Sweat and sebum preferences of the human skin microbiota

Abstract

The microorganisms that inhabit human skin, collectively termed the skin microbiome, must overcome numerous challenges that typically impede microbial growth, including low pH, osmotic pressure, and low nutrient availability. Yet, the skin microbiota thrive on the skin and have adapted to these stressful conditions. Limited skin nutrients are available for microbial use in this unique niche, including those from host-derived sweat, sebum, and corneocytes. Here, we have developed physiologically-relevant, skin-like growth media that is composed of compounds present in human sweat and sebum. We find that skin-associated bacterial species exhibit unique growth profiles in different concentrations of sweat and sebum. The majority of strains evaluated demonstrate a preference for high sweat concentrations, while sebum preference is highly variable, suggesting that the capacity for sebum utilization may be an important driver of skin microbial community structure. Furthermore, these findings provide experimental rationale for why different skin microenvironments harbor distinct microbiome communities. In all, our study further emphasizes the importance of studying microorganisms in an ecologically-relevant context, which is critical for our understanding of their physiology, ecology, and function on the skin.

Comparative genomic and metagenomic investigations of the Corynebacterium tuberculostearicum species complex reveals potential mechanisms underlying associations to skin health and disease

“…This set of genomes includes 22 genomes we had previously described as part of the complex 11 . In addition, we added three recently reported metagenome-assembled genomes (MAGs) from skin predicted to correspond to novel Corynebacterium species 14 and the genome of a C. kefirresidentii we recently isolated from human skin 9 . All 26 genomes, including a total of 8 MAGs, were regarded as high completion and showed low rates of contamination by CheckM analysis 15 (Table S1).…”

“…The lack of genomes for the species complex, despite its prevalence on healthy skin, might be in part due to difficulties with culturing. For instance, we recently found that a single C. kefirresidentii isolate grows best when high concentrations of compounds found in both sebum and sweat are available 9 .…”

“…In our earlier study, we also found that three recently published MAGs from skin microbiomes, proposed novel species of Corynebacterium (based on GTDB release 88) 14 , had >88% ANI to one of the prior defined 22 genomes. We thus included these three genomes, in addition to the genome for a C. kefirresidentii isolate, LK1134, we had isolated from healthy skin and profiled the growth dynamics off across different concentrations of artificially synthesized sebum and sweat 9 .…”

“…We recently found that the three most prevalent species of Corynebacterium in healthy skin microbiomes from a metagenomic survey in our lab 9 , currently classified as Corynebacterium tuberculostearicum, Corynebacterium kefirresidentii , and Corynebacterium aurimucosum type E in GTDB 10 , belong to a narrow clade, which includes at least one additional species 11 . Because the average nucleotide identity (ANI) between genomes in this clade is relatively high and the lowest value observed was at 88%, we refer to the clade as the C. tuberculostearicum species complex 10,11 .…”

“…Isolates of C. kefirresidentii sampled from healthy human skin are lipophilic similar to C. tuberculostearicum and also grow better in the presence of compounds commonly found in sweat 9 . This finding is in accordance with our earlier observation that members of the C. tuberculostearicum species complex are often found at body sites regarded as moist 11 .…”