The Composition and Diversity of the Rhizosphere Bacterial Community of Ammodendron bifolium Growing in the Takeermohuer Desert Are Different from Those in the Nonrhizosphere.

Soil microorganisms play important roles in vegetation establishment and soil biogeochemical cycling. Ammodendron bifolium is a dominant sand-fixing (i.e., stabilizing sand dunes) and endangered plant in the Takeermohuer Desert, and the bacterial community associated with this plant rhizosphere is still unclear. In this study, we investigated the composition and diversity of the bacterial community from the A. bifolium rhizosphere and bulk soil at different soil depths (i.e., 0-40 cm, 40-80 cm, 80-120 cm) using culture and high-throughput sequencing methods. We preliminarily analyzed the edaphic factors influencing the structure of bacterial communities. The results showed that the high-salinity Takeermohuer Desert has an oligotrophic environment, while the A. bifolium rhizosphere exhibited a relatively nutrient-rich environment due to higher contents of soil organic matter (SOM) and soil alkaline nitrogen (SAN) than bulk soil. The dominant bacterial groups in the desert were Actinobacteria (39.8%), Proteobacteria (17.4%), Acidobacteria (10.2%), Bacteroidetes (6.3%), Firmicutes (6.3%), Chloroflexi (5.6%), and Planctomycetes (5.0%) at the phylum level. However, the relative abundances of Proteobacteria (20.2%) and Planctomycetes (6.1%) were higher in the rhizosphere, and those of Firmicutes (9.8%) and Chloroflexi (6.9%) were relatively higher in barren bulk soil. A large number of Actinobacteria were detected in all soil samples, of which the most abundant genera were Streptomyces (5.4%) and Actinomadura (8.2%) in the bulk soil and rhizosphere, respectively. The Chao1 and PD_whole_tree indices in the rhizosphere soil were significantly higher than those in the bulk soil at the same soil depth and tended to decrease with increasing soil depth. Co-occurrence network analyses showed that the keystone species in the Takeermohuer Desert were the phyla Actinobacteria, Acidobacteria, Proteobacteria, and Chloroflexi. Furthermore, the major edaphic factors affecting the rhizosphere bacterial community were electrical conductivity (EC), SOM, soil total nitrogen (STN), SAN, and soil available potassium (SAK), while the major edaphic factors affecting the bacterial community in bulk soil were distance and ratio of carbon to nitrogen (C/N). We concluded that the A. bifolium rhizosphere bacterial community is different from that of the nonrhizosphere in composition, structure, diversity, and driving factors, which may improve our understanding of the relationship between plant and bacterial communities and lay a theoretical foundation for A. bifolium species conservation in desert ecosystems.

Pontibacter kalidii sp. nov., isolated from rhizosphere soil of Kalidium foliatum.

A Gram-negative, aerobic, gliding motile, rod-shaped bacterium, designated XAAS-72T, was isolated from the rhizosphere soil of Kalidium foliatum sampled in the Xinjiang Uyghur Autonomous Region, PR China. Cells grew at 4-45 °C, pH 5.0-8.0 and 0-8% NaCl, with optimal growth at 20-30 °C, pH 6.0-7.0 and 1-2 % NaCl. Strain XAAS-72T is closely related to members of the genus Pontibacter, namely Pontibacter korlensis CCTCC AB 206081T (97.6%) and Pontibacter flavimaris ACCC 19859T (97.2 %), and <94.6 % related to other currently described Pontibacter strains. The average nucleotide identity values between XAAS-72T and P. korlensis CCTCC AB 206081T and P. flavimaris ACCC 19859T were 77.9 and 86.9 %, respectively; the corresponding digital DNA-DNA hybridization values were 21.7 and 31.8 %. Menaquinone-7 was the predominant respiratory menaquinone. The polar lipids consisted of phosphatidylethanolamine, two unidentified aminophospholipids, two unidentified glycolipids and five unidentified lipids. The major cellular fatty acids were summed feature 4 (containing iso-C17 : 1 I/anteiso-C17 : 1 B), summed feature 3 (containing C16 : 1 ω7c/C16 : 1 ω6c) and iso-C15 : 0. The genome length of strain XAAS-72T was 5 054 860 bp with a genomic DNA G+C content of 54.5 mol%. The phenotypic and genotypic data suggest that strain XAAS-72T represents a novel species of the genus Pontibacter, for which the name Pontibacter kalidii sp. nov. is proposed. The strain is XAAS-72T (CGMCC 16594T=KCTC 72095T).

Composition and Distribution Characteristics of Rhizosphere Bacterial Community of Ammodendron bifolium Growing in Takeermohuer Desert Are Different from Those in Non-rhizosphere.

