Edible Fungi In China Research Articles

Telomere-to-Telomere Haplotype-Resolved Genomes of Agrocybe chaxingu Reveals Unique Genetic Features and Developmental Insights.

Agrocybe chaxingu is a widely cultivated edible fungus in China, which is rich in nutrients and medicinal compounds. However, the lack of a high-quality genome hinders further research. In this study, we assembled the telomere-to-telomere genomes of two sexually compatible monokaryons (CchA and CchB) derived from a primarily cultivated strain AS-5. The genomes of CchA and CchB were 50.60 Mb and 51.66 Mb with contig N50 values of 3.95 Mb and 3.97 Mb, respectively. Each contained 13 complete chromosomes with telomeres at both ends. The high mapping rate, uniform genome coverage, high LAI score, all BUSCOs with 98.5%, and all base accuracy exceeding 99.999% indicated the high level of integrity and quality of these two assembled genomes. Comparison of the two genomes revealed that approximately 30% of the nucleotide sequences between homologous chromosomes were non-syntenic, including 19 translocations, 36 inversions, and 15 duplications. An additional gene CchA_000467 was identified at the Mat A locus of CchA, which was observed exclusively in the Cyclocybe cylindracea species complex. A total of 613 (4.26%) and 483 (3.4%) unique genes were identified in CchA and CchB, respectively, with over 80% of these being hypothetical proteins. Transcriptomic analysis revealed that the expression levels of unique genes in CchB were significantly higher than those in CchA, and both CchA and CchB had unique genes specifically expressed at stages of mycelium and fruiting body. It was indicated that the growth and development of the A. chaxingu strain AS-5 required the coordinated action of two different nuclei, with CchB potentially playing a more significant role. These findings contributed to a more profound comprehension of the growth and developmental processes of basidiomycetes.

Risk Assessment of Metals in Black Fungus and Culture Substrates Based on Monte Carlo Simulation

Black fungus is the second-most consumed edible fungus in China. The establishment of a risk assessment mechanism for heavy metals in black fungus is particularly critical to the safety of edible fungi. To clarify a risk assessment mechanism of heavy metal pollution of edible fungi in northeast China, in this study, the contents of Pb, Cr, CD and As in 415 samples were determined, and a total of 1660 valid data were obtained. Then, based on Monte Carlo simulation, a non-parametric probability assessment system for heavy metals in black fungus was established and improved. The results showed that the residual amounts of As, Pb, Cd and Cr in black fungus were in the order of Cr > Pb > As > Cd. The background content of four heavy metals in the main raw materials was preliminarily clarified. Among them, the content of As is between 0.010–0.320 mg·kg−1, Pb is between 0.051–0.792 mg·kg−1, Cd is between 0.019–0.236 mg·kg−1, and Cr is between 0.06–3.41 mg·kg−1. These results indicate that the dietary exposure risk of heavy metals ingested by dried black fungus in Chinese minors and adults is basically safe, but at the high exposure levels of 97.5% sites and 99% sites, Cr is at the light pollution level, and the comprehensive pollution of four heavy metals is at the moderate pollution level. In addition, this study found that raw materials can cause heavy metal accumulation in black fungus, mainly from sawdust, followed by rice bran and wheat bran.

Hericium caput-medusae (Bull.:Fr.) Pers. fermentation concentrate polysaccharides improves intestinal bacteria by activating chloride channels and mucus secretion

