Sulfur deposition changed the community structure of soil nematodes by affecting omnivores-predators

Response of abundant and rare microbial species to 40-year long-term fertilization practices irrespective of bulk and rhizosphere soils

Fertilization practices could exert significant influence on the diversity, interactions, and functions of soil microorganisms. However, little is known about how specific microbial groups and their interactions adapt or evolve in response to agricultural practices, especially long-term mineral fertilization. Here we explored the community assembly process shaping the microbial community and co-occurrence networks of abundant and rare groups based on a high-throughput sequencing approach in a field experiment with 40 years of mineral nitrogen (N) and phosphorus (P) fertilization. The results indicated that fertilization (25-51 %) had a strong impact on microbial community structure, while little difference were found between rhizosphere and bulk soils irrespective of abundant and rare microbial groups. Deterministic processes primarily govern the assembly of both abundant and rare bacterial and fungal taxa. Random forest analysis revealed that soil pH and N-related nutrients (i.e. nitrate nitrogen (NO3--N), dissolved organic nitrogen (DON) and ammonium nitrogen (NH4+-N)) were the key factors influencing microbial community structure. Structural equation modeling and mantel test further indicated that deterministic factors, particularly soil pH, influence co-occurrence network complexity by modulating the microbiome. Overall, these findings provide insights into factors shaping the microbial community assembly and co-occurrence network dynamics in agroecosystems subjected to long-term fertilization.

Vegetation types shape the soil micro-food web compositions and soil multifunctionality in Loess Plateau

Introduction

Vegetation degradation and soil erosion are severe problems in the Loess hilly region, rendering it one of the most ecologically vulnerable areas in China and globally. Vegetation restoration has been recognized as an effective approach to amending the fragile ecological environment and restoring degraded ecosystems.

Methods

The effects of different vegetation types: Caragana korshinskii, Prunus armeniaca L., Pinus tabuliformis Carrière, Medicago sativa L., and the control vegetation Stipa bungeana on soil micro-food webs and soil multifunctionality, as well as their response mechanisms to soil environmental drivers, were investigated using High-throughput sequencing technology.

Results

C. korshinskii significantly enhanced soil physicochemical properties and soil enzyme activities by facilitating the stability of the soil micro-food web structure driven by soil bacteria and fungi and increasing the soil multifunctionality in contrast to S. bungeana. Prunus armeniaca also improved soil multifunctionality by promoting soil organic carbon and alkaline phosphatase activity. However, the stability of the soil micro-food web structure and soil multifunctionality were suboptimal in P. tabuliformis and M. sativa. Soil pH, along with carbon, nitrogen, and phosphorus cycling nutrients and enzymes, profoundly influences the structure of the soil micro-food web and soil multifunctionality; among these factors, those related to the carbon and phosphorus cycles are identified as key influencing factors.

Discussion

Therefore, a vegetation restoration strategy prioritizing C. korshinskii as the dominant vegetation type, supplemented by P. armeniaca, significantly impacts restoring soil multifunctionality and stabilizing the soil micro-food web in Loess hill regions and comparable ecological areas.

Balances among reproduction, antioxidant responses and lipid metabolism underlying the multi-generational effects of N-butylpyridinium bromide on Caenorhabditis elegans

Ionic liquids (ILs) are difficult to degrade and even accumulate in the environment. Accordingly, their long-term toxicities are particularly important to demonstrate their accurate risk assessment. However, their long-term toxicities over generations and the toxicity mechanisms lacked thorough investigation. Presently, N-butylpyridinium bromide ([bpyr]Br), a representative IL, was chosen to measure its long-term effects on Caenorhabditis elegans for seven consecutive generations at 0.0225 and 22.5 mg/L. Toxicity mechanisms were explored in F1, F3, F5 and F7 by combining both antioxidant responses and lipid metabolism. Results showed that [bpyr]Br at low concentration provoked oscillatory effects on the reproduction over 7 generations, with inhibition in F1 and F7 and stimulation in F2, F4 and F5. At high concentration, [bpyr]Br showed similar multi-generational oscillation with greater inhibition in F1 and greater stimulation in F5. The effects of [bpyr]Br on the antioxidant responses to oxidative stress also showed oscillation over generations. The integrated biomarker response (IBR) values showed that [bpyr]Br at low concentration did not provoke significant influences on the overall antioxidant homeostasis in F1 and F3, but significantly stimulated it in F5 and F7. Meanwhile, [bpyr]Br at high concentration stimulated the antioxidant homeostasis in F1 and F7 with non-significant influences in F3 and F5. The IBR values regarding indicators in lipid metabolism showed that [bpyr]Br significantly and commonly stimulated the overall metabolism without concentration-dependent differences. Further analysis implied that [bpyr]Br provoked different mechanisms underlying the responses at low and high concentrations.

