G0140512 fungus strain was isolated from a 4°C refrigerator in the Institute of Fungus Resources of Guizhou University. Morphological study and phylogenic analysis based on the ITS1-5.8S-ITS2 rDNA sequences have proved that this strain is a new taxon of Geomyces, and it is named as G. guiyangensis. The new species can grow at 0°C, and its optimum and lethal temperatures are 15-25°C and 40°C, respectively. The strain can produce obviously melanin in the media. Recently, melanin from the microorganism has been paid more and more attention. G. guiyangensis might be endowed with potential application value.
A disease of pulp rot was frequently found on stored pineapple fruits after harvest in pineapple planting base in Xuwen County of Guangdong Province in recent years, and the disease incidence even reaches about 10% in seriously infected pineapple garden. One pathogenic isolate of Fusarium was obtained by fruit tissue isolation and further pathogenicity test proved that it was pathogenic to pineapple. Based on morphological characteristics and TEF-1α gene sequence analysis, the isolate was identified as Fusarium ananatum. It is the first report of the pathogen responsible for pineapple fruitlet core rot in China.
A comparative study on the developmental processes of four species in Physaraceae, Physarum flavicomum, Physarum melleum, Physarum album and Physarella oblonga, was conducted by hanging drop culture and oats-agar culture. Microstructures of the myxomycetes were observed by differential-interference microscope and scanning electron microscope. The complete life-cycle of P. album was for the first time illustrated. It was showed that the spores of these four myxomycete species unexceptionally germinated by V-shaped split, but germinating duration was slightly different in the same condition. Spores of P. flavicomum needed merely 5h for germination, however the duration of germination of P. oblonga spores took 2d. The myxamoeba of P. oblonga and P. melleum changed into a swarm cell with two flagella, whereas in the same conditions swarm cell was not found in P. flavicomum and P. album. The plasmodia of different species had different growth rate. The plasmodia of P. oblonga, P. melleum, P. flavicomum and P. album respectively needed 2-3d, 2-3d, 7d and 13d for developing fruiting bodies. P. oblonga and P. melleum took 25-30d to complete the life cycle of spore to spore, while P. flavicomum and P. album needed 40-45d.
In order to explore the systematic relationships of the genus Isaria, 5 genes (nrSSU, nrLSU, tef-1α, rpb1 and rpb2) were sequenced and the conjoint analyses were carried out for the species of Isaria and its relatives. Combined the related groups in GenBank, a total of 95 gene datasets were obtained from 58 species with 2-5 genes each. The multi-gene cluster was conducted by using the MEGA and MrBayes softwares. The results showed that Isaria spp. could be divided into 3 groups, i.e., clade A, B and C, with not being monophyletic in the family Cordycipitaceae. The clade A contained Isaria cicadae, I. teniupes, I. coleopterorum, I. fumosorosea and I. cateniannulata. The clade B mainly included I. poprawkii, I. locustica, I. javanica, I. amoenerosea and I. cateniobliqua. Only I. farinosa was filled in the clade C. The 3 groups were partitioned by the species Cordyceps militaris, C. ninchukispora, C. pruinosa etc. The genus Isaria was distinguished from others genera by the characteristics of conidiogenous cell phialophore, consisting of a cylindrical or swollen basal portion, tapering or abrupt into a long distinct neck, and of the chain form of conidium. According to the divergence time based on the distinguished node, it was suggested that Isaria spp. would be firstly diverged 70Mya. While the speciation of Isaria should occur in 60-55Mya. An interesting result was the species formations of the 3 clades in Isaria were quick and simultaneous during this period, and then the genetic stability was kept in most groups. Meanwhile, Mariannaea pruinosa (anamorph of C. pruinosa) and Lecanicillium militaris (anamorph of C. militaris) were closed to the species of Isaria Clade A. Akanthomyces aculeatus (anamorph of C. tuberculata) and L. attenuatum (anamorph of C. confragosa) had close relationships with I. farinosa, while these species were obviously different in traditional classifications. Morphological characteristics were complex in Isaria and its relatives. Thus it is suggested there seems to be some degree of loss and selective adaptive evolution during the quick and simultaneous speciation of the species in the genus.
