Phytoremediation of soils contaminated with high concentrations of multiple heavy metals (HCMHMs) is a promising technique. However, the microbial response mechanisms during the phytoremediation process remain poorly understood. The role of microbes in HCMHMs soil remediation may be underestimated. This study investigated microbial responses and their potential roles in HCMHMs soil remediation using the hyperaccumulator plant Sedum alfredii (S. alfredii). Soil microbial communities were characterised by 16S rRNA sequencing, and metabolic pathways and functions were predicted using PICRUSt2 analysis. The results indicated that the impact of heavy metals on bacterial community structure was more significant than that of S. alfredii. The formation of dominant phyla such as Proteobacteria and Patescibacteria played a crucial role in the bacterial remediation of HCMHMs soils. Proteobacteria utilised the Inorganic ion transport and metabolism gene clusters to translocate heavy metals or reduce their bioavailability and toxicity. Patescibacteria used the Replication, recombination and repair gene clusters to repair damaged genes, enhancing bacterial tolerance of heavy metals. The results provided new insights into the role of microbes during phytoremediation and offered a scientific basis for optimizing phytoremediation technologies. This study demonstrated that dominant phyla effectively mitigated the damage to soil ecological functions from HCMHMs soil.

Toxic heavy metals are currently significant environmental pollutants as their growing ecotoxicity becomes a serious public health concern. Their multiple application in several fields such as the mining industry, agriculture, medicine, technology and many others, leads to a widespread distribution into the environmental systems. Since toxic metals are not biodegradable, their accumulation in soil, water and air contaminates the food chain, which poses a danger to human health. Because of extensive damage caused by metal intoxication on various organs of the human body, the search for therapeutic methods is very important. Removal of heavy metals from the body is usually carried out by the most common and conventional chelation therapy methods. However, for removal from environment the use of chemical methods is often expensive and can lead to the production of secondary pollutants. There is a remarkable attentiveness with respect to recent progress in heavy metals remediation over the past few decades with special emphasis on bioremediation utilized in various environmental areas. The present review is focused to throw light on the possible sources and related intake routes of the harmful metals, the symptoms of poisoning, their impact on the environment and health and the molecular mechanisms, which threaten human health effects. It also aims to provide an overview of the available studies on microbial bioremediation of heavy metals from the environment, including the mechanisms involved in metal removal and some future directions in microbial biodegradation technology.

Salinized soil is an important reserved arable land resource in China. The management and utilization of salinized soil can safeguard the current size of arable land and a stable grain yield. Salt accumulation will lead to the deterioration of soil properties, destroy soil production potential and damage soil ecological functions, which in turn will threaten global water and soil resources and food security, and affect sustainable socio-economic development. Microorganisms are important components of salinized soil. Microbial remediation is an important research tool in improving salinized soil and is key to realizing sustainable development of agriculture and the ecosystem. Knowledge about the impact of salinization on soil properties and measures using microorganisms in remediation of salinized soil has grown over time. However, the mechanisms governing these impacts and the ecological principles for microbial remediation are scarce. Thus, it is imperative to summarize the effects of salinization on soil physical, chemical, and microbial properties, and then review the related mechanisms of halophilic and halotolerant microorganisms in salinized soil remediation via direct and indirect pathways. The stability, persistence, and safety of the microbial remediation effect is also highlighted in this review to further promote the application of microbial remediation in salinized soil. The objective of this review is to provide reference and theoretical support for the improvement and utilization of salinized soil.

Global plastic pollution is one of the serious issues which create a severe environmental damage. Microbial biodegradation is an eco-friendly method to overcome the plastic pollution issue. The aim of this study is to explore microbes from garbage soil to manage the Low-density Polyethylene (LDPE). Active biodegrading microbes were identified by clear zone method using mineral salt medium with LDPE. Genome sequencing has been performed for LDPE-degrading strains and identified as Bacillus subtilis and Streptomyces labedae. The biodegradation of LDPE was carried out by using selected active strains. The analysis of biodegradation process was carried out by extracellular enzyme assay, cell hydrophobicity and viability of cells with elevated pH produced by B.subtilis and S.labedae. The weight loss percentage of polymer sheets by B.subtilis and S.labedae were 80% and 85% respectively. Major deformities and surface modification on the LDPE sheet were evaluated by the formation of cracks and pits on the surface. The functional groups in the treated sheets were observed by using FTIR analysis. The highest reduction in tensile strength was observed. The GC-MS analysis revealed the presence of 30 new compounds during the biodegradation. It evolved CO2 of 5.32 g/l with S. labedae and 4.55 g/l with B.subtilis. Phytotoxicity of LDPE degraded byproduct showed a positive growth rate of 97.8 +/- 0.836% in Trigonella foenum seed. Then the cytotoxicity study revealed that it was non-toxic to L292 cell lines. Both strains have the ability to consume and reduce the LDPE film. These organisms are the promising resources to manage the LDPE and offers an ecofriendly solution to solve global plastic pollution. Hence the achieved research information could be applied at a large scale for degrading various plastic materials.