Synergism between Corynebacterium and Streptococcus sanguinis reveals new interactions between oral commensals

Abstract

The oral microbiome engages in a diverse array of highly sophisticated ecological interactions that are crucial for maintaining symbiosis with the host. Streptococci and corynebacteria are among the most abundant oral commensals and their interactions are critical for normal biofilm development. In this study, we discovered that Streptococcus sanguinis specifically responds to the presence of Corynebacterium durum by dramatically altering its chain morphology and improving its overall fitness. By employing gas chromatography-mass spectrometry (GC-MS) analysis, specific fatty acids were identified in C. durum supernatants that are responsible for the observed effect. Membrane vesicles (MVs) containing these fatty acids were isolated from C. durum supernatants and were able to replicate the chain morphology phenotype in S. sanguinis, suggesting MV as a mediator of interspecies interactions. Furthermore, S. sanguinis responds to C. durum lipids by decreasing the expression of key FASII genes involved in fatty acid synthesis. Several of these genes are also essential for the chain elongation phenotype, which implicates a regulatory connection between lipid metabolism and chain elongation. In addition, C. durum was found to affect the growth, cell aggregation, and phagocytosis of S. sanguinis, revealing a complex association of these species that likely supports oral commensal colonization and survival.

Dysbiosis From a Microbial and Host Perspective Relative to Oral Health and Disease

“…In a healthy microbiome, the pioneer colonizers, in large part streptococci, form one's protective commensal microbiota and attachment sites for subsequent colonizers. Moreover, these organisms, in concert with other species create mutually beneficial environments for the colonizers (Kreth et al, 2005 ; Kolenbrander et al, 2006 ; Jakubovics et al, 2008a , b ; Treerat et al, 2020 ). In rare instances these Streptococci species are responsible for extra-oral second site infections, such as endocarditis or abscess, hearkening back to Casadevall and Pirofski and the need to understand both the nature of the microbe and the host.…”

Differential Response of Oral Mucosal and Gingival Cells to Corynebacterium durum, Streptococcus sanguinis, and Porphyromonas gingivalis Multispecies Biofilms

“…Surprisingly, S. sanguinis , considered a benign if not beneficial bacterium, was able to significantly induce both IL-6 (10-fold in hTERT TIGKs; 66-fold in hPDL005) and IL-8 (173-fold in hTERT TIGKs; 33-fold in hPDL005) gene expression. However, periodontitis associated P. gingivalis ( Hajishengallis et al., 2011 ) and less characterized C. durum ( Treerat et al., 2020 ) showed minimal induction. Counterintuitively, both seemed to either prevent the induction of IL-6 and IL-8 expression in hTERT TIGKs and hPDL005 cells or simply failed to activate these cells.…”

“…The following bacterial strains were used in this study: S. sanguinis SK36 ( Xu et al., 2007 ), C. durum JJ1 (low passage clinical isolate) ( Treerat et al., 2020 ) and P. gingivalis ATCC33277 ( Coykendallet al, 1980 ). S. sanguinis and C. durum were grown in liquid or on agar solidified Bacto™ Brain Heart Infusion medium (BHI, Becton Dickinson & Co.) at 37°C under aerobic (5% CO 2 ) conditions.…”

“…Other examples include metabolic cooperativity ( Miller et al, 2019 ) and the influence on physical properties as recently shown in a dual species model using Streptococcus sanguinis and Corynebacterium durum . Co-incubation of both species resulted in lower rates of S. sanguinis phagocytosis, suggesting that C. durum can protect S. sanguinis from the host innate immune response ( Treerat et al., 2020 ). In addition, most oral microbe-host interactions occur in the context of oral biofilms, and biofilm dwelling microbes may behave quite differently from their planktonic counterparts.…”

Ignoring social distancing: advances in understanding multi-species bacterial interactions

“…More species increase the possibility for horizontal transfer of genetic materials 25 , altered spatial organization 26 , overall habitat modification 27 , and even altered evolutionary trajectories 28 . Additionally, not only are bacterial species being added but so are the bacteriophages they carry and the membrane vesicles they generate 29 , 30 . These changes all can affect interactions, which has led researchers to examine if and when pairwise interactions are scalable.…”