Diversity and Frequency of Bacteria and Fusarium Symbiosis

Abstract

Purpose : Bacteria and fungi interact and modulate the virulence and pathology of each other and the ocular surface during fungal keratitis. This symbiosis can lead to increased corneal damage and visual impairment. Our purpose was to highlight the frequency and diversity of fusarium culture dependent and independent co-pathogens.

Methods : We investigated the diversity and frequency of fusarium associated microbial symbionts using a combination of culture (648, 1990-2019) and whole genome sequencing (n=10). Microbiome diversity was correlated with the presence of mycotoxin genes and select fusarium virulence genes

Results : Twenty-eight co-pathogens (4.3%) were recovered from 648 culture positive Fusarium species during the 30-year period. Co-pathogens diversity was distributed across 15 different strains and 4 phyla. These included: bacteria (25/28, 89.3%), fungi (2, 7.1%), and 1 viral isolate, HSV 1 (3.5%). Staphylococcus aureus (7) and Cutibacterium acnes (6) were recovered in 52% (13/25 of the bacteria and greater than 40% of recovered. All ten fusarium microbiomes were unique and harbored bacteria symbionts ranging from 1-59 species, with an average of 22.9. Microbiomes were characterized by 6 phyla and 97 species. Bacteria species recovered in at least 5 of more of the 10 microbiomes included Propionibacteriaceae (10), Staphylococci (9), Cellulosimicrobium species (8), Janthinobacterium species. (7), Citrobacter species (7. and Streptococci (6). Viruses (11 types), predominantly, bacteriophages associated with Propionibacterium species (7) were documented in 9 microbiomes. Free living amoebae (n=3), Acanthamoeba mauritaniensis (2) and Naegleria fowleri (1) in 3 microbiomes. Trichothecenes (deoxynivalenol, Nivalenol) and Fumonisin mycotoxins genes were found in all microbiomes. Deoxynivalenol and Fumonisin had similar reads (18690, 18725) respectively; followed by Nivalenol (742). There was an inverse relationship between mycotoxins reads and microbiome diversity. Fusarium virulent factors involving general pathology (CPS1-8/10) and proteases (CHS2-9/10) were more likely to be associated with increasing diversity.

Conclusions : Bacteria and other microbes may form a symbiotic relationship with fusarium species contributing to their pathology. These should be considered went managing recalcitrant fusarium keratitis.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.