Biosurfactants produced by novel facultative-halophilic Bacillus sp. XT-2 with biodegradation of long chain n-alkane and the application for enhancing waxy oil recovery

Efficient biosurfactant producers with hydrocarbon degradation capability and harsh environment adaptability are precious bioresources for microbial enhanced oil recovery and petroleum-related bioremediation. In this study, a novel facultative-halophilic strain Bacillus sp. XT-2 was isolated and shown to degrade long-chain hydrocarbons along with lipopeptide biosurfactants production. The biosurfactants exhibited remarkable surface activity and emulsification ability against different hydrocarbons with emulsification index of 73%–87%. High performance liquid chromatography-mass spectrometry (HPLC-MS) method combined with genome sequencing was used to identify the lipopeptide biosurfactants and their corresponding synthetic gene clusters. The results showed that the lipopeptides could be classified to the isoforms and homologs of bacillibactin, fengycin, and surfactin, and strain XT-2 possessed their entire core synthetic genes. Artificial core-flooding experiments demonstrated both cultures of XT-2 and its biosurfactant could significantly increase the oil recovery by 13.43%–25.01%. These findings indicate the novel strain XT-2 and its lipopeptides have great potentials in environmental remediation and petroleum development.