Isolation and identification of antagonistic Bacillus amyloliquefaciens HSE-12 and its effects on peanut growth and rhizosphere microbial community.

The HSE-12 strain isolated from peanut rhizosphere soil was identified as Bacillus amyloliquefaciens by observation of phenotypic characteristics, physiological and biochemical tests, 16S rDNA and gyrB gene sequencing. In vitro experiments showed that the strain possessed biocontrol activity against a variety of pathogens including Sclerotium rolfsii. The strain has the ability to produce hydrolytic enzymes, as well as volatile organic compounds with antagonistic and probiotic effects such as ethyleneglycol and 2,3-butanediol. In addition, HSE-12 showed potassium solubilizing (10.54 ± 0.19 mg/L), phosphorus solubilization (168.34 ± 8.06 mg/L) and nitrogen fixation (17.35 ± 2.34 mg/g) abilities, and was able to secrete siderophores [(Ar-A)/Ar × 100%: 56%] which promoted plant growth. After inoculating peanut with HSE-12, the available phosphorus content in rhizosphere soil increased by 27%, urease activity increased by 43%, catalase activity increased by 70% and sucrase activity increased by 50% (p < 0.05). The dry weight, fresh weight and the height of the first pair of lateral branches of peanuts increased by 24.7, 41.9, and 36.4%, respectively, compared with uninoculated peanuts. In addition, compared with the blank control, it increased the diversity and richness of peanut rhizosphere bacteria and changed the community structure of bacteria and fungi. The relative abundance of beneficial microorganisms such as Sphingomonas, Arthrobacter, RB41, and Micromonospora in rhizosphere soil was increased, while the relative abundance of pathogenic microorganisms such as Aspergillus, Neocosmospora, and Rhizoctonia was decreased.

Combined application of microbial inoculant and kelp-soaking wastewater promotes wheat seedlings growth and improves structural diversity of rhizosphere microbial community.

Industrial processing of kelp generates large amounts of kelp-soaking wastewater (KSW), which contains a large amount of nutrient-containing substances. The plant growth-promoting effect might be further improved by combined application of growth-promoting bacteria and the nutrient-containing KSW. Here, a greenhouse experiment was conducted to determine the effect of the mixture of KSW and Bacillus methylotrophicus M4-1 (MS) vs. KSW alone (SE) on wheat seedlings, soil properties and the microbial community structure in wheat rhizosphere soil. The available potassium, available nitrogen, organic matter content and urease activity of MS soil as well as the available potassium of the SE soil were significantly different (p < 0.05) from those of the CK with water only added, increased by 39.51%, 36.25%, 41.61%, 80.56% and 32.99%, respectively. The dry and fresh weight of wheat seedlings from MS plants increased by 166.17% and 50.62%, respectively, while plant height increased by 16.99%, compared with CK. Moreover, the abundance and diversity of fungi in the wheat rhizosphere soil were significantly increased (p < 0.05), the relative abundance of Ascomycetes and Fusarium spp. decreased, while the relative abundance of Bacillus and Mortierella increased. Collectively, the combination of KSW and the plant growth-promoting strain M4-1 can promote wheat seedlings growth and improve the microecology of rhizosphere microorganisms, thereby solving the problems of resource waste and environmental pollution, ultimately turning waste into economic gain.

Impact of COVID-19 travel-restriction policies on road traffic accident patterns with emphasis on cyclists: A case study of New York City.

