Bacillus subtilis SPB1 is known to produce a highly effective biosurfactant that belongs to the class
of lipopeptides. This biosurfactant has shown relevant properties that could be efficiently applied
in various domains. However, high production and purification costs limit the use of B. subtilis
SPB1 in high-volume applications. The present work aimed to promote an economical production
of this lipopeptide biosurfactant. Statistical experimental designs and response surface methodology
were employed to optimize the concentrations of agro-industrial residues, inoculum size and
humidity for B. subtilis SPB1 biosurfactant production under solid-state fermentation. The best
production yield was approximately 30.67 mg of crude lipopeptide biosurfactant per gram of
solid material. This yield was obtained using a solid substrate ratio of 1.5, a moisture content of
90% and an inoculum size (OD600) of 0.08. These data support the utilization of a mixture of 6 g
of olive leaf residue flour and 4 g of olive cake flour with a 10g total weight of the solid substrate.
A mixture of two by-products of a traditional olive mill factory was demonstrated to be a suitable
substrate for biosurfactant biosynthesis, providing enhanced bacterial growth and leading to a
strong improvement in the yield of tensioactive lipopeptide production.
© 2015 Hosting by Elsevier B.V. on behalf of Far Eastern Federal University. This is an open access