Since the discovery of endofungal bacteria (EFB) for the first time in 1970, scholars have applied techniques popular at their times to pay attention to this biological correlation phenomenon between host fungi and their endobiont bacteria. In recent years, investigations on their interactions have gradually become a new hotspot using diverse research methods. With the continuous expansion and deepening of research on EFB, more and more biological phenomena and theories have been revealed. The research progress concerning investigation methods, colonization location, morphology, classification, host groups, development of the symbiosis, biological function, host healing, isolation, and re-introduction of EFB to fungi are reviewed. The main trend of further studies of EFB is also predicted.
Based on systematic analysis of symplesiomorphy together with synapomorphy Umbilicaria laceratula (1926) has been combined as Lasallia laceratula comb. nov. and Lasallia rossica (1978) has been treated as a heterotypic synonym of Lasallia laceratula. U. caucasica (1885) has been treated as the heterotypic synonym of Lasallia pensylvanica, and Gyrophora proboscidea var. orizabae (1926) is the synonym of Umbilicaria bigleri (1949).
Tobacco endophytic fungi is an important component of the tobacco field ecosystem. Roots are important source of tobacco fungal endophytes. The community structure and functional characteristics of the endophytic fungi from roots of five varieties of tobacco were analyzed by high-throughput sequencing. The results showed that the diversity and richness of endophytic fungal community in the tobacco roots were low. Sordariomycetes, Dothideomycetes, Eurotiomycetes, Agaricomycetes and Leotiomycetes were the main fungal groups. Hypocreales, Capnodiales and Eurotiales were dominant order, and Nectriaceae, Davidiellaceae and Trichocomaceae were dominant family. Undefined saprophytes and animal pathogens were the main ecological functional groups. However, the distribution of community composition and ecological function were significantly different between tobacco varieties.
The establishment of symbiosis between Pinus massoniana, one of the main tree species in southern China, and Suillus bovinus, the dominant ectomycorrhizal (ECM) fungus in the masson pine forest was investigated under aseptic condition. Two stages emerged during the symbiosis establishment. During pre-infection stage (before physical contact), the volatile organic compounds and exudates emitted by Suillus bovinus could promote root growth and lateral root formation of P. massoniana. The symbiotic formation stage could further divide into three periods. The fungus began to contact the roots at day 4 after inoculation and the appressorium formed. In seven days, hyphae began to penetrate the roots, and colonization started. In 28 days of post-inoculation, the Hartig net and mantle formed, and mycorrhizal root tips swelled. In 60 days of post-inoculation, the typical dichotomous branching ECM emerged. The Hartig net and the mantle developed simultaneously, but the Hartig net matured earlier. The results provide reference for further investigation of ECM symbiosis mechanisms and the development of efficient methods of preparing mycorrhizal seedlings of P. massoniana.
To study the community structure of the root symbiotic fungi of Arundina graminifolia and nutritional effect of the fungi on the host, high-throughput sequencing technology was used to identify the fungal species, and biological function of fungi in wild A. graminifolia rhizosphere soil (Rs), rhizoplane (Rp), and endoplane (Ep) was predicted. The average Simpson index of the root symbiotic fungi in Rs, Rp and Ep was 0.972, 0.905, and 0.703 respectively, indicating that the three sites were rich in symbiotic fungi. The Shannon index in Rs was 7.393, significantly higher than that in Rp (4.728) and Ep (2.872), and fungal diversity in Rp was significantly higher than that in Ep (P<0.05). Ascomycota, Basidiomycota, Rozellomycota, Chytridiomycota, Mucoromycota and Mortierellomycota were mainly found in Rp and Ep. Glomeromycota and Kickxellomycota are absent in Rp and Ep. AMOVA analysis confirmed that the difference of fungal community structure between the three niches was extremely significant (P=0.004). The top 20 genera in each ecological niches only involve 40 genera of Ascomycota and Basidiomycota. Ascomycetous 30 genera are dominant, while the species richness of the single genus in Basidiomycota is higher than that in Ascomycota. The saprotrophic fungi dominated (44.07%) in Rs; Rp was mainly colonized by saprophytic, pathogenic and symbiotic fungi; the nutrient types of the fungi in Ep were different, by way of example, symbiotic fungi in sample M1 dominated (97.21%), while in M2 and M3 saprophytes dominated (90.96%). The dominant symbiotic genera are Threlephora, Rhizopogon and Dentiscutata. The saprophytic genera are mainly Funalia and Vuilleminia, belonging to basidiomycetes. Further study is needed for revealing the nutritional relationship between A. graminifolia and root symbiotic fungi.
