Sophorolipids structure

TABLE 7.3. Fermentation of glycerol (pure vs. crude) to sophorolipids by C. bombicola and the effect on predominant structural form. 

The rhamnolipid B (70) has the molecular structure of biosurfactants, comprising a hydrophilic part (rhamnose moiety) and a hydrophobic part ((3-hydroxydecanoate moiety) [151]. The biosurfactant property of this glycolipid was supposed to confer the ability to intercalate into and disrupt the zoospore plasma membrane [152,153]. However, other glycolipids such as sophorolipids and trehalose lipids, which have chemical properties similar to the rhamnolipids, did not show zoosporicidal activity at concentrations up to 1000 pg/ml. 

Similarly, naturally derived surfactants extracted from fermentation broths or prepared by partial hydrolysis of natural extracts can contain polysaccharides, proteins, and phospholipids. For example, rhamnolipids and sophorolipids have unique structural features that cause them to deposit on chemically similar surfaces and modify surface energy even at very low concentrations. Clearly, the emergence of biotechnology in the twenty-first century will drive the development of new surfactants from microbial fermentation, and improve the commercial viability of known surfactants from such processes. 

Other studies [85] have shown that cationic bacitracin, anionic AOT, and nonionic Tween 80 all enhanced cellulose hydrolysis, implying that the charge of the surfactant was not an important consideration. In fact. Tween 80 (0.1%) increased the rate and extent of saccharification by up to 40% [82,85]. The structure of the hydrophilic head group of the surfactant also had little significance [85], Those with a sugar group, sophorolipid and rhamnolipid, worked well, as did bacitracin, which has a peptide hydrophilic group [85]. 

Lactonic sophorolipids exhibit antimicrobial activity and degree of antimicrobial activity is related to the structure of sophorolipids, which is determined by the type of carbon source used for fermentation." Sophorolipids derivatives such as sophorolipids diacetate ethyl ester derivatives have been reported as having spermicidal and virucidal activity and can be used in preparation of microbicidal contraceptions." Administration of sophorolipids reduces the mortality associated with septic shock in rats due their immunomodulatory function." Sophorolipids capped silver nanoparticles are very stable and show strong antimicrobial activity against gram-positive and gram-negative bacteria." ... 

Biosurfactants are classified based on their chemical composition and microbial origin. The chemical structure of biosurfactants contains hydrophilic and hydrophobic groups. Amino acids, peptides and polysaccharides can be present as hydrophilic moieties and saturated or unsaturated fatty acids can be present as hydrophobic moieties in the structure. Structure based classification has following major classes of biosurfactants (Guerra-Santos et al., 1987 Kooper and Goldenberg, 1987) (i) Glycolipids (Rhamnolipids, Trehalolipids and Sophorolipids) (ii) Lipopeptide and lipoprotein (iii) Fatty acids, phospholipids and neutral lipids (iv) Pol5mieric biosurfactants, and (v) Particulate biosurfactants. 

Figure 11.10 Structural comparison of sophorolipids from (a) 1-dodecanol and (b) APG.

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