Expression of lignocellulose hydrolyase genes in filamentous fungi were mainly regulated at the transcriptional level. Identification of the key cellulase regulatory genes would be greatly helpful for improving the cellulase production. In order to discover the novel regulatory genes, the cellulase secretion levels of 57 gene knock-outs of C2H2 zinc finger transcription factors were screened using 2% crystalline cellulose as the sole carbon source. By measuring secreted protein, endo-beta-1,4-glucanase activity, cellobiohydrolase activity, beta-glucosidase activity, xylansae activity and biomass, the cellulase production were found significantly increased by 25%-75% in the mutants L-38, L-85, L-40, L-64, L-99, L-07 and L-86, while significantly reduced by 65%-80% in the mutants L-87, L-06, as compared with the wild type. These observations will provide new data for further studies.
The differences of polysaccharides extracted from fruiting bodies, mycelia and spore powder of Ganoderma lingzhi were compared. Polysaccharide concentration was determined by phonel-sulfate method, and monosaccharide compositions of the polysaccharides were analyzed by ion chromatography-integrated pulsed amperometric detector. HPLC spectrums of various polysaccharides and their changes after treated with α-amylase and endo-1,3-β-glucanase were also compared. The results indicated that polysaccharide content of mycelia was 3.81%, being the highest, and that of spore powder and fruiting body were 1.8% and 0.59%, respectively. Monosaccharide composition and molar ratio of the three polysaccharides from mycelia, fruiting bodies and spore powder were different. In fruiting body, glucose and galactose were the main monosaccharide, but glucose was the main monosaccharide in mycelia and spore powder. HPLC spectrums revealed that the peaks and molecular weights of the three polysaccharides were also different. Changes between HPLC spectrums of polysaccharides treated by endo-1,3-β-glucanase and α-amylase indicated the three polysaccharides had different structure. NO release experiment using RAW 264.7 macrophages revealed that both polysaccharides from mycelia and fruiting bodies showed good activity of stimulating macrophages to release NO, however the polysaccharide from spore powder showed relatively lower activity. The study demonstrated that the polysaccharides of these three materials varied significantly, thus they should be differentially applied in pharmaceutical health care products.
The 95% ethanol extract of Flammulina velutipes fruiting bodies were partitioned into petroleum ether-soluble fraction, CHCl3 fraction, EtOAc fraction, n-BuOH fraction, and residuals. The characteristic components in each fraction were analysized by coloring reaction combined with thin-layer chromatography. The antitumor activities and hypoglycemic activities in vitro were investigated for each fraction. The results showed that compounds such as alkaloids, organic acids, steroids (or triterpenes), flavonoids and anthraquinone were contained in petroleum ether fraction, CHCl3 fraction and EtOAc fraction. Amino acids, protein, sugar, steroid (or triterpenoid) were contained in n-BuOH fraction and residuals, and organic acids and flavonoids were also contained in n-BuOH fraction. Fractions of petroleum ether, CHCl3, EtOAc and residuals showed strongly inhibitory activity on tumor cells SW620, L1210, MCF-7, and K562 and n-BuOH fraction showed weekly antitumor activity. However, CHCl3 fraction and EtOAc fraction showed inhibitory activity to normal cells (WPMY-1). All five fractions showed inhibitory activity to DPP-IV, indicating that components in these fractions may have hypoglycemic activity, especially CHCl3 fraction and EtOAc fraction.
