Methods for investigating biosurfactants and bioemulsifiers: a review

Abstract

Microorganisms produce biosurfactant (BS)/bioemulsifier (BE) with wide structural and functional diversity which consequently results in the adoption of different techniques to investigate these diverse amphiphilic molecules. This review aims to compile information on different microbial screening methods, surface active products extraction procedures, and analytical terminologies used in this field. Different methods for screening microbial culture broth or cell biomass for surface active compounds production are also presented and their possible advantages and disadvantages highlighted. In addition, the most common methods for purification, detection, and structure determination for a wide range of BS and BE are introduced. Simple techniques such as precipitation using acetone, ammonium sulphate, solvent extraction, ultrafiltration, ion exchange, dialysis, ultrafiltration, lyophilization, isoelectric focusing (IEF), and thin layer chromatography (TLC) are described. Other more elaborate techniques including high pressure liquid chromatography (HPLC), infra red (IR), gas chromatography-mass spectroscopy (GC-MS), nuclear magnetic resonance (NMR), and fast atom bombardment mass spectroscopy (FAB-MS), protein digestion and amino acid sequencing are also elucidated. Various experimental strategies including static light scattering and hydrodynamic characterization for micelles have been discussed. A combination of various analytical methods are often essential in this area of research and a numbers of trials and errors to isolate, purify and characterize various surface active agents are required. This review introduces the various methodologies that are indispensable for studying biosurfactants and bioemulsifiers.

Bioemulsification activity assessment of an indigenous strain of halotolerant Planococcus and partial characterization of produced biosurfactants

“…2). There are some reports taking advantage of TLC method to determine BS purity (Satpute et al 2010). Moreover, gas chromatography has been considered as the more powerful method in the separation of different organic mixtures and in the determination of purity of a wide variety of compounds.…”

Marine fungi as source of new hydrophobins

“…These species live in a stressful habitat, under cold, lightless, high-pressure conditions or other types of mechanical stress. Their capability to survive in different environmental conditions makes them attractive to isolate new molecules [17], [18] and [19]. The aim of the present study is to identify marine fungi as source of HFBs.…”

Biosurfactants and Bioemulsifiers Biomedical and Related Applications – Present Status and Future Potentials

“…When at interfaces (solid-liquid, liquid-liquid or vapour-liquid), the hydrophobic moiety of the surface active molecules aggregates at the surface facing the hydrophobic phase (usually the oil phase) while the hydrophilic moiety is oriented towards the solution or hydrophilic phase (mainly water). Their diverse functional properties namely, emulsification, wetting, www.intechopen.com foaming, cleansing, phase separation, surface activity and reduction in viscosity of heavy liquids such as crude oil, make them suitable for utilization for many industrial and domestic application purposes (Gautam & Tiagi, 2006;Franzetti et al, 2010a;Perfumo et al, 2010a;Satpute et al, 2010b). During the past two decades biosurfactants have been under continuous investigation as a potential replacement for synthetic surfactants and are expected to have several industrial and environmental applications mainly related to detergency, emulsification, dispersion and solubilisation of hydrophobic compounds (Banat et al, 2000).…”