Since the COVID-19 outbreak, travel-restriction policies widely adopted by cities across the world played a profound role in reshaping urban travel patterns. At the same time, there has been an increase in both cycling trips and traffic accidents involving cyclists. This paper aims to provide new insights and policy guidance regarding the effect of COVID-19 related travel-restriction policies on the road traffic accident patterns, with an emphasis on cyclists' safety. Specifically, by analysing the accidents data in the New York City and estimating three fixed effects logit models on the occurrence of different types of accidents in a given zip code area and time interval, we derived the following findings. First, while the overall number of road traffic accidents plummeted in the NYC after the stay-at-home policy was implemented, the average severity increased. The average number of cyclists killed or injured per accidents more than tripled relative to levels in similar times in previous years. Second, the declaration of the New York State stay-at-home order was significantly associated with a higher risk of accidents resulting in casualties. The number of Citi Bike trips in the area at the time overwhelmingly predicted severe risk for cyclists. Last, we applied the models to detect hot zones for cyclists' severe accidents. We found that these hot zones tend to be spatially and temporally concentrated, making it possible to devise targeted safety measures. This paper contributes to the understanding of the impact of COVID-19 travel-restriction policies on accidents involving cyclists, reveals higher risks for cyclists as an unintended consequence of travel-restriction policies, and provides an analytical tool for road safety impact evaluation should future travel restrictions be considered.

Impacts of continuous and rotational cropping practices on soil chemical properties and microbial communities during peanut cultivation.

Long-term monocultures have severely inhibited the cultivation of Chinese peanut (Arachis hypogaea L.). In this study, the effects of continuous cropping on soil chemical properties and microbial communities were investigated in peanut fields that had been in crop rotation for 10 years and in monoculture for 10 years. The results found that long-term monoculture increased the activities of available potassium, available phosphorus, available nitrogen, soil organic matter, urease, acid phosphatase and catalase; while decreasing the activity of catalase. The diversity and abundance of soil bacteria and fungi is higher under continuous peanut cultivation. At the genus level, the relative abundance of potentially beneficial microflora genera was higher in the rhizosphere soil of rotational cropping than in continuous cropping, while the opposite was true for the relative abundance of potentially pathogenic fungal genera. Principal coordinates and cluster analysis indicated that continuous cropping altered the structure of the microbial community. The results of the functional predictions showed significant differences in the functioning of the rhizosphere microbial community between continuous and rotational cropping. In conclusion, long-term continuous cropping changed the chemical properties of the soil, altered the structure and function of the soil bacterial and fungal communities in peanut rhizosphere, which to some extent reduced the relative abundance of potentially beneficial microbial genera and increased the relative abundance of potentially pathogenic fungal genera, thus increasing the potential risk of soil-borne diseases and reducing the yield and quality of peanut. Therefore, in the actual production process, attention should be paid not only to the application of chemical fertilizers, but also to crop rotation and the application of microbial fertilizers.

Bacillus licheniformis JF-22 to Control Meloidogyne incognita and Its Effect on Tomato Rhizosphere Microbial Community.

Meloidogyne incognita is one of the most destructive soil pests, causing serious economic losses in tomato production. Here, in vitro experiments demonstrated that the Bacillus licheniformis strain JF-22 has the potential to prevent M. incognita infection. A pot experiment confirmed that B. licheniformis strain JF-22 isolated from the tomato rhizosphere soil and planted in the tomato root-knot nematode disease area effectively prevented and controlled M. incognita, reducing its negative effect on tomato growth. Additionally, the composition of volatile substances secreted by B. licheniformis strain JF-22 was analyzed using solid-phase microextraction and gas chromatography-mass spectrometry. We detected acetoin, 2,3-Butanediol, [R-(R*,R*) ]-, and hexamethyl cyclotrisiloxane as the main components among these volatiles. Using MiSeq sequencing technology and bioinformatics, we analyzed the influence of B. licheniformis strain JF-22 on the microbial community of the tomato rhizosphere. B. licheniformis strain JF-22 changed the composition of the microbial community; particularly, it significantly reduced the diversity of the fungal community. Furthermore, using the FUNGuild and PICRUSt databases, we predicted the effect of JF-22 on microbial community function. In conclusion, B. licheniformis strain JF-22 may be considered as a potential biocontrol agent against M. incognita.

Bacillus subtilis HG-15, a Halotolerant Rhizoplane Bacterium, Promotes Growth and Salinity Tolerance in Wheat (Triticum aestivum).

