Characterization of the Pilosebaceous Microbiota and Biofilm-Forming Capacity of Bacteria Isolated from Healthy Individuals

Background and Aim:The microbial flora colonizing the pilosebaceous unit plays a crucial role in maintaining skin health and homeostasis.This study aimed to isolate, identify, and evaluate the biofilm-forming capacity of bacterial strains derived from the pilosebaceous follicles of healthy human facial skin.Materials and Methods: Facial sebum samples were collected from 15 healthy volunteers.Bacterial strains were isolated and cultured under anaerobic conditions.Species identification was performed using 16S rRNA gene sequencing.The biofilm-forming ability of the isolates was quantified using the crystal violet staining assay.Results: A total of 22 bacterial strains were isolated, predominantly Gram-positive, nonmotile, and morphologically characterized as rod-shaped (20/22) or coccoid (2/22).Colonies appeared opaque and white, with diameters ranging from 0.5 to 1.5 mm.Biochemical profiling showed that most isolates were catalase positive (18/22) and gelatinase positive (20/22), while the majority were oxidase negative (18/22).Three isolates exhibited lipase activity, and eight demonstrated hemolysin production.Based on 16S rRNA gene sequencing, Cutibacterium was identified as the dominant genus, with C. acnes accounting for 68% of the isolates.Biofilm assays revealed variability among C. acnes strains, with isolates Hn15-2, Hn4, and Hn13 displaying strong biofilm-forming capacity. Conclusion:Healthy human facial skin harbors a diverse bacterial community, predominantly composed of Cutibacterium acnes.Notably, several C. acnes isolates demonstrated substantial biofilm-forming ability, suggesting potential implications for skin microbiome stability and pathogenicity.