Nitrogen transformation and its microbial mechanism under co-composting of biogas slurry with garden waste.

Large amount of garden waste is consecutively produced in China every year. The composting with urea and microbial inoculum makes it possible to dispose garden waste in large quantities. However, composting accompanies with serious nitrogen loss and environmental problems. The biogas slurry contains considerable nitrogen nutrients and microorganisms, which theoretically could be used as alternative to urea and bacteria to reduce nitrogen loss, respectively. We set up three treatments of biogas slurry + garden waste (GB), biogas slurry + garden waste + urea (GBU), and biogas slurry + garden waste + urea + microbial inoculum (GBUM) to investigate the decomposition, nitrogen conversion and nitrogen loss in the co-composting process. The results showed that the high tempe-rature period of GB treatment was longer and more stable compared to that of GBU and GBUM treatments. The pH and EC value of GB treatment would benefit composting process and generated products with the highest germination index (GI) (221.8%). In addition, NH3 and N2O emission rates in the GB treatment were 2.59 mg·kg-1·d-1 and 3.65 µg·kg-1·d-1, respectively, being 99.0% and 50.0% lower than that in the GBU treatment and 99.4% and 40.7% lower than that in the GBUM treatment. The results of δ18O vs. δ15NSP dual isotopocule plots approach analysis showed that the GB and GBU treatments were dominated by denitrification, and that the contribution of denitrification was higher in the GB treatment. In contrast, the GBUM treatment was dominated by nitrification. The degree of N2O reduction in GB treatment (83.7%) was higher than the other two treatments. It was clear that GB treatment had the best maturity and lowest nitrogen loss in all treatments by enhancing the N2O reduction process during denitrification to reduce N2O emission. In conclusion, the biogas slurry and garden wastes could be directly co-composted without the limitation of C/N and microbial addition. The co-composting method could protect the environment and save resources leading to the recycling of waste in actual production.

Preoptimized phage cocktail for use in aerosols against nosocomial transmission of carbapenem-resistant Acinetobacter baumannii: A 3-year prospective intervention study.

Using bacteriophages (phages) as environmental sanitizers has been recognized as a potential alternative method to remove bacterial contamination in vitro; however, very few studies are available on the application of phages for infection control in hospitals. Here, we performed a 3-year prospective intervention study using aerosolized phage cocktails as biocontrol agents against carbapenem-resistant Acinetobacter baumannii (CRAB) infection in the hospital. When a CRAB-infected patient was identified in an intensive care unit (ICU), their surrounding environment was chosen for phage aerosol decontamination. Before decontamination, 501 clinical specimens from the patients were subjected to antibiotic resistance analysis and phage typing. The optimal phage cocktails were a combination of different phage families or were constructed by next-evolutionary phage typing with the highest score for the host lysis zone to prevent the development of environmental CRAB phage resistance. The phage infection percentage of the antibiotic-resistant A. baumannii strains was 97.1%, whereas the infection percentage in the antibiotic-susceptible strains was 79.3%. During the phage decontamination periods from 2017 to 2019, the percentage of carbapenem-resistant A. baumannii in test ICUs decreased significantly from 65.3% to 55%. The rate of new acquisitions of CRAB infection over the three years was 4.4 per 1000 patient-days, which was significantly lower than that in the control wards (8.9 per 1000 patient-days) where phage decontamination had never been performed. In conclusion, our results support the potential of phage cocktails to decrease CRAB infection rates, and the aerosol generation process may make this approach more comprehensive and time-saving.

[Identifying the Sources of Groudwater NO3--N in Agricultural Region of Qingdao].

To increase crops yields, applying large amounts of fertilizers has become increasingly common in agricultural regions, resulting in NO3--N groundwater pollution. Agricultural non-point pollution is the main source of groundwater NO3--N pollution. To ensure drinking water safety and quality, it is crucial to clarify the sources of NO3--N pollution in agricultural regions. In this study, 35 sampling sites were randomly selected in the Qingdao agricultural area in 2009 and 2019. The spatial distribution of NO3--N concentration was analyzed by the inverse distance weighting method (IDW). The nitrogen and oxygen isotopes were used as a tool to trace sources of NO3--N and the SIAR model was used to quantify contribution proportion of pollution sources. The results showed that the concentration of NO3--N (average) in groundwater in Qingdao has been reduced from 38.49 mg·L-1 in 2009 to 22.37 mg·L-1 in 2019, but it is still higher than the maximum allowable concentration of NO3--N in drinking water set by the World Health Organization (WHO). The NO3--N concentration gradually increased from south to north both in 2009 and 2019. The cross diagram of δ15N-NO3- and δ18O-NO3- show that the main sources of NO3--N in groundwater in Qingdao are chemical fertilizers, soil nitrogen, and manure and sewage. Water isotopes indicate that precipitation was the main source of groundwater in Qingdao. The SIAR model results indicated that the contribution of each source ranked as follows:manure and sewage (47.42%) > soil nitrogen (27.80%) > chemical fertilizer (14.32%) > atmospheric nitrogen depositions (10.43%). From 2009 to 2019, the quality of groundwater in Qingdao has been improved, but NO3--N pollution still cannot be ignored. According to the results, prevention and control should be made to ensure the safety of drinking water and the sustainable development of agriculture.

