Abstract
Most biosurfactants are obtained using costly culture media and purification processes, which limits their wider industrial use. Sustainability of their production processes can be achieved, in part, by using cheap substrates found among agricultural and food wastes or byproducts. In the present study, crude glycerol, a raw material obtained from several industrial processes, was evaluated as a potential low-cost carbon source to reduce the costs of surfactin production by Bacillus subtilis #309. The culture medium containing soap-derived waste glycerol led to the best surfactin production, reaching about 2.8 g/L. To the best of our knowledge, this is the first report describing surfactin production by B. subtilis using stearin and soap wastes as carbon sources. A complete chemical characterization of surfactin analogs produced from the different waste glycerol samples was performed by liquid chromatography–mass spectrometry (LC-MS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the surfactin produced in the study exhibited good stability in a wide range of pH, salinity and temperatures, suggesting its potential for several applications in biotechnology.
Highlights
Waste glycerol originating from four different industries was evaluated as a low-cost carbon source for the production of lipopeptide biosurfactants by B. subtilis #309
The amino acid sequences of surfactants produced by B. subtilis #309 were similar to those present in the surfactin standard (Figures S2–S6). These results indicate that the chemical structure of surfactants produced by B. subtilis #309 is very similar to that of other surfactin mixtures produced by different Bacillus strains [43,44,45]
B. subtilis #309 was able to grow in a mineral medium containing waste glycerol derived from different industrial processes as a carbon source
Summary
Surfactants are amphiphilic molecules containing at least one hydrophobic and one hydrophilic domain. Surfactants are commonly used as cleaning and washing agents, but they can be applied as dispersants, moisturizers, emulsifiers, anti-caking and foaming agents in many sectors, including cosmetics, food, paper, textiles, petroleum and other industries [2]. They are used to combat microbes, viruses, pests and weeds, as well as in the bioremediation of petroleum-contaminated environments [3,4]. Several studies have shown that the selected surfactants in pharmaceutical formulations can improve the effectiveness of anticancer drugs [5]
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