A Possibility to Use Selected Crop Post-Extraction Wastes to Improve the Composition of Cultivated Mushroom Pleurotus citrinopileatus

A cultivated mushroom species, Pleurotus citrinopileatus, is becoming increasingly popular thanks to its attractive colour and medicinal properties. In this study, P. citrinopileatus was grown in a cultivation medium enriched with wheat bran (WB), thymus post-extraction waste (TPEW) and pumpkin post-extraction waste (PPEW) products. The study showed that the post-extraction wastes are a crucial factor determining the accumulation of minerals, the content/profile of low-molecular-weight organic acids (LMWOAs) and phenolic compounds in fruit bodies, thereby increasing their nutritional value. The use of the waste materials significantly increased LMWOAs contents. The sum of LMWOAs under all cultivation mediums increased, especially quinic, malic and citric acids under the 20% PPEW, 25 and 50% TPEW addition. Total phenolic content, phenolic content, as well as the composition and scavenging effect on DPPH radicals, were strongly dependent on the used substrate. The control variant was poor in phenolic compounds, while the supplementation increased the contents and diversity of these metabolites. In the control, only four phenolic compounds were quantified (chlorogenic, gallic, syringic and vanillic acids), while in the supplemented substrates up to 14 different phenolic compounds (caffeic, chlorogenic, p-coumaric, 2,5-dihydroxybenzoic acid, ferulic, gallic, protocatechuic, salicylic, sinapic, syringic, trans-cinnamic and vanillic acids, catechin and rutin).

Influence of the substrate composition on the yield and nutritional value of the fruiting bodies of the edible mushrooms Pleurotus citrinopileatus and Cyclocybe aegerita

Purpose. To reveal the influence of the substrate compositions on technical indicators and the chemical composition of the fruiting bodies of the golden oyster mushroom and poplar mushroom. Methods. The experimental design included cultivation of two species of wood-decay fungi Pleurotus citrinopileatus Singer (strain 2161 IVK) and Cyclocybe aegerita (V.Brig.) Vizzini (strain 2230 IVK) on three variants of substrate composition. Laboratory, laboratory-production methods for evaluating the effectiveness of growing technology, chemical composition of the obtained raw materials, statistical methods of analysis were applied. Results. The structure and composition of substrates affect the technological characteristics of the culture, physical and chemical properties of fruiting bodies. The shortest fruiting cycle of 35.2 ± 1.7 days was determined for C. aegerita under growing conditions on SC1 substrate which formula included «straw, husks, pellet, rapeseed, corn, and CaCO3» in the ratio of 30: 40: 70: 20: 20: 1. The highest yield (170.5 ± 15.2 g per 1 kg of substrate) in the experiment was determined for P. citrinopileatus on the SC1 substrate composed of «straw / pellets / rapeseed / corn / CaCO3» in the ratio 40: 90: 20: 25: 1. Fruiting bodies of P. citrinopileatus obtained from the SC3 substrate composed of «pellets / rapeseed / corn / CaCO3» in the ratio 60: 110: 20: 30: 1 had the highest protein content – 22.47 ± 0.19%, and fruiting bodies from the SC1 substrate had the least amount of proteins – 17.38 ± 2.60%. Fruiting bodies of C. aegerita contained more lipids than those of P. citrinopileatus, but the factor of the influence of the substrate composition on the total amount of lipids for some cultivars was insignificant. The largest amount of endopolysaccharides was isolated from the fruiting bodies of C. aegerita (6.81 ± 0.41%) cultivated on SC3 substrate, and the smallest in the SC1 variant (1.38 ± 0.25%). The content of endopolysaccharides in the fruiting bodies of P. citrinopileatus had less variability from 2.54 ± 0.54 (SC3) to 4.72 ± 0.61% (SC1). Conclusion. Substrate compositions significantly affect the biological efficiency of cultivars and the content of nutrients in fruiting bodies of the studied species. The obtained results enable producers of mushrooms to predict the production efficiency and quality of grown mushrooms in accordance with the use of available raw materials.

Discovery of two novel laccase-like multicopper oxidases from Pleurotus citrinopileatus and their application in phenolic oligomer synthesis

Background Laccases and laccase-like multicopper oxidases (LMCOs) oxidize a vast array of phenolic compounds and amines, releasing water as a byproduct. Their low substrate specificity is responsible for their tremendous biotechnological interest, since they have been used for numerous applications. However, the laccases characterized so far correspond to only a small fraction of the laccase genes identified in fungal genomes. Therefore, the knowledge regarding the biochemistry and physiological role of minor laccase-like isoforms is still limited. Results In the present work, we describe the isolation, purification and characterization of two novel LMCOs, PcLac1 and PcLac2, from Pleurotus citrinopileatus. Both LMCOs were purified with ion-exchange chromatographic methods. PcLac2 was found to oxidize a broader substrate range than PcLac1, but both LMCOs showed similar formal potentials, lower than those reported previously for laccases from white-rot fungi. Proteomic analysis of both proteins revealed their similarity with other well-characterized laccases from Pleurotus strains. Both LMCOs were applied to the oxidation of ferulic and sinapic acid, yielding oligomers with possible antioxidant activity. Conclusions Overall, the findings of the present work can offer new insights regarding the biochemistry and variability of low-redox potential laccases of fungal origin. Low-redox potential biocatalysts could offer higher substrate selectivity than their high-redox counterparts, and thus, they could be of applied value in the field of biocatalysis.

Produção de biomassa micelial e enzimas lignocelulolíticas de Pleurotus spp. em meio de cultivo líquido

Pleurotus spp. são fungos capazes de degradar a lignocelulose graças à excreção de enzimas com diferentes aplicações industriais. O objetivo deste estudo foi avaliar a influência dos meios de cultivo na produção de biomassa micelial e na atividade de lacase, celulases e xilanase de Pleurotus spp. Pleurotus citrinopileatus U16-23, P. djamor U16-20, U16-25 e U16-28, P. eryngii U16-30, P. ostreatus U16-22 e P. pulmonarius U16-21 foram cultivados por 12 dias a 28 ºC em meio extrato de malte (EM-20 g L-1), meio definido (MD glicose 10 g L-1 e extrato de levedura 2 g L-1), ou em meio bagaço de cana-de-açúcar (BC) igual ao MD, mas substituindo glicose por bagaço (50 g L-1). O maior crescimento ocorreu no meio EM e P. djamor U16-25 a cepa que gerou mais biomassa (7,5 ± 0,1 g L-1). A maioria das cepas apresentou maior atividade de lacase no meio MD e as atividades maiores foram de P. djamor U16-25 (22243 ± 745 U L-1) e P. pulmonarius (20924 ± 46 U L-1). P. citrinopileatus e P. djamor U16-25 não produziram celulases, mas P. djamor U16-20 e P. eryngii produziram as maiores atividades de celulase nos meios EM e MD. Todas as cepas produziram xilanase em e as maiores atividades foram observadas no meio EM e P. djamor U16-28 (67154 ± 1597 U L-1) foi o maior produtor. Pleurotus djamor U16-25 se destacou como produtor de lacase e de xilanase livre de celulase revelando potencial para aplicação na indústria de papel e celulose.