Mycelial Production Research Articles

Simple, inexpensive media for mass production of three entomophthoralean fungi

The entomophthoralean fungi Batkoa sp., Furia sp. and Neozygites floridana have been suggested for biocontrol of insect pests: the first two for control of spittlebug pests of pasture and sugarcane, and the third for mites of agricultural importance. To develop these agents as biopesticides and bioacaricides, it is important to have available culture media that maximize production at low cost. The research reported here evaluates, in different combinations and concentrations, the effect of four complex sources of nitrogen on production of mycelium or hyphal bodies in liquid media of all three species. Yeast extract allowed the highest production of Batkoa sp., with a concentration of 0.5% being the most suitable for vegetative (mycelial) growth. The combination of 0.33% each of yeast extract + beef extract + skim milk allowed the highest production of Furia sp. Mycelium. The combination of yeast extract + skim milk (0.5% of each) allowed the second highest production of Furia sp., and was the most suitable for mass production due to the lower cost. The combination of 1 %each of yeast extract + peptone + skim milk was the most suitable for production of N. floridana hyphal bodies.

Phacidiopycnis washingtonensis--a new species associated with pome fruits from Washington State

A new species of Phacidiopycnis associated with pome fruits is described. The fungus causes fruit rot on apples during storage and is associated with a twig dieback and canker disease of crabapple trees and dead twigs of pear trees. To characterize the biology of the fungus and compare it with Ph. piri, the type species of the genus, effects of nine media and light on mycelial growth and pycnidial production, mycelial growth in response to temperature and mode of conidial germination in response to nutrient were determined. Apple-juice agar, pear-juice agar, prune-juice agar, potato-dextrose agar (PDA) and malt-extract agar, Czapek-Dox agar and oatmeal agar (OMA) favored mycelial growth. Cornmeal agar (CMA) did not favor mycelial growth. Light effect on pycnidial formation was medium dependent. Abundant pycnidia with mature conidia formed in 14 d old PDA and OMA cultures at 20 C, regardless of light, whereas none or very few pycnidia formed on other media in the dark. Fluorescent light stimulated formation of pycnidia except on CMA. The fungus grew at -3-25 C, with optimum growth at 15-20 C. Conidia germinated either by forming germ tubes or less often by budding. Budding of conidia occurred in 1 and 10% pear-juice solutions but not in 100% pear-juice solution. Six isolates of Ph. washingtonensis from different species of pome fruits had identical ITS sequences. The sizes of the ITS region were the same for both Ph. washingtonensis and Ph. piri, and four polymorphic nucleotide sites were found in the ITS region between Ph. washingtonensis and Ph. piri. The similarity in ITS sequences between these two taxa is confirmatory evidence for the erection of the new species of Phacidiopycnis associated with pome fruits we describe here.

Phacidiopycnis washingtonensis—a new species associated with pome fruits from Washington State

A new species of Phacidiopycnis associated with pome fruits is described. The fungus causes fruit rot on apples during storage and is associated with a twig dieback and canker disease of crabapple trees and dead twigs of pear trees. To characterize the biology of the fungus and compare it with Ph. piri, the type species of the genus, effects of nine media and light on mycelial growth and pycnidial production, mycelial growth in response to temperature and mode of conidial germination in response to nutrient were determined. Apple-juice agar, pear-juice agar, prune-juice agar, potato-dextrose agar (PDA) and malt-extract agar, Czapek-Dox agar and oatmeal agar (OMA) favored mycelial growth. Cornmeal agar (CMA) did not favor mycelial growth. Light effect on pycnidial formation was medium dependent. Abundant pycnidia with mature conidia formed in 14 d old PDA and OMA cultures at 20 C, regardless of light, whereas none or very few pycnidia formed on other media in the dark. Fluorescent light stimulated formation of pycnidia except on CMA. The fungus grew at −3–25 C, with optimum growth at 15–20 C. Conidia germinated either by forming germ tubes or less often by budding. Budding of conidia occurred in 1 and 10% pear-juice solutions but not in 100% pear-juice solution. Six isolates of Ph. washingtonensis from different species of pome fruits had identical ITS sequences. The sizes of the ITS region were the same for both Ph. washingtonensis and Ph. piri, and four polymorphic nucleotide sites were found in the ITS region between Ph. washingtonensis and Ph. piri. The similarity in ITS sequences between these two taxa is confirmatory evidence for the erection of the new species of Phacidiopycnis associated with pome fruits we describe here.

