Impact of oxygen supply on surfactin biosynthesis using brewery waste as substrate

Abstract

This work reports surfactin production by B. subtilis ATCC 6051 in a stirred tank bioreactor, where trub was used as a carbon source. Trub is a residue from the brewing industry mainly composed of high-molar-mass proteins and reducing sugars, being a sustainable and low-cost substrate for bioprocess. Despite this, Trub has been little explored as a raw material in bioprocesses. Aiming to evaluate important factors in scale-up process, the impact of oxygen transfer coefficient (KLa) concerning volumetric productivity, and the effect of agitation (150–300 rpm) and aeration (0.5–1.5 vvm) on biosurfactant production by a Full Factorial design were evaluated. Only agitation presented a significant effect on surfactin concentration (SF), where SF was described by a linear regression model (R2 = 0.99). The biosurfactant showed high stability in relation to variations in temperature and pH. In addition, the foam collecting was an efficient method in recovering and enrichment of the product.