Dibyarupa Pal* 1
Koly Dey 1
Barsha Das 1
PCBs are one of the most persistent organohalide groups of environment pollutants which are present in natural gas, coal tar and crude oil. They are produced during the synthesis of plastics and crop protection products and also used in heat transfer fluids. PCBs are accumulating in high percentage in the biota, taking entry in the food chain and causing multiple health hazards1,2,3. They are hydrophobic in nature and tend to accumulate in fat bodies of human system. Their presence has been noted in human’s blood, tissues, and even breast milk and is introduced into the food chain via consumption of meat, fish, and dairy products4-7. Now a days the use of biphenyl and PCBs have been significantly reduced but they still remain in the environment because of their stable chemical structure. PCB molecules consist of a biphenyl nucleus carrying 1 to 10 chlorines, which can create more than 200 possible congeners which differ only in the number and position of the chlorines. Thus, quick removal of these organic pollutants from contaminated environments is urgently required to cover up their damage to our ecosystems8.The source of origin of man-made PCB, its impact on soil and humans along with bioremediation solutions are depicted in the illustrative Fig.1.
Figure 1. Showing the various congener sources, impact and mitigation strategies of PCB
Agricultural lands consist of heterogeneous mixture of soil components both biotic and abiotic in nature. PCBs have direct influence on soil abiotic components like texture, moisture, porosity and soil organic matter whereas enzyme activity of biotic components are hindered by indirect process9-11. Bioremediation of PCBs through microbial degradation is regarded as one of the most cost-effective and energy-efficient methods for their removal from the environment. The process is achieved through naturally occurring microbes like bacteria, fungi and algae to degrade, convert and/or remove toxic PCBs into non-toxic ones12-16. Therefore, primary focus lies on the selection of highly efficient PCB-degrading microbes. Many isolates have already been reported, including Gram-negative strains, such as Pseudomonas, Alcaligenes, Achromobacter, Janibacter, Burkholderia, Acinetobacter, Comamonas, Sphingomonas, Paenibacillus, and Ralstonia, and Gram-positive strain, such as Arthrobacter, Corynebacterium, Rhodococcus, and Bacillus17-18. Advanced degradation of PCB was achieved to 67.7 and 71.7% by eliminating the electronegative contaminants from the soil sample and supplementing with methanol and cowdung as electron donor was also reported by researchers. PCB are present in air, water, biota and agricultural fields but can be transported far away from their generation site to non-point sources like the Arctic regions. Long time PCB exposure causes chronic inflammatory diseases affecting cardiovascular system, disruption of endocrine system19-21.
Properties and Sources
10.5281/zenodo.17297622