# Mycoremediation of PCBs by _Pleurotus ostreatus_: Possibilities and Prospects
## 2 Bioremediation of PCBs  
With all the raising environmental considerations, the clean-up of PCB-contaminated sites has drawn everybody's attention and has become a top priority. Among the many remediation approaches that are available, the use of biological systems represents an effective, cost-competitive, and environmentally friendly alternative to the more commonly used thermal and physicochemical technologies [11]. The most prevalent existing practice in the removal of PCBs from contaminated materials is by incineration at high temperatures. In this procedure, the limitations to be faced are that it is expensive, brings additional risk of producing toxic chlorinated dioxins by combustion under lower temperatures, and has inherent volume limits. Therefore, studies on PCB biodegradation by microbes for the decontamination of water and soil systems have been gaining popularity. Decontamination of soil systems with respect to bioremediation has been well established compared to decontamination in water systems. With key advantages such as cost effectiveness and environmental friendliness gaining emphasis (as with any bioremediation system), bioremediation has received much acceptance. Bacteria plays a key role in PCB biodegradation processes, it has been found. In addition, aerobes and anaerbes have also been reported to participate in their own way in the process. Highly chlorinated biphenyls can be used by anaerbes as electron acceptors, and it is possible to convert them into less chlorinated congeners. Aerobic microorganisms, on the other hand, can deal and co-metabolize lower chlorinated biphenyls [12; 13; 14]. Thus, both anaerobic-aerobic treatments are required to completely mineralize these xenobiotics. Bacterial PCB biodegradation in natural compartments is also well documented [15; 16]. PCB congeners with four or more chlorine atoms undergo bacterial anaerobic reductive dec chlorination, while the lower chlorinated PCB congeners are subjected to co-metabolic aerobic oxidation mediated by dioxygenases, encoded by the bphA gene family [17]. The process of PCB biodegradation mediated by fungi is also well established. Fungi's capacity to transform several PCB congeners in liquid medium have been described [18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36]. A few studies established the successful fungal transformation capacity in soils [18; 19; 20; 21; 22; 23; 24]. Unlike bacteria, ligninolytic cultures of _Phanerohate chrysosporium_, a white-rot fungus, can mineralize tetrachloro- and hexachloro-substituted PCB congeners as well as Aroclor 1254 [37; 38]. Other studies have proven that _P. chrysosporium_ degrades higher levels (10 ppm) of Aroclor 1242, 1254, and 1260 [39]. Fungi, mostly wood-degrading basidiomycetes, are well established for PCB removal [40]. The elaborate fungal hyphae can easily penetrate into the polluted matrix. Additionally, the extracellular oxidative enzymes can scavene even scarcely bioavailable contaminants by nonspecific radical-based reactions. Thus, comparing bacteria and fungi, the latter are said to be more acceptable and recognized for their inputs towards PCB removal. White-rot fungi (WRF) are the most active degraders of lignin to CO\({}_{2}\) in plants [41; 42; 43; 44]. Earlier reports by [PERSON] et al. [45] and [PERSON] [46] indicated that the white-rot fungus _P. chrysosporium_ degrades dioxins, polychlorinated biphenyls (PCBs), and other chloroorganics. _P. chrysosporium_ is the most extensively studied of the ligninolytic white-rot fungi that mineralizes xenobiotics [47; 48; 49; 50]. Several white-rot fungi were tested for their ability to decompose PCBs [51]. Numerous studies have confirmed that white-rot fungi including _P. chrysosporium_[52], _Trametes versicolor_[53], _Lentinus edodes_[22], _Phleba brevispora_[54], Irpex lacteus, Bjerkanderaadusta, _Pycosporus cinnabarinus, Phanerohatee magnoliae_[55], and particularly _Pleurotus ostreatus_[28; 55] could successfully orchestrate PCB removal [1].