Characterization of fungal microbiota on normal ocular surface of humans

Our objective was to characterize the fungal microbiota on normal ocular surface of humans with the culture-based method and high-throughput sequencing approach.

A total of 45 adults were recruited from an urban community, and 90 conjunctival swabs were obtained, one from each eye of each participant. One of the two swabs from each participant was randomly chosen and allocated to internal transcribed spacer (ITS) sequencing, and the other was subjected to conventional fungal cultivation.

Four filamentous fungi were isolated from the 45 samples using the culture-based method, Penicillium citrinum, Aspergillus niger, Phialophora and Trichoderma. In the other 45 samples, 18 samples were positive for PCR amplification and sent for subsequent ITS sequencing. A total of 518 703 valid reads were generated and assigned into 467 operational taxonomic units. Overall, 4 phyla and 94 genera were identified. Two phyla, Basidiomycota (78.67%) and Ascomycota (19.54%), and five genera, Malassezia (74.65%), Rhodotorula (1.93%), Davidiella (1.89%), Aspergillus (1.25%) and Alternaria (0.61%), which accounted for >80% of the fungal microbiome and presented in >80% of the individuals tested, constituted the possible 'core fungal taxa' on normal ocular surface.

The fungal microbiome on normal ocular surface of humans was identified using the high-throughput sequencing method, providing a basis for further investigations on the potential role of the fungal microbiota in ocular health and disease.