Development of Bacterial Cocktail of Staphylococcus hominis, Staphylococcus warneri, Bacillus subtilis, and Micrococcus luteus strains as Active Ingredients for Skincare Formula

The use of microbial skin health care products that balance one's skin microbiome mimicking healthy skin is rapidly increasing. Postbiotics have more advantages in terms of safety, shelf life, active peptides, and other active compounds, such as GABA, which benefit human skin. In our previous study, we isolated skin commensal bacteria, i.e., Staphylococcus hominis MBF12-19J, Staphylococcus warneri MBF02-19J, Micrococcus luteus MBF05-19J, and Bacillus subtilis MBF10-19J. This study aimed to produce a bacterial cocktail (BC) formula of those strains, elevate the BC formula into a ferment lysate (FL), and characterize the activities and test for skin sensitivity. The antibacterial activity was carried out by conducting a competition test using Propionibacterium acnes as an indicator bacterium, whereas the antiradical scavenging activity assay was performed using the DPPH method. Skin sensitivity was tested using the patch test method. The bacterial cocktail was lysed by optimizing the enzymatic and ultrasonication methods, whereas sucrose was added as lyoprotectant to obtain a stable powder FL. Potential activity to inhibit the growth of P. acnes was achieved using a formula of FL consisting of M. luteus MBF05-19J, B. subtilis MBF10-19J, S. warneri MBF02-19J, and S. hominis MBF12-19J at a ratio of 1.5:1.5:0.5:0.5 or equivalent to DNA copy number/mL 1.01E + 16:1.14E + 24:1.96E + 22:1.50E + 18. The skin sensitivity test results showed no sensitivity reaction, guaranteeing that CFS and FL are safe to use for the skin. Sucrose-FL at 12% sucrose formula exhibited higher physical stability than those without. However, the result of potential antiradical scavenging showed mild and very mild activities compared with the use of standard ascorbic acid.