Ligninolytic enzymes from white-rot fungi, such as laccase (Lac) and Mn-peroxidase (MnP), are able to degrade aflatoxin B₁ (AFB1), the most harmful among the known mycotoxins. The high cost of purification of these enzymes has limited their implementation into practical technologies. Every year, tons of spent mushroom substrate (SMS) are produced as a by-product of edible mushroom cultivation, such as Pleurotus spp., and disposed at a cost for farmers. SMS may still bea source of ligninolytic enzymes useful for AFB1 degradation. The in vitro AFB1-degradative activity of an SMS crude extract (SMSE) was investigated. Results show that: (1) in SMSE, high Lac activity (4 U g⁻¹ dry matter) and low MnP activity (0.4 U g⁻¹ dry matter) were present; (2) after 1 d of incubation at 25 °C, the SMSE was able to degrade more than 50% of AFB1, whereas after 3 and 7 d of incubation, the percentage of degradation reached the values of 75% and 90%, respectively; (3) with increasing pH values, the degradation percentage increased, reaching 90% after 3 d at pH 8. Based on these results, SMS proved to be a suitable source of AFB1 degrading enzymes and the use of SMSE to detoxify AFB1 contaminated commodities appears conceivable.

Aflatoxin B1 (AFB₁) is the most harmful mycotoxin that occurs as natural contaminant of agricultural commodities, particularly maize. Practical solutions for detoxification of contaminated staples and reduction of agricultural wastes are scarce. We investigated the capability of the white-rot and edible fungus Plerotus eryngii (king oyster mushroom) to degrade AFB₁ both in vitro and in a laboratory-scale mushroom cultivation, using a substrate similar to that routinely used in mushroom farms. In malt extract broth, degradation of AFB₁ (500 ng/mL) by nine isolates of P. eryngii ranged from 81 to 99% after 10 days growth, and reached 100% for all isolates after 30 days. The growth of P. eryngii on solid medium (malt extract-agar, MEA) was significantly reduced at concentrations of AFB₁ 500 ng/mL or higher. However, the addition of 5% wheat straw to the culture medium increased the tolerance of P. eryngii to AFB₁ and no inhibition was observed at a AFB₁ content of 500 ng/mL; degradation of AFB₁ in MEA supplemented with 5% wheat straw and 2.5% (w/v) maize flour was 71–94% after 30 days of growth. Further, AFB₁ degradation by P. eryngii strain ITEM 13681 was tested in a laboratory-scale mushroom cultivation. The mushroom growth medium contained 25% (w/w) of maize spiked with AFB₁ to the final content of 128 μg/kg. Pleurotus eryngii degraded up to 86% of the AFB₁ in 28 days, with no significant reduction of either biological efficiency or mushroom yield. Neither the biomass produced on the mushroom substrate nor the mature basidiocarps contained detectable levels of AFB₁ or its metabolite aflatoxicol, thus ruling out the translocation of these toxins through the fungal thallus. These findings make a contribution towards the development of a novel technology for remediation of AFB₁- contaminated corn through the exploitation of the degradative capability of P. eryngii and its bioconversion into high nutritional value material intended for feed production.