The bkdR gene of Streptomyces coelicolor is required for morphogenesis and antibiotic production and encodes a transcriptional regulator of a branched-chain amino acid dehydrogenase complex.

Products from the degradation of the branched-chain amino acids valine, leucine, and isoleucine contribute to the production of a number of important cellular metabolites, including branched-chain fatty acids, ATP and other energy production, cell-cell signaling for morphological development, and the synthesis of precursors for polyketide antibiotics. The first nonreversible reactions in the degradation of all three amino acids are catalyzed by the same branched-chain alpha-keto acid dehydrogenase (BCDH) complex. Actinomycetes are apparently unique among bacteria in that they contain two separate gene clusters, each of which encodes a BCDH enzyme complex. Here, we show that one of these clusters in Streptomyces coelicolor is regulated, at least in part, at the level of transcription by the product of the bkdR gene. The predicted product of this gene is a protein with similarity to a family of proteins that respond to leucine and serve to activate transcription of amino acid utilization operons. Unlike most other members of this class, however, the S. coelicolor bkdR gene product serves to repress transcription, suggesting that the branched-chain amino acids act as inducers rather than coactivators of transcription. BkdR likely responds to the presence of branched-chain amino acids. Its role in transcriptional regulation may be rationalized by the fact that transition from vegetative growth to aerial mycelium production, the first stage of morphological development in these complex bacteria, is coincident with extensive cellular lysis generating abundant amounts of protein that likely serve as the predominant source of carbon and nitrogen for metabolism. We suggest that bkdR plays a key role in the ability of Streptomyces species to sense nutrient availability and redirect metabolism for the utilization of branched-chain amino acids for energy, carbon, and perhaps even morphogen synthesis. A null mutant of bkdR is itself defective in morphogenesis and antibiotic production, suggesting that the role of the bkdR gene product may be more global than specific nutrient utilization.

The Growing Effect of Vineyard and Winery Wastes on the Production of Mycelia and Fruit Bodies of Edible and Medicinal Fungi