Ethnopharmacological relevanceAs a traditional edible fungus in China and many other Asian countries, Hericium caput-medusae (Bull. Fr.) Pers. is widely used to improve the health of the gastrointestinal tract. For example, the drug “Weilexin Granules” is mainly composed of H. caput-medusae (Bull. Fr.) Pers. fermentation concentrate. However, the mechanism of action remains to be elucidated. Aims of the studyThe purpose of this study was to assess whether polysaccharides from H. caput-medusae (Bull. Fr.) Pers. fermentation concentrate (HFP) exerts a gut protective effect and a regulatory effect on the intestinal microbiota through the chloride channels and mucus secretion. Materials and methodsHFP was extracted, characterized and different concentrations of HFP (100, 200, 400 mg/kg) were administered to mice for 14 days. The changes in gut microbiota were observed via 16S high throughput sequencing. Short-chain fatty acids (SCFAs) was detected by GC-MS. AB-PAS staining was used to observe the secretion of mucus. The chloride channel activity and protein expression were verified by short-circuit current measurement and Western blot. ResultsHFP regulated the abundance of gut microbiota in mice, with increased levels of Ruminococcaceae and Lachnospiraceae and reduced proportions of Staphylococcus and Enterobacter. HFP enhanced mucus volume as well as increased intestinal fluid secretion by activating the chloride channels. In addition, short-circuit current experiments also proved that HFP activates Cl⁻ currents targeting cystic fibrosis transmembrane conductance regulator (CFTR) and Anoamin1 (ANO1). ConclusionIn conclusion, HFP might increase intestinal fluid secretion by promoting Cl⁻ secretion, which in turn advanced mucus hydration as well as regulated gut microbiota to improve intestinal health. Therefore, H. caput-medusae (Bull. Fr.) Pers. could be potentially used in the regulation of intestinal secretion and microbes.

Identification of phytochemicals from Lentinus edodes and Auricularia auricula with UPLC-Q-Exactive Orbitrap MS

• Phytochemicals of Lentinus edodes was investigated by UPLC-Q-Exactive-Orbitrap MS. Twenty-three compounds were identified in L. edodes. • Phytochemicals of Auricularia auricula were investigated by UPLC-Q-Exactive-Orbitrap MS. Twenty-nine compounds were identified in A. auricula. • There are 9 common ingredients of L. edodes and A. auricula, including 4 amino acids and analogs, 2 flavonoids, 2 nucleosides and analogs and 1 phenol. Lentinus edodes and Auricularia auricula are the first and second largest edible fungi in China with high nutritional and medicinal values. Research about phytochemicals of L. edodes and A. auricula mainly focuses on polysaccharides, other phytochemicals are not fully studied. Phytochemicals of L. edodes and A. auricula were investigated by ultra-high performance liquid chromatography tandem hybrid quadrupole-orbitrap mass spectrometry (UPLC-Q-Exactive-Orbitrap MS). Twenty-three compounds were identified in L. edodes , mainly including amino acids and analogs, flavonoids, nucleosides and analogs, phenols and steroids. Twenty-nine compounds were identified in A. auricula , mainly including amino acids and analogs, nucleosides and analogs, flavonoids and phenols. There are 9 common ingredients of L. edodes and A. auricula , including 4 amino acids and analogs, 2 flavonoids, 2 nucleosides and analogs and 1 phenol.

Investigation and analysis of pesticide residues in edible fungi produced in the mid-western region of China

The present study sought to investigate the levels of multi-pesticide residues in highly consumed edible fungi in China's western regions. A total of 354 edible fungi samples were collected from the local markets, and the concentrations of 53 pesticides in these samples were determined through high performance liquid chromatography mass spectrometer (HPLC/MS/MS). Carbendazim, acephate, procymidone, prochloraz, aldicarb sulfone,etc. were found to be the primary pesticides in the edible fungi samples. Carbendazim had the highest detection rate (70.9%), followed by acephate (13.0%) and procymidone (7.3%), and the detection concentrations were 0.0002–2.7316 mg/kg, 0.0248–0.4985 mg/kg, 0.1807–0.3928 mg/kg, respectively. Nearly 52 (14.7%) edible fungi samples were free of pesticide residues, while the remaining contained one or more pesticide residues. In terms of safety index and risk coefficient, the safety status of edible fungi is acceptable. This study will provide insights into the current contamination status in the key agricultural areas in China and develop food safety regulations to control the excessive use of some pesticides on edible fungi.