Anthracnose on Camellia oleifera is one of the most serious diseases of Camellia in China, and the major causal pathogen is Colletotrichum fructicola. The biological functions of a leucine zipper (bZIP) type transcription factor CfHac1 of C. fructicola was investigated. Our results showed that the transcription factor CfHac1 of C. fructicola has 526 amino acids with a bZIP domain and three unknown function domains, encoded by a 1 627bp gene orthologous to MoHac1 of the rice blast fungus Magnaporthe oryzae. Deletion of CfHAC1 resulted in significant reduction in vegetative growth, sporulation and appressorium formation. Stress response assay showed that the ΔCfhac1 mutant had increased sensitivity to osmotic stress (Sorbitol or KCl). Pathogenicity test showed that the ΔCfhac1 mutant was remarkably decreased in virulence to Ca. oleifera. Our study reveals that the transcription factor CfHac1 plays critical roles in growth, conidiation, appressorium formation, pathogenicity and respond to osmotic stress in C. fructicola.
Zoophthora radicans with wide host range and global distribution is one of the most ubiquitous species of entomophthoroid fungi. To explicate the taxonomic position of Z. radicans and its related species, comparison and phylogenetic analyses of sequence data of three target loci, nuclear 28S rDNA, ITS region and the protein-coding RPB2, from 15 Z. radicans isolates and four other Zoophthora species were performed. Analysis result showed that the length of entire ITS in Z. radicans ranging 1 321-1 324bp is conservative, however, the ITS length in other entomophthoroid species ranging 556-1 654bp is diverse. Phylogenetic tree confirms that Z. radicans is monophyletic, and the species status of Z. occidentalis, Z. anglica and Z. lanceolata is explicit. Z. phalloides may be regarded as a synonym of Z. occidentalis.
The water-soluble yellow pigments (WSYPs) extracted from Cordyceps militaris mycelia were separated, purified and analyzed by high performance liquid chromatography (HPLC). The influence of temperature, light, pH, metal ions and other common food additives on the stability of WSYPs were further investigated by using yellow pigment 4 (YP-4), the main component of WSYPs, as the detection index. The result showed that the WSYPs were mainly composed of five carotenoids with similar structure and solubility in deionized water. The component YP-4 with MS data [M-H] of 521.2657 accounted for 57.43% of total WSYPs. UV characteristic absorption peaks of YP-4 were 209nm, 239nm, 421nm, 445nm and 474nm, and the maximum absorption peak was found at 445nm. Stability tests revealed that the yellow pigments had good processing stability. In the process of WSYPs, the ultraviolet irradiation duration should be reduced as far as possible, and the quantity of acid additives and Fe 3+ should be appropriately controlled.
Aromatic components of edible Lactarius subzonarius in Yanshan Mountains were analysed. 25 volatile components were detected by SPME and GC-MS, including 3 heterocyclic oxygen compounds, 1 aldehydic compound, 13 lipoid compounds, 3 olefin compounds, and 5 alkane compounds. The relative content of 3-hydroxy-4,5-dimethyl-2(5H) -furanone, a volatile component with flavor of fenugreek, is 35.76%, and the component is the main aroma compound of L. helvus. It is inferred that 3-hydroxy-4,5-dimethyl-2(5H) -furanone is the key aroma component of L. subzonarius.
