# Mycoremediation of PCBs by _Pleurotus ostreatus_: Possibilities and Prospects
## 3 _P. ostreatus_ Based Degradation of PCBs: Milestones Achieved  
The oyster mushroom, _P. ostreatus_, is a common mushroom, first cultivated as a subsistence measure during World War I. Now grown commercially around the world for food, oyster mushrooms have been found more useful in industries, i.e., for mycoremediation purposes. As established by earlier researchers, _P. ostreatus_ is the one that is now accepted to be highly promising for removal of PCBs. The state-of-the-art contribution of _P. ostreatus_ in this area of bioremediation of PCBs is briefly presented below. [PERSON] et al., 1993 [PERSON] et al., 1993 [PERSON] et al., 1993, demonstrated that _P. ostreatus_ selectively removed PCBs from soil homogenized with wood chips. _P. ostreatus_ was successfully applied at contaminant concentrations ranging from 100 to 650 ppm for single isomers and 2500 ppm for all PCBs. However, _P. chrysosporium_ could not degrade any PCB except mono- and dichloriphenyl in a solid-state system under normal oxygen levels. However, with this limitation, _P. chrysosporium_ was still reported to be the most versatile of the WRF to degrade Aroclor 1242, 1254, and 1260 [PERSON] et al. (2000). However, with respect to bioremediation of PCB in soil, other WRFs like _Bjerkandern adusta, P. ostreatus_, and _T. versicolor_ exhibited higher biodegradation than _P. chrysosporium_. [PERSON] et al. (2008), studied six strains of white-rot fungi for their biodegradation ability of low chlorinated polychlorinated biphenyl (PCB) in real soil system. _Phanerochate chrysosporium_ and _Trametes versicolor_ did not show any ability to degrade PCBs in soil. By contrast, four strains of _P. ostreatus_ were able to remove about 40% of Delor 103 in two months. All _P. ostreatus_ strains decomposed PCBs selectively with the preference for congeners with chlorine atoms at ortho \(>\) meta \(>\) para positions. This study confirms _P. ostreatus_' unequivocal ability to perform in real world soil environments more efficiently compared to the others (who were all reported to be well accomplished laboratory scale achievers). _P. ostreatus_ produces ligninolytic enzymes which are able to interact with a plethora of waste substrates [PERSON] et al. (2008); [PERSON] et al. (2008); [PERSON] et al. (2008), including PCBs [PERSON] et al. (2008). This mushroom's industrial cultivation faces a problem: the huge turnover of spent mushroom substrate (SMS), a lignocellulosic matrix, that has to be disposed of [PERSON] et al. (2008). With this as the choke, the exploration of new applications for re-utilization of SMS became desirable. SMS is reported to contain high levels of residual extracellular oxidoreductase produced by the still metabolically active mycelium. It is the niche for active microbial community composed of fungi and bacteria [PERSON] et al. (2008); [PERSON] et al. (2008). Thus, application of SMS in bioremediation processes has been probed, and the ability of the SMS and its inherent microbiota to transform different contaminants has been reported [PERSON] et al. (2008); [PERSON] et al. (2008); [PERSON] et al. (2008). SMS from _P. ostreatus_ was previously validated as a low-cost organic substrate for remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil [PERSON] et al. (2008); [PERSON] et al. (2008). Moreover, lignosulfonate, an inducer of lignolytic activity, was found to possess no effect on the degradation of PCBs with _P. ostreatus_ or _Trametes versicolor_. An oxygen concentration of 10% inside the substrate combined with 10% CO\({}_{2}\) also had no influence on the degradation potential of _P. ostreatus_. [PERSON] et al. (2008) carried out an experiment using a mixture of substrate/SMS and sandy soil with PCBs. The results indicated that degradation was dependent on substrate/SMS addition, the concentration of PCBs, and time of incubation. The degree of degradation of a single PCB after 12 weeks of incubation for _Agaricus bisporus_ ranged from 31.32 \(\pm\) 1.52 to 83.91 \(\pm\) 1.07%, while for _P.