Impact of Pharmaceutical Compounds in the Bioremediation of Municipal Biosolids by the White-Rot-Fungi Trametes hirsuta.

The potential of microorganisms for the treatment of municipal biosolids is continuously growing. The present studies evaluated the potency of Trametes hirsuta for the reduction in biosolid mass, production of extracellular enzymes, and removal of pharmaceutical compounds (PhACs) in biosolid slurry in the presence and absence of spiked PhACs [5 non-steroidal anti-inflammatories (NSAIs) and 2 psychoactive compounds (PACs)]. Toxicity after 35 days of fungal treatment was also assessed. Results showed that the growth of T. hirsuta is limited above 25% and wholly inhibited above 50% of biosolids in the slurry. At 12% of biosolid concentration, biosolid mass was reduced by 90%, NSAIs were entirely removed, but PACs' removal was only ~20%. Increasing biosolid content to 25% did not markedly affect biosolid reduction but significantly enhanced the removal of PACs (>50%). Results also showed that both PhACs and biosolids induced the production of oxidative enzymes. In 12% biosolids in the slurry, the oxidative potential measured by the ABTS assay (OABTS) reached 5,000 mM of OABTS in the presence of PhACs, and 2,500 mM of OABTS without PhACs, as compared to 1,200 mM of OABTS in control culture. Finally, we report that white rot fungi (WRF) treatment significantly decreased the toxicity of the biosolids.

Performance evaluation of biocatalytic and biostimulation approaches for the remediation of trace organic contaminants in municipal biosolids.

Trace organic contaminants (TrOCs) in biosolids is creating potential threats for reuse of biosolids. Out of the tested 64 trace organic contaminants, seven pharmaceutically active compounds (PhACs), and three pesticides were detected in biosolids from a municipal wastewater treatment plant. This study encompasses the removal of TrOCs and improvement in the aerobic digestion of biosolids by various pretreatments including utilization of indigenous microbes present in biosolids (T1), the effect of an enzymatic pretreatment (T2), biostimulation by the addition of an external carbon source (T3) and the synergic effect of biostimulation and enzymatic pretreatment (T4). After 28 days of aerobic digestion, total PhACs removal was 44% with T1, which improved to 51%, 54% and 62% in T2, T3 and T4, respectively. Also, total pesticides removal was 10% in T1, which enhanced to 44%, 14% and 54% in T2, T3 and T4, respectively. The extracellular enzyme activities were also monitored in all the treatments and the maximum activities (114 ± 11 U/L lipase, 382 ± 29 U/L phosphatase, 155 ± 8 U/L protease, 304 ± 26 U/L amylase, 108 ± 7 U/L laccase, and 63 ± 2 U/L lignin peroxidase) were observed in T4 after 28 days of digestion. Thus, this study aids in providing changing aspects of enzyme profiles during these processes and the enhanced bioremediation of biosolids through the hydrolytic and oxidoreductase enzymes produced by the indigenous microorganisms.

Simple screening protocol for identification of potential mycoremediation tools for the elimination of polycyclic aromatic hydrocarbons and phenols from hyperalkalophile industrial effluents.

A number of fungal strains belonging to the ascomycota, basidiomycota and zygomycota genera were subjected to an in vitro screening regime to assess their ligninolytic activity potential, with a view to their potential use in mycoremediation-based strategies to remove phenolic compounds and polycyclic aromatic hydrocarbons (PAHs) from industrial wastewaters. All six basidiomycetes completely decolorized remazol brilliant blue R (RBBR), while also testing positive in both the guaiacol and gallic acid tests indicating good levels of lignolytic activity. All the fungi were capable of tolerating phenanthrene, benzo-α- pyrene, phenol and p-chlorophenol in agar medium at levels of 10 ppm. Six of the fungal strains, Pseudogymnoascus sp., Aspergillus caesiellus, Trametes hirsuta IBB 450, Phanerochate chrysosporium ATCC 787, Pleurotus ostreatus MTCC 1804 and Cadophora sp. produced both laccase and Mn peroxidase activity in the ranges of 200-560 U/L and 6-152 U/L, respectively, in liquid media under nitrogen limiting conditions. The levels of adsorption of the phenolic and PAHs were negligible with 99% biodegradation being observed in the case of benzo-α-pyrene, phenol and p-chlorophenol. The aforementioned six fungal strains were also found to be able to effectively treat highly alkaline industrial wastewater (pH 12.4). When this wastewater was supplemented with 0.1 mM glucose, all of the tested fungi, apart from A. caesiellus, displayed the capacity to remove both the phenolic and PAH compounds. Based on their biodegradative capacity we found T. hirsuta IBB 450 and Pseudogymnoascus sp., to have the greatest potential for further use in mycoremediation based strategies to treat wastestreams containing phenolics and PAHs.

Xenobiotic Compounds Degradation by Heterologous Expression of a Trametes sanguineus Laccase in Trichoderma atroviride.

Fungal laccases are enzymes that have been studied because of their ability to decolorize and detoxify effluents; they are also used in paper bleaching, synthesis of polymers, bioremediation, etc. In this work we were able to express a laccase from Trametes (Pycnoporus) sanguineus in the filamentous fungus Trichoderma atroviride. For this purpose, a transformation vector was designed to integrate the gene of interest in an intergenic locus near the blu17 terminator region. Although monosporic selection was still necessary, stable integration at the desired locus was achieved. The native signal peptide from T. sanguineus laccase was successful to secrete the recombinant protein into the culture medium. The purified, heterologously expressed laccase maintained similar properties to those observed in the native enzyme (Km and kcat and kcat/km values for ABTS, thermostability, substrate range, pH optimum, etc). To determine the bioremediation potential of this modified strain, the laccase-overexpressing Trichoderma strain was used to remove xenobiotic compounds. Phenolic compounds present in industrial wastewater and bisphenol A (an endocrine disruptor) from the culture medium were more efficiently removed by this modified strain than with the wild type. In addition, the heterologously expressed laccase was able to decolorize different dyes as well as remove benzo[α]pyrene and phenanthrene in vitro, showing its potential for xenobiotic compound degradation.