Vertical stratification of bacteria and the chemical compounds in crude oil-contaminated soil layers of the semi-deserted Dzungharian Basin.

The largely semi-deserted and deserted Dzungharian Basin sites in the northwest of China geologically represent an extension of the Paleozoic Kazakhstan Block and were once part of an independent continent. For reasons of overdevelopment and unreasonable operations during the process of exploitation and transportation, oil pollutants that were discharged into the soil environment caused serious pollution in this weak ecosystem. To explore the bacterial community composition in detail and their possible origination and potential during the natural attenuation of petroleum contaminants in this type of ecologic niche, GC-MS and high-throughput sequencing techniques were used to resolve the organic compounds and bacterial communities in vertical soil layers. The degradation of petroleum contaminants in semi-deserted and deserted soils mainly occurred in the layer at a depth of 45-55 cm. During this process, aromatic and heterocyclic compounds were significantly enriched in soils. The bacterial communities in this basin exhibited a distinct vertical stratification from the surface layer down to the bottom soil layer. Considering the interaction between the community composition and the geochemical properties, we speculate that the degradation of petroleum contaminants in this semi-deserted and deserted soil might represent a microorganism-mediated process and mainly occur in the deeper soil layer.

[Metabolic characteristics of air microbial communities from sandstorm source areas of the Taklamakan desert].

The aim was to compare the characteristics and the differences in carbon catabolic diversity of air samples collected from five locations that around the edge of Taklamakan desert. The characteristics and the differences of carbon metabolic profiles were detected by using the BIOLOG micro plate (BIOLOG EcoPlate). The results showed that the average well color development (AWCD) curve of all five samples did not reach clear saturation during the incubation time (10 days), but differences among them were significant. The highest AWCD value appeared in Shache and the lowest was in Hotan, which were 0.24 and 0.1, respectively. Carbon utilization showed that all samples exhibited high level of polymer, carbohydrates, amino acids and carboxylic acid; however, amine and the phenol compound were the lowest. Principal components analysis (PCA) indicated that twenty categories of carbon significantly related to PC1 and twelve categories for PC2. Hierarchical cluster analysis showed these five areas could be divided into 2 clusters: (1) Hotan, Pishan, (2) Shache, Luntai, Ulugqat. Canonical correspondence analysis (CCA) showed that those community functional diversities were highly affected by some environmental factors, such as wind speed, altitude, humidity. Further investigation by correlation analysis revealed that the microbial communities using single carbon source were significantly affected by abiotic factors, such as the utilization of beta-methyl-D-glucoside, D-galacturonic acid and putrescine had significantly positive correlation (P < 0.05) with latitude; 2-hydroxy benzoic acid and alpha-D-lactose significantly related to wind speed (P < 0.05); and D-glucosaminic acid was positive with air pressure, but it negatively correlated with altitude (P < 0.05). In conclusion,the carbon sources provided by BIOLOG EcoPlate were utilized slowly by air microbial communities; and the characteristics of the air community carbon catabolic along the edge of the Taklamakan desert revealed regional feature, which may be affected by environmental factors.