Certain plant growth-promoting bacteria (PGPB) reduce salt stress damage in plants. Bacillus subtilis HG-15 is a halotolerant bacterium (able to withstand NaCl concentrations as high as 30%) isolated from the wheat rhizoplane in the Yellow River delta. A qualitative and quantitative investigation of the plant growth-promoting characteristics of this strain confirmed nitrogen fixation, potassium dissolution, ammonia, plant hormone, ACC deaminase, and proline production abilities. B. subtilis HG-15 colonization of wheat roots, stems, and leaves was examined via scanning electron microscopy, rep-PCR, and double antibiotic screening. After inoculation with the B. subtilis HG-15 strain, the pH (1.08-2.69%), electrical conductivity (3.17-11.48%), and Na+ (12.98-15.55%) concentrations of rhizosphere soil significantly decreased (p < 0.05). Under no-salt stress (0.15% NaCl), low-salt stress (0.25% NaCl), and high-salt stress (0.35% NaCl) conditions, this strain also significantly increased (p < 0.05) the dry weight (17.76%, 24.46%, and 9.31%), fresh weight (12.80%, 20.48%, and 7.43%), plant height (7.79%, 5.86%, and 13.13%), and root length (10.28%, 17.87%, and 48.95%). Our results indicated that B. subtilis HG-15 can effectively improve the growth of wheat and elicit induced systemic tolerance in these plants, thus showing its potential as a microbial inoculant that can protect wheat under salt stress conditions.

Effect ofBacillus velezensis JC-K3 on Endophytic Bacterial and Fungal Diversity in Wheat Under Salt Stress.

Plant growth-promoting bacteria (PGPB) can effectively reduce salt damage in plants. Currently, there are many studies on the effects of PGPB on the microbial community structure of rhizosphere soil under salt stress, but fewer studies on the community structure of endophytic bacteria and fungi. We propose that inoculation of endophytic bacteria into the rhizosphere of plants can significantly affect the microbial community structure of the plant's above-ground and underground parts, which may be the cause of the plant's "Induced Systemic Tolerance." The isolated endophytes were re-inoculated into the rhizosphere under salinity stress. We found that, compared with the control group, inoculation with endophytic Bacillus velezensis JC-K3 not only increased the accumulation of wheat biomass, but also increased the content of soluble sugar and chlorophyll in wheat, and reduced the absorption of Na in wheat shoots and leaves. The abundance of bacterial communities in shoots and leaves increased and the abundance of fungal communities decreased after inoculation with JC-K3. The fungal community richness of wheat rhizosphere soil was significantly increased. The diversity of bacterial communities in shoots and leaves increased, and the richness of fungal communities decreased. JC-K3 strain improved wheat's biomass accumulation ability, osmotic adjustment ability, and ion selective absorption ability. In addition, JC-K3 significantly altered the diversity and abundance of endophytic and rhizosphere microorganisms in wheat. PGPB can effectively reduce plant salt damage. At present, there are many studies on the effect of PGPB on the microbial community structure in rhizosphere soil under salt stress, but there are few studies on the community structure changes of endophytic bacteria and fungi in plants.

Cloud Formation From a Localized Water Release in the Upper Mesosphere: Indication of Rapid Cooling.

Polar mesospheric clouds (PMCs) occur in the summer near 82 -85km altitude due to seasonal changes of temperature and humidity. However, water vapor and associated PMCs have also been observed associated with rocket exhaust. The effects of this rocket exhaust on the temperature of the upper mesosphere are not well understood. To investigate these effects, 220 kg of pure water was explosively released at 85 km as part of the Super Soaker sounding rocket experiment on the night of January 25-26, 2018 at Poker Flat Research Range (65°N, 147°W). A cloud formed within 18 s and was measured by a ground-based Rayleigh lidar. The peak altitude of the cloud appeared to descend from 92 to 78 km over 3 min. Temperatures leading up to the release were between 197 and 232 K, about 50 K above the summertime water frost point when PMCs typically occur. The apparent motion of the cloud is interpreted in terms of the expansion of the explosive release. Analysis using a water vapor radiative cooling code coupled to a microphysical model indicates that the cloud formed due to the combined effects of rapid radiative cooling (∼25 K) by meter-scale filaments of nearly pure water vapor (∼1 ppv) and an increase in the frost point temperature (from 150 to 200 K) due to the high concentration of water vapor. These results indicate that water exhaust not only acts as a reservoir for mesospheric cloud production but also actively cools the mesosphere to induce cloud formation.

