Abstract
Purpose :
Information on the metabolic and functional diversity of the ocular surface fungal-associated microbiota and their role in fungal keratitis is just beginning to be explored Fungal associated microbiomes may help modulate carbon substrate utilization, signaling pathways and mycotoxins production at the ocular surface.
Purpose: To compare and document the impact on the functional diversity, carbon utilization profile (n=31) and mycotoxin production of Fusarium keratitis isolates with unique microbiomes after growth on chocolate agar (choc), potato dextrose agar (pda) and sabouraud agar (sab) with antibiotics (gentamicin and chloramphenicol).
Methods :
We used a combination of Whole Genome Sequencing (CosmosID) and Biolog EcoPlates to identify and compare a) Fusarium associated microbiomes; b) percent functional diversity and c) carbon substrate utilization profiles of three Fusarium isolates- Fusarium solani (n=2, FS1, FS2), and Fusarium oxysporum (n=1, FO) recovered from patients with Fusarium keratitis.
Results :
The three fungal microbiomes, FS1, FS2 and FO were unique but dominated by 3 phyla, Actinobacteria (57.3% vs 86% v 46.5%), Firmicutes (41.3% vs 9.4% vs 23%) and Proteobacteria (1.2% vs 4.5% and 23%) respectively. Phylum Bacteroidetes was more commonly associated with the FO community (6.8%) than FS1 or FS2 (both <1%). Modulating species for each community (>1%) included Bacillus species and Cellulosimicrobium cellulans for F1, Staphylococcus epidermidis and Brevundimonas diminuta, FS2, Cutibacterium acnes, Citrobacter koseri, Cellulosimicrobium cellulans, Corynebacterium species and Streptomyces species for FO. Functional diversity and carbon utilization profiles differed by isolates and growth environment. In general, functional diversity was highest for the FS1 and FS2 isolates recovered on sabouraud agar (54.8%, 70.7% vs 25.8%) for FO. Community functional diversity was highest for the FO community when recovered on chocolate (45.6% vs 19.5% vs 38.7%) respectively. Complex polymers and carbohydrates were the preferred carbon substrates for all three communities. Genes for fumonisin and trichothecene expression were more likely to be associated with the two fungal microbiomes harboring minimal numbers of Brevundimonas diminuta
Conclusions :
Fusarium associated microbiota may impact functional diversity, carbon metabolic profiles and fungal-bacterial interactions at the ocular surface.
This is a 2021 ARVO Annual Meeting abstract.