Environmentally friendly rhamnolipid production for petroleum remediation

• Published in: Chemosphere (Oxford) 2020-08, Vol.252, p.126349-126349, Article 126349
• Main Authors: Dobler, Leticia, Ferraz, Helen Conceição, Araujo de Castilho, Livia Vieira, Sangenito, Leandro Stefano, Pasqualino, Ilson Paranhos, Souza dos Santos, André Luis, Neves, Bianca Cruz, Oliveira, Ricardo Rodrigues, Guimarães Freire, Denise Maria, Almeida, Rodrigo Volcan
• Format: Article
• Language: English
• Subjects: Biosurfactant; Crude glycerin; Feedstock; Interfacial tension; Molecular biology; Petroleum; Physical chemistry; Raw; Rhamnolipid
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.126349

Biosurfactants have potential applications in the remediation of petroleum-contaminated sites. Several strategies can be used to reduce the production costs of these surfactants and make the process more environmentally friendly. In this study, we combined some of these strategies to produce the rhamnolipid-type biosurfactant, including the use of the genetically modified strain Pseudomonas aeruginosa-estA, an industrial coproduct as a carbon source, a simple and low-cost medium, and a simple downstream process. The process resulted in a high yield (17.6 g L−1), even using crude glycerin as the carbon source, with substrate in product conversion factor (YRML/s) of 0.444. The cell-free supernatant (CFS) was not toxic to Artemia salina and selected mammalian cell lineages, suggesting that it can be used directly in the environment without further purification steps. Qualitative analysis showed that CFS has excellent dispersion in the oil-displacement test, emulsifying (IE24 = 65.5%), and tensoactive properties. When salinity, temperature and pressure were set to seawater conditions, the values for interfacial tension between crude oil and water were below 1.0 mN m−1. Taken together, these results demonstrate that it is possible to obtain a nontoxic crude rhamnolipid product, with high productivity, to replace petroleum-based surfactants in oil spill cleanups and other environmental applications. •Procedure to rhamnolipid production with low cost, without loss in product quality.•Crude glycerin from biodiesel production can generate high final RML concentration.•Description of RML performance at high pressures.•Cell Free Supernatant as possible final product? - Observations and discussion.