ẢNH HƯỞNG CỦA THỜI GIAN TRỒNG ĐẾN SINH TRƯỞNG, PHÁT TRIỂN CỦA NẤM TRÂN CHÂU (Agrocybe aegerita)

Nghiên cứu được thực hiện trong vụ Xuân Hè tại trường Đại học Nông Lâm, Đại học Huế nhằm xác định được thời vụ thích hợp cho sinh trưởng, phát triển của nấm Trân Châu tại Thừa Thiên Huế. Thí nghiệm được bố trí theo phương pháp hoàn toàn ngẫu nhiên (CRD), gồm 5 công thức với 5 thời điểm cấy giống khác nhau trong tháng 4 và tháng 5 là 1/4; 10/4; 20/4; 30/4 và 10/5, 3 lần lặp lại, mỗi lần lặp theo dõi 10 bịch. Kết quả cho thấy công thức I, thời điểm cấy giống vào 1/4 cho kết quả tốt nhất. Thời gian phủ kín nguyên liệu 43,26 ngày, thời gian xuất hiện quả thể 57,53 ngày và thời gian quả thể trưởng thành và thu hái 65,87 ngày. Chiều dài quả thể đạt 10,69 cm, đường kính quả thể 3,99 cm và trọng lượng quả thể đạt 90,28 g/cụm quả thể, không xuất hiện mẫu nhiễm. Năng suất đạt 225,70 kg/ tấn nguyên liệu khô dẫn đến lãi ròng thu được 13,92 triệu đồng, cao hơn so với các công thức cùng nghiên cứu. ABSTRACT The experiment was carried out during the Summer-Autumn season at University of Agriculture and Forestry, Hue University to determine the suitability of planting time for the growth performation of Southern Poplar mushroom in Thua Thien Hue province. The experiment was arranged in completely randomized design, including 5 treatments, which were 5 different seedling propagation times of April 1st; April 10th; April 20th; April 30th and May 10th in 3 replications and 10 monitoring bags per each replication. The results showed that the experimental treatment I, which were inoculation time on April 1st, gave the best results compared to other experimental treatment such as the time mycelium covered material at 43.26 days; The time to appear mushroom body reached 57.53 days and the time to mature and harvest of mushroom body was 65.87 days; The length of the mushroom body at 10.69cm, the mushroom body diameter at 3.99cm and the weight of the mushroom body gave 90,28 g/mushroom cluster; infection rate gave 0%. The yield was 22.57% compared to the volume of dry material led to the net profit got 13,92 million VND, higher than all of treatments in the same study.

Mapping Potential Determinants of Peroxidative Activity in an Evolved Fungal Peroxygenase from Agrocybe aegerita

Fungal unspecific peroxygenases (UPOs) are hybrid biocatalysts with peroxygenative activity that insert oxygen into non-activated compounds, while also possessing convergent peroxidative activity for one electron oxidation reactions. In several ligninolytic peroxidases, the site of peroxidative activity is associated with an oxidizable aromatic residue at the protein surface that connects to the buried heme domain through a long-range electron transfer (LRET) pathway. However, the peroxidative activity of these enzymes may also be initiated at the heme access channel. In this study, we examined the origin of the peroxidative activity of UPOs using an evolved secretion variant (PaDa-I mutant) from Agrocybe aegerita as our point of departure. After analyzing potential radical-forming aromatic residues at the PaDa-I surface by QM/MM, independent saturation mutagenesis libraries of Trp24, Tyr47, Tyr79, Tyr151, Tyr265, Tyr281, Tyr293 and Tyr325 were constructed and screened with both peroxidative and peroxygenative substrates. These mutant libraries were mostly inactive, with only a few functional clones detected, none of these showing marked differences in the peroxygenative and peroxidative activities. By contrast, when the flexible Gly314-Gly318 loop that is found at the outer entrance to the heme channel was subjected to combinatorial saturation mutagenesis and computational analysis, mutants with improved kinetics and a shift in the pH activity profile for peroxidative substrates were found, while they retained their kinetic values for peroxygenative substrates. This striking change was accompanied by a 4.5°C enhancement in kinetic thermostability despite the variants carried up to four consecutive mutations. Taken together, our study proves that the origin of the peroxidative activity in UPOs, unlike other ligninolytic peroxidases described to date, is not dependent on a LRET route from oxidizable residues at the protein surface, but rather it seems to be exclusively located at the heme access channel.

