Isolation, characterization, and application of biosurfactant by Klebsiella pneumoniae strain IVN51 isolated from hydrocarbon-polluted soil in Ogoniland, Nigeria

Abstract

Background/aim: Considerable attention has been given to the use of biosurfactants in recent times because of their potential industrial and environmental applications and ecological friendliness. Hydrocarbon-polluted soils have been major sources of biosurfactant-producing bacteria; resultantly, this study had been aimed at isolating and characterizing biosurfactant produced by Klebsiella pneumoniae strain IVN51 isolated from hydrocarbon-polluted soil in Ogoniland, Nigeria. Methodology: The biosurfactant screening techniques employed were emulsification assay, emulsification index (E24), lipase activity, haemolytic assay, oil spreading, and tilted glass slide. The bacterial isolate was identified based on phenotypic, biochemical, and molecular means. Thin-layer chromatography (TLC) and gas chromatography mass spectrometry (GC–MS) analyses were used in the classification and characterization of the biosurfactant produced. The biosurfactant produced was applied on selected hydrocarbons to determine its emulsifying capacity. Results: The phylogenetic tree analysis of the 16S rRNA gene classified the isolate as K. pneumoniae strain IVN51. The sequence obtained from the isolate has been deposited in GenBank under the accession number KT254060.1. The result obtained from the study revealed high biosurfactant activity with a maximum E24 of 60 % compared to E24 of 70 % by sodium dodecyl sulphate (SDS). In addition, the biosurfactant showed emulsifying activity against the following hydrocarbons: petrol, kerosene, xylene, toluene, and diesel. The optimum cultural conditions (temperature, pH, carbon, nitrogen, hydrocarbon, inoculum concentration, and incubation time) for growth and biosurfactant production by K. pneumoniae IVN51 were determined. The biosurfactant was characterized as a phospholipid using TLC, while the GC–MS analysis identified the phospholipid as phosphatidylethanolamine. Conclusion: This study has demonstrated the capacity of K. pneumoniae strain IVN51 isolated from hydrocarbon-polluted soil to produce biosurfactant and the effectiveness of the produced biosurfactant in emulsifying different hydrocarbons. Furthermore, the biosurfactant produced was found to belong to the class, phospholipids based on the TLC and GC–MS analyses.