Yanmei Sun

Cardamine violifolia is the only selenium hyperaccumulation plant found in China. It has been developed as a source of medicinal and edible products that we can consume as selenium supplements. Many planting approaches have been developed to increase the selenium content of C. violifolia for nutrient biofortification. However, the contribution of rhizosphere microbes of C. violifolia to selenium enrichment has not been investigated. In this study, four types of selenium, i.e., selenate, selenite, nanoparticles selenium from Bacillus subtilis (B. subtilis-Se), and organic selenium from yeast (yeast-Se), were added to the soil that C. violifolia was grown in, respectively. Selenate led to the greatest accumulation of selenium in C. violifolia, followed by selenite, B. subtilis-Se, and yeast-Se. Except for yeast-Se, the concentration of selenium in C. violifolia positively correlated with the amount of selenium added to the soil. Furthermore, the different types of exogenous selenium exhibited distinct effects on the rhizosphere microbiome of C. violifolia. Alpha and beta diversity analyses demonstrated that rhizosphere microbiome was more obviously affected by selenium from B. subtilis and yeast than from selenate and selenite. Different microbial species were enriched in the rhizosphere of C. violifolia under various exogenous selenium treatments. B. subtilis-Se application enhanced the abundance of Leucobacter, Sporosarcina, Patulibacter, and Denitrobacter, and yeast-Se application enriched the abundance of Singulishaera, Lactobacillus, Bdellovibrio, and Bosea. Bosea and the taxon belonging to the order Solirubrobacterales were enriched in the samples with selenate and selenite addition, respectively, and the abundances of these were linearly related to the concentrations of selenate and selenite applied in the rhizosphere of C. violifolia. In summary, this study revealed the response of the rhizosphere microbiome of C. violifolia to exogenous selenium. Our findings are useful for developing suitable selenium fertilizers to increase the selenium hyperaccumulation level of this plant.

Cardamine violifolia is the only selenium hyperaccumulation plant found in China. It has been developed as a source of medicinal and edible products for selenium supplementation of human. It is essential to increase selenium content of C. violifolia for nutrient biofortification and many planting approaches have been developed to achieve this aim. However, the contribution of rhizosphere microbes of C. violifolia to the selenium enrichment has not been investigated. In this study, four types of selenium, i.e., selenate, selenite, nanoparticles element selenium from Bacillus subtilis, and organic selenium from yeast, was added to the soil for the growth of C. violifolia, respectively. Selenate had the highest accumulation in C. violifolia, following by selenite, B. subtilis-Se, and yeast-Se. Except for yeast-Se, the concentration of selenium in C. violifolia is positively correlated with the amount of selenium added in the soil. Furthermore, different exogenous selenium exhibited distinct effects on the rhizosphere microbiome of C. violifolia. Both Alpha diversity and Beta diversity analyses displayed that rhizosphere microbiome were more obviously affected by selenium from B. subtilis and yeast than that of selenate and selenite. Different microbial species were enriched in the rhizosphere of C. violifolia under various exogenous selenium treatments. B. subtilis-Se application enhanced the abundance of Leucobacter, Sporosarcina, Patulibacter, and Denitrobacter, and Yeast-Se application enriched the abundance of Singulishaera, Lactobacillus, Bdellovirio, and Bosea. Bosea and the taxon belonging to the order of Solirubrobacterales was enriched in the samples with selenite and selenite addition, respectively, and their abundance was linearly related to the concentration of selenate and selenite application in the rhizosphere of C. violifolia. In summary, this study revealed the response of the rhizosphere microbiome of C. violifolia to exogenous selenium and it is of help to develop suitable selenium fertilizers to increase selenium hyperaccumulation level of this plant.

Selenium-enriched peptides from Cardamine violifolia (CSP) have excellent antioxidant functions but little is known about their effects on obesity and associated metabolic disorders in mice fed with a high-fat diet (HFD). In this study, C57BL/6 mice were fed a HFD with or without CSP supplementation (CSPL: 26 μg Se per kg bw per d; CSPH: 104 μg per kg bw per d) for 10 weeks. The results showed that both CSPL and CSPH could ameliorate overweight gain, excess fat accumulation, serum lipid metabolism, and insulin resistance. The potential mechanism might be associated with the increase in thermogenesis, reduced oxidative stress, and inflammation, which regulated the gene expression in lipid and cholesterol metabolism. In addition, CSPL and CSPH also maintained the intestinal integrity and modulated the gut microbiota. Increased Blautia in CSP may be involved in the protective effect against obesity. Furthermore, a distinct increase in Lactobacillus was exclusively found in CSPH, suggesting that a more effective function of CSPH on metabolic disorders might be through the synergism of Blautia and Lactobacillus. Spearman's correlation analysis revealed that these specific genera were significantly correlated with the metabolic improvements. Taken together, CSP supplementation prevented HFD-induced obesity and metabolic disorders, probably by ameliorating oxidative stress and inflammation, regulating metabolic genes, and modulating the gut microbiota compositions.

