Ecology of Thermophilic Fungi in Mushroom Compost, with Emphasis on Scytalidium thermophilum and Growth Stimulation of Agaricus bisporus Mycelium

Twenty-two species of thermophilic fungi were isolated from mushroom compost. Scytalidium thermophilum was present in the compost ingredients, fresh straw, horse droppings, and drainage from compost and dominated the fungal biota of compost after preparation. Of 34 species of thermophilic fungi tested, 9 promoted mycelial growth of Agaricus bisporus on sterilized compost: Chaetomium thermophilum, an unidentified Chaetomium sp., Malbranchea sulfurea, Myriococcum thermophilum, S. thermophilum, Stilbella thermophila, Thielavia terrestris, and two unidentified basidiomycetes. These species will be considered for future experiments on inoculation and more controlled preparation of compost.     

Suppressive effect of non-aerated compost teas on foliar fungal pathogens of tomato

Compost teas are fermented watery extracts of composted materials that are used for their ability to decrease plant disease. Non-aerated compost teas (NCT) prepared from five types of compost were tested for their ability to inhibit the growth of Alternaria solani, Botrytis cinerea, and Phytophthora infestans in vitro. Weekly applications of NCT were also used in greenhouse trials to assess their suppressive effect on powdery mildew (Oidium neolycopersici) and gray mold (B. cinerea) on tomato plants. All NCT significantly inhibited the mycelial growth of A. solani (37–66%), B. cinerea (57–75%), and P. infestans (100%), whereas sterilized teas did not inhibit growth of the tested pathogens. Although NCT failed to efficiently control powdery mildew, they were able to control tomato gray mold for up to 9 weeks in greenhouse experiments. Among the tested compost teas, NCT prepared from sheep manure compost consistently provided the highest inhibition of mycelial growth and the highest disease suppression, in particular of gray mold (>95% disease reduction). The overall relative efficacy of the various NCT did not correlate well with microbial communities or physico-chemical composition of the prepared NCT. Results also suggest that the presence of the microorganisms in the NCT is a prerequisite for inhibition.     

Characters of compost teas from different sources and their suppressive effect on fungal phytopathogens

Compost teas (CT) are fermented watery extracts of composted materials that are used to control plant diseases and on crop fertilization. In this work, aerated (ACT) and non-aerated compost teas (NCT) were obtained from four different composts: spent mushroom substrate compost, grape marc compost, greenhouse horticultural crop residues compost, and vermicompost. Physico-chemical and microbiological analysis were carried out to determine their properties. In vitro assays were performed to assess their suppressive effect on the mycelial growth of eight fungal phytopathogens. In vivo trials aimed to assess their effect on gummy stem blight (Didymella bryonae) and powdery mildew (Podosphaera fusca) in melon plants. Results showed that ACT and NCT filtrates inhibited the in vitro growth of all tested pathogens while autoclaved CT did not completely lose their inhibitory effect, and CT sterilized by microfiltration had no effect on the pathogen growth. The severity of powdery mildew was highly reduced by ACT and NCT from all sources, though in gummy stem blight assay only a delay in disease development was observed. In general, all compost teas showed a high level of microbial populations and nutrients. Results suggest that the efficacy of ACT and NCT firstly depend on the microbiota present in them. We consider compost teas from the four tested sources as a viable way to manage plant diseases and crop fertilization, throughout its integration in pest management programs and fertirrigation systems under different dilution rates.     

Effect of Metabolites Produced by Trichoderma harzianum Biotypes and Agaricus bisporus on Their Respective Growth Radii in Culture

Trichoderma harzianum biotypes Th1, Th2, and Th3 produced volatile metabolites in vitro which had similar fungistatic effects on the growth of Agaricus bisporus. Metabolites present in agar colonized by these strains also inhibited mycelial growth of A. bisporus, although the reduction in growth was less in the presence of metabolites produced by biotype Th2 than that in the presence of metabolites produced by Th1 or Th3. A. bisporus produced metabolites in liquid culture that inhibited the growth of Th1 and Th3 but stimulated the growth of Th2. A compound(s) responsible for the inhibition and stimulation was extracted from A. bisporus culture filtrate and from compost-grown fruit bodies with n-butanol, but the identity of the compound(s) was not determined. We suggest that the stimulation of Th2 by metabolites produced by A. bisporus and the relatively low level of inhibition of A. bisporus by Th2 facilitate colonization of compost by both fungi. However, as compost colonization reaches a maximum, a change in the competitive balance in favor of Th2 results in the inhibition of fruit body production by A. bisporus and the devastating green mold epidemics affecting mushroom production.     