Anti-Gout Effects of the Medicinal Fungus Phellinus igniarius in Hyperuricaemia and Acute Gouty Arthritis Rat Models.

Background: Phellinus igniarius (P. igniarius) is an important medicinal and edible fungus in China and other Southeast Asian countries and has diverse biological activities. This study was performed to comparatively investigate the therapeutic effects of wild and cultivated P. igniarius on hyperuricaemia and gouty arthritis in rat models. Methods: UPLC-ESI-qTOF-MS was used to identify the chemical constituents of polyphenols from wild P. igniarius (WPP) and cultivated P. igniarius (CPP). Furthermore, WPP and CPP were evaluated in an improved hyperuricaemia rat model induced by yeast extract, adenine and potassium oxonate, which was used to examine xanthine oxidase (XO) activity inhibition and anti-hyperuricemia activity. WPP and CPP therapies for acute gouty arthritis were also investigated in a monosodium urate (MSU)-induced ankle swelling model. UHPLC-QE-MS was used to explore the underlying metabolic mechanisms of P. igniarius in the treatment of gout. Results: The main active components of WPP and CPP included protocatechuic aldehyde, hispidin, davallialactone, phelligridimer A, hypholomine B and inoscavin A as identified by UPLC-ESI-qTOF-MS. Wild P. igniarius and cultivated P. igniarius showed similar activities in reducing uric acid levels through inhibiting XO activity and down-regulating the levels of UA, Cr and UN, and they had anti-inflammatory activities through down-regulating the secretions of ICAM-1, IL-1β and IL-6 in the hyperuricaemia rat model. The pathological progression of kidney damage was also reversed. The polyphenols from wild and cultivated P. igniarius also showed significant anti-inflammatory activity by suppressing the expression of ICAM-1, IL-1β and IL-6 and by reducing the ankle joint swelling degree in an MSU-induced acute gouty arthritis rat model. The results of metabolic pathway enrichment indicated that the anti-hyperuricemia effect of WPP was mainly related to the metabolic pathways of valine, leucine and isoleucine biosynthesis and histidine metabolism. Additionally, the anti-hyperuricemia effect of CPP was mainly related to nicotinate and nicotinamide metabolism and beta-alanine metabolism. Conclusions: Wild P. igniarius and cultivated P. igniarius both significantly affected the treatment of hyperuricaemia and acute gouty arthritis models in vivo and therefore may be used as potential active agents for the treatment of hyperuricaemia and acute gouty arthritis.

Effects of

Context In-feed antibiotics are commonly used to improve growth and gut health of weaning pigs. Due to anti-microbial resistance by extensively using antibiotics, however, in-feed antibiotics have been banned in Europe and China. Tremella fuciformis is a traditional edible fungus in China. Recent studies have found that Tremella fuciformis extract (TFE) has anti-inflammatory, anti-cancer and immune-modulatory functions. Therefore, there is the potential to develop Tremella fuciformis as an alternative to antibiotics. Aims The study was performed to explore the effects of TFE on growth performance, and biochemical and immunological parameters of weaned piglets under lipopolysaccharide (LPS) challenge. Methods Forty-eight weaned piglets were assigned into two groups with six pens (four piglets per-pen), receiving a control diet or a control diet with 400 mg/kg TFE (TFE), respectively. After 28 days of the trial, two piglets per pen were selected to be injected with LPS (50 μg/kg of BW) or an equivalent amount of sterile saline. Blood samples were collected at 0 and 3 h after LPS challenge. Key results The results showed that TFE supplementation significantly increased the average daily gain (P < 0.05) and decreased the faecal score (P < 0.05) during the first week, improved the feed conversion ratio (P < 0.05) and BWt gain (P < 0.05) during the whole period. Piglets fed the TFE diet had higher plasma levels of white blood cells (P < 0.05) than that of piglets fed the control diet diet before the LPS challenge. Regardless of the dietary treatment, the LPS challenge significantly decreased the level of white blood cells, and increased the levels of red blood cells, haemoglobin, haematocrit, total protein, interleukin-1β and tumour necrosis factor-α (all P < 0.05). Regardless of the LPS challenge, however, the concentrations of total protein, interleukin-1β and tumour necrosis factor-α were decreased (all P < 0.05) in the plasma of piglets fed the TFE diet compared with the control diet diet. Conclusions In summary, the supplementation of TFE in the weaning diet could improve the growth performance and immunity of piglets. Implication TFE could be used as a bioactive substance for improving growth and immune response in pig production.