Magnaporthe oryzae as an expression host for the production of the unspecific peroxygenase AaeUPO from the basidiomycete Agrocybe aegerita

The filamentous fungus Magnaporthe oryzae has the potential to be developed as an alternative platform organism for the heterologous production of industrially important enzymes. M. oryzae is easy to handle, fast-growing and unlike yeast, posttranslational modifications like N-glycosylations are similar to the human organism. Here, we established M. oryzae as a host for the expression of the unspecific peroxygenase from the basidiomycete Agrocybe aegerita (AaeUPO). UPOs are attractive biocatalysts for selective oxyfunctionalization of non-activated carbon-hydrogen bonds. To improve and simplify the isolation of AaeUPO in M. oryzae, we fused a Magnaporthe signal peptide for protein secretion and set it under control of the strong EF1-promotor. The success of the heterologous production of full-length AaeUPO in M. oryzae and the secretion of the functional enzyme was confirmed by a peroxygenase-specific enzyme assay. These results offer the possibility to establish the filamentous ascomycete M. oryzae as a broad applicable alternative expression system. This is in particular valid for proteins that cannot or not in sufficient yields produced in established systems.

Molecular identification and antimicrobial activities of some wild Egyptian mushrooms: Bjerkandera adusta as a promising source of bioactive antimicrobial phenolic compounds

Background The discovery of potential, new cost-effective drug resources in the form of bioactive compounds from mushrooms is one way to control the resistant pathogens. In the present research, the fruiting bodies of five wild mushrooms were collected from Egypt and identified using internal transcribed spacer region (ITS) of the rRNA encoding gene and their phylogenetic relationships, antimicrobial activities, and biochemical and phenolic compounds were evaluated. Results The sequences revealed identity to Bjerkandera adusta, Cyclocybe cylindracea, Agrocybe aegerita, Chlorophyllum molybdites, and Lentinus squarrosulus in which Cyclocybe cylindracea and Agrocybe aegerita were closely related, while Chlorophyllum molybdites was far distant. Cyclocybe cylindracea and Agrocybe aegerita showed 100% similarity based on the sequenced ITS-rDNA fragment and dissimilar antimicrobial activities and chemical composition were detected. Bjerkandera adusta and Cyclocybe cylindracea showed strong antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus luteus, Streptococcus pneumoniae, and Candida albicans. This activity could be attributed to the detected phenolic and related compounds’ contents. Conclusion Our finding provides a quick and robust implement for mushroom identification that would facilitate mushroom domestication and characterization for human benefit.

Immobilization of the Peroxygenase from Agrocybe aegerita. The Effect of the Immobilization pH on the Features of an Ionically Exchanged Dimeric Peroxygenase

This paper outlines the immobilization of the recombinant dimeric unspecific peroxygenase from Agrocybe aegerita (rAaeUPO). The enzyme was quite stable (remaining unaltered its activity after 35 h at 47 °C and pH 7.0). Phosphate destabilized the enzyme, while glycerol stabilized it. The enzyme was not immobilized on glyoxyl-agarose supports, while it was immobilized albeit in inactive form on vinyl-sulfone-activated supports. rAaeUPO immobilization on glutaraldehyde pre-activated supports gave almost quantitative immobilization yield and retained some activity, but the biocatalyst was very unstable. Its immobilization via anion exchange on PEI supports also produced good immobilization yields, but the rAaeUPO stability dropped. However, using aminated agarose, the enzyme retained stability and activity. The stability of the immobilized enzyme strongly depended on the immobilization pH, being much less stable when rAaeUPO was adsorbed at pH 9.0 than when it was immobilized at pH 7.0 or pH 5.0 (residual activity was almost 0 for the former and 80% for the other preparations), presenting stability very similar to that of the free enzyme. This is a very clear example of how the immobilization pH greatly affects the final biocatalyst performance.

Amino acid profile of eighteen isolates of different edible macrofungal species

Edible mushrooms from India (18 isolates belonging to 4 species) were profiled for protein, free and bound amino acids (AA). The protein content (range of 9.5-32.6%) was highest in Pleurotus cintrinopileatus and P. sajor-caju; free AA (range of 11.6-73.1 mg/g DW) was higher in Hypsizygus tessulatus and Agrocybe aegerita, bound AA (range of 57.4- 171.9 mg/g DW) was also high in H. ulmarius, P. djamor, P. florida, P. sajor-caju. The essential free and bound AAs and chemical scores of isoleucine, tryptophan, phenylalanine were highest, higher in Hericium erinaceus, P. cystidiosus, P. eryngi, P. sajor-caju. The isoleucine (Ile) score in the free fraction of selected mushrooms was comparable or higher than the best five plant sources, while tryptophan (Trp) scores were almost double. Thus, these mushrooms are good sources of Ile, Trp, and aromatic amino acids. The conditionally essential and nonessential AAs were also quantified. This study reveals the diversity in protein and AA and nutritionally superior mushroom species.