Effect of endophytic diazotroph Enterobacter roggenkampii ED5 on nitrogen-metabolism-related microecology in the sugarcane rhizosphere at different nitrogen levels

The Changes of the Endophytic Bacterial Community from Pepper Varieties with Different Capsaicinoids

Capsaicinoids, the key compounds responsible for pepper pungency, have significant commercial and health value, yet the role of endophytic bacteria in their biosynthesis remains unclear. This study investigated the relationship between endophytic bacterial communities and capsaicinoid content across 100 Capsicum annuum varieties. Two high-capsaicinoid (35.0 and 24.8 mg/g) and two low-capsaicinoid (0.8 and 0.9 mg/g) varieties were selected for 16S rRNA sequencing and microbial analysis. High-capsaicinoid varieties exhibited greater bacterial richness and diversity compared to low-capsaicinoid varieties. Taxonomic profiling revealed distinct community compositions: Enterobacter, Bacteroides, and Escherichia_Shigella were enriched in high-capsaicinoid fruits and positively correlated with capsaicinoid levels, while Chujaibacter and Brochothrix dominated the low-capsaicinoid varieties. Functional annotation highlighted nitrogen-fixing bacteria as more abundant in high-capsaicinoid varieties. Inoculating peppers with isolated Enterobacter strains significantly increased capsaicinoid content, confirming its role in biosynthesis. These findings demonstrate that the pepper genotype shapes endophytic bacterial communities, which in turn influence capsaicinoid production through metabolic- and nitrogen-associated pathways. This study provides foundational insights into microbiome-mediated enhancement of pepper pungency, offering potential strategies for agricultural and industrial applications.

High-throughput sequencing-based analysis of the composition and diversity of the endophyte community in roots of Stellera chamaejasme

Stellera chamaejasme (S. chamaejasme) is an important medicinal plant with heat-clearing, detoxifying, swelling and anti-inflammatory effects. At the same time, it is also one of the iconic plants of natural grassland degradation in northwest China, playing a key role in the invasion process. Plant endophytes live in healthy plant tissues and can synthesize substances needed for plant growth, induce disease resistance in host plants, and enhance plant resistance to environmental stress. Therefore, studying the root endophytes of S. chamaejasme is of great significance for mining beneficial microbial resources and biological prevention and control of S. chamaejasme. This study used Illumina MiSeq high-throughput sequencing technology to analyze the composition and diversity of endophytes in the roots of S. chamaejasme in different alpine grasslands (BGC, NMC and XGYZ) in Tibet. Research results show that the main phylum of endophytic fungi in the roots of S. chamaejasme in different regions is Ascomycota, and the main phyla of endophytic bacteria are Actinobacteria, Proteobacteria and Firmicutes (Bacteroidota). Overall, the endophyte diversity of the NMC samples was significantly higher than that of the other two sample sites. Principal coordinate analysis (PCoA) and permutational multivariate analysis of variance (PERMANOVA) results showed significant differences in the composition of endophytic bacterial and fungal communities among BGC, NMC and XGYZ samples. Co-occurrence network analysis of endophytes showed that there were positive correlations between fungi and some negative correlations between bacteria, and the co-occurrence network of bacteria was more complex than that of fungi. In short, this study provides a vital reference for further exploring and utilizing the endophyte resources of S. chamaejasme and an in-depth understanding of the ecological functions of S. chamaejasme endophytes.