Determination of bongkrekic acid in tremella and auricularia auricular by improved QuEChERS method combined with ultra-high performance liquid chromatography-triple quadrupole mass spectrometry

采用改良的QuEChERS方法,结合超高效液相色谱-串联质谱(UHPLC-MS/MS)建立了银耳和木耳中米酵菌酸含量测定的分析方法。对QuEChERS方法的提取、净化条件进行了优化,发现提取液中乙酸含量对米酵菌酸的提取效率影响很大,最终采用5%(v/v)乙酸乙腈为提取溶剂,盐析分层,再用200 mg C18分散固相萃取净化。对UHPLC-MS/MS分析条件也进行了优化,以含0.01%(v/v)甲酸、0.05%(v/v)氨水的水溶液和甲醇为流动相,在Waters HSS T3柱(100 mm×2.1 mm, 1.8 μm)上分离,以电喷雾电离、多反应监测负离子模式进行检测。在优化好的条件下,银耳和木耳中米酵菌酸检测的基质效应分别为-6.3%和-11.5%,表明该方法具有很好的净化效果,样品基质不会对米酵菌酸的检测产生影响。进一步对方法学进行了考察,在1~200 μg/L范围内,线性方程回归系数的平方(R2)大于0.999,以信噪比的3倍和10倍计算的方法检出限和定量限分别为0.15 μg/kg和0.5 μg/kg。银耳中3种添加水平0.5、10、50 μg/kg下的加标回收率为92.4%~102.6%,日内和日间相对标准偏差(RSD)分别为4.3%~4.9%和3.2%~3.5%;木耳的加标回收率为89.6%~102.3%,日内和日间RSD分别为2.4%~9.5%和3.6%~4.1%,表明该方法具有很好的准确度和精密度。最后,将该方法应用于实际样品中米酵菌酸的分析,取得了很好的效果。该工作为银耳和木耳中米酵菌酸的风险防控提供了一种有效的检测技术。

Identification of Secondary Metabolites in Flammulina velutipes by UPLC-Q-Exactive-Orbitrap MS

Flammulina velutipes is the fourth largest edible fungus in China with high nutritional value. In this paper, ultrahigh-performance liquid chromatography tandem hybrid quadrupole-Orbitrap mass spectrometry (UPLC-Q-Exactive-Orbitrap MS) was used to identify the secondary metabolites of F. velutipes. The metabolites were identified by comparing the retention time, accurate molecular weight, and MS2 data with standard databases of mzVault and mzCloud (compound: 17,000+) and BGI high-resolution accurate mass plant metabolome database (plant metabolite: 2500+). Finally, 26 secondary metabolites were preliminarily identified, including flavonoids, phenylpropanoids, organic acids, and steroids.

Assessment and molecular characterization of Bacillus cereus isolated from edible fungi in China

