Candida albicans mannans mediate Streptococcus mutans exoenzyme GtfB binding to modulate cross-kingdom biofilm development in vivo

• DOI: 10.1371/journal.ppat.1006407
• Publication Date: 2017-06-15T21:26:43Z
• Authors: Geelsu Hwang; Yuan Liu; Dongyeop Kim; Yong Li; Damian J. Krysan; Hyun Koo
• Keywords: Mannan

Candida albicans is frequently detected with heavy infection by Streptococcus mutans in plaque-biofilms from children early-childhood caries (ECC). This cross-kingdom biofilm contains an extensive matrix of extracellular α-glucans that produced exoenzyme (GtfB) secreted S. mutans. Here, we report mannans located on the outer surface C. cell-wall mediates GtfB binding, enhancing glucan-matrix production and modulating bacterial-fungal association within biofilms formed vivo. Using single-molecule atomic force microscopy, determined binds remarkable affinity to surface, forming a highly stable strong bond (1–2 nN). However, binding properties was compromised strains defective O-mannan (pmt4ΔΔ) or N-mannan chain (och1ΔΔ). In particular, strength och1ΔΔ strain severely disrupted (>3-fold reduction vs. parental strain). turn, amount fungal significantly reduced, ability mutant develop mixed-species impaired. phenotype independent hyphae established fungal-biofilm regulators (EFG1, BCR1). Notably, mechanical stability weakened, resulting near complete biomass removal shear forces. addition, these vitro findings were confirmed vivo using rodent model. Specifically, observed unable form tooth rats co-infected Likewise, co-infection also incapable biofilms. Taken together, data support mechanism whereby mutans-secreted mannan layer promote formation their co-existence Enhanced understanding GtfB-Candida interactions may provide new perspectives for devising effective therapies disrupt this relationship associated important childhood oral disease.