Process Development Purification and Antimicrobial Applications of Bacterial Biosurfactant

Abstract

Hydrocarbon contaminated samples and extreme environments are reported to be rich sources for isolating biosurfactant producing microorganisms. Therefore, the hydrocarbon contaminated samples were collected from various sections of petroleum refineries and extreme environments. A total of forty-seven bacterial isolates were obtained from the collected samples. Amongst the total forty-seven bacterial isolates, eleven potent biosurfactant producing and concomitant hydrocarbon degraders were obtained after primary screening involving drop collapse method (DCM) and Oil-spreading method (OSM) followed by secondary screening comprising of Haemolytic assay (HA), Cetyl trimethyl ammonium bromide (CTAB) assay, Surface tension (ST), Emulsification index (E24) and Emulsification activity (EA). In qualitative method using 2,6 - Dichlorophenol Indophenol (2,6 - DCPIP) as hydrocarbon utilizing indicator and quantitative method for hydrocarbon degradation for eleven selected potent biosurfactant producers revealed that PS1 isolate showed a maximum degradation (46.32 %) of 2 % (w/v) crude oil with 70.77 % and 77.17 % reduction in peak area of aliphatic and aromatic fractions respectively and simultaneous lowering of surface tension from 59.27 mN/m (control) to 32.43 mN/m in 7 days. Based on the results of thin layer chromatography (TLC), FT-IR and GC-MS analysis, Achromobacter sp. (PS1) (NCBI accession no. KT735240) was confirmed to be a novel glycolipid (rhamnolipid) producer and potent hydrocarbon degrader. The application of the partially purified rhamnolipid biosurfactant as an antimicrobial agent against different pathogenic stains exhibited a broad-spectrum antibacterial activity showing and#8805; 90 % growth inhibition at different rhamnolipid concentrations. The oil recovery using crude culture filterate containing rhamnolipid biosurfactant showed a maximum recovery of 92.21 % from motor-oil impregnated sand. newline