PT  - JOURNAL ARTICLE
AU  - Carla Uranga
AU  - Pablo Arroyo, Jr.
AU  - Brendan M. Duggan
AU  - William H. Gerwick
AU  - Anna Edlund
TI  - Commensal oral <em>Rothia mucilaginosa</em> produces enterobactin – a metal chelating siderophore
AID  - 10.1101/2020.02.20.956391
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.02.20.956391
4099  - http://biorxiv.org/content/early/2020/02/20/2020.02.20.956391.short
4100  - http://biorxiv.org/content/early/2020/02/20/2020.02.20.956391.full
AB  - Next-generation sequencing studies of saliva and dental plaque from subjects in both healthy and diseased states have identified bacteria belonging to the Rothia genus as ubiquitous members of the oral microbiota. To gain a deeper understanding of molecular mechanisms underlying the chemical ecology of this unexplored group, we applied a genome mining approach that targets functionally important biosynthetic gene clusters (BGCs). All 45 genomes that were mined, representing Rothia mucilaginosa, R. dentocariosa and R. aeria, harbored a catechol-siderophore-like BGC. To explore siderophore production further we grew the previously characterized R. mucilaginosa ATCC 25296 in liquid cultures, amended with glycerol, which led to the identification of the archetype siderophore enterobactin by using tandem Liquid Chromatography Mass Spectrometry (LC/MS/MS), High Performance Liquid Chromatography (HPLC), and Nuclear Magnetic Resonance (NMR) spectroscopy. Normally attributed to pathogenic gut bacteria, R. mucilaginosa is the first commensal oral bacterium found to produce enterobactin. Co-cultivation studies including R. mucilaginosa or purified enterobactin revealed that enterobactin reduced growth of certain strains of cariogenic Streptococcus mutans and pathogenic strains of Staphylococcus aureus. Commensal oral bacteria were either unaffected by, reduced in growth, or induced to grow adjacent to enterobactin producing R. mucilaginosa or the pure compound. Taken together with Rothia’s known capacity to ferment a variety of carbohydrates and amino acids, our findings of enterobactin production adds an additional level of explanation to R. mucilaginosa’s colonization success of the oral cavity. Enterobactin is the strongest Fe(III)-binding siderophore known, and its role in oral health requires further investigation.Importance The communication language of the human oral microbiota is vastly underexplored. However, a few studies have shown that specialized small molecules encoded by BGCs have critical roles such as in colonization resistance against pathogens and quorum sensing. Here, by using a genome mining approach in combination with compound screening of growth cultures, we identified that the commensal oral community member mucilaginosa harbors a catecholate-siderophore BGC, which is responsible for the biosynthesis of enterobactin. The iron-scavenging role of enterobactin is known to have positive effects on the host’s iron pool and negative effects on host immune function, however its role in oral health remains unexplored. R. mucilaginosa was previously identified as an abundant community member in cystic fibrosis, where bacterial iron cycling plays a major role in virulence development. With respect to iron’s broad biological importance, iron-chelating enterobactin may explain R. mucilaginosa’s colonization success in both health and disease.