A statistical approach for the valorization of hemicellulosic liquor from sunflower stalk in biosurfactant production

Lignocellulosic waste is a promising alternative for reducing raw material costs for the microbial production of biosurfactants – amphiphilic biomolecules with promising tensoative and emulsifying properties. The current study promoted the valorization of sunflower stalk by using it as a partial substitute for glucose in the production of biosurfactants by Bacillus subtilis LMA-ICF-PC 001. The liquor obtained after an alkaline pretreatment of sunflower stalk samples was rich in hemicelluloses (67.30%) but did not present any growth-inhibitory compounds, such as furfural and hydroxymethylfurfural. A central composite design (CCD) was performed considering hemicellulosic liquor from sunflower stalk, glucose, and mineral salt solution as independent variables. The biosurfactant had a strong capacity for surface tension reduction (58.70%) in media containing 8.16% hemicellulosic liquor, 1.02% glucose, and 1.61% mineral salt solution. Results also indicated that the biosurfactant obtained at 8.16% hemicellulosic liquor, 4.02% glucose, and 1.61% mineral salt solution showed an affinity for emulsifying open-chain hydrocarbons, such as hexane (57.23%). These results highlight the potential of sunflower stalk as a cost-effective and sustainable substrate for biotechnological applications.