It is well known that huge amounts of waste and residue are produced annually during agroindustrial activities, and their utilization could allow self-sustainable processes and products, having a beneficial effect on soil as efficient environmental protection. Many of the lignocellulosic wastes cause serious environmental pollution effects if they are allowed to accumulate in the vineyards, or much worse, to be burned on the soil. At the same time, these wastes could provide an environmentally efficient way to solve the problem by the application of micro-organisms and processes in vine waste treatment and management.The main aim of this work was to find the best way of recycling vine wastes by using them as a growing source for edible and medicinal mushrooms, in order to extend the food chain in vineyard ecosystems. According to this purpose, two fungal species from the Basidiomycetes group—Lentinus edodes (Shiitake) and Pleurotus ostreatus (Oyster Mushroom)—have been used to determine the growing effect of lignocellulosic vineyard wastes used as culture composts as well as winery wastes on the production of mycelia and fruit bodies that could be processed and marketed as useful products, such as food and drugs.The experiments of this research work were achieved by growing all these fungal species in special culture rooms, where all the culture parameters were kept at optimal levels in order to get the highest production of fruit bodies. During the experiments, the effects of culture compost composition (carbon, nitrogen, and mineral sources) as well as other physical and chemical factors (such as temperature, inoculum size, CO2 and O2 concentration, air humidity, watering, light intensity, incubation time) on mycelial net formation and, especially, on fruit body induction were investigated.The registered data revealed that lignocellulosic vine wastes can be used as substrates for mushroom growing only after some mechanical pretreatments to break down the whole lignocellulose structure in order to be more susceptible to fungal enzyme action. All these pretreated lignocellulosic wastes were disinfected by steam sterilization at 120 deg;C for 60 minutes. The final composition of culture composts was improved by adding grain seeds (wheat, rye, rice), CaCO3, and NH4H2PO4, to each kind of culture medium composition, depending on the fungal species used to be grown.All the culture composts for mushroom growing were inoculated using liquid inoculum, aged 5−7 days, and the volume size ranging between 5% and 7% (v/w).The optimal temperatures for incubation and mycelia growth were maintained between 23 °C and 25 °C. The whole period of mushroom growing from inoculation to fruit body formation lasted between 15 and 35 days, depending on each fungal species used in experiments. From all these fungal species tested in our experiments, Pleurotus ostreatus was registered as the fastest mushroom culture (15−20 days), in comparison with the fungal strains of Lentinus edodes (25−30 days).As control samples for each variant of culture composts used for experimental growth of all these fungal species, we used wood chips of the oak that were kept in water 3 days before the experiments and were then steam sterilized for disinfection. Because of their high content of carbohydrates and nitrogen, the variants of culture composts supplemented with wheat grains at a ratio of 1:10 and rice grains at the ratio 1:5 as well as a water content of 60% were optimal for the fruit body production of Pleurotus ostreatus and, respectively, Lentinus edodes. In addition, some strains of this fungal species were grown in our experiments on culture substrates made of winery wastes and rye grains at a ratio of 1:7 and a water content of 50%. A higher ratio of rye grains might lead to an increase of total dry weight of the fruit body, but also could induce the formation of smaller fruit bodies than those of the control samples.The results achieved by using propylene-bag cultures revealed that the composition of culture substrate had significant effects on fruit body production as well as on the characteristic shape of the fruit bodies. The final fruit body production of these fungal species used in experiments was registered between 7 and 10 kg, relative to 100 kg of compost.

The Growing Effect of Vineyard and Winery Wastes on the Production of Mycelia and Fruit Bodies of Edible and Medicinal Fungi

The Growing Effect of Vineyard and Winery Wastes on the Production of Mycelia and Fruit Bodies of Edible and Medicinal Fungi

Submerged Culture Conditions for the Production of Exo- and Endo-Polysaccharides by Ganoderma applanatum (Pers.) Pat.

Ganoderma applanatum is a perennial mushroom (Basidiomycetes) which causes white rot in broadleaved trees. Th e fruit body has been used as a traditional anticancer medicine in China and is reported to have various benefi cial physiological activities such as antitumor, antivirus, and immunostimulating activities. Th ese biological activities are known to be associated with polysaccharides, and protein-bound polysaccharides were isolated from the fruiting bodies and mycelium. Submerged cultures of edible fungi obviously have the potential for higher mycelial production or for inducing mass production of useful substances in compact space in a short time period with easy environmental control. Th e aim of this investigation was to determine the optimal polysaccharide production conditions from G. applanatum in submerged culture. In order to produce the immunostimulating water-soluble polysaccharides from the mycelium, the eff ects of several cultivating factors on polysaccharide production were studied. We were especially interested in the factors aff ecting the re

Growth and biomass of mycorrhizal mycelia in coniferous forests along short natural nutrient gradients

Total fungal biomass, the biomass of ectomycorrhizal and ericoid mycorrhizal (EM + ErM), and arbuscular mycorrhizal (AM) fungi, as well as the production of EM and AM fungi, were estimated in coniferous forest soils along four natural nutrient gradients. Plant community changes, forest productivity, soil pH and N availability increase over relatively short distances (< 100 m) along the gradients. The amounts of the phospholipid fatty acid (PLFA) 18 : 2omega6,9 were used to estimate total fungi (not including AM), and the PLFA 16 : 1omega5 to estimate AM fungi in soil samples. The decrease in the PLFA 18 : 2omega6,9 during incubation of soils was used to estimate EM + ErM biomass. Production of AM and EM mycorrhiza was estimated using ingrowth mesh bags. Total fungal biomass was highest in soils with the lowest nutrient availability and tree productivity. Biomass of ErM + EM was also highest in these soils. We found tendencies that EM mycelial production was lowest in the soils with the highest nutrient availability and tree productivity. Production of AM fungi was highest in nutrient-rich soils with high pH. Our results suggest that mycorrhizal communities change from being ErM-, to EM- and finally to AM-dominated along these gradients. The observed changes in mycorrhizal type in the short nutrient gradients follow similar patterns to those suggested for altitudinal or latitudinal gradients over longer distances.