Soil microorganisms play important roles in vegetation establishment and soil biogeochemical cycling. Ammodendron bifolium is a dominant sand-fixing and endangered plant in Takeermohuer Desert, and bacterial community associated with this plant rhizosphere is still unclear. In this study, we studied the composition and diversity of bacterial community from A. bifolium rhizosphere and bulk soil at different soil depths (i.e., 0-40 cm, 40-80 cm, 80-120 cm) using traditional bacterial isolation and high-throughput sequencing approaches, and preliminarily analyzed the edaphic factors influencing the structure of bacterial communities. Results showed that Takeermohuer Desert with high salinity has been an oligotrophic environment, while the rhizosphere exhibited eutrophication resulting from high content SOM (soil organic matter) and SAN (soil alkaline nitrogen) compared with bulk soil. The dominant bacterial groups in the desert were Actinobacteria (39.8%), Proteobacteria (17.4%), Acidobacteria (10.2%), Bacteroidetes (6.3%), Firmicutes (6.3%), Chloroflexi (5.6%), and Planctomycetes (5.0%) at the phyla level. However, the relative abundances of Proteobacteria (20.2%) and Planctomycetes (6.1%) were higher in eutrophic rhizosphere, and Firmicutes (9.8%) and Chloroflexi (6.9%) relatively higher in barren bulk soil. A large number of Actinobacteria were detected in all soil samples, of which the most abundant genus was Streptomyces (5.4%) and Actinomadura (8.2%) in the bulk soil and rhizosphere, respectively. The Chao1 and PD indexes in rhizosphere were significantly higher than those in bulk soil at the same soil depth, and tended to decrease with increasing soil depth. Co-occurrence network analyses showed that the keystone species in Takeermohuer Desert were Actinobacteria, Acidobacteria, Proteobacteria, and Chlorofexi. Furthermore, the major environmental factors affecting rhizosphere bacterial community were EC (electrical conductivity), SOM, STN (soil total nitrogen), SAN, and SAK (soil available potassium), while bulk soil were distance and C/N (STC/STN). We concluded that A. bifolium rhizosphere bacterial community is different from non-rhizosphere in composition, distribution, and environmental influencing factors, which will have important significances for understanding their ecological functions and maintaining biodiversity.

Response of bacterial communities in saline-alkali soil to different pesticide stresses.

The objective is to understand the diversity of bacteria-degrading pesticide pollutants in Xinjiang saline-alkali soil environment and resolve the lack of suitable degrading bacteria resources for bioremediation of pesticide pollution in this environment. The soil of long-term continuous cropping cotton fields in Xinjiang was used to culture the degrading bacterial communities under long-term stress of five pesticides, such as beta-cypermethrin. Then, the degradation rate and structural composition of each bacterial communities were analyzed. The soil bacterial diversity in Xinjiang saline-alkali cotton fields was high, from which not only imidacloprid and other commonly and once used pesticide-degrading bacterial communities were enriched but also isoprocarb-degrading bacterial communities, which had never been used, were enriched. After long-term passage, the structural composition of each degrading bacterial communities was stable, and the degradation rates were between 17 and 48%, respectively, in a specific culture period. Each degrading bacterial communities covers many reported pesticide-degrading bacterial genera and contains unique bacterial genera in each 3. These results laid a foundation for studying the metabolic pathway of pesticide pollutants in saline-alkali environment and exploring microbial resources in Xinjiang. Graphical Abstract Variety of pesticide degrading bacteria resources in saline alkali soil of Xinjiang.

A case study on thrombolytic treatment of acute aortic saddle embolism using bilateral femoral arterial puncture catheter.

Although peripheral arterial embolism is a common vascular disease, abdominal aortic saddle embolism (ASE) is rare. However, ASE is considered to be quite severe. A rapid and accurate diagnosis followed by timely and appropriate medical intervention is the key to minimize the risk of severe complications and reduce the risk of mortality. We report the case of an 84-year-old female patient who was diagnosed with acute ASE. She was successfully treated using thrombolytic therapy through a bilateral femoral arterial puncture catheter. Our report aims at raising awareness of this potentially fatal disease, highlighting the importance of rapid diagnosis and timely treatment, and exploring the possibility of endovascular treatment for ASE in the future.

[Detection of trace elements in the sediment of Lop Nur samples by ICP-MS].

Twenty eight trace elements in the sediment of Lop Nur in different latitude and longitude were tested by ICP-MS. The results showed that the metal contents in the soil profile followed a growing trend from the surface to the bottom. And the essential element P for living body in each sample was very low, and was the lowest on the surface, while was matched in the other four layers. The results will help to understand the ecosystem evolution of Lop Nur drying up after the sediment deposition.