Mushrooms of the genus Pleurotus are comprised of cultivated edible ligninolytic fungi with medicinal properties and a wide array of biotechnological and environmental applications. Like other ...white-rot fungi (WRF), they are able to grow on a variety of lignocellulosic biomass substrates and degrade both natural and anthropogenic aromatic compounds. This is due to the presence of the non-specific oxidative enzymatic systems, which are mainly consisted of lacasses, versatile peroxidases (VPs), and short manganese peroxidases (short-MnPs). Additional, less studied, peroxidase are dye-decolorizing peroxidases (DyPs) and heme-thiolate peroxidases (HTPs). During the past two decades, substantial information has accumulated concerning the biochemistry, structure and function of the Pleurotus ligninolytic peroxidases, which are considered to play a key role in many biodegradation processes. The production of these enzymes is dependent on growth media composition, pH, and temperature as well as the growth phase of the fungus. Mn²⁺concentration differentially affects the expression of the different genes. It also severs as a preferred substrate for these preoxidases. Recently, sequencing of the Pleurotus ostreatus genome was completed, and a comprehensive picture of the ligninolytic peroxidase gene family, consisting of three VPs and six short-MnPs, has been established. Similar enzymes were also discovered and studied in other Pleurotus species. In addition, progress has been made in the development of molecular tools for targeted gene replacement, RNAi-based gene silencing and overexpression of genes of interest. These advances increase the fundamental understanding of the ligninolytic system and provide the opportunity for harnessing the unique attributes of these WRF for applied purposes.
•Pleurotus ostreatus efficiently degraded PCBs in real contaminated soil.•The best results, represented by 50% degradation, were observed in rhizosphere soil.•P. ostreatus decomposes the aromatic ...moiety of PCBs in soil via chlorobenzoic acids.•The fungus effectively colonized the soil and suppressed other fungi.•Community analysis showed stimulation of bacteria encompassing putative PCB degraders.
The objective of this work was to test the PCB-degrading abilities of two white-rot fungi, namely Pleurotus ostreatus and Irpex lacteus, in real contaminated soils with different chemical properties and autochthonous microflora. In addition to the efficiency in PCB removal, attention was given to other important parameters, such as changes in the toxicity and formation of PCB transformation products. Moreover, structural shifts and dynamics of both bacterial and fungal communities were monitored using next-generation sequencing and phospholipid fatty acid analysis. The best results were obtained with P. ostreatus, which resulted in PCB removals of 18.5, 41.3 and 50.5% from the bulk, top (surface) and rhizosphere, respectively, of dumpsite soils after 12 weeks of treatment. Numerous transformation products were detected (hydoxylated and methoxylated PCBs, chlorobenzoates and chlorobenzyl alcohols), which indicates that both fungi were able to oxidize and decompose the aromatic moiety of PCBs in the soils. Microbial community analysis revealed that P. ostreatus efficiently colonized the soil samples and suppressed other fungal genera. However, the same fungus substantially stimulated bacterial taxa that encompass putative PCB degraders. The results of this study finally demonstrated the feasibility of using this fungus for possible scaled-up bioremediation applications.
ABSTRACT
Spent mushroom substrate (SMS) of Pleurotus ostreatus was supplemented with wheat bran and soybean flour and used as substrate for a new cultivation cycle of the oyster mushrooms Pleurotus ...ostreatus and Pleurotus pulmonarius. The bioconversion efficiency of mushrooms produced over substrate (BE%) used and the chemical composition of sporophores were evaluated. The concentration of mycelial mass, crude exopolysaccharide content and laccase enzyme activity were also determined at the supplemented SMS before inoculation, at 50% and 100% of colonization stages in the new cultivation and in the final re-utilized SMS. The laccase enzyme was extracted to examine SMS potential for the dephenolization of olive mill and winery wastewaters. Results showed that both Pleurotus species exhibited BE over 185%, demonstrating this bioprocess could represent a promising strategy to convert SMS into nutritional food. Data also indicate the strong positive impact that SMS could have in the solid wastes’ management and agribusiness enhancement.
Spent mushroom substrate of Pleurotus ostreatus was used for a second cultivation cycle of the mushrooms Pleurotus ostreatus and Pleurotus pulmonarius and dephenolization of olive mill and winery.
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•P. ostreatus was able to grow and fructify in different substrates.•Production of Pleurotus spp. was tested using paper scraps, blank or printed.•The nutritional and chemical ...composition of Pleurotus ostreatus was highly satisfactory.•This process also provides a profitable way to recycle paper.
Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm. is the third most produced edible mushroom worldwide, due to its ability to colonise and degrade a large variety of lignocellulosic substrates. Therefore, the objective of this work was to evaluate the chemical composition of fruiting bodies of P. ostreatus grown on blank and printed paper substrates, in comparison with samples grown on oat straw (control). The nutritional properties of the control sample were similar to values reported in the literature, while the chemical composition of the samples obtained using paper scraps, either blank or printed, was highly satisfactory. The results obtained validated the nutritional characteristics of the samples, highlighting a profitable means to recycle paper.
•BPA was efficiently degraded by laccases from P. ostreatus and P. pulmonarius.•Thirteen aromatic and aliphatic BPA metabolites were identified by GC–MS.•The acute BPA toxicity decreased from 85% to ...25% using the P. ostreatus laccase.•P. pulmonarius laccase treatment did not reduce the toxicity.
