Growing concerns regarding the impact of the accumulation of plastic waste over several decades on the environmental have led to the development of biodegradable plastic. These plastics can be degraded by microorganisms and absorbed by the environment and are therefore gaining public support as a possible alternative to petroleum-derived plastics. Among the developed biodegradable plastics, oxo-biodegradable polymers have been used to produce plastic bags. Exposure of this waste plastic to ultraviolet light (UV) or heat can lead to breakage of the polymer chains in the plastic, and the resulting compounds are easily degraded by microorganisms. However, few studies have characterized the microbial degradation of oxo-biodegradable plastics. In this study, we tested the capability of Pleurotus ostreatus to degrade oxo-biodegradable (D2W) plastic without prior physical treatment, such as exposure to UV or thermal heating. After 45 d of incubation in substrate-containing plastic bags, the oxo-biodegradable plastic, which is commonly used in supermarkets, developed cracks and small holes in the plastic surface as a result of the formation of hydroxyl groups and carbon-oxygen bonds. These alterations may be due to laccase activity. Furthermore, we observed the degradation of the dye found in these bags as well as mushroom formation. Thus, P. ostreatus degrades oxo-biodegradable plastics and produces mushrooms using this plastic as substrate.

Mushrooms have been used for food and medicinal purposes since ancient period. The β-glucans found in mushrooms are currently considered to be responsible for some of the medicinal properties of mushrooms, thereby motivating studies on characterization of these compounds. In our study, we tested the effect of nitrogen supplementation on the productivity and nutritional composition of Pleurotus ostreatus mushrooms. The fungi were grown in various substrates supplemented with urea or rice bran, and the biological efficiency, mineral composition, protein and β-glucan content were evaluated. The growth of P. ostreatus in substrates with nitrogen supplementation increases the mushroom's productivity and nutritional value. Our results also indicate that nitrogen supplementation, a simple technique, efficiently increases the β-glucan content of mushrooms.

The mushroom Pleurotus ostreatus has nutritional and medicinal characteristics that depend on the growth substrate. In nature, this fungus grows on dead wood, but it can be artificially cultivated on agricultural wastes (coffee husks, eucalyptus sawdust, corncobs and sugar cane bagasse). The degradation of agricultural wastes involves some enzyme complexes made up of oxidative (laccase, manganese peroxidase and lignin peroxidase) and hydrolytic enzymes (cellulases, xylanases and tanases). Understanding how these enzymes work will help to improve the productivity of mushroom cultures and decrease the potential pollution that can be caused by inadequate discharge of the agroindustrial residues. The objective of this work was to assess the activity of the lignocellulolytic enzymes produced by two P. ostreatus strains (PLO 2 and PLO 6). These strains were used to inoculate samples of coffee husks, eucalyptus sawdust or eucalyptus bark add with or without 20 % rice bran. Every five days after substrate inoculation, the enzyme activity and soluble protein concentration were evaluated. The maximum activity of oxidative enzymes was observed at day 10 after inoculation, and the activity of the hydrolytic enzymes increased during the entire period of the experiment. The results show that substrate composition and colonization time influenced the activity of the lignocellulolytic enzymes.

a b s t r a c tThe elimination of antinutritional factors of the Jatropha curcas L. seed cake is important for decreasing environmental damage and adding economic value to this residue of the biodiesel industry. In this study, we analyzed the ability of Pleurotus ostreatus to degrade antinutritional factors and produce edible mushrooms using different proportions of the J. curcas seed cake as substrate. After 60 d of incubation at 25 C, we observed 95% phytic acid and 85% tannins reductions, and high mushrooms productivity. There was no evidence of tannins or phytic acid in these mushrooms. Furthermore, the phorbol ester concentration observed in these mushrooms was around 1000-fold lower than that found in the nontoxic variety of J. curcas. Thus, P. ostreatus can degrade the antinutritional factors found in J. curcas seed cake. The jatropha seed cake can potentially be used for mushroom production, with high nutritional value, and animal ration, after treated by P. ostreatus, adding economic value to the biodiesel residue and avoiding inadequate disposal in the environment.

Selenium (Se) is an essential element to human. However, this element can be in low content in soil of some regions. Se deficiency may cause Keshan disease, thyroid dysfunction and osteoarthritis. The Se-enriched cereals are an interesting way to prevent these diseases. But, recent studies have shown that Se-enriched mushrooms are a better Se source. This occurs due to the high capacity of the fungi to absorb and transform the inorganic Se to organic forms, which are more bioavailable. Pleurotus ostreatus and Pleurotus eryngii are mushrooms species worldwide consumed and able to Se bioaccumulate. However, depending on the level of this element, it can be toxic for the fungus. Here we showed that the presence of the Se in culture medium decreases fungal growth rate, hyphae diameter and septum distance and causes alteration in color of colony. A garlic strong smell was directly proportional to Se level. P. eryngii was more tolerant to Se than P. ostreatus. So, it is important to screen this element level for Se-enriched mushroom production.

Mushrooms absorb minerals and are able to accumulate them as functional organic compounds during growth.<strong> </strong>Iron is one of the elements required for various metabolic processes<strong> </strong>but low intake has resulted to some nutritional deficiencies.<strong> </strong>This study investigated<strong> </strong>the effect of different iron concentrations in the culture media on mycelial growth, biomass production, hyphae diameter and distance between septa of six species of <em>Pleurotus,</em> namely <em>Pleurotus</em> <em>ostreatus;</em> <em>Pleurotus</em> <em>cornucopiae</em>; <em>Pleurotus</em> <em>djamor</em>; <em>Pleurotus</em> <em>pulmonarius</em>, and <em>Pleurotus</em> <em>djamor</em> v. <em>roseus</em>. These macrofungi were further grown on substrate based <em>Urochloa</em> <em>decumbens</em> with addition of Fe (0, 500 and 1000 mg Kg^-1). The mycelial growth rate and biomass produced by <em>Pleurotus </em>species<em> </em>decreased (P&lt;0.05)<em> </em>as iron concentration increased from (0 - 100) mg L^-1. This shows an inhibitory interaction between the fungi and iron at higher concentration. The hyphae diameter and distance between septa of the examined fungi were respectively ranged from 45 µm to 80 µm and 40 µm to 119 µm at iron concentration of (0 -100) mg L^-1. The estimated iron uptake in cultivated <em>Pleurotus</em> species ranged from 37.8 µg g^-1 to 96.6 µg g^-1 when 500 mg Kg^-1 and 1000 mg Kg^-1 of Fe was added to the substrate. The cultivation of edible macrofungi enriched with iron could improve the socio economic status and play a nutritional role in decreasing anemia.

The enrichment of edible mushrooms with lithium (Li) may be a strategy to provide forms of lithium that are more soluble and bioavailable for humans. Therefore, it is important to determine which species of fungi are able to grow in the presence of Li, and which concentrations of Li allow fungal growth. Twelve white rot fungi strains were grown in potato dextrose agar media, supplemented with 0 to 1.65 g L -1 lithium chloride (LiCl). The fungal growth rate, morphological alterations of the colonies, changes in the length of the lag phase, fungal dry mass, changes in hyphae diameter and cell length were evaluated. Most fungi had decrease in their growth rates and dry mass, and had macroscopic/microscopic morphological alterations at increasing LiCl concentration. Generally, the fungi were sensitive to LiCl. However, Pholiota nameko was moderately tolerant to LiCl and Pleurotus ostreatusroseus tolerate the highest LiCl level tested, suggesting that it is the most appropriate fungus for Li-enrichment.

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