Genomic insights into Pseudoalteromonas sp. JSTW coping with petroleum-heavy metals combined pollution.

Worldwide marine compound contamination by petroleum products and heavy metals is a burgeoning environmental concern. Pseudoalteromonas, prevalently distributed in marine environment, has been proven to degrade petroleum and plays an essential role in the fate of oil pollution under the combined pollution. Nevertheless, the research on the reference genes is still incomplete. Therefore, this study aims to thoroughly investigate the reference genes represented by Pseudoalteromonas sp. JSTW via whole-genome sequencing. Next-generation sequencing technology unfolded a genome of 4,026,258 bp, database including Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were utilized to annotate the genes and metabolic pathways conferring to petroleum hydrocarbon degradation. The results show that common alkane and aromatic hydrocarbon degradation genes (alkB, ligB, yqhD, and ladA), chemotaxis gene (MCP, cheA, cheB, pcaY, and pcaR), heavy-metal resistance, and biofilm genes (σ54, merC, pcoA, copB, etc.) were observed in whole-genome sequence (WGS) of JSTW, which indicated that strain JSTW could potentially cope with combined pollution. The degradation efficiency of naphthalene in 60 h by JSTW was 99% without Cu2+ and 67% with 400 mg L-1 Cu2+ . Comparative genome analysis revealed that genomes of Pseudoalteromonas lipolytica strain LEMB 39 and Pseudoalteromonas donghaensis strain HJ51 shared similarity with strain JSTW, suggesting they are also the potential degradater of petroleum hydrocarbons under combined pollution. Therefore, this study provides a WGS annotation and reveals the mechanism of response to combined pollution of Pseudoalteromonas sp. JSTW.

Enhanced bioremediation of cyclohexaneacetic acid in offshore sediments with green synthetic iron oxide and Pseudoalteromonas sp.

Naphthenic acids (NAs) have been found to exert serious threats on offshore sediment ecosystems and human health in recent years, which entails us the urgent need for NAs remediation. Bioremediation is considered an ideal method for sediment remediation due to ecological sustainability and economic feasibility. However, current bioremediation efficiency of offshore sediments suffers from relatively slow and there has never any attempts to bioremediate offshore sediment NAs contamination hitherto. In this study, the green synthetic iron oxides (gFeOx) based on Laminaria extracts was employed to enhance the biodegradation of NAs (Cyclohexylacetic acid, CHAA) in offshore sediments by Pseudoalteromonas sp. JSTW (an indigenous microorganism). The results showed that CHAA (20 mg·kg-1) in offshore sediments was removed almost 100% within 7 days at 30 mg·kg-1 gFeOx and 0.6 mg·kg-1 Strain JSTW. High-throughput sequencing results revealed that the structure and function of sediment microbial community were essentially restored to uncontaminated levels after bioremediation, highlighting the joint remediation approach is an efficient and eco-friendly method. Overall, this work has firstly provided insights into the application for NAs in situ bioremediation in offshore sediments.

A novel degradation mechanism of naphthenic acids by marine Pseudoalteromonas sp.

Naphthenic acids (NAs) are a persistent toxic organic pollutant that occur in different environment worldwide and cause serious threat to the ecosystem and public health. However, knowledge on the behavior and fate of NAs in marine environments still remains unknown. In this study, the degradation mechanism of NAs (cyclohexylacetic acid, CHAA) was investigated using an common indigenous marine Pseudoalteromonas sp. The results showed that CHAA could be degraded completely under aerobic condition, but could not be utilized directly under anaerobic condition. Interestingly, transcriptome and key enzyme activity results showed the CHAA degradation pathway induced under aerobic condition could still work in anaerobic condition. The degradation was activated by acetyl-CoA transferase and sequentially formed the corresponding cyclohexene, alcohol, and ketone with the assistance of related enzymes, and finally cleaved by hydroxymethylglutarate-CoA lyase. Besides, there was a positive correlation between chemotaxis and aerobic degradation genes (r = 0.976, P < 0.05), the chemotaxis would enhance bacterium movement and NAs biodegradation. It is proposed that bacterium could translocate to NAs and accomplish biodegradation from aerobic to anaerobic environments, which was a new anaerobic degradation pathway of NAs. This study provides new insights into the fate of NAs and other organic contaminants in marine environment.