The Effect of Salt-Tolerant Antagonistic Bacteria CZ-6 on the Rhizosphere Microbial Community of Winter Jujube (Ziziphus jujuba Mill. "Dongzao") in Saline-Alkali Land.

As the main economic crop cultivated in the Yellow River Delta, winter jujube contains various nutrients. However, soil salinization and fungal diseases have affected the yield and quality of winter jujube. In order to use plant growth-promoting rhizobacteria (PGPR) to reduce these damages, the antagonistic bacteria CZ-6 isolated from the rhizosphere of wheat in saline soil was selected for experiment. Gene sequencing analysis identified CZ-6 as Bacillus amyloliquefaciens. In order to understand the salt tolerant and disease-resistant effects of CZ-6 strain, determination of related indicators of salt tolerance, pathogen antagonistic tests, and anti-fungal mechanism analyses was carried out. A pot experiment was conducted to evaluate the effect of CZ-6 inoculation on the rhizosphere microbial community of winter jujube. The salt tolerance test showed that CZ-6 strain can survive in a medium with a NaCl concentration of 10% and produces indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase. Studies on the inhibition mechanism of pathogenic fungi show that CZ-6 can secrete cellulase, protease, and xylanase. Gas chromatography-mass spectrometry (GC-MS) analysis showed that CZ-6 can release volatile organic compounds (VOCs), including 2-heptanone and 2-nonanone. In addition, the strain can colonize the rhizosphere and migrate to the roots, stems, and leaves of winter jujube, which is essential for plant growth or defense against pathogens. Illumina MiSeq sequencing data indicated that, compared to the control, the abundance of salt-tolerant bacteria Tausonia in the CZ-6 strain treatment group was significantly increased, while the richness of Chaetomium and Gibberella pathogens was significantly reduced. Our research shows that CZ-6 has the potential as a biological control agent in saline soil. Plant damage and economic losses caused by pathogenic fungi and salt stress are expected to be alleviated by the addition of salt-tolerant antagonistic bacteria.

Observations of Reduced Turbulence and Wave Activity in the Arctic Middle Atmosphere Following the January 2015 Sudden Stratospheric Warming.

Measurements of turbulence and waves were made as part of the Mesosphere-Lower Thermosphere Turbulence Experiment (MTeX) on the night of 25-26 January 2015 at Poker Flat Research Range, Chatanika, Alaska (65°N, 147°W). Rocket-borne ionization gauge measurements revealed turbulence in the 70- to 88-km altitude region with energy dissipation rates between 0.1 and 24 mW/kg with an average value of 2.6 mW/kg. The eddy diffusion coefficient varied between 0.3 and 134 m2/s with an average value of 10 m2/s. Turbulence was detected around mesospheric inversion layers (MILs) in both the topside and bottomside of the MILs. These low levels of turbulence were measured after a minor sudden stratospheric warming when the circulation continued to be disturbed by planetary waves and winds remained weak in the stratosphere and mesosphere. Ground-based lidar measurements characterized the ensemble of inertia-gravity waves and monochromatic gravity waves. The ensemble of inertia-gravity waves had a specific potential energy of 0.8 J/kg over the 40- to 50-km altitude region, one of the lowest values recorded at Chatanika. The turbulence measurements coincided with the overturning of a 2.5-hr monochromatic gravity wave in a depth of 3 km at 85 km. The energy dissipation rates were estimated to be 3 mW/kg for the ensemble of waves and 18 mW/kg for the monochromatic wave. The MTeX observations reveal low levels of turbulence associated with low levels of gravity wave activity. In the light of other Arctic observations and model studies, these observations suggest that there may be reduced turbulence during disturbed winters.

