Sophorolipids hydrolysis

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]. 

The acidic form of classical sophorolipid (a deacetylated compound) produced by alkaline hydrolysis of the native lactonic form (Fig. 2) was successfully converted by enzymatic biotransformation (glycosidase catalysis) to an acidic glucose lipid [44]. Another modification was performed with alkyl-amines leading to alkylamides of the acidic sophorolipid [123]. Bisht et al. [128] reported an efficient chemoenzymatic route that led to an 6-O-acryloyl-sophorolipid macrolactone analog. The homopolymerization of this monomer as well as its copolymerization with acrylic acid and acrylamide led in maximum to a molecular weight of 4.2 x 10" Da. The first total synthesis of a major component of the microbial classical lactonic sophorolipid was described by Fiirstner et al. [129]. 

Diacetylated lactonic sophorolipids have both esteric and glycosidic bonds which exhibit different sensitivities to either acid or alkaline hydrolysis. The latter will only hydrolyse the esters whereas acid hydrolysis at first cleaves the esters and, under more harsh reaction conditions, removes the sophorose moiety to yield a hydroxy fatty acid. In performing alkaline hydrolysis, the gradual removal of the esters transforms the solid... 

Figure 11.6 Alkaline (first step) and acid (both steps) hydrolysis of a diacetylated lactonic sophorolipid.

Figure 11.12 Sophorolipid from dodecyl glutarate before (left) and after (right) alkaline hydrolysis.

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