The effects of arbuscular mycorrhizas on soil aggregation depend on the interaction between plant and fungal species.

• Arbuscular mycorrhizal fungi (AMF) and roots mediate soil stabilization, although the mechanisms and how their interactions affect soil stabilization are not known. We tested the effects of specific plant-fungus combinations on aggregate stabilization, and whether hyphal length and root biomass determine stabilization, predicting that fungi producing more hyphae, and plants with higher root biomasses, would better stabilize soils. • The percentage of water-stable aggregates (%WSA1-2mm ), hyphal lengths, and root biomass were measured from a five AMF×nine plant factorial experiment. Arbuscular mycorrhizal fungi with greater extradical mycelium production were represented by the Gigasporaceae and plants of high root biomass by grasses. Other taxa represented lower hyphal lengths and root biomass. • An interaction between symbionts with respect to %WSA1-2mm was observed. Root biomass and total hyphal lengths were not positively correlated with %WSA. Combinations of grasses with Gigasporaceae fungi had the lowest %WSA. • Mechanisms underlying aggregation were not elucidated by measuring root biomass and total hyphal lengths alone, suggesting other physiological or architectural mechanisms may be responsible.

Produção de micélio de Crinipellis perniciosa em quatro meios de cultura, visando extração de DNA

A produção de massa micelial é o primeiro passo para obter amostras de DNA de qualidade e quantidade suficiente para análises moleculares. Neste trabalho, objetivou-se analisar a quantidade e a qualidade do DNA de Crinipellis perniciosa extraído a partir de massa micelial obtida em quatro meios de cultura. Foi avaliado o peso de micélio liofilizado produzido nos seguintes meios de cultura: 1. extrato de levedura (2,5%); 2. extrato de malte (2,5%); 3. BD (batata 20% e dextrose 2%) e 4. extrato de malte + BD (50% de cada meio). O crescimento micelial foi iniciado a partir de um disco de micélio colocado no centro de placas de Petri de 90 mm contendo o meio testado e mantidas a 25 ºC e fotoperíodo de 12 h, por dez dias. Foi utilizado o DIC com dez repetições. O micélio produzido foi liofilizado e o DNA extraído utilizando-se o método do SDS com a desproteinização feita com ou sem fenol. A pureza do DNA baseada na relação A260/A280 e a integridade em gel de agarose 0,8% foram analisadas. A quantidade de micélio produzida nos meios de cultura 1 e 4 foi maior do que nos meios 2 e 3. O DNA extraído a partir de micélio produzido nos meios 2 e 3 apresentou maior integridade, obtendo-se produtos de amplificação mais nítidos. A desproteinização com fenol possibilitou a extração de DNA mais puro. Porém, DNA de ótima qualidade e em quantidade suficiente pode ser extraído a partir de micélio produzido em meios baratos como o BD, sem a necessidade da desproteinização com fenol.

Production of an anti-complement exo-polymer produced by Auricularia auricula-judae in submerged culture.

Exo-polymer (EP) was produced at 1.2 g l(-1) in submerged culture of Auricular auricula-judae. Crude EP (AJ-0) has 70% anti-complementary activity (inhibition of total complementary hemolysis 50%; ITCH50). The activating pathway of the complement system occurred through both the classical and alternative pathways, though the major pathway was the classical one. Fractionation of AJ-0 using Sepharose CL-6B gel chromatography gave three major fractions (AJ-Fr-I, II and III) of which the first was the most active. The mycelial growth and EP production of A. auricula-judae were optimal at pH 6, 25 degrees C and pH 5, 25 degrees C, respectively.

