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.
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