Arsenite Oxidation

Removing arsenic by food-processing waste (Zizyphus jujuba seeds) and study on its adsorptive properties. Technogenic and ecological safety, 5(1/2019), 62-70. Abstract Research was carried out to remove arsenic from synthetic AMD, raising the pH of the solution and using waste material for food processing by adsorbing arsenic to recover impurities. Arsenite can be quickly converted into arsenate, the more thermodynamically stable. Attention was paid to biomaterials, which are by-products or agricultural waste. Zizyphus seeds were used for this purpose as cheaper and often available food waste materials, due to the potential sorption capacity of arsenic. In order to clean the soils in contaminated towns and mining districts, establish its adsorption potential and enable food production in these areas, collective soil samples were taken from a depth of 0-40 cm from the area of 5 cities and 10 sub-regions of Anguran, province Zanjan in Iran. In the trials, the amount of As(III) and/or arsenate(V) in the soil was evaluated. Their content was tested using ICP-MS. The adsorption process was significantly dependent on adsorbent concentrations and also time. The efficiency and the complicated mechanism of the uptake of Arsenic ions onto the soils depend on the concentration of cellular surface of the Jujube seed powder and also the time of being interaction. 10 % of Jujube seed attained maximum removal all Arsenic ions in this study. Significant differences in decreasing toxic metal were observed among the time of 48 hours and 1 week in all concentrations of bio-adsorbent. The maximum adsorption of toxic metals varied between 80 and 90 % depending on the contact time, stirring action and concentrations of studied bio-adsorbent Ziziphus jujuba seeds. With higher biomass doses the removal efficiency of As was higher even at the same time of being contact. Authors suggest more studies on the mechanism in the next projects and utilizing other dead bio-masses.

—Aiming at accurately and rapidly identifying our heavy metal resistant rhizobial strains, genomic average nucleotide identity (ANI) and core genome analyses were performed to investigate the phylogenetic relationships among 45 strains in the families of Rhizobiaceae and Bradyrhizobiaceae. The results showed that both of the ANI and core-genome phylogenetic trees revealed similar relationship. In ANI analysis, the 90%, 75% and 70% ANI values could be the thresholds for species, genus and family, respectively. Analyzing the genomes using multi-dimensional scaling and scatter plot showed highly consistent with the ANI and core-genome phylogenetic results. With these thresholds, the 45 strains were divided into 24 genomic species within the genera Agrobacterium, Allorhizobium, Bradyrhizobium, Sinorhizobium and a putative novel genus represented by Ag. albertimagni AOL15. The ten arsenite-oxidizing and antimonite tolerant strains were identified as Ag. radiobacter, and two Sinorhizobium genomic species differing from S. fredii. In addition, the description of Pararhizobium is questioned because ANI values greater than 75% were detected between P. giardinii H152T and Sinorhizobium strains. Also, reversion of the species definition for several strains in R. etli and R. leguminosarum was suggested. Our results demonstrate that analyses of ANI and core-genome are rapid and confident methods to identify the rhizobial strains, and it will be also convenient when more genome data are accumulated.