Sophorolipids biosynthesis

Ashby, R.D. A. Nunez D.K.Y. Solaiman T.A. Foglia. Sophorolipid biosynthesis from a biodiesel coproduct stream./. Am. Oil Chem. Soc. 2005b, 82, 625-630. 

Figure 14.4 Sophorolipid biosynthesis and fermentation. (Adapted from Williams K. Biosurfactants for cosmetic application Overcoming production challenges. MMG 445 Basic Biotechnology 2009 5 78 83 http //ejournal.vudat.msu.edu/index.php/mmg445/article/viewFile/357/375..)...

Huang FC, Peter A, Schwab W (2014) Expression and characterization of CYP52 genes involved in the biosynthesis of sophorolipid and alkane metabolism from Starmerella bombicola. Appl Environ Microbiol 80 766-776... 

Sophorolipids may be produced on substrates that are, in part, directly incorporated into the molecule as the hydrophobic moiety, as opposed to, for example, rhanmoUpids where the biosynthesis occurs with the de novo synthesis of the hydrophobic part. Specifically, when providing C. bombicola with oleic acid and an otherwise suitable medium, the yeast will incorporate this fatty acid into a sophorolipid. By contrast, when capric acid is provided to Pseudomonas aeruginosa, the fatty acid is not directly converted into a rhamnolipid but is metabolized instead. The possibility of direct incorporation is a clear indication as to why sophorolipid production is among the highest of all biosurfactants. 

Native sophorolipids are understood to be produced by the wild-type organism and contain a C16-C18 hydroxy fatty acid. Two types of variations occur the nature of the lipophilic moiety and the amount of esterification. For the lipophilic moiety, predominantly hydroxy stearic acid is observed in the case of de novo synthesis [23] and when feeding a fatty acid of a suitable length, the concurrent hydroxy fatty acid is found. The extent of the esterification, either acetylation or lactonization, determines the solubility of the final product and is influenced by the pH. A value of 3-3.5 predominantly yields the poorly soluble diacetyl lactone and biosynthesis using a pH of 2 results in a more soluble and thus less esterified product. It is this last parameter that most influences the emulsifying properties of the sophorolipids. Adapting these properties to specific applications is further explored in Section 11.2. 

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