By liquid flask cultivation method, mycelial biomass was chosen for main indicator to screen medium composition and conditions for liquid fermentation of Paecilomyces hepiali strain PH-2. Through further orthogonal experiment, mycelial yield and adenosine content were used as joint indicators to determine the optimized medium formula of PH-2 strain fermentation for high yield of mycelia and adenosine. The optimized medium formula consists of corn starch 40g/L, glucose 5g/L, corn steep liquor 25g/L, MgSO4·7H2O 1g/L, KH2PO4 1g/L, ZnSO4 1.5g/L, and vitamin B1 25mg/L. Culture conditions were as follows: the initial pH of 6.0, fermentation temperature of 26℃, fluid volume of 150mL/500mL, inoculation quantity of 8% (V/V), rotary speed of 120r/min, and fermentation duration of seven days. In this process, the mycelial biomass reached 25.2g/L. With high performance liquid chromatography (HPLC) method, the content of adenosine in P. hepiali mycelia was 2.76mg/g. The method is simple, rapid, accurate, and can be used for the detection of adenosine in P. hepiali mycelia or its related products. This process optimization results in high yield, and the mycelia are of good quality.
Choosing intracellular polysaccharide yield as a target, the single factor method was used to screen the suitable carbon source, nitrogen source and inorganic salts for the culture medium of Cordyceps gunnii. The optimal medium combination was studied using orthogonal test, and the fermentation kinetics of Cordyceps gunnii was achieved using the optimal medium. The results showed that the optimal medium for intracellular polysaccharide yield of Cordyceps gunnii was composed of glucose 35g/L, peptone 15g/L, ZnSO4 1g/L, KH2PO4 1g/L, K2HPO4 0.5g/L, and (5.169±0.274)g/L. The intracellular polysaccharide yield obtained by using the optimal medium was about 1.80 fold of that obtained by using non-optimized medium. The fermentation kinetic plots showed that the best culture duration for intracellular polysaccharide production was 144h and a yield of (6.794±0.221)g/L was obtained, which was the highest intracellular polysaccharide yield of Cordyceps gunnii hitherto reported.
Citrinin (CTN), a tetraketide metabolite of Penicillium citrinum, is a common mycotoxin found in human foods and animal feeds (corn, grain, cheese etc), causing food poison or carcinogenesis to human and animals. For rapid detection of citrinin, accurate and reliable methods are in demand. In this study, specific aptamers against citrinin were selected by using the systematic evolution of ligands by exponential enrichment (SELEX) method. After 15 rounds of SELEX cycles, 17 aptamers were obtained. Of which, aptamer Apt-13 having a close affinity to CTN was further selected based on secondary structure analysis. The dissociation constant (Kd) of Apt-13 was 0.06µmol/L. An accurate and rapid CTN detection method was developed by further using Apt-13 and PicoGreen, a specific double-stranded DNA binding and non-labeled fluorescent dye. The detection procedure could be finished in 30min. The limit of detection (sensitivity) of this method was 50ppb, which could meet the national standard for CTN residue detection. No cross reactions were found to other mycotoxins. This aptamer-based method exhibited more advantages than traditional antibody-based methods due to its low cost, thus could be used as an alternative tool for mycotoxin detection.
Three species of stromatic pyrenomycetous fungi of the genus Kretzschmaria (Xylariales, Xylariaceae) are reported. K. milleri and K. sandvicensis are newly recorded in China. K. zonata was recorded only from Tainwan Province previously, but now it is also found in other provinces of the country. K. milleri collected from Hunan Province is characterized by its papillate opening ostioles; K. sandvicensis collected from Yunnan and Hunan provinces is distinguished by its spore-length germ slit; K. zonata collected from Yunnan, Hainan and Zhejiang provinces has darker and smaller ascospores. The morphological descriptions and photographs of the species are provided based on the Chinese collections.
Four new Chinese records of Entoloma s.l., E. bisporigerum, E. caesiellum, E. formosum and E. pallidocarpum, were collected from Northeast China. Illustrated descriptions of these four species are provided based on the Chinese materials.
Cortinarius olivaceofuscus, Cortinarius fuscobovinus and Cortinarius croceus were discovered in Greater Hinggan Mountains of Inner Mongolia in China for the first time. Detailed morphological descriptions and illustrations are provided and ITS sequences of these taxa were generated and submitted to the GenBank. The results of ITS sequence blasts are consistent with the morphological identification. The examined specimens are deposited in the Herbarium of Mycology of Jilin Agricultural University (HMJAU).
