Effects of time-space conversion on microflora structure, secondary metabolites composition and antioxidant capacity of Codonopsis pilosula root.

In order to study the relationship between medicinal plant Codonopsis pilosula phenotype, secondary metabolites, antioxidant capacity and its rhizosphere soil nutrients, root-related microorganisms under seasonal and geographical changes, high-throughput sequencing technology was used to explore the bacterial community structure and variation in rhizosphere soil and root endosphere from six regions of Dingxi City, Gansu Province during four seasons. Secondary metabolites composition and antioxidant capacities of C. pilosula root collected successively from four seasons were determined. The chemical properties, nutrient content and enzyme activities of rhizosphere of C. pilosula were significantly different under different temporal and spatial conditions. All soil samples were alkaline (pH 7.64-8.42), with water content ranging from 9.53% to 19.95%, and electrical conductivity varied widely, showing obvious time-scale effects. Different time scales were the main reasons for the diversity and structure of rhizosphere bacterial community of C. pilosula. The diversity and richness of rhizosphere bacterial community in autumn and winter were higher than those in spring and summer, and bacterial community structure in spring and summer was more similar to that in autumn and winter. The root length and diameter of C. pilosula showed significant time gradient difference under different spatiotemporal conditions. Nutrition and niche competition lead to significant synergistic or antagonistic interactions between rhizosphere bacteria and endophytic bacteria, which invisibly affect soil properties, abundance of functional bacteria and even yield and quality of C. pilosula. Soil properties, rhizosphere bacteria and endophytic bacteria directly promoted root phenotype, stress resistance and polysaccharide accumulation of C. pilosula.

Differences in geological conditions have reshaped the structure and diversity of microbial communities in oily soils.

High-throughput sequencing was used to study the microbial community structure diversity changes in oil-contaminated soils under different spatial distances and environmental conditions. 239 Phyla, 508 Classes, 810 Orders, 1417 Families, 2048 Genera, 511 Species of microbial communities were obtained from 16 samples in three regions. The physicochemical properties of the soil, microorganisms' community structure has been changed by Petroleum hydrocarbon (PHA). Alpha diversity results showed that the soil contained high bacterial diversity, especially in Qingyang's loess soil. The bacterial abundance was in the order of loess soil > black soil > sandy soil. Beta diversity revealed that spatial distance limitation and random variation of repeated samples may be the main factors leading to soil heterogeneity and microbial community structure differences. The dominant bacteria phyla with broad petroleum hydrocarbon degradation ability such as Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were identified. Pseudomonas, Bacillus, Nocardioides, Oceanobacillus, Sphingomonas, Alkanindiges and Streptomyces were identified as functional microbial for the PHA degradation. The microbial communities manifested the co-exclusion under different geological conditions, and played the key role in the soil PHA degradation through amino acid metabolism, energy metabolism and carbohydrate metabolism. The correlation results of amos structural equation showed that the diversity and abundance of soil microorganisms in different regions were controlled by soil PHA content and environmental factors. Altitude, annual average temperature and annual rainfall were positively correlated with microbial diversity. Annual rainfall and soil physical and chemical factors exhibited the most significant influence on it. Microbial diversity indirectly affected the PHA content in different type soil. We believe that reshape the structure and diversity of microbial communities in soil could be changed and reshaped by different geological conditions, pollutants and soil type. This study can provide helps for understanding the ecological effect of geomicrobiology formation under the driving force of geographic environment and other factors.