Call for biotechnological approach to degrade plastic in the era of COVID-19 pandemic.

Plastic pollution is a global issue and has become a major concern since Coronavirus disease (COVID)-19. In developing nations, landfilling and illegal waste disposal are typical ways to dispose of COVID-19-infected material. These technologies worsen plastic pollution and other human and animal health problems. Plastic degrades in light and heat, generating hazardous primary and secondary micro-plastic. Certain bacteria can degrade artificial polymers using genes, enzymes, and metabolic pathways. Microorganisms including bacteria degrade petrochemical plastics slowly. High molecular weight, strong chemical bonds, and excessive hydrophobicity reduce plastic biodegradation. There is not enough study on genes, enzymes, and bacteria-plastic interactions. Synthetic biology, metabolic engineering, and bioinformatics methods have been created to biodegrade synthetic polymers. This review will focus on how microorganisms' degrading capacity can be increased using recent biotechnological techniques.

Successive use of microorganisms to remove chromium from wastewater.

Heavy metal pollution is a direct consequence of the extensive utilization of heavy metals in various industrial processes. The persistence and nondegradability of heavy metals cause them to bioaccumulate in nature, and when they come in direct contact with the pristine environment, they not only contaminate it severely but also pose dire consequences to the health of all living forms on earth, including humans. Chromium (Cr) is one of the heavy metals which has been extensively used in various industrial processes such as mining, alloy manufacturing, tanning of hides and skins, pigment production, etc. However, it is regarded as a priority pollutant due to its highly toxic, teratogenic, mutagenic, and carcinogenic nature, and the U.S. Environmental Protection Agency (EPA) also categorized it into group "A" human carcinogen. In contrast to water-soluble hexavalent chromium (Cr6+), its reduced form, trivalent chromium (Cr3+), is relatively benign and readily precipitated at environmental pH. Thus, bioremediation of Cr6+ through microorganisms including bacteria, yeast, and algae provides a promising approach to decontaminate a metal-polluted environment. This review describes an overview of the microbial reduction of Cr6+, resistance mechanism, and the antioxidant profiling exhibited by these microorganisms when exposed to Cr6+. It also describes the pilot-scale study of the successive use of bacterial, fungal, and algal strains and the subsequent use of microbially purified water for the cultivation of plant growth. Multiple metal-resistant microorganisms are a good bioresource for green chemistry to eradicate environmental Cr6+. KEY POINTS: • Hexavalent chromium (Cr6+) is highly toxic for living organisms including humans. • Microbial Cr resistance is mediated at the genetic, proteomic, and molecular levels. • Successive use of microorganisms is the best strategy to exterminate Cr6+from the environment.