Applied Biotechnology: Isolation and Detection of an Efficient Biosurfactant from Pseudomonas sp. Comparative Studies against Chemical Surfactants
Abstract
The use of biosurfactants became essential because of its multiple properties and applications. The high toxicity to the environment led to search for new alternatives such as the reduction or replacement by biological surfactants. Because of this, it is in our interest to produce biosurfactants from a non-pathogenic Pseudomonas. We obtained lower values of critical micelle concentration (CMC) from the culture broth than obtained from dodecyl sulfate sodium (SDS) and Pluronic F-68, used as pure surfactans. We found values of critical micellar concentration close to 0.15 mg/L in the purified fraction by adsorption chromatography. We determine by mass spectrometry this strain possibly produces two families of biosurfactants. Majority fraction might be formed by cyclic lipopeptides whose molecular weights could be located in the range of 1100-1200 Da. However, it is necessary perform confirmatory structural studies and to determine the specific structure of these analytes.
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Introduction
Biosurfactants are a group of secondary metabolites synthesized by a great variety of micro-organisms. The properties of biosurfactants include the reduction of surface and interfacial tensions between liquids, solids and gases [1]. Due to their biodegradability and low critical micelle concentration (CMC) are ideal surfactants for environmental application [2]. These molecules have been studied extensively and now we have a good amount of information regarding their production, types and properties [3]. The principal action of these molecules will depend on its specific structure and production characteristics [4].
Biosurfactants possess a nonpolar region of long chain fatty acids and polar hydrophilic groups, such as carbohydrate, amino acid phosphate or cyclic peptides [5]. Because of this can be divided into two groups, low molecular mass this class includes phospholipids, glycolipids and lipopeptides. In general, show lower surface and interstitial tension. Another group is high molecular mass that used as emulsion stabilizing agents such as polymeric surfactants and lipoproteins [6], [3].
When are compared with synthetic surfactants, biosurfactants have several advantages, including high biodegradability, low toxicity, low irritancy, and compatibility with human skin [7], [8].
Biosurfactants not only act modifying the surface properties, but also alteration of compound bio-availability and interaction with membranes [9]. This explain their importance in the area of the therapeutic and biomedical [10], [8], [4].
Certain species of Pseudomonas are able to produce and excrete biosurfactants of great interest [11], [12]. The genomes of its species are very varied and flexible. This is reflected in their versatile secondary metabolism, which enables the production of a wide variety of organic compounds displaying a range of biological function including surfactants [13], [14]. The objective of this work is to produce biosurfactants with low values of CMC in culture supernatant and to identify the family of surfactant belong to which it belongs. It is important we to obtain these type of compounds from a non-pathogenic Pseudomonas. With this work, we started the studio of production of a surfactant of biological origin that can compete in the near future with synthetic surfactants.
Conclusion
In the present work, we produce biosurfactants from non pathogenic Pseudomonas. We have obtained a possible product with surfactant activity through the addition of an ultrafiltration step in the production process, which is able to compete with a synthetic surfactant. This we demonstrate it with the CMC values achieved.
We detected two families of analytes secreted in the culture supernatant by mass spectrometry. We were able to isolate the majority fraction by adsorption chromatography; we believe that the strain used produced cyclic lipopeptides due to the molecular weights found. However, it is necessary to perform nuclear magnetic resonance studies and other structural studies that allow the detection of functional groups and confirm the above. We will continue to work on the characterization of the analytes found (biosurfactants), with possible applications as adjuvants in the agricultural sector.