Vol. 21 No. 12 (2023)

Việc tạo ra phân bón sinh học mới là lĩnh vực rất được quan tâm trong nông nghiệp hiện đại. Nghiên cứu này tập trung vào xạ khuẩn có hoạt tính chitinase cao, tạo màng sinh học, thúc đẩy sinh trưởng và kháng nấm bệnh hại cây trồng. Trong nghiên cứu này, hai chủng xạ khuẩn YSS-3.3 và YWS-5.1 được phân lập từ các mẫu đất và giá thể chitin thu tại vườn quốc gia Yok Đôn ở Tây Nguyên. Các chủng này có hoạt tính chitinase cao và tạo màng sinh học. Phân tích trình tự gen 16S rRNA cho thấy chúng có quan hệ di truyền gần gũi nhất với loài Luteimicrobium album, với độ tương đồng trình tự 99,41% và độ phủ trình tự 100%. Phương pháp nuôi cấy trên đĩa thạch chỉ ra rằng các chủng xạ khuẩn sở hữu hoạt tính thủy phân cellulose và tinh bột; hòa tan kẽm, kali và phosphate khó tan; và tổng hợp siderophores. Phân tích bằng UV-HPLC cho thấy các chủng này cũng sản xuất hormone tăng trưởng cây trồng như IAA, GA3 và zeatin. Kỹ thuật nuôi cấy kép chỉ ra rằng các các chủng xạ khuẩn có hoạt tính đối kháng nấm Fusarium oxysporum. Từ những cơ sở trên, L. albumYSS-3.3 và L. albumYWS-5.1 là các ứng cử viên tốt cho các nghiên cứu tiếp theo liên quan đến ứng dụng trong nông nghiệp. Các chủng này cũng là nguồn nguyên liệu tiềm năng để thực hiện các nghiên cứu sâu về trình tự bộ gen, hệ thống chitinase, cellulase và amylase của chúng.

The assessment of productivity of some important wild macrofungi helps us to predict the mushroom supply in different natural conditions and make recommendations on development of empirical models for achieving highest productivity. This study aimed to evaluate productivity of seven important macrofungi in the forest from 90 plots in 03 National Parks belongings to the Central Hiaghlands for nearly 3 years (from 2021 to 2023). The macrofungi included 6 edible species: Boletus edulisBull., Agaricus bisporus(J.E.Lange Imbach), Ramaria botrytoides(Pk.) Comb., Amanita caesarea(Scop.) Pers., Termitomyces eurrhizus(Berk.) R. Heim. and Auricularia nigricans(Sw.) Birkebak, Looney & Sánchez- García and 01 medicinal species: Ganoderma lucidum(Curtis) P. Karst. to build the predicted models for them. The method of collecting and determining the fresh weight of edible mushrooms in the field was carried out weekly from May to November every year. The average yield of Ganoderma lucidumwas the highest at 19.22 ± 2.95 kg-1ha-1year and the lowest of Ramaria botrytoides: 2.42 ± 0.54 kg-1ha-1year. Using the quadratic polynomial function to build predicting models, 07 prediction models were built for each mushroom species and 04 predicting models for each National Park and in the Central Highlands with sufficient reliability as shown by high determination coefficient (R2 = 0.7518-0.9909).

This study aimed to isolate and characterize some specific biological traits of Talaromycesspp. Capable of dissolving insoluble potassium. Five fungal strains with morphological features resembling Talaromyces were isolated from 10 soil samples collected in Ha Noi and Thai Binh provinces. Using selective Aleksandrov medium, three strains NM1, NM2, and TB were identified as having the capability to decompose insoluble potassium. Based on the morphological characteristics and the sequence analysis of the ITS region, the strains NM1, NM2 and TB were determined to be closely related to Talaromyces funiculosusspecies. Study on the effects of time and pH on the potassium solubilization ability of three fungal strains showed that the solubility index (SI) was highest on the fifth day of culture ranging from 2.26-2.33 and the SI was the highest at pH 6, ranging from 2.22-2.56. Additionally, the results also showed that all three fungal strains NM1, NM2, and TB had the ability to solubilize insoluble phosphate and synthesize siderophores.

Cordyceps spp. belong to the most valuable medicinal caterpillar fungi. However, consumers hardly know the origin and species of Cordycepsspp. commercialized on the market. This study aimed to identify 12 collected Cordyceps samples collected at various locations in Vietnam by ITS sequencing and evaluate the genetic diversity these sampless using RAPD and ISSR markers. 12 Cordyceps accessions were identified as Cordyceps militarisusingITS sequencing. 15 RAPD markers and 15 ISSR markers successfully detected 340 loci of which 291 were polymorphic and a total of 2092 scorable bands were obtained.The similarity coefficientof 12 Cordyceps spp. accessionsrangedfrom 0.568 to 0.841 when combined RAPD and ISSR markers, indicating high genetic diversity. At a genetic similarity of 0.7, the UPGMA dendrogram constructed based on RAPD and ISSR makers separated 12 Cordyceps accessions into three distinct clusters. The correlation analysis between the matrices of similarity coefficients using Mantel’s test revealed a strong correlation among matrices analyzed by RAPD, ISSR or pooled data. Our results could provide useful information for the exploitation and breeding of Cordyceps militarisaccessions.

