Table 1.
Basic descriptions of the function of each microbe, relationship to social behaviour, and supporting references. Provided to support biological significance of each microbe.
| microbe | function | references |
|---|---|---|
| phyla | ||
| Bacteroidetes | Gram-negative bacteria phylum that is associated with decreased likelihood of neurological disorders and depression | [10,15] |
| Firmicutes | Gram-positive phylum that is negatively associated with social stress and avoidance, and depressive behaviours | [10,15] |
| family | ||
| Lachnospiraceae | considered a core microbe in adult microbiomes; lack of the family in development is linked to neurodevelopmental disorders | [15,54] |
| Ruminococcaceae | core microbe: associated with enzyme degradation of plant material; decreased abundance associated with autism in humans | [53,55] |
| Bifidobacteriaceae | core family, associated with higher dominance behaviours | [56] |
| Prevotellaceae | significantly enriched in animals exhibiting dominant behaviours | [56] |
| genus | ||
| Lactobacillus | modulates inflammatory response; increased Lactobacillus reduces stress response and anxiety | [57] |
| Clostridium | social stress correlated with abundance of Clostridium; increased abundance also associated with isolation | [10] |
| Desulfovibrio | increased abundance leads to decreased memory, social isolation and impaired learning behaviours | [16] |
| Coprococcus | reduced levels were associated with autism spectrum disorder compared with healthy controls; associated with better life quality | [58] |
| Faecalibacterium | has been associated with upregulation of T cells and anti-inflammatory function | [27,59] |
| Sutterella | more abundant in individuals with higher sociality index, associated with increased direct connectivity in wild social systems | [27] |
| Streptococcus | includes pathogenic strains that can cause disease; associated with less sociality and isolation | [27] |
| Prevotella | more abundant in individuals with higher sociality index; reduced abundance also associated with autism spectrum disorder | [27] |
| species | ||
| Bacteriodes fragilis | corrects abnormalities in gut lining and corrects the toxic release of cytokines from other microbes; is associated with decreased instances of autism spectrum disorder in mice | [15] |
| Bifiodbacterium longum | associated with object exploration, memory and decreased anxiety symptoms | [16] |
| Streptococcus bovis | associated with pathology of endocarditis and chronic inflammation; very common pathogenic microbe in animal guts | [60] |