Screening Thermotolerant White-Rot Fungi for Decolorization of Wastewaters

Abstract

To select a thermotolerant fungal strain for decolorization of wastewaters, ligninolytic enzyme production (lignin peroxidase, manganese peroxidase [MnP], and laccase), decolorization, and removal of total phenol and chemical oxygen demand (COD) were detected. Thirty-eight fungal strains were studied for enzyme production at 35 and 43 degrees C on modified Kirk agar medium including 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and MnCl2. Thirteen strains grew on manganese-containing agar and provided green color on ABTS-containing agar plates under culture at 43 degrees C. Decolorization of wastewater from alcohol distillery (WAD) by these strains was compared under static culture at 43 degrees C, and Pycnoporus coccineus FPF 97091303 showed the highest potential. Thereafter, immobilized mycelia were compared with free mycelia for WAD decolorization under culture conditions of 43 degrees C and 100 rpm. The immobilized mycelia on polyurethane foam enhanced the ligninolytic enzyme production as well as total phenol and color removal. At about the same COD removal, MnP and laccase produced by immobilized mycelia were 2 and 19 times higher than by free mycelia; the simultaneous total phenol and color removal were 3.1 and 1.5 times higher than the latter. Moreover, decolorization of synthesis dye wastewater was carried out at 43 degrees C and 100 rpm. More than 80% of 300 mg/L of reactive blue-5 was decolorized by the immobilized mycelia within 1 to 2 d for four cycles.

Polyurethane as substrate for fungal strains

“…To establish if the selected molds have the enzymes related to PU degradation, four specific culture media were used for the detection of those enzymatic activities. YES medium to determine protease activity, Tween 80 medium for esterase activity, Christensen urea medium for urease activity and PDA-ABTS (2,2'-azino-bis (3-ethylbenzhiazoline-6-sulphhonic acid) medium [14] for laccase activity. [11].…”

The use of heavy metals in mycoremediation of synthetic dyes

“…Murugesan and co-workers [19] reported strong inhibition of laccase activity caused by the presence of Fe 2+ ions. Therefore, the effect of heavy metals in the discoloration processes is very different based on synthetic dyes, as well as the fungal species involved [30][31][32][33]. This is due to high structural variability of synthetic dyes, and thus is due to different classes of enzymes involved in the discoloration of dyes.…”

Wood production, wood technology, and biotechnological impacts

“…that enzymes are not produced in such high amounts as required for industrial application, or iii. that available enzymes are not as ideal for specific applications, screenings are also ongoing for the other main types of fungal enzymes acting in lignocellulose degradation [e.g., see receent publications of Kiiskinen et al (2004), Krogh et al (2004), Dhouib et al (2005), Kabe et al (2005), Chairattanamanokorn et al (2006), Guimaraes et al (2006), Songulashvili et al (2007)]. …”