Deep relationships between bacterial community and polycyclic aromatic hydrocarbons in soil profiles near typical coking plants.

Bacterial communities play an important role in maintaining the normal functioning of ecosystems; therefore, it is important to understand the effects of polycyclic aromatic hydrocarbons (PAHs) on the bacterial community. In addition, understanding the metabolic potential of bacterial communities for PAHs is important for the remediation of PAH-contaminated soils. However, the deep relationship between PAHs and bacterial community in coking plants is not clear. In this study, we determined the bacterial community and the concentration of PAHs in three soil profiles contaminated by coke plants in Xiaoyi Coking Park, Shanxi, China, using 16S rRNA and gas chromatography coupled with mass spectrometry, respectively. The results show that 2 ~ 3 rings PAHs are the main PAHs and Acidobacteria (23.76%) was the dominant bacterial community in three soil profiles. Statistical analysis showed that there were significant differences in the composition of bacterial communities at different depths and different sites. Redundancy analysis (RDA) and variance partitioning analysis (VPA) illustrate the influence of environmental factors (including PAHs, soil organic matter (SOM), and pH) on the vertical distribution of soil bacterial community, and PAHs were the main factors affecting the bacterial community in this study. The co-occurrence networks further indicated correlations between bacterial community and PAHs and found that Nap has the greatest effect on bacterial community compared with other PAHs. In addition, some operational taxonomic units (OTUs, OTU2, and OTU37) have the potential to degrade PAHs. PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) was used for further study on the potential of microbial PAHs degradation from a genetic perspective, which showed that different PAH metabolism genes were present in the genomes of bacterial communities in the three soil profiles, and a total of 12 PAH degradation-related genes were isolated, mainly dioxygenase and dehydrogenase genes.

Molecular Toxicity of Metal Oxide Nanoparticles in Danio rerio.

Metal oxide nanoparticles can exert adverse effects on humans and aquatic organisms; however, their toxic mechanisms are still unclear. We investigated the toxic effects and mechanisms of copper oxide, zinc oxide, and nickel oxide nanoparticles in Danio rerio using microarray analysis and the comet assay. Copper oxide nanoparticles were more lethal than the other metal oxide nanoparticles. Gene ontology analysis of genes that were differentially expressed following exposure to all three metal oxide nanoparticles showed that the nanoparticles mainly affected nucleic acid metabolism in the nucleus via alterations in nucleic acid binding. KEGG analysis classified the differentially expressed genes to the genotoxicity-related pathways "cell cycle", "Fanconi anemia", "DNA replication", and "homologous recombination". The toxicity of metal oxide nanoparticles may be related to impairments in DNA synthesis and repair, as well as to increased production of reactive oxygen species.