stained with lactophenol cotton blue for microscopic observation. Four genus of filamentous fungi two species of yeast from the genus Candida were isolated from the beach sand samples. The identified fungal genus were: Aspergillus, Candida, Rhizopus, Trichoderma, and Ascomycetes. The genus Aspergillus showed the highest percentage of growth. The isolated filamentous fungal species were: A. niger, A. flavus, A. glaucus, and A. terreus. However, A. niger was the predominant species. The Candida species identified were Candida albicans and Candida tropicalis. The average filamentous fungi count (including Candida) in the samples was 40 CFU. This indicates that the sand is classified as being of average quality based on the results. Most of the fungi identified are pathogenic to humans. In particular, Aspergillus, in high concentrations, can cause aspergillosis, which leads to lung problems such as infections.