Expression of sfp gene and hydrocarbon degradation by Bacillus subtilis

Bacillus subtilis C9 produces a lipopeptide-type biosurfactant, surfactin, and rapidly degrades alkanes up to a chain length of C-19. The nucleotide s equence of the sfp gene cloned from B. subtilis C9 was determined and its d educed amino acid sequence showed 100% homology with the sfp gene reported before [Nakano et al. (1992) Mol. Gen. Genet. 232: 313-321]. To transform a non-surfactin producer, B. subtilis 168, to a surfactin producer, the sfp gene cloned from B. subtilis C9 was expressed in B. subtilis 168. The trans formed B. subtilis SB103 derivative of the strain 168 was shown to produce surfactin measured by its decrease in surface tension, emulsification activ ity, and TLC analysis of the surface active compound isolated from the cult ure broth. Like B. subtilis C9, B. subtilis SB103 containing sfp gene readi ly degraded aliphatic hydrocarbons (C10-19), though its original strain did not. The addition of surfactin (0.5%, w/v) to the culture of B. subtilis 1 68 significantly stimulated the biodegradation of hydrocarbons of the chain lengths of 10-19; over 98% of the hydrocarbons tested were degraded within 24 h of incubation. These results indicate that the lipopeptide-type biosu rfactant, surfactin produced from B. subtilis enhances the bioavailability of hydrophobic hydrocarbons.