Green synthesized lignin nanoparticles for the sustainable delivery of pyraclostrobin to control strawberry diseases caused by Botrytis cinerea.

Lignin, renowned for its renewable, biocompatible, and environmentally benign characteristics, holds immense potential as a sustainable feedstock for agrochemical formulations. In this study, raw dealkaline lignin (DAL) underwent a purification process involving two sequential solvent extractions. Subsequently, an enzyme-responsive nanodelivery system (Pyr@DAL-NPs), was fabricated through the solvent self-assembly method, with pyraclostrobin (Pyr) loaded into lignin nanoparticles. The Pyr@DAL-NPs shown an average particle size of 250.4 nm, demonstrating a remarkable loading capacity of up to 54.70 % and an encapsulation efficiency of 86.15 %. Notably, in the presence of cellulase and pectinase at a concentration of 2 mg/mL, the release of Pyr from the Pyr@DAL-NPs reached 92.66 % within 120 h. Furthermore, the photostability of Pyr@DAL-NPs was significantly improved, revealing a 2.92-fold enhancement compared to the commercially available fungicide suspension (Pyr SC). Bioassay results exhibited that the Pyr@DAL-NPs revealed superior fungicidal activity against Botrytis cinerea over Pyr SC, with an EC50 value of 0.951 mg/L. Additionally, biosafety assessments indicated that the Pyr@DAL-NPs effectively declined the acute toxicity of Pyr towards zebrafish and posed no negative effects on the healthy growth of strawberry plants. In conclusion, this study presents a viable and promising strategy for developing environmentally friendly controlled-release systems for pesticides, offering the unique properties of lignin.

Inhibition mechanism of Rhizoctonia solani by pectin-coated iron metal-organic framework nanoparticles and evidence of an induced defense response in rice.

Nanocrop protectants have attracted much attention as sustainable platforms for controlling pests and diseases and improving crop nutrition. Here, we reported the fungicidal activity and disease inhibition potential of pectin-coated metal-iron organic framework nanoparticles (Fe-MOF-PT NPs) against rice stripe blight (RSB). An in vitro bacterial inhibition assay showed that Fe-MOF-PT NPs (80 mg/L) significantly inhibited mycelial growth and nucleus formation. The Fe-MOF-PT NPs adsorbed to the surface of mycelia and induced toxicity by disrupting cell membranes, mitochondria, and DNA. The results of a nontargeted metabolomics analysis showed that the metabolites of amino acids and their metabolites, heterocyclic compounds, fatty acids, and nucleotides and their metabolites were significantly downregulated after treatment with 80 mg/L NPs. The difference in metabolite abundance between the CK and Fe-MOF-PT NPs (80 mg/L) treatment groups was mainly related to nucleotide metabolism, pyrimidine metabolism, purine metabolism, fatty acid metabolism, and amino acid metabolism. The results of the greenhouse experiment showed that Fe-MOF-PT NPs improved rice resistance to R. solani by inhibiting mycelial invasion, enhancing antioxidant enzyme activities, activating the jasmonic acid signaling pathway, and enhancing photosynthesis. These findings indicate the great potential of Fe-MOF-PT NPs as a new RSB disease management strategy and provide new insights into plant fungal disease management.

Different characteristics of microbial diversity and special functional microbes in rainwater and topsoil before and after 2019 new coronavirus epidemic in Inner Mongolia Grassland.

Grassland ecosystems are vital terrestrial ecosystems. As areas sensitive to climate change, they are critical for assessing the effects of global climate change. In China, grasslands account for over 40% of the land area. There is currently limited information on microbial diversity evolution in different grassland areas, particularly microorganisms with ice nucleation activity (INA) and their potential resources with potential influence to regulate regional precipitation and climate. We used Illumina MiSeq to sequence the 16S rRNA V3-V4 hypervariable region and performed a simple droplet freezing experiment to determine the variation in the grassland microbial community species composition and community structure. Rainwater and topsoil samples from the Hulunbuir Grassland in Inner Mongolia collected over three years were characterized. The dominant bacterial genus in the rainwater was Massilia, and the dominant fungus was Cladosporium. Additionally, the dominant bacteria in the soil were Sphingomonas, and the dominant fungus was Gibberella. There were differences in the microbial communities before and after the coronavirus disease epidemic. Pathogenic microorganisms exhibited inconsistent responses to environmental changes. The low relative abundance of known high-INA microorganisms and the higher freezing temperature indicated that unknown high-efficiency biological ice nucleating particles may be present. We found significant differences in species diversity and richness between the rainwater and soil populations in grassland areas by analyzing the sample community structures. Our research results revealed the species composition and structure of the microbiota in grassland ecosystems in China, indicating that environmental media and human activities may affect the microbiota in the grassland area and indicating underlying microorganisms with high INA.