Growth Characteristics of Polyporales Mushrooms for the Mycelial Mat Formation

Mushroom strains of Polyporales from the genera Coriolus, Trametes, Pycnoporus, Ganoderma, and Formitella were explored in terms of mycelial growth characteristics for the application of mushroom mycelia as alternative sources of materials replacing fossil fuel-based materials. Among the 64 strains of Polyporales, G. lucidum LBS5496GL was selected as the best candidate because it showed fast mycelial growth with high mycelial strength in both the sawdust-based solid medium and the potato dextrose liquid plate medium. Some of the Polyporales in this study have shown good mycelial growth, however, they mostly formed mycelial mat of weak physical strength. The higher physical strength of mycelial mat by G. lucidum LBS5496GL was attributed to its thick hyphae with the diameter of 13 µm as revealed by scanning electron microscopic analysis whereas the hyphae of others exhibited less than 2 µm. Glycerol and skim milk supported the best mycelial growth of LBS5496GL as a carbon and a nitrogen source, respectively.     

Optimization of rice bran and food waste compost contents in mushroom culture medium to maximize mycelial growth rate and fruit body yield of Pleurotus ostreatus

The objective of this study was to find optimum rice bran (RB) and food waste compost (FWC) contents in culture medium for mycelial growth rate and fruit body yield of oyster mushroom, Pleurotus ostreatus. RB (0–20%) and FWC (20–40%) contents significantly affected the fruit body yield of P. ostreatus. Within the design boundaries, the optimum conditions for maximum mycelial growth rate (14.8 cm 20 d⁻¹) were 9.3% RB and 24% FWC. The optimum conditions for maximum fruit body yield (91 g bottle⁻¹) were 12% RB and 25% FWC, which was 153% higher than value (36 ± 11 g bottle⁻¹) at the control condition of 80% w/w sawdust and 20% w/w RB. Our results proved a good potential of FWC to serve as an alternative growth medium for cultivating oyster mushroom, P. ostreatus. This may improve the production efficiency of edible mushrooms to help minimize production costs and maximize farm profits.     

Carbon sequestration and community composition of ectomycorrhizal fungi across a geothermal warming gradient in an Icelandic spruce forest

Soil warming (0–5.5 °C above controls) effects on ectomycorrhizal growth, carbon sequestration and community composition were examined in a Picea sitchensis forest spanning a geothermal gradient in Iceland. Fungal communities were assayed with sand-filled ingrowth meshbags incubated in the soil for 5 months. Meshbags amended with compost made from maize leaves (a C4 plant enriched in ¹³C) were incubated for 5 or 12 months and used to estimate C sequestration by the fungal community. Despite increases in tree growth, moderate warming only slightly reduced or had no effect on mycelial growth and had no effect on fungal carbon sequestration or overall ectomycorrhizal community composition. Warming was associated with increased abundance of ascomycetes, particularly pyronemataceous ectomycorrhizal fungi, and altered saprotrophic community composition. Increased nitrate availability and root turnover may explain the lack of a positive ectomycorrhizal growth response to increased tree growth and observed shifts in community composition with warming.     

Growth promotion of Suillus luteus by adenosine in vitro

In this work, adenosine has been shown to stimulate Suillus luteus mycelial growth, branching, and aggregates on solid substrate. Adenosine promoted S. luteus mycelial growth and branching, and the fungus responded significantly at a concentration as low as 0.01 mg/ml. The highest mycelial biomass and density of three strains were observed at 0.16 mg/ml in SNP-20, 0.08 mg/ml in SAF-501, and 0.16 mg/ml in PT-501. Adenosine enhanced mycelial aggregate at concentration of 0.02 mg/ml in SNP-20. The study suggests that adenosine promotes S. luteus mycelial growth, branching, and aggregation. Thus, it may be a good candidate as a biological elicitor of mycelial growth for S. luteus.     