[Effects of organic and inorganic fertilizers on emission and sources of N2O in vegetable soils.] / æœ‰æœºè‚¥å’Œæ— æœºè‚¥å¯¹èœåœ°åœŸå£¤N2OæŽ’æ”¾åŠå ¶æ¥æºçš„å½±å“.

To clarify the microbial pathway of the N2O production and consumption under different fertilizers and provide theoretical basis for the reduction of N2O emission and rational management of fertilization in vegetable soils, we examined dynamics of N2O flux and isotope signatures under different fertilizer treatments in the vegetable soils of Beijing, by setting up four treatments (organic-acetylene, organic-nonacetylene, inorganic-acetylene, inorganic-nonacetylene) and using the stable isotope technique of natural N2O abundance. The results showed that the cumulative N2O emission from organic-acetylene group, organic-nonacetylene group, inorganic-acetylene group and inorganic-nonacetylene group was (374±37), (283±34), (458±36), (355±41) g·m-2 in cabbage growing season, respectively. N2O fluxes were significantly lower in treatments with organic fertilizer than those with inorganic fertilizer and significantly higher in acetylene group than nonacetylene group. The degree of N2O reduction were similar in both fertilizer treatments, and higher nitrification was found in inorganic fertilizer than organic fertilizer treatments. Acetylene only inhibited partial nitrification and partial N2O reduction at the peak of N2O emission. When the emission was reduced, N2O reduction could be completely suppressed. Therefore, the inorganic fertilizer might trigger nitrification and promote higher N2O emission. The high concentration of N2O could withstand that acetylene to inhibite N2O reduction. Hence, using organic fertilizers instead of some inorganic ones could effectively reduce N2O emission in vegetable soils of Beijing. The N2O concentration threshold should be considered when we identify N2O source by acetylene inhibition method.

Transcriptome analysis around the onset of strawberry fruit ripening uncovers an important role of oxidative phosphorylation in ripening.

Although much progress has been made towards understanding the ripening of non-climacteric fruit using the strawberry as a model plant, the defined molecular mechanisms remain unclear. Here, RNA-sequencing was performed using four cDNA libraries around the onset of ripening, and a total of 31,793 unigenes and 335 pathways were annotated including the top five pathways, which were involved in ribosome, spliceosome, protein processing, plant-pathogen interaction and plant hormone signaling, and the important DEGs related to ripening were annotated to be mainly involved in protein translation and processing, sugar metabolism, energy metabolism, phytohormones, antioxidation, pigment and softening, especially finding a decreased trend of oxidative phosphorylation during red-coloring. VIGS-mediated downregulation of the pyruvate dehydrogenase gene PDHE1α, a key gene for glycolysis-derived oxidative phosphorylation, could inhibit respiration and ATP biosynthesis, whilst promote the accumulation of sugar, ABA, ETH, and PA, ultimately accelerating the ripening. In conclusion, our results demonstrate that a set of metabolism transition occurred during green-to-white-to-red stages that are coupled with more-to-less DEGs, and the oxidative phosphorylation plays an important role in the regulation of ripening. On the basis of our results, we discuss an oxidative phosphorylation-based model underlying strawberry fruit ripening.

[Effects of soil water condition on N2O emission and its sources in vegetable farmland of North China Plain]. / 不同灌溉量对华北平原菜地N2OæŽ’æ”¾åŠå ¶æ¥æºçš„å½±å“.