Evolution of PM2.5 bacterial community structure in Beijing's suburban atmosphere.

Biosafety has become one of the greatest challenges facing humanity. Outbreaks of infectious diseases caused by bacteria and viruses have had a huge impact on public health. In addition, non-severe polluted air quality has gradually become the norm; however, literature on the impacts of bioaerosols under long-term exposure to low concentrations of PM2.5 in China is limited. This study analyzed the evolution of the PM2.5 bacterial community in the Huairou district of Beijing under different pollution conditions. We used high-throughput sequencing to seasonally analyze samples over a year (from July 2018 to May 2019) and winter samples from different years (2015, 2016, 2018, and 2019). The results showed that the bacterial diversity and community composition of PM2.5 were significantly different in different seasons, whereas under different pollution levels, there were no significant differences. During the observation period, the number of bacterial species decreased with the increase in pollution; however, a high proportion of bacteria can exist as core species under different pollution levels for a long time. Furthermore, bacteria can be relatively stable in the local environment during the same season but in different years. Although the relative abundances of different bacteria change differently with the variation in pollution level, there is no statistical difference. Importantly, there was a higher abundance of opportunistic pathogenic bacteria when the air quality index was 0-100 in winter. This study comprehensively revealed the characteristics of the evolution of bacterial communities under different pollution levels and in different years and emphasized the health effects of non-pollution air quality. This study can provide a theoretical basis for establishing a sound environmental microbial monitoring and defense system.

Survey of background microbial index in inhalable particles in Beijing.

As a potential transmission route for diseases, aerosols have an important impact on human health. At present, research concerning the biological components of atmospheric particulate matter (PM) is of increasing interest. However, previous research has mainly focused on serious pollution conditions, creating a knowledge gap regarding background atmospheric microbes. In this study, we observed the atmosphere of Huairou in Beijing for one year, analyzed the characteristics of the physiological metabolic activity of the microorganisms as an index to determine the air quality, and further explored the microbial communities. From January 2018 to January 2019, a total of 157 days of microbial activity data for PM2.5 and PM10 were obtained through the use of a modified fluorescein diacetate (FDA) hydrolysis method. Our results showed that there was no significant difference between the microbial activity of PM2.5 and PM10, even though there was significant seasonal variation. At increasing pollution levels, the results showed that the microbial activity decreased at first, and then increased as the conditions worsened. The microbial community of PM2.5 was analyzed using the high-throughput sequencing method. There were significant seasonal differences in species richness and community diversity of bacteria in PM2.5, whereas there was variation only in its fungi species richness. Notably, the microbial community dominated by bacteria has a significant influence on microbial activity. From the perspective of microbial community composition, this study uncovered the possible causes of microbial activity variation and identified the key bacteria and fungi. These results will provide a theoretical basis for both improving air biological pollution predictions and ambient air quality evaluations.

Seasonal variation characteristic of inhalable microbial communities in PM2.5 in Beijing city, China.

Bacteria and fungi are primary constituents of airborne microbes in fine particulate matter (PM2.5) and significantly impact human health. However, hitherto, seasonal variation and effect of air pollution on microbial community composition and structure are poorly understood. This study analyzed the bacterial and fungal composition of PM2.5 under different air pollution levels during different seasons in Beijing. We altogether collected 75PM2.5 samples during four seasons from April 2014 to January 2015, under different air pollution levels and employed high-throughput sequencing methods to analyze microbial composition. The results showed that air pollution decreased species richness and community diversity of bacteria in PM2.5. The variation in bacterial and fungal community composition and structure was significantly related to the season but there was no correlation between their abundance and pollution levels. Pathogenic bacteria and fungi were more abundant in winter than other seasons. To best of our knowledge, this is the first study that demonstrates seasonal variation characteristics of bacteria and fungi in PM2.5 in heavy haze contaminated areas and highlights the effects of air pollution on the atmospheric microbial community. This study would be useful to other bioaerosol studies focusing on the role of the atmospheric particulate matter on human health.

