Skincare potential of a sustainable postbiotic extract produced through sugarcane straw fermentation by Saccharomyces cerevisiae

Postbiotics are defined as a "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host." They can be produced by fermentation, using culture media with glucose (carbon source), and lactic acid bacteria of the genus Lactobacillus, and/or yeast, mainly Saccharomyces cerevisiae as fermentative microorganisms. Postbiotics comprise different metabolites, and have important biological properties (antioxidant, anti-inflammatory, etc.), thus their cosmetic application should be considered. During this work, the postbiotics production was carried out by fermentation with sugarcane straw, as a source of carbon and phenolic compounds, and as a sustainable process to obtain bioactive extracts. For the production of postbiotics, a saccharification process was carried out with cellulase at 55°C for 24 h. Fermentation was performed sequentially after saccharification at 30°C, for 72 h, using S. cerevisiae. The cells-free extract was characterized regarding its composition, antioxidant activity, and skincare potential. Its use was safe at concentrations below ~20 mg mL-1 (extract's dry weight in deionized water) for keratinocytes and ~ 7.5 mg mL-1 for fibroblasts. It showed antioxidant activity, with ABTS IC50 of 1.88 mg mL-1 , and inhibited elastase and tyrosinase activities by 83.4% and 42.4%, respectively, at the maximum concentration tested (20 mg mL-1 ). In addition, it promoted the production of cytokeratin 14, and demonstrated anti-inflammatory activity at a concentration of 10 mg mL-1 . In the skin microbiota of human volunteers, the extract inhibited Cutibacterium acnes and the Malassezia genus. Shortly, postbiotics were successfully produced using sugarcane straw, and showed bioactive properties that potentiate their use in cosmetic/skincare products.