Screening and Identification of Bacteria from Crude Oil Contaminated Soil with Biosurfactant-Producing Potentials

Surface-active substances called biosurfactants lower interfacial and surface tension, and are usually generated at the microbial cell surface. Soils contaminated by hydrocarbons have been identified as a significant source of bacteria that produce biosurfactants. From crude oil contaminated soil undergoing bioremediation, bacteria that produce biosurfactants were isolated and identified through biochemical and molecular methods. The isolate ND 102 was identified as Ralstonia insidiosa BT48 with Accession number KJ848571.1 and 97% similarity. Isolate ND301 was identified as Burkholderia anthina with accession number JQ659867.1 and 97% similarity, while isolate ND112 was identified as Klebsiella sp.SR-143 with accession number KC455423.1 and 96% similarity. The methods used for biosurfactant screening included oil spreading technique, blood hemolysis and emulsification assays. The highest and lowest emulsification percentage was 50% and 20.8% by isolate ND 301 and ND 102 respectively. All isolates showed positive haemolytic activity and ability to reduce surface tension by oil spreading technique. The maximum inhibition zone of 19.0 ± 0.1mm was by ND 301 while ND 102 with 4.3 ± 0.3mm was lowest. The results show that these isolates may be useful for environmental bioremediation and clean-up of oil spilled sites.