BackgroundBacillus cereus is a foodborne pathogen commonly found in nature and food and can cause food spoilage and health issues. Although the prevalence of B. cereus in foods has been reported worldwide, the extent of contamination in edible fungi, which has become increasingly popular as traditional or functional food, is largely unknown. Here we investigated the prevalence, toxin genes’ distribution, antibiotic resistance, and genetic diversity of B. cereus isolated from edible fungi in China.ResultsSix hundred and ninety-nine edible fungi samples were collected across China, with 198 (28.3%) samples found to be contaminated by B. cereus, with an average contamination level of 55.4 most probable number (MPN)/g. Two hundred and forty-seven B. cereus strains were isolated from the contaminated samples. Seven enterotoxin genes and one cereulide synthetase gene were detected. The detection frequencies of all enterotoxin genes were ≥ 80%, whereas the positive rate of the cesB gene in B. cereus was 3%. Most isolates were resistant to penicillins, β-lactam/β-lactamase inhibitor combinations, cephems, and ansamycins, but were susceptible to penems, aminoglycosides, macrolides, ketolide, glycopeptides, quinolones, phenylpropanol, tetracyclines, lincosamides, streptogramins, and nitrofurans. Meanwhile, 99.6% of all isolates displayed multiple antimicrobial resistance to three or more classes of antimicrobials. Using genetic diversity analysis, all isolates were defined in 171 sequence types (STs), of which 83 isolates were assigned to 78 new STs.ConclusionsThis study provides large-scale insight into the prevalence and potential risk of B. cereus in edible fungi in China. Approximately one-third of the samples were contaminated with B. cereus, and almost all isolates showed multiple antimicrobial resistance. Detection frequencies of all seven enterotoxin genes were equal to or more than 80%. These new findings may indicate a need for proper pre-/post-processing of edible fungi to eliminate B. cereus, thereby preventing the potential risk to public health.

Functional principal component analysis for near-infrared spectral data: a case study on Tricholoma matsutakeis

Abstract Tricholoma matsutakeis (TM) is the most expensive edible fungi in China. Given its price and exclusivity, some dishonest merchants will sell adulterated TM by combining it with cheaper fungi in an attempt to earn more profits. This fraudulent behavior has broken food laws and violated consumer trust. Therefore, there is an urgent need to develop a rapid, accurate, and nondestructive tool to discriminate TM from other edible fungi. In this work, a novel detection algorithm combined with near-infrared spectroscopy (NIR) and functional principal component analysis (FPCA) is proposed. Firstly, the raw NIR data were pretreated by locally weighted scatterplot smoothing (LOWESS) and multiplication scatter correction (MSC). Then, FPCA was used to extract valuable information from the preprocessed NIR data. Then, a classifier was designed by using the least-squares support-vector machine (LS-SVM) to distinguish categories of edible fungi. Furthermore, the one-versus-one (OVO) strategy was included and the binary LS-SVM was extended to a multi-class classifier. The 166 samples of four varieties of fungi were used to validate the proposed method. The results show that the proposed method has great capability in near infrared spectra classification, and the average accurate of FPCA-LSSVM is 97.3% which is greater than that of PCA-LSSVM (93.5%).

Genome Sequence Analysis of Auricularia heimuer Combined with Genetic Linkage Map.

Auricularia heimuer is one of the most popular edible fungi in China. In this study, the whole genome of A. heimuer was sequenced on the Illumina HiSeq X system and compared with other mushrooms genomes. As a wood-rotting fungus, a total of 509 carbohydrate-active enzymes (CAZymes) were annotated in order to explore its potential capabilities on wood degradation. The glycoside hydrolases (GH) family genes in the A. heimuer genome were more abundant than the genes in the other 11 mushrooms genomes. The A. heimuer genome contained 102 genes encoding class III, IV, and V ethanol dehydrogenases. Evolutionary analysis based on 562 orthologous single-copy genes from 15 mushrooms showed that Auricularia formed an early independent branch of Agaricomycetes. The mating-type locus of A. heimuer was located on linkage group 8 by genetic linkage analysis. By combining the genome sequence analysis with the genetic linkage map, the mating-type locus of A. heimuer was located on scaffold45 and consisted of two subunits, α and β. Each subunit consisted of a pair of homeodomain mating-type protein genes HD1 and HD2. The mapping revealed conserved synteny at the whole mating-type loci and mirror symmetry relations near the β subunit between A. heimuer and Exidia glandulosa. This study proposed the potential for the bioethanol production by consolidated bioprocessing of A. heimuer. It will promote understanding of the lignocellulose degradation system and facilitate more efficient conversion of the agricultural wastes used for mushroom cultivation. It also will advance the research on the fruiting body development and evolution of A. heimuer.