To understand the mechanisms of agricultural N2O emission, we investigated the N2O emission dynamics, the N2O isotope signatures, and the site preference value under different soil water conditions in the vegetable farmland of North China, by using the stable isotope technique and the acetylene inhibition method. The results demonstrated that N2O emission was significantly affec-ted by the water condition, and N2O emissions from soil with water-filled pore space (WFPS) of 70% were significantly higher than that with 50% WFPS. N2O emission occurred mostly in the early stage of fertilization, and decreased rapidly in the later stage of fertilization. At 50% WFPS, nitrification was the major process generating N2O during the early fertilization stage, accounting for approximately 90% of the N2O emission. However, the contribution of nitrification decreased sharply, whereas denitrification became the dominant process, accounting for 80% of the N2O emission 7 days after the fertilization. On the other hand, at 70% WFPS, denitrification was the main process releasing N2O during the early fertilization stage, decreasing from 70% to 40% and then gradually increasing to 80% 10 days after the fertilization. Overall, N2O emission was mainly dominated by the denitrification. The effect of different water treatments on soil nitrification and denitrification took place mainly in the early stage of fertilization, and N2O emission was gradually dominated by the denitrification at the later stage. These results suggested we could reduce N2O emission by approp-riately reducing the amount of irrigation in the vegetable farmland of North China.

[A review on development of stable isotope technique in the studies of N2O formation mechanism]. / ç¨³å®šåŒä½ç´ æŠ€æœ¯åœ¨åœŸå£¤N2Oæº¯æºç ”ç©¶ä¸­çš„åº”ç”¨.

As one of three major greenhouse gases, nitrous oxide (N2O) has solicited substantial attention. Stable isotope has been widely used to explore the sources of N2O emissions. Here, we briefly introduced the microbial processes involved in N2O emissions, and the main influencing factors. We further summarized the development of N2O isotope signature of δ15N, δ18O and SP (site preference of 15N in different positions of N2O molecule) in exploring the N2O formation mechanism. The application of these techniques, especially the SP values, is still at the primary stage in China. Therefore, this paper focused on the development of the isotope ratios analysis in partitioning N2O sources from foreign countries, and put forward suggestions on the future research in China.

Regulatory T cells from active non-segmental vitiligo exhibit lower suppressive ability on CD8+CLA+ T cells.

BACKGROUND: Recent studies have shown that vitiligo is a T-cell mediated autoimmune disease. Skin-homing cytotoxic T lymphocytes expressing cutaneous lymphocyte-associated antigen (CLA) have been suggested to be responsible for the destruction of melanocytes in vitiligo. An aberration in the suppressive function of regulatory T cells (Tregs) has been reported in vitiligo patients. However, whether the weakened suppressive ability of the Tregs contributes to hyper-activated skin homing CD8(+)CLA(+) T cells remains to be determined. OBJECTIVES: To investigate the inhibition of circulating Tregs on the proliferation of autologous CD8(+)CLA(+) T cells in non-segmental vitiligo patients. METHODS: CD8(+)CLA(+) T cells and Tregs were obtained from the peripheral blood of 13 non-segmental vitiligo patients and 7 controls. The proliferative responses of CD8(+)CLA(+) T cells were assessed in the absence or presence of autologous Tregs, and the levels of Transforming Growth Factor ß1(TGF-ß1) and IL-10 in culture supernatants were detected by enzyme-linked immunosorbent assay. RESULTS: The proliferative responses of circulating CD8(+)CLA(+) T cells in the presence of Tregs were significantly higher in the active vitiligo than in the stable vitiligo and control groups. Tregs from active vitiligo patients exhibited a lower inhibitory effect on proliferation of CD8(+)CLA(+) T cells. The levels of TGF-ß1 produced by Tregs were significantly lower in active vitiligo than other groups and anti-TGF-ß1 antibodies could abrogate the suppressive function of Tregs. CONCLUSIONS: The functional activity of Tregs is compromised in active vitiligo patients. TGF-ß1 plays an important role in the autoimmune mechanism of the disease.

[The role of phospholipase D in cellular signaling].

Phospholipase D (PLD) hydrolyzes structural phospholipids of biological membrane to produce phosphatidic acid (PA) and a free-head group. Both of these compounds can participate in signal transduction. Since the activation of PLD involved in many cellular signaling cascades was identified in recent years, knowledge of and interest in PLD have grown greatly, and significant progress has been made toward understanding PLD. This paper reviewed the research progress on gene structure, regulation and cellular function of PLD. PLDs are encoded by a multiple heterogenous gene family. The overall domain structures of plant PLDs are similar, but important differences occur in some of the motifs. The small structural variations underlie distinct regulatory and catalytic properties and cellular function in signaling. PA and other messengers produced by other phospholipase pathways can be interconverted with the action of lipid kinase and phosphatase. PLD is thought to function as an integral part of a network involving other lipid-signaling enzymes and messengers. Some research evidence demonstrated the specificity of PLDs in signal transduction with plant species, cell types, stimuli and cellular processes. Some important questions about PLD study were also raised.