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.

High-Yield Di-Rhamnolipid Production by Pseudomonas aeruginosa YM4 and its Potential Application in MEOR

“…As the name implies, rhamnolipids contain a hydrophilic group made up of one or two (l)-rhamnose units and a hydrophobic group consisting of one or two β-hydroxy fatty acid moieties. Rhamnolipid surfactants were shown to reduce the surface tension of water from 72 to 28 mN/m, and the interfacial tension of water–oil systems from 43 to <1 mN/m [1,2,3]. They display both prominent surface activity and high emulsifying activity, which make them well suited for application in microbial enhanced oil recovery (MEOR).…”

Rhamnolipids From Pseudomonas aeruginosa Are Elicitors Triggering Brassica napus Protection Against Botrytis cinerea Without Physiological Disorders

“…Due to their antimicrobial and defense eliciting properties, RLs are likely to possess potential applications in agriculture ( Chen et al, 2017 ). Reducing production costs by using raw materials such as industrial waste or byproducts demonstrate the economic potential of these compounds ( Bagheri Lotfabad et al, 2017 ; Chen et al, 2017 ). In addition, their low toxicity and biodegradability assets reinforce their attractiveness ( Johann et al, 2016 ; Liu et al, 2016 ).…”

Preparation of Hybrid Sol-Gel Materials Based on Living Cells of Microorganisms and Their Application in Nanotechnology

“…Over the last two decades, immobilization in a sol-gel matrix of microorganisms such as Escherichia coli [ 19 , 27 , 32 , 41 ], Pseudomonas [ 43 , 44 , 45 ], Streptococcus [ 46 ], and Bacillus [ 47 ] has been intensively studied (Figure 6). During the formation of sol-gel materials, the release of lower alcohols (ethanol or methanol) often occurs.…”