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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

We illustrate the methods involved in screening and identification of the biosurfactant producing microbes. Methods for chromatographic characterization and chemical identification of the biosurfactants, determining the industrial applicability of the biosurfactant in enhancing residual oil recovery are also presented.

Abstract

Biosurfactants are surface-active compounds capable of reducing the surface tension between two phases of different polarities. Biosurfactants have been emerging as promising alternatives to chemical surfactants due to less toxicity, high biodegradability, environmental compatibility and tolerance to extreme environmental conditions. Here, we illustrate the methods used for screening of microbes capable of producing biosurfactants. The biosurfactant producing microbes were identified using drop collapse, oil spreading, and emulsion index assays. Biosurfactant production was validated by determining the reduction in surface tension of the media due to growth of the microbial members. We also describe the methods involved in characterization and identification of biosurfactants. Thin layer chromatography of the extracted biosurfactant followed by differential staining of the plates was performed to determine the nature of the biosurfactant. LCMS, 1H NMR, and FT-IR were used to chemically identify the biosurfactant. We further illustrate the methods to evaluate the application of the combination of produced biosurfactants for enhancing residual oil recovery in a simulated sand pack column.

Introduction

Biosurfactants are the amphipathic surface-active molecules produced by microorganisms that have the capacity to reduce the surface and the interfacial tension between two phases1. A typical biosurfactant contains a hydrophilic part that is usually composed of a sugar moiety or a peptide chain or hydrophilic amino acid and a hydrophobic part that is made up of a saturated or unsaturated fatty acid chain2. Due to their amphipathic nature, biosurfactants assemble at the interface between the two phases and reduce the interfacial tension at the boundary, which facilitates the dispersion of one phase into the other

Protocol

1. Growth of microbial strains

  1. Weigh 2 g of Luria Broth powder and add to 50 mL of distilled water in a 250 mL conical flask. Mix the contents until the powder dissolves completely and make up the volume to 100 mL using distilled water.
  2. Similarly, prepare two more flasks of 100 mL of Luria Broth and place cotton plugs on the neck of the flasks.
  3. Cover the cotton plugs with aluminum foil and autoclave the flasks for 15 min at 121 °C and 15 psi to sterilize the media.

Representative Results

Three bacterial strains (Rhodococcus sp. IITD102, Lysinibacillus sp. IITD104, and Paenibacillus sp. IITD108) were screened for the production of biosurfactants by various assays, which included drop collapse assay, oil displacement assay, emulsion index assay, and surface tension reduction. Cell-free supernatants of all the three bacterial strains and a solution of chemical surfactant resulted in a drop collapse and, therefore, were scored positive for the presence of the biosurfactants (

Discussion

Biosurfactants are one of the most versatile group of biologically active components that are becoming attractive alternatives to chemical surfactants. They have a wide range of applications in numerous industries such as detergents, paints, cosmetics, food, pharmaceuticals, agriculture, petroleum, and water treatment due to their better wettability, lower CMC, diversified structure, and environmental friendliness18. This has led to an increased interest in discovering more microbial strains capab.......

Acknowledgements

The authors would like to thank the Department of Biotechnology, Government of India, for financial support.

....

Materials

NameCompanyCatalog NumberComments
1 ml pipetteEppendorf, GermanyG54412G
1H NMRBruker Avance AV-III type spectrometer,USA
20 ul pipetteThermo scientific, USAH69820
AutoclaveJAISBO, IndiaSer no 5923Jain Scientific
Blue flame burnerRocker scientific, Taiwandragon 200
ButanolGLR inovations, IndiaGLR09.022930
C18 columnAgilent Technologies, USA770995-902
CentrifugeEppendorf, Germany5810R
ChloroformMerck, India1.94506.2521
Chloroform-dSRL, India57034
Falcon tubesTarsons, India546041Radiation sterilized polypropylene
FT-IRThermo Fisher Scientific, USA Nicolet iS50
Fume hoodKhera, India47408Customied
glacial acetic acidMerck, India1.93002
Glass beadsMerck, India104014
Glass slidesPolar industrial Corporation, USABlue Star75 mm * 25 mm
Glass woolMerk, India104086
Hydrochloric acidMerck, India1003170510
IncubatorThermo Scientific, USAMaxQ600Shaking incubator
IncubatorKhera, IndiaSunbim
Iodine resublimedMerck, India231-442-4 resublimed Granules
K12 –Kruss tensiometerKruss Scientific, GermanyK100
Laminar air flow cabnetThermo Scientific, China1300 Series A2
LCMSAgilent Technologies, USA1260 Infinity II
Luria BrothHIMEDIA, IndiaM575-500GPowder
MethanolMerck, India107018
NinhydrinTitan Biotech Limited, India1608
p- anisaldehydeSigma, USA204-602-6
Petri plateTarsons, India460090-90 MMRadiation sterilized polypropylene
SaponinMerck, India232-462-6
Sodium chlorideMerck, India231-598-3
Test tubesBorosil, India9800U06Glass tubes
TLC platesMerck, India1055540007
VortexGeNei, India2006114318
Water BathJulabo, IndiaSW21C

References

  1. Desai, J. D., Banat, I. M. Microbial production of surfactants and their commercial potential. Microbiology and Molecular Biology Reviews. 61 (1), 47-64 (1997).
  2. Banat, I. M.

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BiosurfactantsEnhanced Oil RecoveryScreeningCharacterizationMicrobial StrainsDrop Collapse AssayOil Spreading AssaySand Pack Column Technique

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