Enrichment of antibiotic resistance genes in roots is related to specific bacterial hosts and soil properties in two soil-plant systems.

Soil microorganisms carrying antibiotic resistance genes (ARGs) can colonize plants as endophytes, posing a huge risk to human health. However, the distribution and transmission patterns of ARGs in different soil-plant systems are unclear. Here, we investigated the distribution of ARGs and the microbial communities in the soil-wheat and soil-cucumber systems by quantitative PCR (qPCR) and 16S rRNA gene sequencing. The results showed that the relative abundances of seven ARGs and intI1 in roots were higher than those of other samples in both soil-plant systems. Pseudomonas, Enterobacteriaceae, Rhizobiales and Gammaproteobacteria were dominant potential bacterial hosts of endophytic ARGs, with enrichment patterns similar to that of ARGs in roots. In addition, more ARGs were significantly positively correlated with intI1 in roots, indicating that ARGs may be more prone to horizontal gene transfer (HGT). Variation partitioning analysis (VPA) and structural equation models (SEM) revealed that the variations of ARGs were mainly directly affected by the HGT of intI1 and indirectly affected by soil properties in roots. These results demonstrated that root could have a strong proliferative effect on ARGs entering host plant endophytes. Overall, our findings enhanced the understanding distribution patterns of ARGs in different soil-plant systems, and provided an effective basis for developing measures to minimize the spread of ARGs.

Pristine and sulfidized zinc oxide nanoparticles alter bacterial communities and metabolite profiles in soybean rhizocompartments.

A better understanding of bacterial communities and metabolomic responses to pristine zinc oxide manufacture nanoparticles (ZnO MNPs) and its sulfidized product (s-ZnO MNPs), as well as their corresponding Zn ions in rhizocompartments, critical in the plant-microbe interactions, could contribute to the sustainable development of nano-enabled agriculture. In this study, soybean (Glycine max) were cultivated in soils amended with three Zn forms, namely ZnSO4·7H2O, ZnO MNPs and s-ZnO MNPs at 0, 100 and 500 mg·kg-1 for 70 days. Three Zn forms exposures profoundly decreased the bacterial alpha diversity in roots and nodules. High dose (500 mg·kg-1) groups had a stronger impact on the bacterial beta diversity than low dose (100 mg·kg-1) groups. In the rhizosphere soil and roots, 500 mg·kg-1 of ZnSO4 and s-ZnO MNPs treatments showed the largest shifts in bacterial community structure, respectively. In addition, several significant changed bacterial taxa and metabolites were found at the high dose groups, which were associated with carbon and nitrogen metabolism. PLS-DA plot showed good discrimination in metabolomic profiles of rhizosphere soil and roots between three Zn forms treatments and control. Most metabolic pathways perturbed were closely linked to oxidative stress. Overall, our study indicates either dissolved or nano-particulate Zn exposure at high dose can drastically affected bacterial communities and metabolite profiles in soybean rhizocompartments.

Effect of nanohydroxyapatite/biochar/sodium humate composite on phosphorus availability and microbial community in sandy soils.

Phosphorus (P) is essential for crop growth as an indispensable nutrient; however, there has been growing concern over the low use efficiency of P used in current fertilizers. We synthesized and characterized a potential P fertilizer nanohydroxyapatite/biochar/sodium humate (nHAP/BC/HANa) composite. To study the impact of the composite on soil chemical properties and microbial community in sandy soils, we set up four treatments as follows: (1) biochar (BC), (2) nanohydroxyapatite (nHAP), (3) nHAP/BC/HANa composite, and (4) sodium humate (HANa) was added separately into soils amended with nHAP/BC (nHAP/BC + HANa) to compare its performance with that of the nHAP/BC/HANa composite. A key finding was that the nHAP/BC/HANa composite not only significantly increased the soil available P content and alkaline phosphatase activity but also the increased organic matter content compared to the control. Additionally, leaching losses of P in soils amended with the nHAP/BC/HANa composite were lower than those in soils amended with the nHAP/BC + HANa, which suggested that the nHAP/BC/HANa composite had great potential to decrease P loss in sandy soils. Moreover, bacterial communities were more sensitive than fungal communities to all treatments. The bacterial communities showed the most significant changes in the nHAP/BC/HANa treatments. Results from Mantel tests further indicated that the strongest correlation between bacterial communities and soil properties occurring in the nHAP/BC/HANa treatments. Random forest analysis was conducted to identify the dominant microbial taxa, such as Proteobacteria, Acidobacteria, and Gemmatimonadetes, for predicting changes in soil properties. There was an asymptotical transition in bacterial community assembly processes from stochastic to deterministic in the nHAP/BC/HANa treatments. In conclusion, we demonstrated that nHAP/BC/HANa composite had the remarkable contribution to soil P availability in sandy soils, and simultaneously promoted the bacterial functions potential for P cycling, which present valuable insights to the development of potential P fertilizer.

Design and analysis of wearable pupillometer for autonomic neuropathy of diabetic patients.

Diabetes is a familiar disease in modern society. In the early stage of diabetes, symptoms are unobvious, but they usually induce diabetic autonomic neuropathy or, worse, cardiovascular autonomic neuropathy. Pupillometers are effective instruments for observing human pupils. This article presents a novel wearable pupillometer design, without external light artifacts, and an embedded algorithm with blinking elimination, which investigates autonomic neuropathy through recording pupil dynamics triggered by an external sensitive invisible light source. The pupillometer is experimented on 36 healthy subjects and 10 diabetic patients under four different colors (white, red, green, and blue) as well as two different light intensities: 50 and 500 mcd. Ten parameters derived from pupil diameter, pupil response time, and pupil response speed will be evaluated for the healthy subjects and diabetic patients. The results show that three in four parameters related to pupil diameters, one in four related to light intensities, and one in two related to pupil response speed could have significant differences (p<0.05) between healthy subjects and diabetic patients. These parameters obtain over 85% sensitivity, 83% specificity, and 88% accuracy. The pupillometer is proven reliable, effective, portable, and inexpensive for diagnosing diabetes in an early stage.

Evaluation of the nanofibrillar structure of Dioscorea opposite extract for cell attachment.

Dioscorea opposite has been widely used in traditional herbal medicine in the Far East, ameliorating symptoms ranging from abdominal swelling to pain. Previous studies have focused on understanding the chemical components that lead to the medicinal effects of the extract. In this study, we examined the nanostructures formed by the soluble and insoluble parts of the sticky excretion from the mucilaginous rhizome of Dioscorea opposite and evaluated their cellular response. Using atomic force microscopy, we found that the soluble extract of the excretion had the capacity to form a nanofibrillar scaffold composed of uniform ∼10 nm nanofibers with a typical pore size of ∼40 nm, while the insoluble extract formed some nanofibers without specific structure. Cellular response to the two types of nanostructures was tested by seeding with HeLa and MC3T3 cells. The observations suggested that the nanofibrillar scaffold formed from the soluble extract provided an excellent platform for HeLa cell attachment and growth and to a lesser degree for MC3T3 cells, while nanofibers from the insoluble extract displayed no cell attachment and growth. Further analysis by direct incubation of the soluble extract with growing cells indicated that components from the extract preferentially bound to HeLa cells, but not to MC3T3 cells, which might help explain the observed preference of HeLa cells on the nanofibrillar scaffold. The nanofibrillar scaffold created from the Dioscorea opposite extract and its ability to sustain the attachment of specific cell types demonstrate the potential for this natural nanomaterial in tissue engineering applications.