Isolation and Molecular Identification of New Benzene Degrading Lysinibacillus Strains from Gasoline Contaminated Soil

The aim of this study was to isolate and identify aerobic benzene-degrading bacteria from soil sample contaminated with gasoline. Soil samples were collected from gasoline-contaminated sites located around gas stations in the Al-Mafraq city of Jordan. Ten grams of soil were transferred to Stanier's medium supplemented with 1% benzene and aerobically incubate at 30?C for 72 h. Five morphologically different bacterial isolates were recovered from soil samples and designated as 1J1, 2J2, DJ2, 3J4 and 1J1-2. These isolates were subjected to analyses for identification and characterization. All isolates were Gram positive, endospore-forming, motile, mesophilic and rod-shaped aerobic bacteria. Biochemically, all were catalase and oxidase positive except DJ2, which was negative for oxidase. Based on their 16S rDNA sequences, they appear to be closely related to the genus Lysinibacillus (L). Isolate 1J1 revealed 91% homology with L. fusiformis, suggesting a member of a new genus with some similarity to the genus Lysinibacillus. Isolates 2J2, DJ2, 3J4 and 1J1-2 exhibited more than 97% sequence identity to L. xylanilyticus, L. odeysseyi, L. macrolides and L. boronitolerans, respectively. The 16S rDNA sequences of these isolates were deposited in GenBank database. All isolates grew best in Stanier's medium when the optimal growth conditions were 1% benzene, 30?C and pH 6.8. In conclusion, five novel bacterial isolates with similarity to the genus Lysinibacillus that utilize benzene as the sole carbon and energy source were isolated and characterized from soil samples contaminated by gasoline. These five isolates can be considered as ideal candidates for bioremediation of benzene from soils.