Abstract

PETROLEUM CONTAMINATED SOIL AS RICH SOURCE OF BIOEMULSIFIER PRODUCING ENTEROBACTER CLOACAE

Shivani Kulkarni, Shrutika Yerwa, Bhakti Thakkar and Sougata Ghosh*

Abstract

Bioemulsifier producing bacteria is a promising solution to address petroleum-derived hydrocarbon contamination of soil. Microorganisms can produce bioemulsifier to increase bioavailability, degradation and utilization of contaminating hydrocarbons as sole carbon source. Herein, we report isolation and characterization of bioemulsifier producing bacterial strains isolated from oil contaminated soils like garage and temple. Oil spreading assay was used for screening, and positive strains were grown in minimal medium supplemented with oil and emulsification index and activity was evaluated in cell-free supernatant. A total of 9 bacterial strains were tested, and 5 were positive for the bioemulsifier production. Isolate TS4 showed 27.64 unit/mL, 22.77 unit/mL, 15.23 unit/mL and 8.93 unit/mL emulsification activity against coconut oil, mustard oil, engine oil and groundnut oil, respectively. Isolate TS5 showed 33.87 unit/mL, 35.51 unit/mL, 37.59 unit/mL and 23.48 unit/mL emulsification activities against coconut oil, mustard oil, engine oil and groundnut oil, respectively. Similarly they showed efficient emulsification index against all of the above mentioned oil. Media optimization studies with Plackett Burman design indicated the significant effect of K2HPO4, NH4Cl and oil concentration on bioemulsifier production. The potent bioemulsifying bacteria TS4 and TS5 were identified as Enterobacter cloacae. Hence we conclude that the bacterial isolates exhibiting superior emulsification activity can be used for bioremediation in the oil spill affected soil.

Keywords: Enterobacter cloacae, Bioemulsifier, Emulsification index, Emulsification activity, Plackett Burman design.