Evidence for a missing source of efficient ice nuclei.

It has been known for several decades that some bioaerosols, such as ice-nucleation-active (INA) bacteria, especially Pseudomonas syringae strains, may play a critical potential role in the formation of clouds and precipitation. We investigated bacterial and fungal ice nuclei (IN) in rainwater samples collected from the Hulunber temperate grasslands in North China. The median freezing temperatures (T50) for three years' worth of unprocessed rain samples were greater than -10 °C based on immersion freezing testing. The heat and filtration treatments inactivated 7-54% and 2-89%, respectively, of the IN activity at temperatures warmer than -10 °C. We also determined the composition of the microbial community. The majority of observed Pseudomonas strains were distantly related to the verified ice-nucleating Pseudomonas strains, as revealed by phylogenetic analysis. Here, we show that there are submicron INA particles <220 nm in rainwater that are not identifiable as the known species of high-INA bacteria and fungi and there may be a new potential type of efficient submicroscale or nanoscale ice nucleator in the regional rainwater samplers. Our results suggest the need for a reinterpretation of the source of high-INA material in the formation of precipitation and contribute to the search for new methods of weather modification.

Influences of Land Use/Cover Types on Nitrous Oxide Emissions during Freeze-Thaw Periods from Waterlogged Soils in Inner Mongolia.

Nitrous oxide emissions during freeze/thaw periods contribute significantly to annual soil N2O emissions budgets in middle- and high-latitude areas; however, the freeze/thaw-related N2O emissions from waterlogged soils have hardly been studied in the Hulunber Grassland, Inner Mongolia. For this study, the effects of changes in land use/cover types on N2O emissions during freeze-thaw cycles were investigated to more accurately quantify the annual N2O emissions from grasslands. Soil cores from six sites were incubated at varying temperature (ranging from -15 to 10°C) to simulate freeze-thaw cycles. N2O production rates were low in all soil cores during freezing periods, but increased markedly after soil thawed. Mean rates of N2O production differed by vegetation type, and followed the sequence: Leymus chinensis (LC) and Artemisia tanacetifolia (AT) steppes > LC steppes ≥ Stipa baicalensis (SB) steppes. Land use types (mowing and grazing) had differing effects on freeze/thaw-related N2O production. Grazing significantly reduced N2O production by 36.8%, while mowing enhanced production. The production of N2O was related to the rate at which grassland was mowed, in the order: triennially (M3) > once annually (M1) ≥ unmown (UM). Compared with the UM control plot, the M3 and M1 mowing regimes enhanced N2O production by 57.9% and 13.0% respectively. The results of in situ year-round measurements showed that large amounts of N2O were emitted during the freeze-thaw period, and that annual mean fluxes of N2O were 9.21 µg N2O-N m-2 h-1 (ungrazed steppe) and 6.54 µg N2O-N m-2 h-1 (grazed steppe). Our results further the understanding of freeze/thaw events as enhancing N2O production, and confirm that different land use/cover types should be differentiated rather than presumed to be equivalent, regarding nitrous oxide emission. Even so, further research involving multi-year and intensive measurements of N2O emission is still needed.

[Diversity of bacterial aerosols in precipitation of Shanghai area].

In the present study, 16S rRNA gene sequencing based approaches were used to analyze the bacterial communities and diversity in the precipitation samples from Shanghai city, which were carried out in different months in 2012. Five clone libraries were established based on the rainwater samples collected during 5 different precipitation periods. The results showed that Proteobacteria (alpha-, beta-, gamma-) (32.5% - 94.1%) were dominant in the precipitation, including Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria, while other 6 bacterial communities, such as Bacteroidetes, Actinobacteria, Deinococcus-Thermus, Cyanobacteria, Acidobacteria, and Firmicutes, were involved as well. Furthermore, a small proportion of undetermined bacteria (TM7, 2.5%) were also found. In addition, microbial diversity in the sample of SH6 was obviously more than those in other samplers. The investigation revealed that there was a difference in the bacterial communities and diversity in precipitation of different months.