Microbial Interventions in Bioremediation of Heavy Metal Contaminants in Agroecosystem

Abstract

Soil naturally comprises heavy metals but due to the rapid industrialization and anthropogenic events such as uncontrolled use of agrochemicals their concentration is heightened up to a large extent across the world. Heavy metals are non-biodegradable and persistent in nature thereby disrupting the environment and causing huge health threats to humans. Exploiting microorganisms for the removal of heavy metal is a promising approach to combat these adverse consequences. The microbial remediation is very crucial to prevent the leaching of heavy metal or mobilization into the ecosystem, as well as to make heavy metal extraction simpler. In this scenario, technological breakthroughs in microbes-based heavy metals have pushed bioremediation as a promising alternative to standard approaches. So, to counteract the deleterious effects of these toxic metals, some microorganisms have evolved different mechanisms of detoxification. This review aims to scrutinize the routes that are responsible for the heavy metal(loid)s contamination of agricultural land, provides a vital assessment of microorganism bioremediation capability. We have summarized various processes of heavy metal bioremediation, such as biosorption, bioleaching, biomineralization, biotransformation, and intracellular accumulation, as well as the use of genetically modified microbes and immobilized microbial cells for heavy metal removal.

Hormesis Responses of Growth and Photosynthetic Characteristics in Lonicera japonica Thunb. to Cadmium Stress: Whether Electric Field Can Improve or Not?

“…Heavy metals in soils are mainly derived from metalliferous mining and waste water irrigation, overuse of agricultural fertilizers and pesticides, warfare and military training, and over recent decades, heavy metals have become ubiquitous environmental contaminants all over the world [ 3 , 4 ]. Increasing emissions of heavy metals pose a significant threat to human health, because they may be accumulated in plants, animals or microorganisms and enter into the food chain [ 5 , 6 , 7 , 8 ]. Among heavy metals, cadmium (Cd) is one of the most hazardous pollutants and can cause leaf chlorosis, nutritional imbalance, and growth and photosynthesis inhibition [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

Exploring the Extreme Acid Tolerance of a Dynamic Protein Nanocage

“…[53][54][55][56] Further, bioleaching and bioremediation approaches aimed at recovering valuable or toxic metals could benefit from acid stable nanoencapsulation systems able to sequester specific metal-binding enzymes of interest. 24,57 Finally, a number of biomedical applications of protein nanocages related to drug delivery or intracellular targeting of acidic compartments could also benefit from robust and easily engineerable nanocages like AaEnc. 58,59 In sum, AaEnc is the first characterized highly acid stable encapsulin nanocage with a unique pHdependent dynamic pore and, therefore, represents a novel useful tool for the nanocage engineering community.…”

“…53–56 Further, bioleaching and bioremediation approaches aimed at recovering valuable or toxic metals could benefit from acid stable nano-encapsulation systems able to sequester specific metal-binding enzymes of interest. 24,57 Finally, a number of biomedical applications of protein nanocages related to drug delivery or intracellular targeting of acidic compartments could also benefit from robust and easily engineerable nanocages like AaEnc. 58,59…”

“…For example, the melting temperature of the T=4 shell from Quasibacillus thermotolerans was reported to be nearly 87°C, 10 while the encapsulin from Brevibacterium linens was shown to be stable across a broad range of pH values (pH 5 to 11). 21 However, a number of biotechnological and industrial processes – including lignocellulose hydrolysis for biofuel production, 22 breakdown of complex sugars for monosaccharide production, 22 and bioleaching to prevent metal contamination and enable bioremediation in the mining industry 23,24 – would benefit from modular protein cages stable at acidic conditions below pH 5. Even though evolutionary adaptations of thermostable proteins have been well characterized and include oligomerization, large hydrophobic cores, and disulfide bond formation, adaptations that lead to acid-stable proteins are poorly understood.…”

A Review on Succession of Bioremediation Including Microbial Interventions for Reducing Heavy Metal Ions Contamination of Natural Environment

“…Recently, a range of processes of heavy metal bioremediation, such as biosorption, bioleaching, biomineralization, biotransformation, and intracellular accumulation, as well as the application of genetically modified microbes and immobilized microbial cells for heavy metal bioremediation, have been well overviewed [66]. For the elimination of heavy metal ions from the polluted sites, bioremediation methods are in practice [67].…”