The hot-water extraction technique of fruiting body polysaccharides of Floccularia luteovirens (FLPs) collected in Serxü of northwestern Sichuan, Qinghai-Tibet Plateau was optimized by using single factor experimental design and response surface methodology (RSM). Hydroxyl radical and superoxide anion radical scavenging activity were examined to confirm the antioxidant activity of FLPs. The results showed that the optimal hot-water extraction conditions were extraction temperature of 89.31°C, extraction time of 5.08h, and solid-liquid ratio of 1:48.54g/mL. Under such a optimization condition, FLPs exhibited strong antioxidant activity of scavenging hydroxyl radical in vitro. It was indicated that the design was reliable and feasible, and could applied to production of functional polysaccharide foods and drugs.
This study aims at screening the active extract from Isaria cicadae for controlling obesity and its complications. An obesity mouse model was prepared by feeding high fat and cholesterol diet to mice. Isaria cicadae extracts (ethyl alcohol extract, aqua destillata extract and alkaline water extract) were fed to the mice for 35 days by gavage. Histopathological changes of liver and colon, serum levels of total cholesterol (T-CHO), total triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoproteincholesterol (HDL-C) and gut microbiota were monitored. Results showed that all of the three extractions could reduce the body weight and improve the serum levels of T-CHO, TG, LDL-C and HDL-C of the experimental mice. The pathological observation revealed that the damages of liver and colon tissues induced by high fat and cholesterol diet were ameliorated more or less, and the alpha and beta diversity and gut microbiota composition were also improved. The ethyl alcohol extract of Isaria cicadae (ICE) has the best effect among the three tested samples, indicating that ICE would be the most active extract for obesity control while the functional mechanism remains to be studied.
Laccase is a copper-containing single-electron polyphenol oxidase, which can catalyze oxidation of various phenols and dyes, and has great potential in the treatment of dye wastewater. Pleurotus eryngii has a strong ability to produce laccase, but laccase production is restricted by environmental conditions to a large extent. In this study, the culture conditions of P. eryngii for increasing laccase production were optimized and the ability of the crude enzyme to decolorize azo dye methyl orange solution was also observed. The results showed that the laccase production capacity of P. eryngii was strongly increased upon condition that the mass proportion of nitrogen source was 0.5%, pH value 5.5, cultural temperature 28°C and 5.0mmol/L Mg 2+ was added. Under such an optimized condition, the laccase activity reached 78.0U/L in 6 days. In 28h, the decolorization rate of azo dye methyl orange by the crude enzyme reached 90%. The result indicated that the decolorization reaction was a pseudo-first-order kinetic reaction. The dye was not fully mineralized, but generated small molecular intermediates.
The fungal community structure and ecological function of core fungal microbiome in sclerotia, external mycelial layer covering ossified cicada epidermis and habitat soil of Isaria cicadae were investigated. The relationship between fungi in internal and external environment during natural growth of Isaria cicadae was preliminarily explored. 6 Isaria cicadae isolates and soil samples collected from Mount Dajiang and Guiyang Forest Park were detected by high throughput sequencing technique. The results showed that the fungal community structure in sclerotia was similar to that in external mycelial layer covering ossified cicada epidermis. 43 genera, 58 genera and 260 genera of fungi were detected from sclerotia, external mycelial layer covering ossified cicada epidermis and soil adhering to surfaces of ossified cicada, respectively. However, the fungal community structures of habitat soil of Isaria cicadae sampled from the two sample sites were different. Isaria, Mortierella and an unclassified genus were dominant for soil sample from Mount Dajiang, while Mortierella and Cryptococcus, Russula and Isaria were dominant for soil samples from Forest Park, and the relative abundance of Isaria spp. in the soil adhering to surfaces of ossified cicada was significantly higher than that in other soil samples. The analysis of core fungal microbiome showed that 10 OTUs, 5 OTUs and 20 OTUs were detected from sclerotia, external mycelial layer covering ossified cicada epidermis and soil adhering to surfaces of ossified cicada, respectively. The ecological functional groups relative to plants were also detected. For instance, ectomycorrhizal fungi were detected from sclerotia, plant pathogens were detected from external mycelial layer covering ossified cicada epidermis, arbuscular mycorrhizal and plant saprophytic fungi were detected from soil adhering to surfaces of ossified cicada.