Production of Fungal Mycelial Protein in Submerged Culture of Soybean Whey

Various soybean whey media were tested as substrate for seven species of fungi in submerged culture. Very little mycelial growth was obtained with Morchella hybrida, Collybia velutipes, Cantharellus cibarius, and Xylaria polymorpha. Agaricus campestris failed to grow. Tricholoma nudum and Boletus indecisus showed the greatest rate of growth and production of mycelial protein and the best utilization of soybean whey solids, with much shorter incubation times compared with those of the other species. T. nudum developed as spheres having diameters of about 5 to 8 mm, instead of the usual slurry or yeastlike form, in the presence of added ammonium acetate. B. indecisus always developed as spheres. Mycelial yields and production of protein by T. nudum greatly decreased with the addition of more than 1% glucose to soybean whey, whereas with B. indecisus the yield of protein almost doubled when up to 3% glucose was added. The effect of minerals on mycelial growth was determined. With soybean whey concentrated to 50%, the rate of mycelial growth of T. nudum was nearly doubled, but protein content of mycelia was greatly reduced. Mycelial growth and yield of protein of B. indecisus grown in concentrated whey were increased greatly. About 4 to 6 g of mycelial protein per liter can be obtained from fermentation in soybean whey, depending upon the medium used. Utilization of soybean whey by fungal fermentation may have economic value in whey disposal and in the production of products of high protein content.     

A method for estimating biomass ofAgaricus bisporus in a solid substrate,composted wheat straw

Summary Growth ofAgaricus bisporus mycelium in liquid cultures, or linear growth in compost, was directly proportional to the quantity of extracellular laccase. Laccase activity measured during the mycelial colonisation of composted straw can therefore be used to quantify the mycelial growth. Immunological methods indicate that the laccase appears to be a specific product ofA. bisporus or very closely related species.     

The effect of some microphagous saprobic nematodes on mushroom culture

When added to spawned mushroom compost the microphagous saprobic nematodes Pelodera cylindrica, Mesorhabditis spiculigera and Acrobeloides bütschlii did not affect mycelial growth or compost pH. The eelworms multiplied at first but their numbers declined as the mycelium colonized the compost. In contrast, the fungal-feeding Aphelenchoides composticola increased rapidly and destroyed the mycelium. Excess water, and the presence of the fungal competitor of mushroom, Chaetomium olivaceum, allowed some increase of the microphagous forms. Different numbers of Mesorhabditis spiculigera added to the ‘casing’ had no effect on mushroom yield but the mushroom ‘flushes’ seemed less pronounced. Reasons for the failure of the saprobic eelworms to affect mushroom, and the possibility of synergistic pathogenicity by these eelworms and bacteria, are discussed.     

Compost Grown Agaricus bisporus Lacks the Ability to Degrade and Consume Highly Substituted Xylan Fragments

The fungus Agaricus bisporus is commercially grown for the production of edible mushrooms. This cultivation occurs on compost, but not all of this substrate is consumed by the fungus. To determine why certain fractions remain unused, carbohydrate degrading enzymes, water-extracted from mushroom-grown compost at different stages of mycelium growth and fruiting body formation, were analyzed for their ability to degrade a range of polysaccharides. Mainly endo-xylanase, endo-glucanase, β-xylosidase and β-glucanase activities were determined in the compost extracts obtained during mushroom growth. Interestingly, arabinofuranosidase activity able to remove arabinosyl residues from doubly substituted xylose residues and α-glucuronidase activity were not detected in the compost enzyme extracts. This correlates with the observed accumulation of arabinosyl and glucuronic acid substituents on the xylan backbone in the compost towards the end of the cultivation. Hence, it was concluded that compost grown A. bisporus lacks the ability to degrade and consume highly substituted xylan fragments.     

Growth and stability of ethene-utilizing bacteria on compost at very low substrate concentrations

Ethene-utilising micro-organisms on compost may be applied in a packed bed to scrub the plant hormone ethene from air. Ethene at the concentrations tested (50–200 vpm) supported growth of micro-organisms present in compost and also of ethene-grown Mycobacterium E3 cells immobilised on compost.     