Manganese (Mn) is an environmental contaminant and its overexposure contributes to the pathophysiological processes of numerous disorders of the central nervous system in humans with mechanisms of action not completely understood. Activation of astrocytes and the subsequent release of neurotoxic factors have been implicated to contribute to neurodegeneration. Here, we assessed the molecular basis of the effects of Mn on modulation of matrix metalloproteinases-2 (MMP-2) and -9 (MMP-9) in rat astrocyte cultures. Primary cultures of rat astrocytes were exposed to different doses of MnCl₂. Culture supernatants and cell lysates were used for the detection of MMP-2 and MMP-9 levels and mRNA expression, respectively. The exposure of astrocytes to MnCl₂ induced the levels and expression of MMP-9 in a dose-dependent manner. The addition of resveratrol (RSV) inhibited both levels and expression of MMP-9 in astrocytes, whereas N-acetylcysteine (NAC) and quercetin (QRC) were ineffective in inhibiting MMP-9. As a possible mechanism of Mn-induced MMP-9, we determined intracellular redox state in Mn-treated astrocytes by assessing superoxide dismutase (SOD) activity and intracellular reactive oxygen species (ROS) and found a significant increase of ROS and a decrease of SOD activity. RSV, NAC, and QRC restored the redox state. The study of the mitogen-activated protein kinase signaling pathway demonstrated that MMP-9 transcription is mainly regulated by extracellular-regulated protein kinases (ERK). Pretreatment with RSV significantly reduced ERK activation suggesting that its ability to counteract MMP-9 overexpression is due not only to a general redox balance phenomenon but also to the modulation of ERK signaling pathway.

Matrix metalloproteinases (MMPs) released by glial cells are important mediators of neuroinflammation and neurologic damage in HIV infection. The use of antiretroviral drugs able to combat the detrimental effect of chronic inflammation and target the exaggerated MMP activity might represent an attractive therapeutic challenge. Recent studies suggest that CCR5 antagonist maraviroc (MVC) exerts immunomodulant and anti-inflammatory activity beyond its anti-HIV properties. We investigated the in vitro effect of MVC on the activity of MMPs in astrocyte and microglia cultures. Primary cultures of rat astrocytes and microglia were activated by exposure to phorbol myristate acetate (PMA) or lypopolysaccharide (LPS) and treated in vitro with MVC. Culture supernatants were subjected to gelatin zymography and quantitative determination of MMP-9 and MMP-2 was done by computerized scanning densitometry. MMP-9 levels were significantly elevated in culture supernatants from both LPS- and PMA-activated astrocytes and microglia in comparison to controls. The treatment with MVC significantly inhibited in a dose-dependent manner the levels and expression of MMP-9 in PMA-activated astrocytes (p<0,05) and, to a lesser extent, in PMA-activated microglia. By contrast, levels of MMP-2 did not significantly change, although a tendency to decrease was seen in PMA-activated astrocytes after treatment with MVC. The inhibition of levels and expression of MMP-9 in PMA-activated glial cells did not depend on cytotoxic effects of MVC. No inhibition of MMP-9 and MMP-2 were found in both LPS-activated astrocytes and microglia. The present in vitro study suggests that CCR5 antagonist compounds, through their ability to inhibit MMP-9 expression and levels, might have a great potential for the treatment of HIV-associated neurologic damage.

Biochar (BC) and hydrochar (HC) are carbonaceous products obtained through, respectively, pyrolysis and hydrothermal carbonization processes of biomass. Both materials are multi-functional soil amendments. Ligninolytic fungi are primary decomposers of recalcitrant lignocellulosic material in nature through their extensive hyphal network and enzymes. In this work, two BC samples from red spruce pellets (BC_SP) and grapevine pruning residues (BC_GV) and two HC samples from urban pruning residues (HC_UP) and the organic fraction of solid urban wastes (HC_SU) were tested at concentrations of 0.4% and 2% (w/v) on the growth and enzyme activity of Trametes versicolor, Pleurotus ostreatus and Pleurotus eryngii. In all treatments with the lower concentration, BC and HC significantly stimulated fungal growth (up to about 90% increase for HC_SU on T. versicolor), whereas at the higher dose some inhibition was observed on T. versicolor by BC_SP and P. ostreatus by BC_SP, BC_GV and HC_UP. The two materials, especially HC, at both doses noticeably increased the activity of laccase from T. versicolor and P. eryngii, up to 21 and 13 times, respectively, for HC_UP compared to controls. The activity of manganese peroxidase from P. ostreatus was also greatly stimulated by BC and HC, especially when added at the higher concentration. The overall results obtained in this study suggest potential benefits for ligninolytic fungi from the presence of these materials in soil at adequate dose of application.