Exploring new bacterial‐fungal interactions: the role of mannan degradation in Streptococci growth

• Published in: The FASEB journal 2022-05, Vol.36 (S1), p.n/a
• Main Authors: Ticer, Taylor, Fultz, Robert, Glover, Janiece, Engevik, Melinda A.
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.2022.36.S1.R6069

Background Streptococci colonize multiple sites of the human body, including the oral cavity, nasopharynx, skin, respiratory, genitourinary and gastrointestinal tracts. At these various body sites, Streptococci not only interact with other microbes, but also with fungal organisms, such as Candida and Saccharomyces species. Several studies have identified an interaction between Streptococci and Candida species, but the details of these interactions are still being discovered and it is unclear if Candidaspecies can provide a nutrient source to support the growth of Streptococci. Candida and Saccharomyces species are covered by a polymer of mannose known as mannan. Mannan makes up the outermost layer of the fungal cell wall. A few gut microbes have been found to possess glycosyl hydrolases that degrade mannan, but the mannan‐degrading capacity of Streptococci has yet to be examined. Hypothesis We hypothesized that Streptococci that possess mannan‐degrading glycosyl hydrolases can enzymatically cleave mannose residues. We speculated that freed mannose residues could serve as a carbon source to promote Streptococci growth. Methods & Results Using the Carbohydrate‐Active enZYme Database (CAZY) and Integrated Microbial Genomes (IMG) database, we analyzed the ability of 90 Streptococci genomes to transport and utilize mannose and to degrade diverse mannose‐linkages found on mannan. Our computational analysis identified that most Streptococci were able to transport mannose and drive glycolysis, but