ABSTRACT
Synthetic chlorine derivatives of hydrocarbon compounds consisting two benzene rings joined through a single carbon-carbon bond are polychlorinated biphenyls or commonly called PCBs. These were the most persistent between 1930 to 1980 as organic pollutants. Plasticizers, coatings, inks, resins, fire repellents, paints, insecticide extensions, and dye microencapsulation are just a few of the applications. Being resistant to acids as well as alkalis and thermally stable, PCBs’ have been widely utilized in dielectrics. Due to their widespread use and polluting properties, environmental contamination may occur from the disposal of products which contain PCBs as ingredient. A number of PCBs can be found in the environmental components even after years of their disposal. Synthetic PCBs because of their unique properties persist in the environment resulting into severe toxic effects in animals as well as human beings. PCBs, being resistant to breakdown (bacterial and chemical), enters into the food chain via lipids of aquatic plankton. Their accumulation in food chain leads to their biomagnification. These organic contaminants are inhaled, ingested, and consumed by the general public. Thus, their removal is extremely important. The most frequent remediation includes phyto-remediation, microbial-degradation, de-halogenation via chemical reagent, and removal through activated carbon (AC). Some recent remediation processes include reductive dehalogenation via nanoscale zero-valent iron, ultrasonic radiation, supercritical water oxidation (SCWO), bimetallic systems, AC covered with biofilms and electro-kinetic remediation, etc. Some of the strategies are in developmental stage and thus further research is still need to be progressed. Rather, there is no completely developed technology which is efficient enough. Carvone, which is a plant-derived monoterpene, acts as a non-toxic inducing agent for culturing PCB degrading microorganisms. Bio-surfactants (BSs) are those surface-active compounds which are naturally synthesized by a variety of microorganisms. Being biodegradable, less toxic, and effective at high temperature, pH, and due to diverse applicability, BSs’ have recently gained great attention towards remediation. Also, these can be manufactured from economical substrates for degradation of PCBs. Incorporation of such substrates has gained considerable attention for bacterial growth and biodegradation of PCBs. These remediation strategies are found much effective in removing PCBs from the soil. The present chapter focuses on biosurfactants, their types, impacts, and applications. It also explains about carvone and surfactant grown bacteria with specific reference to bio-remediation approach. The chapter also discusses the future research perspectives towards bioremediation via carvone and surfactant grown bacteria.
