Characteristics and source apportionment of black carbon the urban and desert underlying surfaces.

The spatial distribution of black carbon (BC) concentrations was highly variable across different underlying surfaces. Differences in meteorological conditions and emission sources led to great temporal and spatial variations in BC characteristics. As the most important absorbing aerosol, BC can affect radiation, clouds, and surface snow. BC mass concentrations were measured using a seven channel aethalometer (AE-33) in the Urumqi and Taklimakan Deserts from January to December 2022. The aethalometer data, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) models were used to analyse the variation characteristics, potential sources, and affected areas. Results showed that the BC concentrations in the Taklamakan Desert and Urumqi were in the range of 0-500 ng·m-3, accounting for 66.20 % and 59.50 % of the total, respectively. The backward trajectory simulation of BC mass concentration in the tower and Urumqi using the HYSPLIT model found that the airflow trajectories in the tower in summer corresponded to the BC concentration in the following order: trajectory 4 > trajectory 3 > trajectory 2 > trajectory 1, and trajectory 4 originated from the Turpan airflow accounting for 46.19 % of the total, which corresponded to the highest BC concentration of 621.73 ng·m-3. The trajectories of the airflow in Urumqi in summer corresponded to the BC concentration in the order of high to low, and the BC concentration in summer corresponded to the highest concentration in the Turpan airflow. BC concentrations arranged from high to low were trajectory 1 > trajectory 5 > trajectory 3 > trajectory 4 > trajectory 2. Trajectories 3, 4, and 5 airflow directions were the same, and the airflow trajectory accounted for 47.48 %, corresponding to BC concentrations of 599.82 ng·m-3, 579.99 ng·m-3, and 555.85 ng·m-3, respectively. Tower in the spring compared with other seasons of the CWT value of >400 ng·m-3 had the widest coverage, and Urumqi had more source areas contributing to moderate pollution concentration weights in winter (400 ng·m-3 < CWT < 800 ng·m-3). The conclusions of this study provide a scientific basis for regional environmental management and the formulation of air pollution measures in Xinjiang.

Population structure and selection signal analysis of indigenous sheep from the southern edge of the Taklamakan Desert.

Analyzing the genetic diversity and selection characteristics of sheep (Ovis aries) holds significant value in understanding their environmental adaptability, enhancing breeding efficiency, and achieving effective conservation and rational utilization of genetic resources. In this study, we utilized Illumina Ovine SNP 50 K BeadChip data from four indigenous sheep breeds from the southern margin of the Taklamakan Desert (Duolang sheep: n = 36, Hetian sheep: n = 74, Kunlun sheep: n = 27, Qira black sheep: n = 178) and three foreign meat sheep breeds (Poll Dorset sheep: n = 105, Suffolk sheep: n = 153, Texel sheep: n = 150) to investigate the population structure, genetic diversity, and genomic signals of positive selection within the indigenous sheep. According to the Principal component analysis (PCA), the Neighbor-Joining tree (NJ tree), and Admixture, we revealed distinct clustering patterns of these seven sheep breeds based on their geographical distribution. Then used Cross Population Extended Haplotype Homozygosity (XP-EHH), Fixation Index (FST), and Integrated Haplotype Score (iHS), we identified a collective set of 32 overlapping genes under positive selection across four indigenous sheep breeds. These genes are associated with wool follicle development and wool traits, desert environmental adaptability, disease resistance, reproduction, and high-altitude adaptability. This study reveals the population structure and genomic selection characteristics in the extreme desert environments of native sheep breeds from the southern edge of the Taklimakan Desert, providing new insights into the conservation and sustainable use of indigenous sheep genetic resources in extreme environments. Additionally, these findings offer valuable genetic resources for sheep and other mammals to adapt to global climate change.

Diversity, novelty, antimicrobial activity, and new antibiotics of cultivable endophytic actinobacteria isolated from psammophytes collected from Taklamakan Desert.

Three hundred and twenty endophytic actinobacterial strains were isolated from psammophytes collected from Taklamakan Desert and identified. Among them, three strains already had been identified as new species of two genera and sixteen isolates showed relatively low 16S rRNA similarities < 98.6% to validly described species. Seventy-five of the isolates were selected as representative strains to screen antibacterial activity and mechanism. Forty-seven strains showed antagonistic activity against at least one of the indicator bacteria. Two Streptomyces strains produced bioactive compounds inducing DNA damage, and two Streptomyces strains produced bioactive compounds with inhibitory activity on protein biosynthesis. Notably, the strain Streptomyces sp. 8P21H-1 that demonstrated both strong antibacterial activity and inhibitory activity on protein biosynthesis was prioritized for exploring new antibiotics. Under the strategy of integrating genetics-based discovery program and MS/MS-based molecular networking, two new streptogramin-type antibiotics, i.e., acetyl-griseoviridin and desulphurizing griseoviridin, along with known griseoviridin, were isolated from the culture broth of strain 8P21H-1. Their chemical structures were determined by HR-MS, and 1D and 2D NMR. Desulphurizing griseoviridin and griseoviridin exhibited antibacterial activities by inhibiting translation.

Bioprospecting of Soil-Derived Actinobacteria Along the Alar-Hotan Desert Highway in the Taklamakan Desert.