Plant-Soil Mediated Effects of Long-Term Warming on Soil Nematodes of Alpine Meadows on the Qinghai-Tibetan Plateau

Global warming is one of the most pressing environmental issues today. Our study aimed to investigate how warming affected plant and soil nematode communities in alpine meadows on the Qinghai−Tibetan Plateau over the past seven years. An artificial warming experiment with different gradients was conducted from 2011 to 2018, including temperature increases of 0 °C (CK), 0.53 °C (A), 1.15 °C (B), 2.07 °C (C), and 2.17 °C (D), respectively. Cyperaceae plants were shown to be eliminated by increasing temperature, and plant community composition tended to cluster differently under different warming gradients. The number of nematodes decreased with the increase in soil depth, and the majority of them were observed in the topsoil layer. The individual densities of soil nematodes were 197 ind.·100 g−1 dry soil at 10−20 cm and 188 ind.·100 g−1 dry soil at 20−30 cm in the A treatment, which was significantly higher than the CK (53 and 67 ind.·100 g−1 dry soil) (p < 0.05). The lowest relative abundance of bacterivore nematodes (Ba) was 31.31% in treatment A and reached the highest of 47.14% under the warming gradient of D (p < 0.05). The abundance of plant parasitic nematodes (Pp) was significantly reduced to 26.03% by excessive warming (2.17 °C increase) in comparison to CK (41.65%). The soil nematode community had the highest diversity with a 0.53 °C increase in soil temperature; 1.15 °C warming gradients were lower, and nematode communities tended to be simplified (p < 0.05). All nematode channel ratio (NCR) values were above 0.5, indicating that warming did not change the decomposition pathway of soil organic matter dominated by the bacterial channels. The Wasilewska Index (WI) in the D treatment increased significantly compared to other treatments (p < 0.05), indicating that the mineralized pathway of the food web was primarily involved with Ba and fungivores nematodes (Fu), which is conducive to the growth of micro-biophagous nematodes. The plant parasite index (PPI) decreased significantly in the D treatment compared with other treatments (p < 0.05), indicating that a high warming gradient caused a reduction in the maturity of Pp nematodes. The maturity index (MI) increased in the D treatment compared with A, B, and C treatments, indicating that overheating affected the nematode community in the later stage of succession and caused the soil to be less disturbed. A partial least squares path model (PLSPM) showed that warming indirectly affects Fu and Pp diversity by directly impacting the plant community as well as indirectly affecting Ba by directly affecting soil properties. In conclusion, plant diversity and community composition profoundly affect the soil nematode communities, thus reflecting the dynamic processes and evolution of soil ecosystems.

Polymerizations with Elemental Sulfur: From Petroleum Refining to Polymeric Materials

The production of elemental sulfur from petroleum refining has created a technological opportunity to increase the valorization of elemental sulfur by the synthesis of high-performance sulfur-based plastics with improved optical, electrochemical, and mechanical properties aimed at applications in thermal imaging, energy storage, self-healable materials, and separation science. In this Perspective, we discuss efforts in the past decade that have revived this area of organosulfur and polymer chemistry to afford a new class of high-sulfur-content polymers prepared from the polymerization of liquid sulfur with unsaturated monomers, termed inverse vulcanization.

Nitrogen and Sulfur Additions Improved the Diversity of nirK- and nirS-Type Denitrifying Bacterial Communities of Farmland Soil

Anthropogenic nitrogen (N) and sulfur (S) deposition can change above- and belowground biodiversity, including soil microbial diversity. The diversity of denitrifying microorganisms is of great significance to the calculation of the global nitrogen cycle and nitrogen flux. For a long time, nirK and nirS have been used as the functional genes to study denitrifying microorganisms, and have gradually become molecular markers for studying the composition and diversity of denitrifying bacteria. Here, three-time exposures to N and S applications (7, 30, and 60 days), were independently established. Additionally, the abundance, diversity, and structure of nirK- and nirS-type denitrifying communities were examined by sequencing analyses in response to three treatments, namely, N and S (T_N/S), sodium chloride (T_NaCl) and deionized water (pH = 7.0) (CK). Our results suggest that T_N/S led to higher electrical conductivity (EC), total nitrogen (TN), total organic carbon (TOC), nitrate nitrogen (NO₃^--N), ammonium nitrogen (NH₄⁺-N), and lower pH compared with T_NaCl and CK, which affected the diversity of nirK- and nirS-type denitrifying bacterial communities. We also observed that the nirK-type denitrifying community demonstrated a higher sensitivity to N and S additions. Overall, our results are important for the understanding of nitrogen in soil and N₂O emissions.