Sphingobium nicotianae sp. nov., isolated from tobacco soil.

Bacterial strain H33T was isolated from tobacco plant soil and was characterized using a polyphasic taxonomy approach. Strain H33T was a Gram-stain-negative, rod-shaped, non-motile and strictly aerobic bacterium. Phylogenetic analyses based on 16S rRNA gene sequences and coding sequences of the up-to-date bacterial core gene set (92 protein clusters) indicated that H33T belongs to the genus Sphingobium. Strain H33T showed the highest 16S rRNA gene sequence similarity to Sphingobium xanthum NL9T (97.2%) and showed 72.3-80.6 % average nucleotide identity and 19.7-29.2 % digital DNA-DNA hybridization identity with the strains of other species of the genus Sphingobium. Strain H33T grew optimally at 30°C, pH 7 and could tolerate 0.5 % (w/v) NaCl. The isoprenoid quinones were ubiquinone-9 (64.1%) and ubiquinone-10 (35.9%). Spermidine was the major polyamine. The major fatty acids of H33T were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). The polar lipid profile consisted of a mixture of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, sphingoglycolipid, two unidentified lipids, two unidentified glycolipids, two unidentified aminoglycolipids and an unidentified phospholipid. The genomic DNA G+C content of H33T was 64.9 mol%. Based on the phylogenetic and phenotypic data, H33T was considered a representative of a novel species in the genus Sphingobium. We propose the name Sphingobium nicotianae sp. nov., with H33T (=CCTCC AB 2022073T=LMG 32569T) as the type strain.

Comparison of the response of microbial communities to region and rootstock disease differences in tobacco soils of southwestern China.

Introduction: Soil microorganisms are essential for crop growth and production as part of soil health. However, our current knowledge of microbial communities in tobacco soils and their impact factors is limited. Methods: In this study, we compared the characterization of bacterial and fungal communities in tobacco soils and their response to regional and rootstock disease differences. Results and discussion: The results showed that the diversity and composition of bacterial and fungal communities responded more strongly to regional differences than to rootstock diseases, while bacterial niche breadth was more sensitive than fungi to regional differences. Similarly, the core bacterial and fungal taxa shared by the three regions accounted for 21.73% and 20.62% of all OTUs, respectively, which was much lower than that shared by RD and NRD in each region, ranging from 44.87% to 62.14%. Meanwhile, the differences in topological characteristics, connectivity, and stability of microbial networks in different regions also verified the high responsiveness of microbial communities to regions. However, rootstock diseases had a more direct effect on fungal communities than regional differences. Conclusion: This provided insight into the interactions between microbial communities, regional differences, and rootstock diseases, with important implications for maintaining soil health and improving tobacco yield and quality.

Differences in microbial diversity and environmental factors in ploughing-treated tobacco soil.

During agricultural production, plowing affects the existing traits of the planted soil, including environmental factors (physicochemical properties and soil enzymatic activity) and microbial community, but whether deep tillage and conventional tillage cause differences in soil microecology are unknown. In this study, the 16S rRNA high-throughput sequencing technology was combined with soil environmental factor detection to analyze the differences in microbial diversity of smokey soils at different depths. As a result, the composition and structure of microbial community varied in different soil depth after plowing. Two dominant phyla, Actinobacteria and Acidobacteria, have varied a lot between the deep-plowing treatment HS3 (the sample in 10-20 cm depth after deep-plowing treatment) sample and the conventional tillage HC3 (treatment the sample in 10-20 cm depth after conventional tillage) sample. The abundance of Actinobacteria has increased significantly, while the abundance of Acidobacteria has decreased significantly. Moreover, deep tillage increased the activity of sucrase (S-SC) and nitrate reductase (NR) in samples with soil depth below 20 cm. In summary, deep tillage disturbed spatial microbial diversity and environmental factors significantly. This would provide new guidance for improving farmland management strategies, optimizing the activation methods of soil layers, further improving crop planting soil, and increasing crop yield.