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For successful management of pollution problems, the use of bacteria is now a popular and widespread technique. Alcaligenes faecalis, an inhabitant of the natural environment, is equipped with machinery for cleaning up different types of contaminants, including heavy metals and xenobiotics. A. faecalis, a gram‐negative, flagellated, nonfermentive, aerobic member of the subgroup proteobacteria, often shows anaerobic respiration using nitrate or nitrite as terminal electron acceptors. It is also gifted with the power of nitrogen fixation and thereby could be used as a biofertilizer. The bacterium also has the unique ability to act as a probiotic and can often be used as a biocontrol agent due to its antimicrobial properties. Hence, for sustainable management of the environment, various strains of this bacterium as active bio‐remediators, bio‐pesticides, biofertilizers, and probiotics are being increasingly applied. [ABSTRACT FROM AUTHOR]

The increase in population has resulted in a rapid increase in waste that is being dumped within the environment. The addition of various harmful and contaminating compounds results in the degradation of the environment and has a direct impact on human health. Various research studies that are taking place in recent times help in the enhancement of the naturally available microbes to degrade toxic compounds that are liberated into the environment. Although various types of bioremediation techniques are available, microbe-associated remediation is proven to be the best option due to its effectiveness, no generation of toxic by-products, and natural availability of microbes with the ability to take up nutrients from the toxic contaminants that exist on the surface of the earth. Both ex situ and in situ bioremediation can be accomplished with the help of these microbes. In most cases, this is done through biofilm-assisted seclusion of pollutants, more precisely by means of extracellular polymeric substances (EPSs) of biofilm matrix. In recent times, various types of techniques have been implemented like proteomics, genomics, fluxomics and transcriptomics for bringing about maximum remediation by the microbial species. In order to explore the different kinds of microbial communities involved in natural bioremediation, the strategic approach of metagenomic analysis is adopted, which has brought about a technological drift in remediation, even at a genomic level. As chemical mode of remediating wastes are associated with the release of various harmful chemicals those can be toxic to the environment, the use of biological systems can be a potential agent in the conversion of complex waste materials to simpler substances so that it mixes with the environment in easier manner. Microbes are the potential entities that can easily act on the waste materials and bring about remediation in an effective manner. [ABSTRACT FROM AUTHOR]

Enhanced population growth, rapid industrialization, urbanization and hazardous industrial practices have resulted in the development of environmental pollution in the past few decades. Heavy metals are one of those pollutants that are related to environmental and public health concerns based on their toxicity. Effective bioremediation may be accomplished through "ex situ" and "in situ" processes, based on the type and concentration of pollutants, characteristics of the site but is not limited to cost. The recent developments in artificial neural network and microbial gene editing help to improve "in situ" bioremediation of heavy metals from the polluted sites. Multi-omics approaches are adopted for the effective removal of heavy metals by various indigenous microbes. This overview introspects two major bioremediation techniques, their principles, limitations and advantages, and the new aspects of nanobiotechnology, computational biology and DNA technology to improve the scenario. [ABSTRACT FROM AUTHOR]

Hexavalent chromium among the chromium containing compounds is the most harmful and potentially toxic, imparts severe hazard to humans besides plants, including the entire environment. There have been found many bacterial, algal, fungal and plant species that can thrive and grow under this Cr (VI) stress. These organisms have evolved to employ different strategies to reduce the effects of Cr (VI) toxicity. Generally, strategies like biosorption, biotransformation, use of various enzymes like chromate reductase, uptake and metabolize Cr (VI) through membrane transport, conversion of Cr (VI) to Cr (III), a potentially non-toxic state and discharging these metals from the cells into the surrounding environment after reduction are applied to detoxify the effects produced by Cr (VI). Therefore, this review article focuses on the various bioremediation procedures adopted by different organisms with a view into the molecular aspects and the genetic background manipulation behind these bioremediation strategies. [ABSTRACT FROM AUTHOR]

Mining and various industrial activities, along with generation and accumulation of heavy metals due to agricultural and domestic activities are languishing human health and the environment as a whole. Employment of conventional strategies in eradicating these toxic loads, are way expensive and concerned with the production of secondary wastes. Biofilm being a syntropic microbial consortium, through the mechanism of cell communication and signaling, quorum sensing and modulating strategies accomplish the removal of contaminant metals from environment. Such biofilm mediated bioremediation may be explicitly explained by implementing synthetic biology models and through unique mathematical modelling of mechanisms of multi species biofilm formation and survival strategies in toxic environments. Microbial metabolism for extracellular electron transfer (EET) and development of niche-specific microbial electrochemistry-driven biotechnologies, exploit the bio electrochemical system of electroactive biofilms (EABs) for removal of metal ions from environment. The multi omics platform predicts the pathways of modified metal-biofilm interaction and sequestration strategies as crucial mechanism to accelerate biofilm mediated bioremediation processes. • Environmental heavy metal accumulation is detrimental for mostly all living entities. • Biofilm mediated bioremediation may be an option for eradication of such toxic loads. • Mechanisms of microbial metabolism and multi species biofilm formation for survival. • Implementation of mathematical models and synthetic biology techniques. [ABSTRACT FROM AUTHOR]

[Display omitted] • Characterization of a Cr (VI) tolerant strain of Serratia marcescens AJRR-22. • Determination of Cr (VI) resistance in AJRR-22 with subsequent physiological changes. • Confirmation of intracellular NADH dependent bio-reduction by molecular docking. • Elucidate sustainability of AJRR-22 as potential candidate for Cr (VI) bioremediation. Environmental accumulation of hexavalent chromium [Cr(VI)] in the food chain can induce detrimental effects on plants and animals, which calls for effective remediation strategies using biological entities. The bacterium isolated from an iron mine in Odisha, India, is identified as Serratia marcescens AJRR-22. This multi-metal tolerant strain is capable of bio-converting up to 350 mg/L Cr(VI) within 72 h of incubation. Observable electron dense precipitates in transmission electron microscopic images, data patterns in fluorescence microscopy and flow cytometry clearly reveal the chromate reduction ability of the strain. The molecular study is depicted by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopic analyses. Furthermore, a simulation study to estimate the interactions of chromium bound flavin reductase with predicted docked complexes suggests significant negative Gibbs free energy and a low inhibition constant (K i), signifying strong spontaneous binding of Cr(VI) to the enzyme, which makes the strain an efficient candidate for chromium bioremediation. [ABSTRACT FROM AUTHOR]