Scanning Electron Microscope Studies of Interactions between Agaricus bisporus (Lang) Sing Hyphae and Bacteria in Casing Soil

Relationships between the hyphae of Agaricus bisporus (Lang) Sing and bacteria from the mushroom bed casing layer were examined with a scanning electron microscope. Hyphae growing in the casing layer differed morphologically from compost-grown hyphae. Whereas the compost contained thin single hyphae surrounded by calcium oxalate crystals, the casing layer contained mainly wide hyphae or mycelial strands without crystals. The bacterial population in the hyphal environment consisted of several types, some attached to the hyphae with filamentlike structures. This attachment may be important in stimulation of pinhead initiation.     

淋洗后生活垃圾堆肥建植高羊茅草坪生理生态响应

以不同淋洗方式处理后的生活垃圾堆肥为基质进行草坪植物培植,研究了高羊茅的生理生态响应。结果表明,淋洗处理堆肥中高羊茅的发芽率及株高等生长指标均优于未淋洗的原堆肥对照组,其中水肥淋洗比例为1∶1的处理中,高羊茅的最大发芽率比对照提高89.6%。通过对超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）3种保护酶的活性及脯氨酸和丙二醛（MDA）含量等指标的测定可以看出,经淋洗处理后的堆肥基质对草坪植物的胁迫程度均小于原堆肥,更有利于草坪植物的正常生长。综合高羊茅生长指标及生理指标来考虑,堆肥处理的最佳淋洗比例为水∶堆肥的质量比为2∶1。     

Alleviation of Drought Stress in Turfgrass by the Combined Application of Nano-compost and Microbes from Compost

Drought stress is a key environmental factor limiting the growth and productivity of plants. Turfgrasses are often affected by drought in north China due to water shortage. In the present study, the impact of nanosized compost either alone or in combination with drought tolerant isolates from compost on turfgrass response to drought was investigated. Municipal solid waste (MSW) compost was processed into nanosized particles and added in turfgrass soil. Microorganisms in the MSW compost were screened for drought stress tolerance using increasing concentrations of polyethylene glycol (PEG 6000). Festuca arundinacea Schreb. plants were inoculated with this mixture and exposed to drought stress by reducing the amount of water added at vegetative growth stage. The drought-tolerant isolates from compost were identified as Bacillus cereus, Lysinibacillus sp. and Rhodotorula glutinis. Our results revealed that nanocompost and microbial inoculation minimized the drought stress-imposed effects significantly increasing shoot biomass, root biomass, and chlorophyll content. Similarly, nanocompost-treated and inoculated seedlings showed higher levels of antioxidant enzymes and lower MDA content compared to nontreated control under drought stress. The combination of nano-sized compost and microbial inoculation were more efficient than nanocompost alone in terms of influencing growth and physiological status of the seedlings under drought stress. Our data suggest that nanocompost combined with drought-tolerant isolates may enhance drought tolerance in turfgrass by promoting plant growth and increasing the capacity to eliminate toxic reactive oxygen species (ROS).     

Characteristics of a Hydrated, Alginate-Based Delivery System for Cultivation of the Button Mushroom

The production of the button mushroom Agaricus bisporus with mycelium-colonized alginate pellets as an inoculant of the growing medium was investigated. Pellets having an irregular surface and porous internal structure were prepared by complexing a mixture of 1% sodium alginate, 2 to 6% vermiculite, 2% hygramer, and various concentrations of Nutrisoy (soy protein) with calcium chloride. The porous structure allowed the pellets to be formed septically and then inoculated and colonized with the fungus following sterilization. By using an enzyme-linked immunosorbent assay (ELISA) to estimate fungal biomass, the matrix components of the pellet were found to be of no nutritive value to A. bisporus. Pellets amended with Nutrisoy at a concentration of 0.5 to 8% supported extensive mycelial growth, as determined by significantly increased ELISA values, with a concentration of 4% being optimal and higher concentrations proving inhibitory. The addition of hydrated, mycelium-invaded pellets to the compost or casing layer supported the thorough colonization of the growing substrate and culminated in the formation of mushrooms that showed normal development and typical morphology. Yields and sizes of mushrooms were comparable from composts seeded with either colonized pellets or cereal grain spawn. Similarly, amending the casing layer with pelletized-mycelium-colonized compost resulted in a 2- to 3-day-earlier and more-synchronous emergence of mushrooms than with untreated casing. This technology shows the greatest potential as a pathogen-free inoculant of the casing layer in the commercial cultivation of mushrooms.     

