title: Two schemes for production of biosurfactant from Pseudomonas aeruginosa MR01: Applying residues from soybean oil industry and silica sol-gel immobilized cells.
abstract: Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover, rhamnolipid mixtures extracted from different cultures showed critical micelle concentrations (CMC) in the range of ≃24 to ≃36mg/l with capability to reduce the surface tension of aqueous solution from 72 to ≃27-32mN/m. However, the sol-gel technique using tetraethyl orthosilicate (TEOS) was used as a gentler method in order to entrap the P. aeruginosa MR01 cells in mold silica gels. Immobilized cells can be utilized several times in consecutive fermentation batches as well as in flow fermentation processes. In this way, reusability of the cells may lead to a more economical fermentation process. Approximately 90% of cell viability was retained during the silica sol-gel immobilization and ≃84% of viability of immobilized cells was preserved for 365days of immobilization and storage of the cells in phosphate buffer at 4°C and 25°C. Moreover, mold gels showed good mechanical stability during the seven successive fermentation batches and the entrapped cells were able to efficiently preserve their biosurfactant-producing potential.
authors.affiliation: National Institute of Genetic Engineering and Biotechnology (NIGEB), Department of Industrial and Environmental Biotechnology, Tehran, Iran. Electronic address: bagheril@nigeb.ac.ir.
authors.forename: Tayebe
authors.initials: T
authors.lastname: Bagheri Lotfabad
authors.affiliation: National Institute of Genetic Engineering and Biotechnology (NIGEB), Department of Industrial and Environmental Biotechnology, Tehran, Iran. Electronic address: Nakisa_pl@yahoo.com.
authors.forename: Negisa
authors.initials: N
authors.lastname: Ebadipour
authors.affiliation: Sharif University of Technology, School of Chemical and Petroleum Engineering, Tehran, Iran. Electronic address: roosta@sharif.edu.
authors.forename: Reza
authors.initials: R
authors.lastname: Roostaazad
authors.affiliation: National Institute of Genetic Engineering and Biotechnology (NIGEB), Department of Industrial and Environmental Biotechnology, Tehran, Iran. Electronic address: maryam_partovi88@yahoo.com.
authors.forename: Maryam
authors.initials: M
authors.lastname: Partovi
authors.affiliation: Faculty of Chemistry, North Tehran Branch, Islamic Azad University, Tehran, Iran. Electronic address: mbahmaie@savola.com.
authors.forename: Manochehr
authors.initials: M
authors.lastname: Bahmaei
mesh_terms: D005525:Food-Processing Industry; D006017:Glycolipids / Q000737:chemistry* / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods; D007220:Industrial Waste; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D058428:Silica Gel / Q000737:chemistry*; D013024:Soybean Oil / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D006017:Glycolipids; D007220:Industrial Waste; D013501:Surface-Active Agents; C418382:rhamnolipid; D058428:Silica Gel; D013024:Soybean Oil
keywords: Immobilization; Inexpensive wastes; LC–MS; P. aeruginosa MR01; Rhamnolipids; Silica sol–gel