A Review on Bioremediation Using Nanobiotechnology and Microbial Heavy Metal Resistance Mechanisms

Various human actions have raised the level of heavy metal (HM) pollution in the environment. From contaminated water and soil, the HMs infiltrate into the agricultural crops that are consumed by animals as well humans. Deposition of heavy metals leads to DNA damage and several digestive, reproductive, and respiratory system-related health problems. Various microorganisms have evolved mechanisms of HM resistance, tolerance, detoxification, and metabolization. Physicochemical methods of HM treatment are expensive and non-ecofriendly. Therefore, remediation of contaminated soil and water using microorganisms or bioremediation has become a topic of interest for scientists. Bioremediation is a cheaper, eco-friendly and more efficient method. The present review attempts to describe various mechanisms (biosorption, bioaccumulation, biotransformation and active export) by which microbes resist and remediate heavy metal pollution. In addition, the role of different types of consortia/co-culture in bioremediation has been discussed. Microbes, such as fungi, bacteria, and protozoa can remove metals both singly and in amalgamation. Furthermore, an advanced nanotechnology approach for metal ion treatment from wastewater has been briefly discussed. To fully utilize the microbial potential for heavy metal removal and create better strategies to alleviate environmental pollution, a deeper knowledge of the molecular, biochemical, and genetic mechanisms used by these species is required.