Strategies in a metallophyte species to cope with manganese excess

Current progress on manganese in constructed wetlands: Bibliometrics, effects on wastewater treatment, and plant uptake

Constructed wetlands (CWs) are a pollutant treatment design inspired by natural wetlands and are widely utilized for the removal of common pollutants. The research focus lies in the circulation of manganese (Mn) in the environment to enhance pollutant removal within CWs. This paper provides a comprehensive review of recent advancements in understanding the role and effects of Mn in chemical weapons, based on literature retrieval from 2002 to 2021. Ecological risk assessment and heavy metals within CWs emerge as current areas of research interest. Mn sources within CWs primarily include natural deposition, heavy metal wastewater, and intentional addition. The cycling between Mn(II) and Mn(IV) facilitates enhanced wastewater treatment within CWs. Moreover, employing a Mn matrix proves effective in reducing ammonia nitrogen wastewater, organic pollutants, as well as heavy metals such as Cd and Pb, thereby addressing complex pollution challenges practically. To comprehensively analyze influencing factors on the system's performance, both internal factors (biological species, design parameters, pH levels, etc.) and external factors (seasonal climate variations, precipitation patterns, ultraviolet radiation exposure, etc.) were discussed. Among these factors, microorganisms, pollutants, and temperature are the most important influencing factors, which emphasizes the importance of these factors for wetland operation. Lastly, this paper delves into plant absorption of Mn along with coping strategies employed by plants when faced with Mn poisoning or deficiency scenarios. When utilizing Mn for the regulation of constructed wetlands, it is crucial to consider the tolerance levels of associated plant species. Furthermore, the study predicts future research hotspots encompass high-efficiency catalysis techniques, matrix-filling approaches, and preparation of resource utilization methods involving Mn nanomaterials.

Response mechanism of psychrotolerant Bacillus cereus D2 towards Ni (II) toxicity and involvement of amino acids in Ni (II) toxicity reduction

The toxic effect of Nickel (Ni (II)) on humans and animals has been previously addressed. Owing to the important application of psychrotolerant bacteria in Ni (II) damage remediation in contamination sites at low temperatures, the response mechanism of psychrotolerant bacteria to Ni (II) toxicity must be elucidated. Therefore, the effect of Ni (II) toxicity on a psychrotolerant Bacillus cereus D2 was studied, showing a way to alleviate the Ni (II) toxicity in strain D2. The results showed that strain D2 growth was completely inhibited at a concentration of 100 mg/L of Ni (II). The main effects of Ni (II) toxicity on strain D2 were membrane damage and reactive oxygen species-dependent oxidative stress. Additionally, Ni (II) toxicity resulted in dysregulation of the cell cycle in strain D2. Furthermore, metabolomic analysis showed that the biosynthesis of amino acids and ABC transporters were significantly affected, and the relative abundance of seven important amino acids changed in a concentration-dependent manner. Addition of 20 mM or 5 mM amino acids to 100 mg/L Ni (II)-treated strain D2 restored its growth. This study provides insights into the way to alleviate the Ni (II) toxicity in strain D2, thus contributing to the development of bioremediation strategies.