White-rot fungi are capble of degrading wood lignin by extracellular lignin modifying enzyme system, in which laccase plays an important role in ligninolysis and is widely used in some industries. This study was carried out with the objective of identifying the white rot fungus TD16 and selected suitable conditions for the biosynthesis of laccase to apply in the biopulping. The strain TD16 was studied for biological characteristics and sequence of the ITS - rDNA gene analyzed. The fruiting bodies have a scalloped shape and the edges are smooth. The upper surface of fruiting bodies is dark brown with concentric circular veins. The hymenium layer is white-brown and rough. On MEA medium, the colonies of TD16 fungal strain are fluffy, snow white, and evenly circular. The strain TD16 has a relatively fast growth rate and can produce extracellular enzymes. The strain TD16 was identified as Trametes polyzonaand named as Trametes polyzonaTD16. The optimal culture conditions for enhanced laccase biosynthesis were investigated. Trametes polyzonaTĐ16 showed the highest laccase activity of upto 8.135 U/ml on MT2 medium containing 0.0625mM CuSO4after 7 days of fermentation at 37ºC and pH of 5.0.

Oyster mushrooms (Pleurotusspp.) are one of the most commonly cultivated mushrooms in the world. In Vietnam, Pleurotus mushrooms have been popularly grown, especially in the southern region. The classification of oyster mushrooms is important in conservation and development of genetic resources. One of the primary methods for accurate classification of oyster mushrooms is based on their macroscopic and microscopic characteristics. Besides, classification based on the analysis of consensus sequences was widely applied, with ITS being the most used sequence region in fungal genetics. The objective of this study was to identify 15 oyster mushroom strains collected from the southern region through a combination of morphological characteristic analysis and ITS sequencing. The results showed that 10 strains were identified as P. pulmonarius, while 5 other strains were identified as P. ostreatus. The identification results based on ITS sequences were compatible with the morphological identifications. Following the phylogenetic tree based on ITS sequences, 10 phoenix cultivars belonged to P. pulmonariusclade, supported by a bootstrap value of 88%. The oyster cultivars and blue oyster cultivar belonged to Pleurotus cf. floridanus(P. ostreatus species), supported by a bootstrap value of 80%. The results of this study increased the basic data for identification and conservation purposes.

The golden lingzhi strain Toc1 (Tomophagus cattienensis)is a new strain that was discovered in the Cat Tien National Park in Đong Nai provine and it was identified to be a precious mushroom species. In this study, mycelial of strain Toc1 were incubated in 4 temperature levels (20 ± 1C, 25 ± 1C, 30 ± 1Cand 35 ± 1C); culture medium supplemented 5 different carbon sources (glucose, fructose, saccharose, maltose and lactose), 5 different nitrogen sources (yeast extract, peptone, ammonium clorua, ammonium nitrate and ammonium sulfate), 6 mineral salt sources (kali cloride, kali nitrate, natri nitrate, dikali phosphat, kali dihydrophosphat and magie sulfate). Beside that, mycelial of this strain were cultivated in 4 substrates added different wheat bran ratio (0%, 5%, 10% and15%). This study aims to figue out the optimal temperature, the suitable carbon, nitrogen and mineral salt source for mycelial growth of golden lingzhi mushroom strain Toc1 and also evaluating effect of the wheat bran ratio, which was supplemented on substrate, on formation and fruiting body development of this strain. The results showed that the optimal temperature for mycelial growth is 25C±1. Glucose and yeast extract were considered the most suitable carbon and nitrogen sources for mycelial growth. This strain grew very well on culture supplemented K2HPO4. The substrate containing 89% sawdust, 5% corn powder, 1% CaCO3and 5% wheat bran performed the highest BE, reached 15,97%.

Rooting shank or black root mushroom, Hymenopellis radicata(Xerula radicata, Oudemansiella radicata),is a wild edible mushroom known for its high nutritional and medicinal value and, thus, significant potential for the food and pharmaceutical industries. The objective of this study was to select Hymenopellis radicatafrom five different sources and compared under controlled growing conditions in Da Nang city, Vietnam. The substrates consisted of 80.0 w% rubber tree sawdust, 10.0 w% rice bran, 9.0 w% cornmeal, and 1.0 w% CaCO3, with 30 bags per experiment, replicated three times. The mushrooms were evaluated for their growth, biological efficiency, and fruiting body quality. Data analysis identified a superior genetic source (designated as M2), which was recommended for cultivation in Da Nang city. Mycelial growth rate on the substrate was 6.26±0,24mm/day, biological efficiency of 12.06±0.38%, total protein content in the fruiting body of 31.2 w% dry weight, lipid content of <1.0 w% dry weight, and absence of E.coliand Salmonella. Notably, Hymenopellis radicataexhibited a high cadmium uptake capacity (~3.7 mg/kg dry weight), surpassing the permissible limit of 0.2 mg/kg according to QCVN 8-2:2011/BYT, while showing no affinity for lead.

