## 4 Discussion
ostreatus_ and for _L. edodes_, the fungi that colonized the soil the least, possibly the enzymatic activity that they presented came from the mycelium that remained alive in the substrates. Finally, versatile peroxidase catalyzes oxidation for both organic and inorganic substrates, phenols or aromatic amines, and is characterized by oxidizing substrate compounds with high and low redox potential [55]. Because of these results, it is clear that _A. bisporus_ treatment reached the highest biodegradation of TPHs (Table 3). These results agreed with the visual aspect of the microcosms, total hydrolase, dehydrogenase and ligninolytic activities. [PERSON] et al. [50] reported that _A. bisporus_ was more effective than _P. ostreatus_ SMS in a TPHs contaminated soil after biostimulation with NPK. I [48]. However, _L. edodes_ and _P. ostreatus_ SMSs showed the second highest removal of TPHs. This result was unexpected since vigorous fungal colonization was not observed (Figure 1). Furthermore, the enzymatic activities were not significantly higher than the control treatment. Therefore, it can be deduced that, for both fungal species, a greater degradation occurred because their respective SMSs favored the soil microbiota that is already resistant to high contamination levels. [PERSON] et al. [4] highlighted that the microbial variety is reduced in the contaminated soils due to the influences of the toxic petroleum hydrocarbons upon the organisms. Therefore, the population of degrading microbes ranges from 1% to 10% of the population in a contaminated environment, whereas those in an uncontaminated environment are less than 1% of the population. Another explanation could be that _L. edodes_ and _P. ostreatus_ SMSs contain inherent microbiota highly specific to degrade hydrocarbons such as _Proteobacteria_, _Microbacterium_, _Brevundimonas_, and _Devosia_ as was previously reported for _P. ostreatus_ SMS [26]. [PERSON] et al. [49] highlighted the key role of the synergistic effects of soil microbiota and lignin-modified fungi to promote the degradation of aliphatic hydrocarbons, specifically C\({}_{28}\)-C\({}_{34}\). The assessment of TPH degradation by chains is not a common issue. In this work, the TPHs biodegradation was assessed by degradation of TPHs, aliphatic and aromatic chains and by the number of carbons of these chains. The degradation effectiveness of each treatment by aliphatic and aromatic chains followed the same pattern than TPHs degradation, _A. bisporus_ SMS > _P. ostreatus_ SMS and _L. edodes_ SMS > _P. eryngii_ SMS (Table 3) and it was maintained in many of the specific aliphatic and aromatic chains. The interpretation of the degradation effectiveness of each SMS by the carbon chain length demonstrated the ability of all the tested SMSs to enhance the biodegradation of light aliphatic and aromatic hydrocarbons. However, _P. eryngii_ SMS was the only which was not able to improve the degradation of the heavy aliphatic fraction C\({}_{21}\)-C\({}_{35}\) with respect to control. For the heavy aromatic hydrocarbons (EC\({}_{21}\)-EC\({}_{35}\)), none of the _Pleurotus_ SMSs improved the degradation of the control treatment but _L. edodes_ and _A. bisporus_ SMSs were able to stimulate the degradation of EC\({}_{21}\)-EC\({}_{35}\). Therefore, despite all the SMSs were able to improve the hydrocarbon degradation, their potential to remove heavy fractions was different or even seem impaired for the heaviest fractions (>C\({}_{35}\) and >EC\({}_{35}\)). For example, aromatic hydrocarbons such as PAHs with high molecular weight having more than three benzene rings are difficult to degrade by soil microbiota because of their low availability [56] as was seen in this work (Table 3). Because the bioremediation process depends on the bioavailability of contaminants and the biodegradation performed by the microbial communities [57], an additional strategy could be the use of surfactants such as saponin or Tween 80, between other possibilities, that enhance TPH removal through increasing its solubility [58].