Taklamakan desert is known as the largest dunefield in China and as the second largest shifting sand desert in the world. Although with long history and glorious culture, the Taklamakan desert remains largely unexplored and numerous microorganisms have not been harvested in culture or taxonomically identified yet. The main objective of this study is to explore the diversity, novelty, and pharmacological potential of the cultivable actinomycetes from soil samples at various sites along the Alar-Hotan desert highway in the Taklamakan desert. A total of 590 actinobacterial strains were recovered by the culture-dependent approach. Phylogenetic analysis based on 16S ribosomal RNA (rRNA) gene sequences unveiled a significant level of actinobacterial diversity with 55 genera distributed in 27 families of 12 orders. Thirty-six strains showed relatively low 16S rRNA similarities (<98.65%) with validly described species, among which four strains had already been characterized as novel taxa by our previous research. One hundred and forty-six actinobacterial isolates were selected as representatives to evaluate the antibacterial activities and mechanism of action by the paper-disk diffusion method and a double fluorescent protein reporter "pDualrep2" system, respectively. A total of 61 isolates exhibited antagonistic activity against the tested "ESKAPE" pathogens, among which seven strains could produce bioactive metabolites either to be able to block translation machinery or to induce SOS-response in the pDualrep2 system. Notably, Saccharothrix sp. 16Sb2-4, harboring a promising antibacterial potential with the mechanism of interfering with protein translation, was analyzed in detail to gain deeper insights into its bioactive metabolites. Through ultra-performance liquid chromatography (UPLC)-quadrupole time-of-flight (QToF)-MS/MS based molecular networking analysis and databases identification, four families of compounds (1-16) were putatively identified. Subsequent bioassay-guided separation resulted in purification of four 16-membered macrolide antibiotics, aldgamycin H (8), aldgamycin K (9), aldgamycin G (10), and swalpamycin B (11), and their structures were elucidated by HR-electrospray ionization source (ESI)-MS and NMR spectroscopy. All compounds 8-11 displayed antibacterial activities by inhibiting protein synthesis in the pDualrep2 system. In conclusion, this work demonstrates that Taklamakan desert is a potentially unique reservoir of versatile actinobacteria, which can be a promising source for discovery of novel species and diverse bioactive compounds.

Microbacterium karelineae sp. nov. isolated from a halophyte plant in the Taklamakan desert.

A bacterial strain, designated TRM 80801T, was isolated from the Karelinea in Taklamakan desert, Xinjiang Uygur Autonomous Region, north-west China. Cells were Gram-stain-positive, aerobic, non-motile, short rods. Strain TRM 80801T grew at 4-50 °C, with optimum growth at 28 °C, and grew at pH 6.0-11.0 and 1-15 % (w/v) NaCl. Phylogenetic analyses of the 16S rRNA gene sequences placed strain TRM 80801T within the genus Microbacterium with the highest similarities to Microbacterium suaedae YZYP 306T (98.97 %) and Microbacterium indicum BBH6T (98.17 %), respectively. The DNA G+C content of TRM 80801T is 69.38 mol%. The cell-wall peptidoglycan contained the amino acids ornithine, glutamic acid, glycine and alanine, the diagnostic diamino acid was ornithine. The acyl type of the peptidoglycan was glycolyl. Whole-cell sugars were ribose, mannose, glucose, rhamnose and galactose. The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The predominant menaquinones were MK-10, MK-11 and MK-12. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol. The whole-genome average nucleotide identity (ANI) value between strain TRM 80801T and Microbacterium suaedae YZYP 306T is 70.2 %. On the basis of the evidence presented in this study, strain TRM 80801T is representative of a novel species in the genus Microbacterium, for which the name Microbacterium karelineae sp. nov. is proposed. The type strain is TRM 80801T (=CCTCC AB 2019248T=KCTC 49357T).

Bacillus populi sp. nov. isolated from Populus euphratica rhizosphere soil of the Taklamakan desert.

A rod-shaped, endospore-forming, aerobic bacterium, designated FJAT-45347T, was isolated from rhizosphere soil collected from the Taklamakan desert in Xinjiang (PR China). Growth was observed at 15-35 °C (optimum 25 °C), in 0 % and 20.0 % NaCl (optimum 8.0 %) and at pH 7.5-12.0 (optimum 8.0), respectively. The cell-wall peptidoglycan contained meso-diaminopimelic acid and the isoprenoid quinone was MK-7. The main fatty acids were iso-C15 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic analysis based on 16S rRNA gene sequences affiliated FJAT-45347T to the genus Bacillus, and it showed the highest sequence similarities to Bacillus clarkii DSM 8720T (96.1 %). The average nucleotide identity and in silico DNA-DNA hybridization values between FJAT-45347T and the most closely related species were 68.5 and 26.2 %, respectively, which were lower than the thresholds commonly used to define species (96 and 70 %, respectively), indicating that it represented a member of a different taxon. The DNA G+C content was 40.6 mol%. The phenotypic characters and taxono-genomics study revealed that FJAT-45347T represents a novel species of the genus Bacillus, for which the name Bacilluspopuli sp. nov. is proposed. The type strain is FJAT-45347T (=DSM 104632T=CCTCC AB 2016257T).

Sequencing and analysis of the whole mitochondrial genome of a variegated racerunner from Taklamakan Desert.

The whole mitochondrial genome of a variegated racerunner (Eremias vermiculata) from the Taklamakan Desert was determined using polymerase chain reaction and directly sequenced with a primer walking method. The mitogenome sequence was 19 796 bp in size, containing 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region (D-loop), which is similar to the typical mtDNA of vertebrates. Mitochondrial genomes analyses using maximum parsimony and Bayesian analyses yielded identical phylogenetic trees, indicating a close phylogenetic affinity of the seven Eremias species. Monophyly of the genus Eremias and E. vermiculata was recovered. The mitogenome presented here will contribute to the examination of genetic differentiation for E. vermiculata and understanding of the mitochondrial DNA evolution in Eremias.