Skin and wound microbiome have been identified as key modulators of health and disease. Although the general composition of this microbiome follows large trends there are large inter-individual variation. Wound healing is a complex multistep process that involves an inflammatory phase that conditions many of the subsequent stages of healing. Skin barrier rupture results in exposure to bacterial compounds suggesting a key role of the wound microbiome in the healing process.
We here aimed to systematically study the skin bacterial composition in normal and wounded animals in 32 different strains of mice from the collaborative cross. 
The healing speed of excisional wounds varied significantly across strains (P<0.0001) allowing their separation into fast and slow groups. 16S sequencing was performed on faeces and skin swabs prior to wounding and at D3 and D10 post-wounding in 115 mice from all strains (n=3-5 per strain). Although all collaborative cross strains originated from 8 common founders and although they were maintained in the same animal facility, we observed significant changes in alpha diversity between strains (p=0.00024, ANOVA) and at different time points (p=0.00096) during healing. Strain and therefore genetic background was the most important factor determining bacterial composition. 
Genome wide association study of abundance of individual commensal bacteria at genus level identified loci strongly predictive of high abudance. Within these loci, genes regulating the activity of NLRP3 or other members of the innate immunity carried significant polymorphisms.
In conclusions, skin and wound microbial composition affects the healing of wounds across multiple murine strains. However this should be considered in the context of the background genetic of murine strains.

Skin bacterial composition is driven largely by host genetic background and polymorphisms regulating innate immunity.