Adaptive responses and metabolic strategies of Novosphingobium sp. ES2-1-17β-estradiol analyzed through integration of genomic and proteomic approaches

Microbes and nutrient shift in a Closed Aquatic Ecosystem (CAES) during four weeks of operation

A Closed Aquatic Ecosystem (CAES) housed an aquatic plant Ceratophyllum demersum, zebrafish (Danio rerio), and microbes that were simultaneously obtained with the zebrafish, and it was used to study the operation of the ecosystem. The results indicated that the CAES can operate steadily for about 4 weeks. The dissolved oxygen (DO), pH, and conductivity values of the ecosystem regularly oscillated, while the total nitrogen of the water decreased and the total phosphate slightly increased. Additionally, the chemical oxygen demand (COD, a measure of organic compounds) of the water after the experiment increased to 39 times more than that of the water before the experiment. The meta-genomic data showed that the number of genera decreased by 38 % and the top 10 most abundant genera were almost completely different before and after the experiment, which demonstrated a great shift in the microbes during the operation process. These results suggested that although the CAES operated steadily during the 28-day experiment, there were more organic materials and less nitrogen in the water by the end of the experiment, which may have influenced the structure and operation of the ecosystem. Thus, it is necessary to remove superfluous plant biomass from the CAES and supply nitrogen to keep the ecosystem stable.

Responses to phytoplankton community succession and expression of key functional genes in plateau lakes under 17β-estradiol interference

Steroid estrogens (SEs) have garnered global attention because of their potential hazards to human health and aquatic organisms at low concentrations (ng/L). The ecosystems of plateau freshwater lakes are fragile, the water lag time is long, and pollutants easily accumulate, making them more vulnerable to the impact of SEs. However, the knowledge of the impact of SEs on the growth and decomposition of phytoplankton communities in plateau lakes and the eutrophication process is limited. This study investigated the effects and mechanisms of SEs exposure on dominant algal communities and the expression of typical algal functional genes in Erhai Lake using indoor simulations and molecular biological methods. The results showed that phytoplankton were sensitive to 17β-estradiol (E2β) pollution, with a concentration of 50, and 100 ng/L E2β exposure promoting the growth of cyanophyta and chlorophyta in the short term; this poses an ecological risk of inducing algal blooms. E2β of 1000 ng/L exposure led to cross-effects of estrogenic effects and toxicity, with most phytoplankton being inhibited. However, small filamentous cyanobacteria and diatoms exhibited greater tolerance; Melosira sp. even exhibited "low inhibition, high promotion" behavior. Exposure to E2β reduced the Shannon-Wiener diversity index (H'), Pielou index (J), and the number of dominant algal species (S) in phytoplankton communities, leading to instability in community succession. E2β of 50 ng/L enhanced the expression levels of relevant functional genes, such as ftsH, psaB, atpB, and prx, related to Microcystis aeruginosa. E2β of 50 ng/L and 5 mg/L can promote the transcription of Microcystis toxins (MC) related genes (mcyA), leading to more MC production by algal cells.

Insights into the biodegradation of pentachlorobiphenyl by Microbacterium paraoxydans: proteomic and metabolomic studies

Bacterial degradation mechanism for high chlorinated pentachlorobiphenyl (PentaCB) with worse biodegradability has not been fully elucidated, which could limit the full remediation of environments afflicted by the complex pollution of polychlorinated biphenyls (PCBs). In this research, a new PentaCB-degrading bacterium Microbacterium paraoxydans that has not been reported was obtained using enzymatic screening method. The characteristics of its intracellular enzymes, proteome and metabolome variation during PentaCB degradation were investigated systematically compared to non-PentaCB conditions. The findings indicate that the degradation rate of PentaCB (1 mg/L) could reach 23.9% within 4 hours and achieve complete degradation within 12 hours, with the mixture of intracellular enzymes being most effective at a pH of 6.0. During the biodegradation of PentaCB, the 12 up-regulated proteins characterized included ABC transporter PentaCB-binding protein, translocase protein TatA, and signal peptidase I (SPase I), indicating the presence of functional proteins for PentaCB degradation in both the cytoplasm and the outer surface of the cytoplasmic membrane. Furthermore, five differentially enriched metabolites were strongly associated with the aforementioned proteins, especially the up-regulated 1, 2, 4-benzenetriol which feeds into multiple degradation pathways of benzoate, chlorocyclohexane, chlorobenzene and aminobenzoate. These relevant results help to understand and speculate the complex mechanisms regarding PentaCB degradation by M. paraoxydans, which have both theoretical and practical implications for PCB bioremediation.

Metagenomic insights into phenanthrene biodegradation in electrical field-governed biofilms for groundwater bioremediation

Electrical fields (EFs)-assisted in-situ bioremediation of petroleum-contaminated groundwater, such as polycyclic aromatic hydrocarbons, has drawn increasing attention. However, the long-term stability, the EFs influence, and metabolic pathways are still poorly understood, hindering the further development of robust technology design. Herein, a series of EFs was applied to the phenanthrene-contaminated groundwater, and the corresponding system performance was investigated. The highest removal capacity of phenanthrene (phe) (7.63 g/(m3·d)) was achieved with EF_0.8 V biofilm at a hydrolytic retention time of 0.5 d. All the biofilms with four EFs exhibited a high removal efficiency of phe over 80% during a 100-d continuous-flow operation. Intermediates analysis revealed the main pathways of phe degradation: phthalate and salicylate via hydroxylation, methylation, carboxylation, and ring cleavage steps. Synergistic effects between phe-degraders (Dechloromonas), fermentative bacteria (Delftia), and electroactive microorganisms (Geobacter) were the main contributors to the complete phe mineralization. Genes encoding various proteins of methyl-accepting (mcp), response regulator (cheABDRY), and type IV pilus (pilABCMQV) were dominant, revealing the importance of cell motility and extracellular electron transfer. Metagenomics analysis unveiled phe-degrading genes, including ring reduction enzymes (bamBCDE), carboxylase of aromatics (ubiD), and methyltransferase protein (ubiE, pcm). These findings offered a molecular understanding of refractory organics' decompositions in EFs-governed biotechnology.