Isolation And Characterization Of Amphiphilic Functional Biopolymers

Abstract

Amphiphilic compounds are produced extracellularly by microorganisms on cell surfaces or excreted extracellularly. They contain hydrophilic and hydrophobic moieties that produce surface and interfacial tension between molecules at the surface and interface respectively. These biopolymers are promising natural surfactants and emulsifiers that offer several advantages, such as lower toxicity, biodegradability and ecological acceptability over the chemically synthesized surfactants/emulsifiers. So, the present study focused on isolation of amphiphilic biopolymer producing bacteria from environmental samples and assessing the potential of these isolates by various screening methods. In this study, from a total of 156 samples collected from diverse environmental sources, 23 bacterial isolates were screened for amphiphilic biopolymer producing ability using a variety of tests like drop collapse test, BATH (Bacterial adhesion to hydrocarbon) assay, hemolytic activity assay, CTAB Agar plate method, surface tension measurement and emulsification activity. Five bacterial strains with higher emulsification activity (45% to 64%) were finally selected. Further studies on amphiphilic compounds production by these isolates revealed no significant effect (p < 0.05) of temperature and pH on the emulsification activity against different hydrocarbons (diesel, xylene and petrol). High biopolymer production (250 - 405 mgL-1) from all the five strains was achieved in mineral salt medium with glucose as sole carbon source at 60 hrs. Characterization of amphiphilic biopolymers elaborated by the isolates revealed a chemical composition of proteins (6-12 %) and sugars (1-5 %). Emulsification activity of the biopolymers varied against different hydrocarbons tested. The results of the study of these amphiphilic biopolymers have possible application in bioremediation of environment contaminated with various hydrocarbons and other industrial applications.