Extending the hyphal area of the ectomycorrhizal fungus Laccaria parva co-cultured with ectomycorrhizosphere bacteria on nutrient agar plate

The members of Proteobacteria have been frequently detected from ectomycorrhizal roots; however, their function in the mycelial growth of ectomycorrhizal fungi remains uncertain. This study examined the extension of the hyphal area of Laccaria parva co-cultured with the ectomycorrhizosphere bacteria. One mycelial disk of L. parva was placed on the center of a plastic dish containing diluted modified Melin-Norkrans agar media, and each bacterial strain was incubated 2?cm away from the mycelial disk at four orthogonal directions. Several strains of Rhizobiaceae, including those closely related to Bradyrhizobium, significantly increased the extension of the hyphal areas of several strains of L. parva; however, the majority of bacteria tended to decrease them. The effects of bacteria on the hyphal growth area differed according to the combination of strains of bacteria and L. parva in several cases, indicating that the interactions between bacteria and L. parva can be specific at the strain level.     

Molecular and cultural characterization of Morchella spp. from disturbed environments of central-southern Chile

In Northwestern Patagonia (Chile), three species of Morchella from undisturbed environments have been identified to date: Morchella tridentina, Morchella andinensis and Morchella aysenina, all belonging to the Elata clade and associated mainly with Nothofagus forests. In this study, the search for Morchella specimens was extended to disturbed environments in Central-Southern Chile, to further explore Morchella species diversity in the country, which is still very limited. The Morchella specimens were identified through multilocus sequences analysis, and the mycelial cultures were characterized, establishing comparisons with specimens from undisturbed environments. To the best of our knowledge, these results reveal for the first time in Chile the presence of the species Morchella eximia and Morchella importuna, and in the case of the last one also the first record in South America. These species were found associated almost exclusively with harvested or burned coniferous plantations. The in vitro mycelial characterization revealed certain inter- and intra-specific patterns of the morphology, such as pigmentation, mycelium type, and development and formation of sclerotia, which varied according to growth media and incubation temperature. The growth rates (mm/day) and mycelial biomass (mg) were significantly influenced by the temperature (p < 0.05), with maximum rates (>10 mm/day) and biomass (approx. 20 mg) between 20 and 24 °C, while a significant growth reduction (70–90%) was observed at 28 °C, mainly in the species from undisturbed environments. Potato-dextrose (PDA) medium stimulated the greatest mycelial density and sclerotia formation in most of the isolates, mainly in M. eximia (UDEC-LAF 236 isolate) which recorded the best mycelial growth performance. Among isolates, UDEC-LAF 236 also showed the best performance in sclerotia production (>350 sclerotia/dish) in 10 days of growth. This study contributes to the knowledge of the diversity of Morchella species in Chile by broadening the species range to those from disturbed environments. It also provides molecular and morphological characterization of the in vitro cultures of different Morchella species. The report on M. eximia and M. importuna, species known as cultivable, adapted to local climatic and edaphic conditions could represent the first step to developing artificial Morchella cultivation methods in Chile.     

Co-treatment with Origanum Oil and Thyme Oil Vapours Synergistically Limits the Growth of Soil-borne Pathogens Causing Strawberry Diseases

Vapours from origanum oil (O) and thyme oil (T) were applied to the four soil-borne strawberry pathogens Fusarium oxysporum f. sp. fragariae, Colletotrichum fructicola, Lasiodiplodia theobromae, and Phytophthora cactorum, causing Fusarium wilt, anthracnose, dieback, and Phytophthora rot, respectively. Increasing T vapour doses in the presence of O vapour strongly inhibited mycelial growths of the four pathogens and vice versa. When mycelia of F. oxysporum f. sp. fragariae and P. cactorum exposed to the combined O + T vapours were transferred to the fresh media, mycelial growth was restored, indicating fungistasis by vapours. However, the mycelial growth of C. fructicola and L. theobromae exposed to the combined O + T vapours have been slightly retarded in the fresh media. Prolonged exposure of strawberry pathogens to O + T vapours in soil environments may be suggested as an alternative method for eco-friendly disease management.