[Study on the role of autophagy in heme oxygenase 1 preventing hepatic ischemia/reperfusion injury in rats].

OBJECTIVE: To identify the role of autopahgy in the protective mechanism of heme oxygenase 1 (HO-1) against hepatic ischemia/reperfusion (I/R) injury. METHODS: Forty healthy male Sprague-Dawley (SD) rats were randomly (random number table) divided into five groups (n = 8 in each group), namely sham group, model group, cobalt protoporphyrin (CoPP) group, zinc protoporphyrin (ZnPP) group and 6-amino-3-methylpurine (3-MA) group. Partial hepatic I/R model was established by clamping the pedicles of left and median lobes for 1 hour and reopening for 6 hours in rats, and the rats in sham group were only received celiotomp without hepatic I/R. In the CoPP group, CoPP (a HO-1 inducer, 5 mg/kg) was administered i.p 24 hours before I/R. In the ZnPP or 3-MA group, besides pretreatment with CoPP, the rats were given ZnPP (a HO-1 inhibitor, 25 mg/kg) or 3-MA (an autophagy inhibitor, 30 mg/kg) i.p 1 hour before I/R. Serum alanine aminotransferase (ALT) was determined with automatic biochemistry analyzer. The hepatic pathological scores (PS) were determined under light microscope using hematoxylin-eosin (HE) staining. The hepatocyte apoptosis index (AI) was assessed with terminal dexynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. Autophagosomes in liver tissue were counted under electron microscope. The mRNA expressions of HO-1, caspase-3, Beclin-1 and Atg-5 in the liver were determined by reverse transcription-polymerase chain reaction (RT-PCR). The HO-1 activity was also measured by the generation of bilirubin with the method of double-wave spectrophotometry. RESULTS: Compared with the sham group, the level of serum ALT significantly increased in the I/R group (U/L: 560.3±73.6 vs. 49.1±13.8, P < 0.01), HE staining showed a severe hepatic injury (PS: 12.0±2.0 vs. 1.3±0.9, P < 0.01), TUNEL staining showed a higher hepatocytes apoptosis and the expression of caspase-3 significantly increased [AI: (19.38±3.07)% vs. (3.25±1.28)%, caspase-3 mRNA (2-ΔΔCt): 4.62±0.40 vs. 1.05±0.15, both P < 0.01]. However, there was no significant difference in the expression of HO-1 and the genes associated with autophagy between the two groups. In the CoPP group, the hepatic injury was blunted compared with that in the I/R group [ALT (U/L): 223.3±34.4 vs. 560.3±73.6, PS: 5.6±2.3 vs. 12.0±2.0, AI: (11.38±2.39)% vs. (19.38±3.07)%, caspase-3 mRNA (2-ΔΔCt): 2.42±0.33 vs. 4.62±0.40, all P < 0.01]. HO-1 was induced in the CoPP group and autophagy was also increased significantly after I/R when compared with those in the I/R group [HO-1 mRNA (2-ΔΔCt): 3.01±0.71 vs. 1.14±0.20, HO-1 activity (pmol×mg-1×h-1): 259±37 vs. 113±26, the number of autophagosomes: 8.75±0.87 vs. 1.25±0.71, Beclin-1 mRNA (2-ΔΔCt): 2.85±0.28 vs. 1.15±0.11, Atg-5 mRNA (2-ΔΔCt): 2.44±0.25 vs. 1.14±0.12, all P < 0.01]. In the ZnPP group, the activity of HO-1 was much lower than that in the CoPP group, and as a result autophagy was decreased and liver injury was increased. In the 3-MA group, although there was no difference in the activity of HO-1 compared with that in the CoPP group, autophagy was inhibited, and the protective effect of CoPP was eliminated. CONCLUSIONS: HO-1 could regulate the level of autophagy during liver I/R, and in turn autophagy might mediate the protective effects of HO-1 against liver I/R injury.