This Small Business Innovation Research Phase-I project will address the development of modified sophorolipid (MSL) surfactant molecules by simple and scalable modification of natural SLs adopting "green chemistry principles". Natural SLs will be produced through fermentation with yeast Candida bombicola. Strategies for SL modification will focus on methods that are simple, green, and minimize manufacturing cost. Furthermore, MSLs also include approaches to meet specific application needs, for example, designing MSLs for oil spill cleanup and bioemulsifiers/dispersants. Proposed approach is to identify compounds with attractive properties for hard surface cleaning, degreasing, and oil phase emulsification, foaming, dispersion, detergency and antimicrobial fouling agents. Preliminary results show that by developing MSLs with the appropriate structural features the performance of products is greatly enhanced for commercially important surfactant applications. Successful completion of the proposed Phase-I research program will result in a detailed investigation of structure-property relationships for MSLs to determine compounds with superior functional performance for commercial applications that will further engage strategic industrial partners.
The broader impact/commercial potential of this project address the market pull for green surfactant products by designing a library of MSLs by simple chemical modification to fine tune performance of nature's molecules. The aim is to create SL derived biosurfactant molecules with fine tuned surfactant properties for specific applications. Furthermore, the surfactant molecules developed will be eco-friendly, biodegradable, and composed of 80-to-100% readily renewable carbon. SyntheZyme MSL surfactants will contribute to the on-going green chemistry revolution. MSLs introduced into the market are expected to replace petroleum-derived chemical surfactants many of which are produced by harsh chemical processes. SyntheZyme's MSLs will be particularly important for applications where surfactants are disposed or used within environmental systems as well as for uses involving human contact.
Surfactants function by bringing together immiscible components such as oil and water. They accomplish this important task by having within the same molecule hydrophilic water compatible and hydrophobic or oil-like components. The world surfactant industry depends on chemical surfactants for a wide range of applications within household, environmental, industrial and medical sectors. The world surfactant market reached US $24.33 billion in 2009 and continues to grow such that, by 2018, surfactants are expected to generate revenues of more than US $41 billion. Biosurfactants have gained increased attention from industry due to their biodegradability, low toxicity, ecological acceptability and ability to be produced from renewable and inexpensive agricultural materials. Industrial applications where biosurfactants have been used or show potential for use include enhanced oil recovery, crude oil drilling, lubricants, bioremediation of pollutants, health care (antimicrobial agents), cosmetics, agriculture (bio-control), and food processing. However, commercialization of biosurfactants has thus far been hampered by either high manufacturing cost and/or poor performance attributes that are not competitive with current petroleum based commercial products. The primary goal of the Phase I program was to demonstrate the feasibility of developing cost effective biosurfactants products by modifications of sophorolipids, a member of the biosurfactants family. Funding from a previous NSF-SBIR Phase II program (Award # 1058511) in addition to additional work in this NSF Phase I program resulted in the development of a proprietary fermentation process for sophorolipid manufacture as well as isolation of the lactonic sophorolipid product in high purity. Furthermore, we showed that the total projected cost of modified sophorolipid esters is $1.29-1.43 per pound. To determine modifications of sophorolipids that would result in high-performance products, a series of sophorolipid esters were successfully synthesized without addition of organic solvents (e.g. in bulk reactions) by direct ring-opening of lactonic sophorolipids by n-alkanols that differed in chain length. By increasing the n-alkanol sophorolipid ester chain length, we systematically increased the affinity of modified sophorolipids oil phases. Product purification was achieved by simple removal of excess alcohol under vacuum. In addition, a new approach for the modification of sophorolipids was successfully demonstrated using cross metathesis chemistry. By adopting this strategy we removed the ester link along the hydrophobic tail of sophorolipid esters. This approach provides us with a powerful route to further control structural parameters of modified sophorolipids to fine-tune their functional attributes for target commercial applications. Studies were performed by combining different modified sophorolipids as well as other biobased formulation ingredients. This work identified important synergies that greatly enhanced the performance of modified sophorolipids for emulsification of commercially important oil phases used in foods. These results validated the hypothesis posed in the Phase I program proposal that, unlike natural sophorolipid, modified sophorolipids can be efficient formulation ingredients for the formation and stabilization of commercially important oil-in-water emulsion systems. A standard method was used to evaluate the hard surface cleaning & degreasing effectiveness of modified sophorolipids. Results of this work showed that modified sophorolipids have excellent potential for use as commercial hard surface cleaners. Antifouling activity of SL-esters against pathogenic microorganisms that colonize medical devices leading to infection was investigated. As a model system, the human pathogenic bacterium Pseudomonas aeruginosa was circulated in a silicone flow tube along with nutrients that support its growth. By adding low quantities of a sophorolipid ester to the circulating media cell growth and accumulation on silicone tube surfaces was largely prevented (97% inhibition). Furthermore, modified sophorolipids were identified that showed excellent performance in preventing spoilage of formulated products. This property extends the shelf life of formulated products by introducing green antimicrobial agents. Finally, the most promising derivatives developed in this program were evaluated to determine their biodegradability in a waste-treatment environment. Mineralization reached 60% during a 28-day incubation qualifying these compounds as "ultimately biodegradable."
