Tea saponin enhanced bioleaching of Fusarium solani to remove hexavalent chromium from soil.

Hexavalent chromium pollution is one of the most serious types of site pollution. In this study, a microorganism was screened to remove most hexavalent chromium from soil by leaching in 24 h. After ITS sequencing, the microorganism was identified as belonging to the genus Fusarium solani. The optimization experiment of leaching conditions determined that the removal rate reached the maximum 80% when the rotation speed was 200 rpm, the liquid-soil ratio was 15:1, the temperature was 35℃, and the pH was 7. The study has also shown that tea saponin can effectively strengthen the leaching of Fusarium solani to remove hexavalent chromium from the soil. Compared with tea saponin, the strengthening effect of glucose and rhamnolipid was relatively small. The removal rate of hexavalent chromium reached 85% when the added amount of tea saponin was 0.02 g/mL. The leaching solution destroyed part of the iron-manganese nodule structure of the soil, and its hydroxyl, carboxyl, and other groups complexed metal ions into the solution to achieve the purpose of removing hexavalent chromium. However, since the main crystal of the soil was SiO2, there was no obvious change in the XRD of the soil. Toxicity test showed that after leaching, the content of hexavalent chromium leached was 0.28 mg/L (< 1.5 mg/L), which meet the entry standard of the landfill site.

Identification of key gene networks controlling polysaccharide accumulation in different tissues of Polygonatum cyrtonema Hua by integrating metabolic phenotypes and gene expression profiles.

Plant polysaccharides, a type of important bioactive compound, are involved in multiple plant defense mechanisms, and in particular polysaccharide-alleviated abiotic stress has been well studied. Polygonatum cyrtonema Hua (P. cyrtonema Hua) is a medicinal and edible perennial plant that is used in traditional Chinese medicine and is rich in polysaccharides. Previous studies suggested that sucrose might act as a precursor for polysaccharide biosynthesis. However, the role of sucrose metabolism and transport in mediating polysaccharide biosynthesis remains largely unknown in P. cyrtonema Hua. In this study, we investigated the contents of polysaccharides, sucrose, glucose, and fructose in the rhizome, stem, leaf, and flower tissues of P. cyrtonema Hua, and systemically identified the genes associated with the sucrose metabolism and transport and polysaccharide biosynthesis pathways. Our results showed that polysaccharides were mainly accumulated in rhizomes, leaves, and flowers. Besides, there was a positive correlation between sucrose and polysaccharide content, and a negative correlation between glucose and polysaccharide content in rhizome, stem, leaf, and flower tissues. Then, the transcriptomic analyses of different tissues were performed, and differentially expressed genes related to sucrose metabolism and transport, polysaccharide biosynthesis, and transcription factors were identified. The analyses of the gene expression patterns provided novel regulatory networks for the molecular basis of high accumulation of polysaccharides, especially in the rhizome tissue. Furthermore, our findings explored that polysaccharide accumulation was highly correlated with the expression levels of SUS, INV, SWEET, and PLST, which are mediated by bHLH, bZIP, ERF, ARF, C2H2, and other genes in different tissues of P. cyrtonema Hua. Herein, this study contributes to a comprehensive understanding of the transcriptional regulation of polysaccharide accumulation and provides information regarding valuable genes involved in the tolerance to abiotic stresses in P. cyrtonema Hua.

Papaya leaves extract as a novel eco-friendly corrosion inhibitor for Cu in H2SO4 medium.

The papaya leaves were extracted via ultra-pure water. The obtained papaya leaves extract (PLE) was used as the eco-friendly inhibitor for Cu in the H2SO4 corrosion medium. The experimental results showed that PLE was a mixed-type inhibitor and exhibited excellent anti-corrosion nature over a certain temperature range. Morphological analysis test results at different temperatures strongly proved the anti-corrosion nature of PLE. The XPS test results found that an adsorption film of Cu-S bond and Cu-N bond was formed on the Cu surface. This barrier film conformed to Langmuir mono-layer adsorption. Corrosion kinetics and thermodynamic parameters were calculated and discussed.