Complete mitochondrial sequence of Auricularia heimuer, one of the most popular edible fungus in China

Auricularia heimuer is one of the most popular edible fungi in China. It has high economic and medicinal value. The complete mitochondrial genome of A. heimuer is 40586 bp. It contains 48 genes, including 25 protein-coding genes, 22 tRNA genes, and 1 gene coding RNase P RNA. The G + C content is 37.92%. The phylogenetic relationships were constructed on the Bayesian inference method. It showed that A. heimuer was in distance to other species of Russulales, Polyporales, and Agaricales. The complete genome sequence of A. heimuer will provide a useful resource for the genetic and systematics studies.

A Gustatory Receptor Used for Rapid Detection of Tyrophagus putrescentiae in Fungi Hosts

The storage mite, Tyrophagus putrescentiae, found worldwide in many habitats, is an important pest of edible fungi in China. Storage mites are tiny and difficult to observe, especially when they occur in fungi composts. In this study, one gustatory receptor protein (TputGR1) was identified from the transcriptome of T. putrescentiae. Phylogenetic analysis of GRs families from 10 arthropod species revealed that TputGR1 had high homology with the SccaGR1 of Sarcoptes scabiei and TurtGR1-2 of Tetranychus urticae, but low homology with other insect species, Drosophila melanogaster, Anopheles gambiae, Bombyx mori, Aedes aegypti, Culex quinquefasciatus, and Pediculus humanus. We developed a detection system for the mite on fungi hosts using the GR protein and the loop-mediated isothermal amplification (LAMP). This procedure was rapid (60 min from sampling to result) and had high sensitivity (0.5 ng/mL). LAMP provided rapid and reliable detection of T. putrescentiae. It has good specificity for single samples and for large-scale surveys.

High-Temperature Induced Changes of Extracellular Metabolites in Pleurotus ostreatus and Their Positive Effects on the Growth of Trichoderma asperellum

Pleurotus ostreatus is a widely cultivated edible fungus in China. Green mold disease of P. ostreatus which can seriously affect yield is a common disease during cultivation. It occurs mostly after P. ostreatus mycelia have been subjected to high temperatures. However, little information is available on the relationship between high temperature and green mold disease. The aim of this study is to prove that extracellular metabolites of P. ostreatus affected by high temperature can promote the growth of Trichoderma asperellum. After P. ostreatus mycelia was subjected to high temperature, the extracellular fluid of P. ostreatus showed a higher promoting effect on mycelial growth and conidial germination of T. asperellum. The thiobarbituric acid reactive substance (TBARS) content reached the maximum after 48 h at 36°C. A comprehensive metabolite profiling strategy involving gas chromatography-mass spectrometry (GC/MS) combined with liquid chromatography-mass spectrometry (LC/MS) was used to analyze the changes of extracellular metabolites in response to high temperature. A total of 141 differential metabolites were identified, including 84.4% up-regulated and 15.6% down-regulated. Exogenous metabolites whose concentrations were increased after high temperature were randomly selected, and nearly all of them were able to promote the mycelial growth and conidial germination of T. asperellum. The combination of all selected exogenous metabolites also has the promotion effects on the mycelial growth and conidial germination of T. asperellum in a given concentration range in vitro. Overall, these results provide a first view that high temperature affects the extracellular metabolites of P. ostreatus, and the extensive change in metabolites promotes T. asperellum growth.

Effect of Fungal Species on the Development and Reproductive Traits of the Fungal-Feeding Mite Rhizoglyphus robini (Astigmata: Acaridae).

