A Pseudomonas aeruginosa Strain Ikw1 Produces an Unusual Polymeric Surface-Active Compound in Waste Frying Oil-Minimal Medium

Abstract

A Gram-negative bacterium isolated from the sub-surface water of Ikang River, Niger Delta region, Nigeria produced an unusual biosurfactant in waste frying oil-minimal medium. Cultural and biochemical characterizations as well as 16S rRNA sequencing identified the bacterium as a strain of Pseudomonas aeruginosa with 100% sequence homology with Pseudomonas aeruginosa strain HNYM41. Biochemical characterizations, thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and Fourier transform-infrared (FT-IR) spectrometry identified the active compound as a glycolipopeptide (peptidoglycolipid) composed of 40.36% carbohydrates, 20.16% proteins and 34.56% lipids. The biosurfactant reduced surface tension of water from 72.00 to 24.62 dynes/cm at a critical micelle concentration (CMC) of 20.80 mg/L indicating excellent effectiveness and efficiency properties. Commendable oil-washing property (79.92% oil recovery) with an elution rate of 0.68 mL/min at 70°C, foaming and foam stability, excellent emulsification activity in kerosene, crude oil and palm oil and a significant (P = 0.000; R2 = 0.9901) oil solubilization property indicate excellent oil recovery, detergency and remediation potentials of the biosurfactant. Oil displacement, emulsifying and antimicrobial activities of the compound were relatively stable at relevant temperatures, pH and NaCl levels suggesting suitability for applications in hydrophobic compound remediation, emulsion stabilization and preservation of formulations.