Negative Consequences on the Growth, Morphometry, and Community Structure of the Kelp Macrocystis pyrifera (Phaeophyceae, Ochrophyta) by a Short Pollution Pulse of Heavy Metals and PAHs

Community response of soil microorganisms to combined contamination of polycyclic aromatic hydrocarbons and potentially toxic elements in a typical coking plant

Both polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) of coking industries impose negative effects on the stability of soil ecosystem. Soil microbes are regarded as an essential moderator of biochemical processes and soil remediation, while their responses to PAHs-PTEs combined contamination are largely unknown. In the present study, soil microbial diversity and community composition in the typical coking plant under the chronic co-exposure of PAHs and PTEs were investigated and microbial interaction networks were built to reveal microbial co-occurrence patterns. The results indicated that the concentrations of PAHs in the soil inside the coking plant were significantly higher than those outside the plant. The mean concentration of ∑16PAHs was 2894.4 ng·g^-1, which is 5.58 times higher than that outside the plant. The average Hg concentration inside the coking plant was 22 times higher than the background value of Hebei province. The soil fungal community inside the coking plant showed lower richness compared with that of outside community, and there are significant difference in the bacterial and fungal community composition between inside and outside of coking plant (p < 0.01). Predicted contribution of different environmental factors to each dominant species based on random forest identified 20 and 25 biomarkers in bacteria and fungi, respectively, that were highly sensitive to coking plant soil in operation, such as Betaproteobacteria，Sordariomycetes and Dothideomycetes. Bacterial and fungal communities were shaped by the soil chemical properties (pH), PTEs (Hg), and PAHs together in the coking plant soils. Furthermore, the bacterial and fungal interaction patterns were investigated separately or jointly by intradomain and interdomain networks. Competition is the main strategy based on the co-exclusion pattern in fungal community, and the competitive relationship inside the coking plant is more complex than that outside the plant. In contrast, cooperation is the dominant strategy in bacterial networks based on the co-occurrence pattern. The present study provided insights into microbial response strategies and the interactions between bacteria and fungi under long-term combined contamination.

Transcriptomic analyses reveal increased expression of dioxygenases, monooxygenases, and other metabolizing enzymes involved in anthracene degradation in the marine alga Ulva lactuca

To analyze the mechanisms involved in anthracene (ANT) degradation in the marine alga Ulva lactuca, total RNA was obtained from the alga cultivated without ANT and with 5 μM of ANT for 24 h, and transcriptomic analyses were performed. A de novo transcriptome was assembled, transcripts differentially expressed were selected, and those overexpressed were identified. Overexpressed transcripts potentially involved in ANT degradation were: one aromatic ring dioxygenase, three 2-oxoglutarate Fe (II) dioxygenases (2-OGDOs), and three dienelactone hydrolases that may account for anthraquinone, phthalic anhydride, salicylic acid, and phthalic acid production (pathway 1). In addition, two flavin adenine dinucleotide (FAD)-dependent monooxygenases, four cytP450 monooxygenases, two epoxide hydrolase, one hydroxyphenylpyruvic acid dioxygenase (HPPDO), and two homogentisic acid dioxygenases (HGDOs) were identified that may also participate in ANT degradation (pathway 2). Moreover, an alkane monooxygenase (alkB), two alcohol dehydrogenases, and three aldehyde dehydrogenases were identified, which may participate in linear hydrocarbon degradation (pathway 3). Furthermore, the level of transcripts encoding some of mentioned enzymes were quantified by qRT-PCR are in the alga cultivated with 5 μM of ANT for 0-48 h, and those more increased were 2-OGDO, HGDO, and alkB monooxygenase. Thus, at least three pathways for ANT and linear hydrocarbons degradation may be existed in U. lactuca. In addition, ANT metabolites were analyzed by gas chromatography and mass spectrometry (GC-MS), allowing the identification of anthraquinone, phthalic anhydride, salicylic acid, and phthalic acid, thus validating the pathway 1.

Transfer of Pollutants from Macrocystis pyrifera to Tetrapygus niger in a Highly Impacted Coastal Zone of Chile

PAHs and heavy metals are characteristic pollutants in urbanized coastal areas, especially those with industrial activity. Given this context and the ability of Macrocystis pyrifera to drift when detached and provide trophic subsidy in coastal systems, we analyzed the potential transfer of pollutants to the herbivore Tetrapygus niger, through diet, in an industrialized coastal zone in Central Chile (Caleta Horcón) and characterized the impacted zone using diverse polluted ecotoxicological indices. For this purpose, a culture experiment was conducted where M. pyrifera individuals from Algarrobo (control site) were cultivated in Caleta Horcón and then used as food for T. niger. The contents of both PAHs and heavy metal contents were subsequently determined in algal tissue and sea urchin gonads as well as in the seawater. The results show that algae cultivated in Caleta Horcón had higher concentrations of naphthalene (NAF) compared to those from a low industrial impact zone (Algarrobo) (2.5 and 1.8 mg kg-1, respectively). The concentrations of Cu, As, and Cd were higher in Caleta Horcón than in Algarrobo in both M. pyrifera and T. niger. For all metals, including Pb, higher concentrations were present in T. niger than in M. pyrifera (between 5 and 798 times higher). Additionally, as indicated by the toxicological indices MPI (0.00804) and PLI (10.89), Caleta Horcón is highly contaminated with metals compared to Algarrobo (0.0006 and 0.015, respectively). Finally, the bioconcentration factor (BCF) and trophic transfer factor (TTF) values were greater than one in most cases, with values in Caleta Horcón exceeding those in Algarrobo by one or two orders of magnitude. This study provides evidence that Caleta Horcón is a highly impacted zone (HIZ) compared to Algarrobo, in addition to evidence that the biomagnification of certain pollutants, including the possible responses to contaminants, are apparently not exclusively transferred to T. niger through diet.