Production of rhamnolipids by semi-solid-state fermentation with Pseudomonas aeruginosa RG18 for heavy metal desorption
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Foaming problem and cost of substrate limit the commercial application of rhamnolipids, a potential biosurfactant produced by Pseudomonas aeruginosa. We explored the production of rhamnolipids by a semi-solid-state (SSS) fermentation strategy with glycerol as carbon source and rapeseed/wheat bran as matrix, along with the capacity of the produced rhamnolipids to solubilize lead and cadmium in aqueous solution. Structural analysis by MALDI-TOF MS indicated the increased proportion of mono-rhamnolipids from SSS fermentation. E24 results showed the stronger emulsification capacity and reduced water tension of the SSS fermentation product. Rhamnolipids from SSS fermentation can desorb lead/cadmium from contaminated soil effectively and heavy metals in exchangeable and carbonate forms were easily removed. Our findings suggest that SSS fermentation is an alternative for the economical production of rhamnolipids and the product can be used to solubilize heavy metals from soils.
KeywordsRhamnolipids Semi-solid-state fermentation Emulsification capacity Heavy metal desorption
This work is supported by the National Natural Science Foundation of China Nos. 31201384 and 31271888, the National High-tech R&D Program of China No. 2012AA021505, the Program of Introducing Talents of Discipline to Universities (111-2-06), the Fundamental Research Funds for the Central Universities (JUSRP51632A), the Industry Education Research Cooperation Project of Jiangsu Province (BY2016022-15).
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Conflict of interest
The authors declare that they have no competing interests.
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