The basidiomycete fungi Lentinus crinitus and Psilocybe castanella are being evaluated in a bioremediation process of soils contaminated with organochlorine industrial residues in the Baixada Santista, São Paulo. The aim of the present study was to determine the influence of pH on the fungal growth, in vitro decolorization of anthraquinonic dye Remazol Brilliant Blue R (RBBR) and laccase activity. The pH of the culture medium influenced the growth of L. crinitus and P. castanella, which presented less growth at pH 5.9 and pH 2.7, respectively. The fungi were able to modify the pH of the culture medium, adjusting it to the optimum pH for growth which was close to 4.5. Decolorization of the RBBR was maximal at a pH of 2.5 to 3.5. Higher laccase activity was observed at pH 3.5 and pH 4.5 for L. crinitus and P. castanella, respectively. pH was found to be an important parameter for both the growth of these fungi and the enzymatic system involved in RBBR decolorization.

Hexachlorobenzene (HCB) is a pollutant still found in the environment despite being widely banned. Considering that basidiomycetes are useful to degrade a variety of organochlorinated pollutants, we therefore report the influence of HCB on the ligninolytic enzymatic system of Deconica castanella. The inoculum was prepared with sugarcane bagasse and soybean flour and was added in soil with and without HCB (2000 mg kg soil −1 ), 5% emulsion containing soybean oil and Tween 20 at proportion 9:1, v:v; with 70% moisture at 25 • C. Fungal biomass was quantified by widely acknowledged growth biomarker ergosterol. The extraction of the enzymatic complex was performed and laccase, Mn-dependent peroxidase (MnP), and lignin peroxidase (LiP) activities were determined. Furthermore, HCB and its metabolites were quantified by gas chromatography and chlorides by potentiometric titration. Results evidenced that HCB did not interfere in fungal growth, though the only detected enzymatic activity was laccase. MnP and Lip were not detected during D. castanella growth in soil. The peak of laccase enzymatic activity occurred in the presence of HCB. In addition, the laccase exhibited thermostability. Therefore, we hereby shed light on the role of laccase in the degradation of HCB by an efficient low-cost and environmentally safe detoxification mechanism.

The initial alkaline pH and the concentration of sodium chloride in the synthetic liquid medium were a key factor in the capability of twenty-five white-rot fungi strains to decolorise the dye Reactive Blue 19. Six strains decolorised 90% of the dye at pH 8.0, and only Peniophora cinerea decolorized 90% of the dye at pH 9.0. Fourteen strains were capable of decolorising the dye in saline medium (sodium chloride 10 g l -1 ). P. ostreatus, P. cinerea and T. villosa were able to decolorize the dye both in medium with initial pH 8.0 or in saline medium. These three strains were selected and evaluated for simulated alkali-saline textile effluent decolorisation in different conditions: time of cultivation for effluent addition (0, 5, 7 and 9 days), initial pH (4.5 and 8.0) and agitation (0 and 120 rpm). P. ostreatus and P. cinerea decolorised the alkali-saline textile effluent by 93.0 and 25.4%, when the medium's initial pH was 8.0 or 4.5, respectively, and the effluent was added in the 7th day of growth. T. villosa decolorized 40% when the effluent was added on the 9th day of cultivation at pH 4.5. Agitation increased the effluent decolorisation by T. villosa, but inhibition was observed for P. cinerea and P. ostreatus. The results showed that each fungus presented a specific behavior in relation to the best culture conditions for decolorisation of alkali-saline effluent containing reactive dyes. The strains of P. ostreatus, P. cinerea and T. villosa were considered as promising alternative for the biodegradation of this effluent, employing the strategy of effluent addition after a certain period of fungal growth.