Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/28/2005
Publication Date: 8/21/2005
Citation: Solaiman, D., Gunther, N.W., Ashby, R.D., Foglia, T.A., Kaplan, D.L. 2005. Production of microbial biosurfactants from soy molasses [abstract]. Society of Industrial Microbiology Annual Meeting. p. 75.
Technical Abstract: Microbial biosurfactants (MBSs) are surface-active molecules that have potential applications in pharmaceutical, bioremediation, cosmetic, food, agricultural and oil-recovery industries. Since renewable feedstocks are used in their production, MBSs are "green" molecules with minimal environmental footprints. Furthermore, many MBSs are also biologically active molecules that serve as antimicrobial and immune-response enhancing agents, making them even more attractive for certain applications. There is a need, however, to lower the costs of production for these biosurfactants to be commercially viable. We have studied the use of low-cost agro-based feedstocks for the fermentative production of biosurfactants including sophorolipids (SLs), rhamnolipids (RLs) and emulsans. In this paper, the use of soy molasses in the production of these biosurfactants is presented. SLs are produced by Candida bombicola in the presence of carbohydrate and lipid feedstocks. When we used soy molasses as the carbohydrate substrate (with oleic acid as the lipid substrate) in a batch-culture fermentation to produce SL, a product yield of 21 g SL/liter of culture was obtained. Compositional analysis showed that the major constituent (81% relative abundance) of the product is SL containing a hydroxy-oleoyl chain in lactone form (97%). We also studied the use of soy molasses in the synthesis of RL by a non-pathogenic Pseudomonas strain. Under a static growth condition optimal for RL production by this bacterium, we obtained crude RLs at a yield of 10 g/l culture using soy molasses as substrate. Compositional analysis showed that the major constituent of the product is a mono-rhamnoselipid species with the lipid moiety consisting of dimeric hydroxy-acyl chains of 10- and 12-carbon length. We also investigated the use of soy molasses in the production of emulsan by Acinetobacter venetianus RAG-1, and showed that a product yield of 15.8 mg/100 ml culture could be achieved. We further demonstrated that the product possesses significant macrophage activation and adjuvant activity. In summary, these studies showed that the low-cost soy molasses is suitable for use in the production of microbial biosurfactants. With further process optimization to improve the yields, it is expected that the production cost of these biosurfactants could be lowered by the use of this agro-based feedstock.