Responses of seawater bacteria in the bioremediation process of petroleum contamination by immobilized bacteria

Bioremediation of petroleum contaminated seawater by immobilized bacteria has gained great interests. Better understanding the responses and migration mechanisms of indigenous seawater bacteria is significant for analyzing the bioremediation mechanism. In this paper, the specific bacteria, Shewanella algae (Sp1), was immobilized by Enteromorpha biochar. The immobilized Sp1 and exogenous nutrients were used as bio-augmentation and bio-stimulation, and the degradation rate of diesel could reach 97.3 ± 2.1% after 30-day remediation. Interestingly, the microbial community analysis demonstrated that Sp1, immobilized in the beads, disappeared after bioremediation, while some indigenous bacteria in the seawater, including genus Alcanivorax, Parvibaculum, Hyphomonas and so on, were detected in the internal of the immobilized beads. This phenomenon indicated that some genus might migrate from seawater into the immobilized beads, presumably attributed to the fact that the immobilized beads gave protection for these bacteria. This finding could serve as a new evidence to clarify the succession of microbial community in bioremediation process, which had not been reported in previous studies. Meanwhile, this study could make contribution to the investigation of potential secondary marine pollution in the bioremediation process.