What Is the Impact of Microplastics and Lipid Regulators on Marine Meiofauna? Case Study of Polyvinyl Chloride, Atorvastatin, and Simvastatin

A microcosm experiment was carried out to provide a deeper insight into the toxic mechanisms exerted by two lipid regulator agents, as well as their interactions with the polyvinyl chloride microplastic on marine meiofauna. Two concentrations of Atorvastatin “A” and of Simvastatin “S”, (i.e., 0.6 mg.kg−1 and 6 mg.kg−1), as well as a single dosage of polyvinyl chloride microplastics “P” at 20 mg.kg−1, separately and their combined mixtures (“AP” and “SP”) were used on coastline dwelling marine meiofauna, with a main focus on nematodes. The results showed a significant reduction in meiofauna abundance in treatments compared to control. SIMPER analysis highlighted a significant decrease in the abundance of epigrowth feeders (2A), which possess conical (co) tails, and indistinct (id) amphideal foveas compared to control microcosms, reflected mainly in the decrease in abundance of the species Prochromadorella longicaudata. Furthermore, the contamination with microplastic affected only the omnivores-carnivores guild. Another finding of the current experiment is that the mixtures of microplastic with drugs lead to synergic interactions that increased their toxic effects on marine nematode communities.

Identification of Canola Roots Endophytic Bacteria and Analysis of Their Potential as Biofertilizers for Canola Crops with Special Emphasis on Sporulating Bacteria

Canola (Brassica napus L. var. oleracea) is the third most common oil-producing crop worldwide after palm and soybean. Canola cultivation requires the use of chemical fertilizers, but the amount required can be reduced by applying plant growth-promoting bacteria (PGPB). Among PGPB, endophytic bacteria have certain advantages as biofertilizers, but canola endophytic bacteria have rarely been studied. In this work, we identified a collection of bacterial endophytes isolated from canola roots using MALDI-TOF MS, a technique that is still rarely used for the identification of such bacteria, and rrs gene sequencing, a methodology that is commonly used to identify canola endophytes. The results demonstrated that some bacterial isolates from canola roots belonged to the genera Bacillus, Neobacillus, Peribacillus (Pe.), and Terribacillus, but most isolates belonged to the genera Paenibacillus (P.) and Pseudomonas (Ps.). Inoculation of these isolates indicated that several of them could efficiently promote canola seedling growth in hydroponic conditions. These results were then confirmed in a microcosm experiment using agricultural soil, which demonstrated that several isolates of Pseudomonas thivervalensis, Paenibacillus amylolyticus, Paenibacillus polymyxa, Paenibacillus sp. (Paenibacillus glucanolyticus/Paenibacillus lautus group), and Peribacillus simplex (previously Bacillus simplex) could efficiently promote canola shoot growth under greenhouse conditions. Among them, the isolates of Paenibacillus and Peribacillus were the most promising biofertilizers for canola crops as they are sporulated rods, which is an advantageous trait when formulating biofertilizers.

Coordinated Diel Gene Expression of Cyanobacteria and Their Microbiome

Diel rhythms have been well recognized in cyanobacterial metabolisms. However, whether this programmed activity of cyanobacteria could elicit coordinated diel gene expressions in microorganisms (microbiome) that co-occur with cyanobacteria and how such responses in turn impact cyanobacterial metabolism are unknown. To address these questions, a microcosm experiment was set up using Lake Erie water to compare the metatranscriptomic variations of Microcystis cells alone, the microbiome alone, and these two together (whole water) over two day-night cycles. A total of 1205 Microcystis genes and 4779 microbiome genes exhibited significant diel expression patterns in the whole-water microcosm. However, when Microcystis and the microbiome were separated, only 515 Microcystis genes showed diel expression patterns. A significant structural change was not observed for the microbiome communities between the whole-water and microbiome microcosms. Correlation analyses further showed that diel expressions of carbon, nitrogen, phosphorous, and micronutrient (iron and vitamin B12) metabolizing genes were significantly coordinated between Microcystis and the microbiome in the whole-water microcosm. Our results suggest that diel fluxes of organic carbon and vitamin B12 (cobalamin) in Microcystis could cause the diel expression of microbiome genes. Meanwhile, the microbiome communities may support the growth of Microcystis by supplying them with recycled nutrients, but compete with Microcystis for iron.

Impact of Sediment-Spiked Fludioxonil On Benthic Macroinvertebrates And Zooplankton From The Yangtze River Delta, China

In China, the fungicide fludioxonil, that accumulates and persists in sediments, has a widespread agricultural use to control various fungal diseases. Its residues may cause toxic effects to benthic and pelagic aquatic fauna, thereby impacting ecosystem service functions of aquatic ecosystems.To assess the environmental risks of fludioxonil, sediment-spiked single-species toxicity tests with benthic macroinvertebrates as well as a sediment-spiked indoor freshwater microcosm experiment were performed. The microcosm test systems were populated with benthic invertebrates also used in the single-species tests. In all experiments artificial sediment was used. The single-species tests were conducted with 8 benthic macroinvertebrates covering different taxonomic groups typical for the Yangtze River Delta, China. The 28d-EC10 values thus obtained were used to construct species sensitivity distributions (SSDs) and the hazardous concentration to 5% of the species tested (HC5) was used to derive a provisional long-term Tier-2 regulatory acceptable concentration (RAC) for benthic invertebrates by applying an assessment factor of 3.The microcosm experiment was conducted to study treatment-related responses of benthic macroinvertebrates and pelagic zooplankton. The lowest No Observed Effect Concentrations (NOECs) of benthic invertebrate and of pelagic zooplankton populations were used to derive provisional long-term Tier-3 RACs for, respectively, benthic and pelagic invertebrates by applying an assessment factor of 2. The RACs thus obtained were compared with Predicted Environmental Concentrations (PECs) of fludioxonil in overlying water and the sediment compartment of edge-of-field ponds after application of this fungicide in rice, grape, wheat, maize and tomato crops. Overall, the risks of long-term exposure of fludioxonil to benthic invertebrates and pelagic zooplankton species in these Chinese edge-of-field ponds appear to be relatively small, but some risks cannot be excluded for ponds adjacent to rice.

Monitoring for seismological and geochemical groundwater effects of high-volume pumping of natural gas at the Stenlille underground gas storage facility, Denmark

The large natural gas storage facility at Stenlille, Denmark, has been monitored to investigate the effect of pumping large amounts of gas into the subsurface. Here, we present a new dataset of microseismicity at Stenlille since 2018. We compare these data with methane in groundwater, which has been monitored since gas storage was established in 1989. Further, we conducted a controlled 172 day microcosm experiment of methane oxidation on an isolated microbial community under both aerobic and anaerobic conditions. For this experiment, water was filtered from a well at Stenlille with elevated levels of thermogenic methane and ethane. No microseismic activity was detected in the gas storage area above an estimated detection level of ML 0.0 for the established network. The long-term monitoring for methane in groundwater has still only detected one leak, in 1995, related to a technical problem during injection. The microcosm experiment revealed that oxidation of methane occurred only under aerobic conditions during the experiment, as compared to anaerobic conditions, even though the filtered water was anoxic