Bisphenol A (BPA) is an endocrine disruptor compound, that is continuously released into the environment and is barely degraded in wastewater treatment plants. In this work, crude laccases from Pleurotus ostreatus and Pleurotus pulmonarius were used for the first time to degrade BPA in aqueous solution. The residual BPA was quantified by HPLC and the BPA metabolites produced by action of the laccases were identified by GC–MS. BPA at 100mg/L and 200mg/L (0.88mmol/L) were 100% and 85% removed, respectively, in a 1h reaction by both fungal laccases at a concentration of 8U/L. Thirteen aromatic and aliphatic BPA metabolites were identified, including p-isopropenylphenol, methylpent-3-oic acid, ethyl-3-ethoxy propanoate, and 4-ethyl-2-methoxyphenol. The acute BPA toxicity decreased from 85% to less than 5% using the P. ostreatus laccase. On the other hand, P. pulmonarius laccase, did not caused reduction in toxicity, possibly because at least one BPA metabolite was as toxic as the parent compound itself. The results of this study suggest a feasible method for the complete removal of BPA from polluted environments using crude laccase from P. ostreatus.
Fungal cells are surrounded by a tight cell wall to protect them from harmful environmental conditions and to resist lysis. The synthesis and assembly determine the shape, structure, and integrity of ...the cell wall during the process of mycelial growth and development. High temperature is an important abiotic stress, which affects the synthesis and assembly of cell walls. In the present study, the chitin and β-1,3-glucan concentrations in the cell wall of
Pleurotus ostreatus
mycelia were changed after high-temperature treatment. Significantly higher chitin and β-1,3-glucan concentrations were detected at 36 °C than those incubated at 28 °C. With the increased temperature, many aberrant chitin deposition patches occurred, and the distribution of chitin in the cell wall was uneven. Moreover, high temperature disrupts the cell wall integrity, and
P. ostreatus
mycelia became hypersensitive to cell wall-perturbing agents at 36 °C. The cell wall structure tended to shrink or distorted after high temperature. The cell walls were observed to be thicker and looser by using transmission electron microscopy. High temperature can decrease the mannose content in the cell wall and increase the relative cell wall porosity. According to infrared absorption spectrum, high temperature broke or decreased the glycosidic linkages. Finally,
P. ostreatus
mycelial cell wall was easily degraded by lysing enzymes after high-temperature treatment. In other words, the cell wall destruction caused by high temperature may be a breakthrough for
P. ostreatus
to be easily infected by
Trichoderma
.
Fungal glucuronoyl esterases (FGEs) catalyze cleavage of the ester bond connecting a lignin alcohol to the xylan-bound 4-
O
-methyl-
d
-glucuronic acid of glucuronoxylans. Thus, FGEs are capable of ...degrading lignin-carbohydrate complexes and have potential for biotechnological applications toward woody biomass utilization. Therefore, identification and characterization of new FGEs are of critical importance. Firstly, in this study, we built a phylogenetic tree from almost 400 putative FGEs obtained on BLAST analysis and defined six main clades. In the phylogenetic tree, all the putative FGEs of ascomycetes cluster in clades I to IV, and most of the putative FGEs of basidiomycetes (B-FGEs) cluster in clades V to VI. Interestingly, several B-FGEs were found to cluster in clade II; most FGEs of clade II were found to have higher theoretical isoelectric points than those in the other five clades. To gain an insight into the putative FGEs in the clades that have not been characterized yet, we chose the FGEs of
Ceriporiopsis subvermispora
(
Cs
GE) and
Pleurotus eryngii
(
Pe
GE), which belong to clades V and II, respectively. The catalytic domains of both
Cs
GE and
Pe
GE were successfully expressed using
Pichia pastoris
, and then purified. Benzyl glucuronic acid was used as a substrate to confirm the activities of the
Cs
GE and
Pe
GE, and the hydrolyzed product, glucuronic acid, was quantified spectrophotometrically. Both
Cs
GE and
Pe
GE clearly exhibited the esterase activity. Additionally, we demonstrated that
Pe
GE exhibits high tolerance toward several denaturing agents, which may make it a potentially more applicable enzyme.
Previous studies have demonstrated the feasibility of employing by-products of the olive and wine sectors for the production of
mushrooms with enhanced functionalities. In this work we investigated ...the influence of endogenous and exogenous factors on free amino acids (FAAs) profile of
,
and
mushrooms produced on wheat straw (WS), alone or mixed with grape marc (GM), and on by-products of the olive industry (OL). Overall, 22 FAAs were determined in substrates and mushrooms, including all the essential amino acids, the neurotransmitter γ-aminobutyric acid (GABA) and ornithine. On a dry weight (dw) basis, total FAAs ranged from 17.37 mg/g in
to 130.12 mg/g in
samples, with alanine, leucine, glutamine, valine and serine predominating. Similar distribution patterns were followed by the monosodium glutamate (MSG)-like, sweet and bitter FAAs. Significant differences in FAAs level were observed among the species examined and among the cultivation substrates used. Principal Component Analysis (PCA) performed on the entire FAAs profile of six
strains, clearly separated
from
and
, in accordance to their phylogenetic affinity. This is the first report of FAAs in
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