The bulb mite, Rhizoglyphus robini (Claparède; Astigmata: Acaridae), is a cosmopolitan pest with a broad host range, including commercially grown edible fungi in China. In this study, we recorded the development and reproductive traits of the bulb mite reared on four mushroom species: Agaricus bisporus Lange, Pleurotus ostreatus Kumm, Pleurotus pulmonarius (Fr.) Quél., and Lentinula edodes (Berk.) Pegler at six constant temperatures ranging from 15 to 31°C and 80% RH. Developmental time for the immature stages was significantly affected by fungal species, ranging from 9.45 ± 1.83 d (reared on L. edodes at 31°C) to 26.39 ± 2.10 d (reared on A. bisporus at 15°C). Edible fungi species significantly affected intrinsic rates of natural increase (rm) at 31°C (varied from 0.23 to 0.28) as did the mite's net reproductive rates (R0) (103.78, 90.43, 70.77, and 97.45, respectively). Longevity, fecundity and female lifespan were dependent on host fungi.

The Qingyuan Mushroom Culture System as Agricultural Heritage

Qingyuan County, Zhejiang, China is recognized as a source of mushrooms around the world and as Mushroom City in China. Because of a favorable ecological environment and abundant forest resources, mushroom farmers in Qingyuan have engaged in mushroom production for 800 years and continued to form unique mushroom production systems where people and nature live in a harmonious way, and a rich and colorful mushroom culture. The Qingyuan Mushroom Culture System was named the Nationally Important Agricultural Heritage systems of China in 2014. Based on analysis of the importance of agricultural heritage and the necessity and urgency of protection, here we examine the agricultural heritage of the Qingyuan mushroom culture system as a research case study and comprehensively describe its heritage values, including supply materials and production, ecosystem services, cultural inheritance and multi-function agricultural development. These results provide reference values for agricultural heritage protection and inheritance of edible fungi in China, agricultural sustainable development and extension of agricultural function.

First Report of Pantoea beijingensis Induced Soft Rot Disease of Pleurotus nebrodensis in China.

Pleurotus nebrodensis is a popular edible fungus in China. In December 2009, soft rot disease appeared on fruiting bodies of P. neberodensis in greenhouses located at Haidian District of Beijing, China. Early symptoms were water-soaked lesions on the pilei of the fruiting bodies. Lesions then spread and purulent tissues were formed. Severe soft rot induced production of deformed fruiting bodies and offensive odor. Diseased fruiting bodies stopped growth and commercial losses were estimated at 5 to 10%. Internal sections of the diseased pilei about 0.5 × 0.5 cm were suspended in 0.85% NaCl and the suspension was spread on trypticase soy agar (TSA) media. After incubation at 30°C for 2 days, dominant bacterial colonies were yellow, smooth, round, and convex. Cells were gram-negative, short rods, non-capsulated, motile, and non-spore forming. The 16S rRNA gene (1,408 bp, GenBank Accession No. KF849293) was amplified by using the universal forward primer P1 (5'-AGAGTTTGATCCTGGTCAGAACGCT-3') and the universal reverse primer P6 (5'-TACGGCTACCTTGTTACGACTTCACCCC-3'). Neighbor-joining tree analysis based on 16S rRNA gene sequences demonstrated the isolates belonged to the genus Pantoea and showed highest similarity with Pantoea beijingensis LMG 27579T (99.9% similarity, 2 base pair differences), which was isolated from the diseased fruiting bodies of P. eryngii in China. Pantoea sp. PA4, reported to be the pathogen of soft rot disease of P. eryngii in Korea (1), showed 99.8% similarity with P. ananatis ATCC 33244T, which suggested our isolates belonged to a different species with Pantoea sp. PA4 (supported by 97.9% similarity between the present isolates and Pantoea sp. PA4) (2). Results of physiological properties and enzyme activities determined by the API 20E, API 20NE, API 50CH, API ZYM (bioMérieux), and GN2 MicroPlate (Biolog) system showed that there was no difference between the present isolates and P. beijingensis LMG 27579T. Pathogenicity tests for these isolates were performed with bacterial suspensions (approximately 1 × 106 CFU/ml) that were grown for 24 h in trypticase soy broth (TSB). Fruiting bodies of P. nebrodensis were induced after spawn was run for 30 days in plastic bags. When the young fruiting bodies were forming, the prepared bacterial suspension was sprayed onto the surface of the pilei. Sterilized TSB media was used as a negative control. All inoculated fruiting bodies were then incubated at 16°C with 80 to 95% relative humidity. Assays were conducted twice and five fruiting bodies were used each time. Results were observed after 5 to 10 days of incubation. The symptoms that developed were similar to those observed in the original samples. The negative control remained symptomless. Koch's postulates were fulfilled by re-isolating bacteria, which were identical to the original isolates based on 16S rRNA gene sequence analysis, physiological properties and enzyme activities. Pantoea ananatis was first reported as a pathogen of Pleurotus eryngii, causing soft rot disease (1), but to the best of our knowledge, this is the first report of P. beijingensis- induced soft rot disease of P. nebrodensis in China. This disease may be an emerging disease problem in the near future and information on this pathogen will be useful in the development of management practices.