In this work, in order to improve the yield and quality of Ganoderma lingzhis in Vietnam, three lingzhi varieties, DT, D18 and D20, were irradiated with gamma rays (60Co) on the mycelium at different doses (0.25, 0.5, 0.75, 1.0; 1.25, 1.5and 2kGy). The evaluation results selected five mutant strains DTL0,5; DTL0,75; DTL1; DTL1,25 and D18L0,75, these strains showed strong mycelium, early fruiting body formation, and early harvest maturity and dry mushroom yield increased by 13-16% compared to the control. The polysaccharide content of DTL0.75; DTL1; DTL1.25 and thetriterpenoid content of DTL1.25 and D18L0.75 were considerably higher than the parental strains. The results indicated that the irradiation intensity had significantly effect on the development as well as the active pharmaceutical ingredients of the mutant strains, specifically, the irradiation doses from 0.5-1.25kGray had a positive effect growth, productivity and quality of mutant strains; and irradiation dose ≥ 1.5kGray is not beneficial for the mycelial development of mutant strains.

Oyster mushrooms (Pleurotusspp.) are widely consumed in the world due to their delicious taste, high nutritional value and medicinal properties. For breeding program to develop new cultivars, besides phenotypic characteristics genetic characterization of the material is important since it helps breeders to choose suitable materials for hybridization. This study analyzed the genetic diversity of 10 oyster mushroom accessions using 20 RAPD markers and 17 ISSR markers to provide information for oyster mushroom breeding programs. The markers amplified a total of 560 loci with 552 polymorphic loci and 2,138 PCR product bands. When combining both RAPD and ISSR markers, the genetic similarity coefficient of 10 oyster accessions ranged from 0.459 to 0.755. At the average genetic similarity coefficient of 0.579, 10 oyster mushroom accessions were divided into 3 main groups. These results indicate that 10 collected oyster mushroom accessions had a high level of genetic diversity and can be used for new oyster mushrooms breeding program.

FM6lingzhistrainwasdiscoveredgrowingnaturallyinPuMatNationalPark, ConCuongDistrict,NgheAnProvine.This study aims to use the ITS4/ITS5 primer pair to amplify the ITS region of the new collected mushroom strain to identify this strainandinitiallyinvestigatethegrowthcharacteristicsofthemyceliaondifferent carbonandnitrogensources.Inaddition,theeffectofwheatbranratioaddedtothe culturesubstrateonthemycelialgrowthandtheformationoffruitingbodiesofthisstrain was evaluated.The results ofsequencingandrunningBLASTonNCBIshowedthatFM6strainwasmorethan99% similartothe speciesGanodermaorbiforme.Fructose(15g/l) andNH4Cl(2g/l)werethemost suitablecarbonandnitrogensources,respectively,forthegrowth of lingzhistrainFM6.Substrate supplementedwith 10%wheatbranperformedthehighestBE,reaching 8.84%

This study was conducted to understand the diversity of species composition of macrofungi belonging to the phylum Basidiomycota in Son Tra Nature Reserve, Da Nang city by performing a line transect survey in 3 sub-areas divided into 15 different areas. Macrofungi specimens were collected at altitudes between 300 and 690 m above sea level. Among the specimens collected, we have identified 110 taxa belonging to 42 genera, 23 families, 10 orders, and 3 classes of the phylum Basidiomycota. Among them, species such as Microporus xanthopusand Stereum hirsutumare encountered more frequent during the sampling process. The life-styles of Basidiomycota macrofungi in Son Tra were either saprophytic, parasitic or symbiotic. The classification revealed that they can be divided into medicinal group, edible group, or group containing decomposers of organic matter to create humus for the soil. However, some species e also belonged to poisonous group.

Black Lingzhi, Amauroderma subresinosumof the the family Ganoderma, contains numerous bioactive compounds, such as sterols, flavonoids, phenols, fatty acids, amino acids, polysaccharides, and triterpenes. Whileactive constituents, distribution, and morphological characteristics of black lingzhi have been studied in Vietnam, there has been limited research conducted to determine the ideal culture conditions that promote mycelial growth. This study aimed to determine the optimal culture conditions for mycelialgrowthof Amauroderma subresinosumstrain Am-4, collected from Bao Lam, Lam Dong province. Strain Am-4 was cultured on Ohta, PDA, SDA, MEA, MCM, and Czapek media under different pH levels, temperatures, carbon, nitrogen, and mineral salt sources. Our results indicated that strain Am-4 exhibited rapid mycelialgrowth on MEA medium at 25°Cand pH5. The strain showed the highest growth rate when cultured in a medium containing glucose and NaNO3as the carbon and nitrogen sources, respectively, with the optimal glucose/NaNO3ratio being 10:1. Additionally, ZnSO4.7H2O was found tobetheoptimal mineral salt source. Under the optimized culture conditions, strain Am-4 exhibited fast mycelial growth with a compact density.