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Herein, the inoculation with strain wp-6 promoted the growth of wheat seedlings by improving the energy production and conversion of wheat seedlings and alleviating salt stress. Soil salinization decreases crop productivity due to high toxicity of sodium ions to plants. Plant growth-promoting rhizobacteria (PGPR) have been demonstrated to alleviate salinity stress. However, the mechanism of PGPR in improving plant salt tolerance remains unclear. In this study, physiological analysis, proteomics, and metabolomics were applied to investigate the changes in wheat seedlings under salt stress (150 mM NaCl), both with and without plant root inoculation with wp-6 (Bacillus sp.). Under salt stress, root inoculation with strain wp-6 increased plant biomass (57%) and root length (25%). The Na+ content was reduced, while the K+ content and K+/Na+ ratio were increased. The content of malondialdehyde was decreased by 31.94% after inoculation of wp-6 under salt stress, while the content of proline, soluble sugar, and soluble protein were increased by 7.48%, 12.34%, and 4.12%, respectively. The peroxidase, catalase, and superoxide dismutase activities were increased after inoculation of wp-6 under salt stress. Galactose metabolism, phenylalanine metabolism, caffeine metabolism, ubiquinone and other terpenoid-quinone biosynthesis, and glutathione metabolism might play an important role in promoting the growth of salt-stressed wheat seedlings after the inoculation with wp-6. Interaction analysis of differentially expressed proteins and metabolites found that energy production and transformation-related proteins and six metabolites (d-arginine, palmitoleic acid, chlorophyllide b, rutin, pheophorbide a, and vanillylamine) were mainly involved in the growth of wheat seedlings after the inoculation with wp-6 under salt stress. Furthermore, correlation analysis found that inoculation with wp-6 promotes the growth of salt-stressed wheat seedlings mainly through regulating amino acid metabolism and porphyrin and chlorophyll metabolism. This study provides an eco-friendly method to increase agricultural productivity and paves a way to sustainable agriculture.

Solution chemistry is of great importance to the removal of arsenic by coagulation through influencing the speciation of arsenic, the in situ precipitation of metal salts coupled with the adsorption and coprecipitation behavior of arsenic during coagulation. While the researches on the influence of solution chemistry in As(III) removal by titanium salts, a promising candidate for drinking water treatment was still deficient. Batch tests were performed to evaluate the removal of As(III) by titanium salts coagulation under solution chemistry influences. The results indicated that As(III) removal by Ti(SO4)2 and TiCl4 increased first and then decreased with the rising of solution pH from 4 to 10. TiCl4 preformed better in As(III) removal than Ti(SO4)2 at pH 4–8, but the opposite trends were observed at pH 9–10. XPS analysis indicated that the involvement of surface hydroxyl groups was primarily responsible for As(III) adsorption on Ti(IV) precipitates. As(III) removal was inhibited in the presence of SO42− mainly by competitive adsorption, especially at elevated SO42− concentration under acidic and alkaline conditions. F− exerted a greater suppressive effect than SO42− via indirectly hindering Ti(IV) precipitate formation, and through direct competitive adsorption with H3AsO3, the inhibitive effect increased as F− concentration increased and depended highly on solution pH. As(III) removal was promoted by co-existing Fe(II) primarily through the facilitation of Ti(IV) precipitation, especially under neutral and alkaline conditions, while it was inhibited to a different extent by the presence of high-concentration Mn(II) possibly via competitive adsorption. The presence of Ca2+ and Mg2+ enhanced the removal of As(III), but the positive effect did not increase as ionic concentration elevated.