Safety assessment of the fermented Phylloporia ribis (Lonicera japonica Thunb.) mycelia by oral acute toxicity study in mice and 90-day feeding study in rats

Phylloporia ribis is an edible fungus in China. Its fermented mycelia have been approved by the National Health and Family Planning Commission (NHFPC) of PR China for use as a novel food material, but little information on its safety is available. The present research was the first to evaluate acute and subchronic toxicity in experimental animals of fermented Phylloporia ribis mycelia (FPM) following standard procedures. In acute toxicity study, FPM was orally administered to male and female mice twice a day at single dose of 10g/kg bw. The Maximum Tolerated Dose (MTD) of FPM for mice of both sexes was over 10g/kg bw. No death and abnormal behaviors occurred during 14days study except for an increased locomotor activity in three animals. In 90-day feeding study, male and female Sprague–Dawley rats were fed diets containing 10.0%, 5.0%, 2.5%, 1.25% and 0% (control) FPM for 90days. The treatment caused no effects on mortality, gross pathology, histology, hematology, and blood chemistry, no dose-dependent changes in food consumption, but caused effect on body weight gain compared with control group. The No Observed Adverse-Effect Level (NOAEL) of FPM was greater than 8.7g/kg bw/day in both sexes of rats.

Non-volatile components of several novel species of edible fungi in China

Four species of newly commercial edible mushrooms in China, including red oyster mushroom ( Pleurotus djamor), ferula mushroom ( Pleurotus ferulae), white-ling mushroom ( Pleurotus nebrodensis) and purple spore oyster ( Pleurotus sapidus) were studied. Their carbohydrate, polysaccharide, crude fibre, crude protein, crude fat and ash contents were in the ranges of 46.2–59.9%, 9.02–18.8%, 11.2–17.2%, 15.6–30.3%, 1.65–7.35% and 3.84–5.83%, respectively. Their mineral element contents varied significantly, with the (highest) potassium contents ranging from 12.3 to 16.3 mg/g of dry weight and the (lowest) zinc contents ranging from 0.02 to 0.18 mg/g of dry weight detected among six mineral elements. Their total soluble sugar contents ranged from 9.37 (red oyster mushroom) to 31.9 mg/g (purple spore oyster) with the same levels in ferula mushroom (20.2 mg/g) as white-ling mushroom (23.7 mg/g). Their total amino acid contents and essential amino acid contents ranged from 84.4 to 192 mg/g and from 24.8 to 71.5 mg/g, respectively. Glutamic acid, aspartic acid, leucine and arginine were four major amino acids in these four species of mushrooms. Their palatable amino acid contents were high in ferula mushroom (53.6 mg/g), moderate in white-ling mushroom and purple spore oyster (about 33.8 mg/g), and low in red oyster mushroom (15.8 mg/g). Results showed that these four species of newly commercial mushrooms in China were distinctly different in non-volatile components.