Cadmium (Cd) is a naturally occurring heavy metal found in the soil. However, its concentrations can be substantially increased by anthropogenic activities, presenting considerable environmental challenges. One effective remediation strategy is soil bioremediation, which employs indigenous bacteria to mitigate contamination. This study aimed to identify Cd-resistant bacteria and assess their potential for bioremediating Cd-contaminated soil. Two Cd-resistant bacterial strains, designated C9 and C27, were isolated from Cd-contaminated soil at concentrations ranging from 100 to 500 mg/L. Morphological analysis and 16S rDNA sequencing identified both strains as Bacillus cereus. The strains’ capacity to adsorb and remove Cd from solutions was assessed, as well as their resistance to other heavy metals, including Zinc (Zn) and Thallium (Tl). Optimal Cd adsorption was observed at 36 h for strain C9 and at 48 h for strain C27, with maximum removal rates achieved at a Cd concentration of 70 μM. Both strains demonstrated substantial resistance to heavy metals in the order Zn > Cd > Tl on solid media. Additionally, they exhibited strong salt tolerance, starch hydrolysis, citrate utilization, and ammonia production capabilities. Notably, both strains produced significantly higher levels of siderophores compared to the model bacterium Bacillus subtilis 3,610, with strain C9 exhibiting superior siderophore production. This enhanced siderophore activity is hypothesized to contribute to Cd resistance. Collectively, these findings suggest that strains C9 and C27 have significant potential for the bioremediation of Cd-contaminated environments. Future research will focus on elucidating the molecular mechanisms underlying heavy-metal resistance and optimizing their application in large-scale bioremediation strategies.

To study the structure-performance relationship, a series of nanostructured Fe-Cu binary oxides (FCBOs) were prepared by varying synthesis conditions. The obtained binary oxides were well characterized using X-ray diffraction (XRD), transmission electron microscope (TEM), Brunner-Emmet-Teller (BET), magnetic and Zeta potential measurement techniques. Both As(V) and As(III) sorption on the FCBOs were evaluated by batch tests. Results show that the surface structure and crystallinity of FCBOs are greatly dependent on preparation conditions. The crystallinity of FCBOs gradually increases as the synthesis pH value increasing from 9.0 to 13.0, from amorphous phase to well-crystalline one. Simultaneously, the morphology change of FCBOs from irregular agglomerate to relatively uniform polyhedron has been observed. The sorption of arsenic is greatly influenced by the crystallinity and structure of FCBOs, decreasing with increasing degree of crystallinity. The amorphous FCBO has higher surface hydroxyl density than well-crystalline one, which might be the reason of higher sorption performance. As(V) is sorbed by the FCBOs via formation of inner-sphere surface complexes and As(III) is sorbed through formation of both inner- and outer-sphere surface complexes. This investigation provides new insights into structure-performance relationship of the FCBO system, which are beneficial to develop new and efficient sorbents.

Aluminum (Al) toxicity significantly restricts crop production on acidic soils. Although rice is highly resistant to Al stress, the underlying resistant mechanisms are not fully understood. Here, we characterized the function of OsNIP1;2, a plasma membrane-localized nodulin 26-like intrinsic protein (NIP) in rice. Aluminum stress specifically and quickly induced OsNIP1;2 expression in the root. Functional mutations of OsNIP1;2 in two independent rice lines led to significantly enhanced sensitivity to Al but not other metals. Moreover, the Osnip1;2 mutants had considerably more Al accumulated in the root cell wall but less in the cytosol than the wild-type rice. In addition, compared with the wild-type rice plants, the Osnip1;2 mutants contained more Al in the root but less in the shoot. When expressed in yeast, OsNIP1;2 led to enhanced Al accumulation in the cells and enhanced sensitivity to Al stress, suggesting that OsNIP1;2 facilitated Al uptake in yeast. These results suggest that OsNIP1;2 confers internal Al detoxification via taking out the root cell wall’s Al, sequestering it to the root cell’s vacuole, and re-distributing it to the above-ground tissues.