Turicibacter

Taxonomy#

Turicibacter sanguinis—the type species; originally isolated from blood cultures, hence the species name. Family Turicibacteraceae, order Erysipelotrichales, class Erysipelotrichia, phylum Firmicutes. The genus is distantly related to the core Clostridia despite being within Firmicutes; Erysipelotrichia represents a distinct evolutionary lineage.

Metal Dependencies#

Iron. Turicibacter has modest iron requirements typical of low-GC Firmicutes. Iron-dependent oxidoreductases support its facultative metabolism.

The genus name sanguinis (from blood) reflects its original isolation site, not an iron-piracy strategy, though its ability to survive in blood suggests adaptation to iron-rich environments.

Serotonin Transporter Interaction#

Turicibacter is one of the few gut bacteria demonstrated to directly interact with the host serotonin transporter (SERT/SLC6A4). This interaction.

Allows Turicibacter to sense and respond to host serotonin levels. Influences local serotonin availability in the gut, affecting motility, secretion, and immune signaling. Creates a bidirectional communication channel between host serotonin biology and microbial ecology.

Connects to the broader serotonin regulation pathway where Clostridia stimulate EC cell serotonin production.

Dietary Responsiveness#

Turicibacter shows dramatic dietary responsiveness. Ketogenic diet: 120-fold increase in abundance in mice,^{[1]Ketogenic diet enhances neurovascular function with altered gut microbiome in young healthy miceDavid Ma, Amy C. Wang, Ishita Parikh et al. · 2018Open reference 1 ↓} among the most extreme dietary expansions reported for any gut taxon.

This extreme responsiveness suggests Turicibacter thrives on the metabolic byproducts of ketosis (ketone bodies, altered bile acid composition) rather than dietary fiber.

Autism Spectrum Disorder#

The picture is complex. MR suggests a possible positive association with ASD (OR = 1.14, borderline significance).^{[4]Li 2023 — Gut Microbiota and Autism Spectrum Disorders: A Bidirectional Mendelian Randomization StudyZhi Li, Shuai Liu, Fang Liu et al. · 2023Open reference 4 ↓}

A systematic review found Turicibacter consistently decreased in ASD alongside Bifidobacterium, Blautia, Dialister, Prevotella, and Veillonella.^{[5]Liu 2019 — Altered Composition and Function of Intestinal Microbiota in ASD: A Systematic ReviewFeitong Liu, Jie Li, Fan Wu et al. · 2019Open reference 5 ↓}

The discrepancy may reflect the difference between causal (MR) and observational findings, or treatment effects in observational cohorts.

Key Studies#

^{[2]Role of immune cells in mediating the effect of gut microbiota on Hashimoto's thyroiditis: a 2-sample Mendelian randomization studyPei XQ, Wang WH, Gao YH et al. · 2024Open reference 2 ↓} (MR)—HT risk factor (OR 1.16).^{[3]Gut Microbiota and Risk of Coronary Heart Disease: A Two-Sample Mendelian Randomization StudyXiang-zhi Hu, Ling-ling Fu, Bin Ye et al. · 2024Open reference 3 ↓} (MR)—CHD risk factor (OR 1.12).^{[4]Li 2023 — Gut Microbiota and Autism Spectrum Disorders: A Bidirectional Mendelian Randomization StudyZhi Li, Shuai Liu, Fang Liu et al. · 2023Open reference 4 ↓} (MR)—Possible ASD association (OR 1.14).

^{[1]Ketogenic diet enhances neurovascular function with altered gut microbiome in young healthy miceDavid Ma, Amy C. Wang, Ishita Parikh et al. · 2018Open reference 1 ↓} (animal model)—120-fold ketogenic diet expansion.^{[6]Variations in diet cause alterations in microbiota and metabolites that follow changes in disease severity in a multiple sclerosis modelLibbey JE, Sanchez JM, Doty DJ et al. · 2018Open reference 6 ↓} (animal model)—EAE severity correlation.