Phytoremediation of heavy metal-contaminated sites: Eco-environmental concerns, field studies, sustainability issues and future prospects

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physico-chemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metals-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches, evaluate their efficacy to remove toxic metals from our natural environment, explore current scientific progresses, field experiences and sustainability issues and revise world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in 21st century

Biofuel production using thermochemical conversion of heavy metal-contaminated biomass (HMCB) harvested from phytoextraction process

Over the past few decades, bioenergy production from heavy metal-contaminated biomasses (HMCBs) has been drawing increasing attention from scientists in diverse disciplines and countries owing to their potential roles in addressing both energy crisis and environmental challenges. In this review, bioenergy recovery from HMCBs, i.e. contaminated plants and energy crops, using thermochemical processes (pyrolysis, gasification, combustion, and liquefaction) has been scrutinized. Furthermore, the necessity of the implementation of practical strategies towards sustainable phytoextraction and metal-free biofuels production has been critically discussed. To meet this aim, the paper firstly delivers the fundamental concepts regarding the remediation of the brownfields using phytoremediation approach, and then, reviews recent literature on sustainable phytoextraction of heavy metals from polluted soils. Thereafter, to find out the possibility of the cost-efficient production of metal-free biofuels from HMCBs using thermochemical methods, the impacts of various influential factors, such as the type of feedstock and metals contents, the reactor type and operating conditions, and the role of probable pre-/post-treatment on the fate of heavy metals and the quality of products, have also been discussed. Finally, based on relevant empirical results and techno-economic assessment (TEA) studies, the present paper sheds light on pyrolysis as the most promising thermochemical technique for large-scale electricity and heat recovery from HMCBs

Molecular Modeling of Structures and Interaction of Short Peptides and Sortase Family Protein of Enterococcus Faecalis: Basis for Developing Peptide-Based Therapeutics Against Multidrug Resistant Strains

The Enterococcus faecalis (E. faecalis) infection starts with initial adhesion to a host cell or abiotic surface by multiple adhesions on its cell membrane. The pathogenicity is due to virulence factors SrtA, SrtC, EbpA, EbpB, EbpC, and Aggregation Substance. E. faecalis developed resistance to the majority of standard therapies. Additionally, a notable key feature of E. faecalis is its ability to form biofilm in vivo. E. faecalis strains show resistance to aminoglycosides and β-lactam antibiotics with different degree of susceptibility. Sortases (SrtA and SrtC) are enzymes spatially localized at the septal region in majority of gram-positive bacteria during the cell cycle, which in-turn plays an important role in proper assembling of adhesive surface proteins and pilus on cell membrane. The studies have also proved that the both SrtA and SrtC were focally localized in E. faecalis and essential for efficient bacterial colonization and biofilm formation on the host tissue surfaces Using homology modeling and protein-peptide flexible docking methods, we report here the detailed interaction between peptides and EfSrt (Q836L7) enzyme. Plausible binding modes between EfSrt and the selected short biofilm active peptides were revealed from protein-peptide flexible docking. The simulation data further revealed critical residues at the complex interface and provided more details about the interactions between the peptides and EfSrt. The flexible docking simulations showed that the peptide-EfSrt binding was achieved through hydrogen bonding, hydrophobic, and van der Waals interaction. The strength of interactions between peptide-EfSrt complexes were calculated using standard energy calculations involving non-bonded interactions like electrostatic, van der Waals, and hydrogen bonds.</p