Pot experiments were set up to simulate the soil contamination by three initial concentrations of sulfamethoxazole (SMX) (S1, 100 mg/kg; S2, 200 mg/kg; S3, 300 mg/kg). The content of SMX in soil and its accumulation in lettuce were analysed. Additionally, the effects of SMX on soil microorganisms and antibiotic resistance genes were studied by Illumina high-throughput sequencing and droplet digital polymerase chain reaction (ddPCR). The results demonstrated that the SMX content in soil reduced by 97%, 86% and 75% in the S1, S2 and S3 treatment groups after 120 days, respectively. The accumulated SMX in lettuce was positively correlated with the initial concentration of SMX in soil. SMX contamination significantly reduced the bacterial diversity and altered the composition of bacterial and fungal communities in soil. The dominant bacterial and fungal genera in the SMX-contaminated soil were obviously different from those in the control soil. The relative abundance of sul1 (sulfonamide resistance gene) remarkably increased in the SMX-contaminated soil, while that of other ARGs, such as sul2 and tetracycline and quinolone resistance genes, showed no significant change.

Deoxynivalenol (DON) is one of the most prevalent food- and feed-associated mycotoxins. It frequently contaminates agricultural commodities and poses serious threats to human and animal health and leads to tremendous economic losses globally. Much attention has been paid to using microorganisms to detoxify DON. In this study, a Bacillus licheniformis strain named YB9 with a strong ability to detoxify DON was isolated and characterized from a moldy soil sample. YB9 could degrade more than 82.67% of 1 mg/L DON within 48 h at 37 °C and showed strong survival and DON degradation rate at simulated gastric fluid. The effects of YB9 on mice with DON intragastrical administration were further investigated by biochemical and histopathological examination and the gut microbiota was analyzed by 16S rRNA Illumina sequencing technology. The results showed that DON increased the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and creatinine (Cr), decreased those of immunoglobulin G (IgG) and IgM in serum, and resulted in severe pathological damage of the liver, kidney, and spleen. By contrast, YB9 supplementation obviously inhibited or attenuated the damages caused by DON in mice. In addition, YB9 addition repaired the DON-induced dysbiosis of intestinal flora, characterized by recovering the balance of Firmicutes and Bacteroidetes to the normal level and decreasing the abundance of the potentially harmful bacterium Turicibacter and the excessive Lactobacillus caused by DON. Taken together, DON-degrading strain YB9 might be used as potential probiotic additive for improving food and feed safety and modulating the intestinal microbial flora of humans and animals.

Microbiomes can aid in the protection of hosts from infection and disease, but the mechanisms underpinning these functions in complex environmental systems remain unresolved. Soils contain microbiomes that influence plant performance, including their susceptibility to disease. For example, some soil microorganisms produce antimicrobial compounds that suppress the growth of plant pathogens, which can provide benefits for sustainable agricultural management. Evidence shows that crop rotations increase soil fertility and tend to promote microbial diversity, and it has been hypothesized that crop rotations can enhance disease suppressive capacity, either through the influence of plant diversity impacting soil bacterial composition or through the increased abundance of disease suppressive microorganisms. In this study, we used a long-term field experiment to test the effects of crop diversity through time (i.e., rotations) on soil microbial diversity and disease suppressive capacity. We sampled soil from seven treatments along a crop diversity gradient (from monoculture to five crop species rotation) and a spring fallow (non-crop) treatment to examine crop diversity influence on soil microbiomes including bacteria that are capable of producing antifungal compounds. Crop diversity significantly influenced bacterial community composition, where the most diverse cropping systems with cover crops and fallow differed from bacterial communities in the 1-3 crop species diversity treatments. While soil bacterial diversity was about 4% lower in the most diverse crop rotation (corn-soy-wheat + 2 cover crops) compared to monoculture corn, crop diversity increased disease suppressive functional group prnD gene abundance in the more diverse rotation by about 9% compared to monocultures. Identifying patterns in microbial diversity and ecosystem function relationships can provide insight into microbiome management, which will require manipulating soil nutrients and resources mediated through plant diversity.