Optimization of submerged culture requirements for the production of mycelial growth and exopolysaccharide by Cordyceps jiangxiensis JXPJ 0109.

The objective of the present study was to investigate the optimal culture requirements for mycelial growth and exopolysaccharide production by Cordyceps jiangxiensis JXPJ 0109 in submerged culture. The effects of medium ingredients (i.e. carbon and nitrogen sources, and growth factor) and other culture requirements (i.e. initial pH, temperature, etc.) on the production of mycelia and exopolysaccharide were observed using a one-factor-at-a-time method. More suitable culture requirements for mycelial growth and exopolysaccharide production were proved to be maltose, glycerol, tryptone, soya bean steep powder, yeast extract, medium capacity 200 ml in a 500-ml flask, agitation rate 180 rev min(-1), seed age 4-8 days, inoculum size 2.5-7.5% (v/v), etc. The optimal temperatures and initial pHs for mycelial growth and exopolysaccharide production were at 26 degrees C and pH 5 and at 28 degrees C and pH 7, respectively, and corresponding optimal culture age were observed to be 8 and 10 days respectively. According to the primary results of the one-factor-at-a-time experiments, the optimal medium for the mycelial growth and exopolysaccharide production were obtained using an orthogonal layout method to optimize further. Herein the effects of medium ingredients on the mycelial growth of C. jiangxiensis JXPJ 0109 were in the order of yeast extract > tryptone > maltose > CaCl2 > glycerol > MgSO4 > KH2PO4 and the optimal concentration of each composition was 15 g maltose (food-grade), 10 g glycerol, 10 g tryptone, 10 g yeast extract, 1 g KH2PO4, 0.2 g MgSO4, and 0.5 g CaCl2 in 1 l of distilled water, while the order of effects of those components on exopolysaccharide production was yeast extract > maltose > tryptone > glycerol > KH2PO4 > CaCl2 > MgSO4, corresponding to the optimal concentration of medium was as follows: 20 g maltose (food-grade), 8 g glycerol, 5 g tryptone, 10 g yeast extract, 1 g KH2PO4, and 0.5 g CaCl2 in 1 l of distilled water. Under the optimal culture requirements, the maximum exopolysaccharide production reached 3.5 g l(-1) after 10 days of fermentation, while the maximum production of mycelial growth achieved 14.5 g l(-1) after 8 days of fermentation. This is the first report on the submerged culture requirements for mycelial growth and exopolysaccharide in C. jiangxiensis, and this two-step optimization strategy in this study can be widely applied to other microbial fermentation processes.

Mycelial production, spread and root colonisation by the ectomycorrhizal fungi Hebeloma crustuliniforme and Paxillus involutus under elevated atmospheric CO2.

Effects of elevated atmospheric carbon dioxide (CO2) levels on the production and spread of ectomycorrhizal fungal mycelium from colonised Scots pine roots were investigated. Pinus sylvestris (L.) Karst. seedlings inoculated with either Hebeloma crustuliniforme (Bull:Fr.) Quel. or Paxillus involutus (Fr.) Fr. were grown at either ambient (350 ppm) or elevated (700 ppm) levels of CO2. Mycelial production was measured after 6 weeks in pots, and mycelial spread from inoculated seedlings was studied after 4 months growth in perlite in shallow boxes containing uncolonised bait seedlings. Plant and fungal biomass were analysed, as well as carbon and nitrogen content of seedling shoots. Mycelial biomass production by H. crustuliniforme was significantly greater under elevated CO2 (up to a 3-fold increase was observed). Significantly lower concentrations and total amounts of N were found in plants exposed to elevated CO2.

뽕나무버섯(Armillaria mellea) 균사체 생산의 최적화

뽕나무 버섯균은 식용버섯으로써 노인병, 중풍, 현기증, 두통, 신경쇠약, 불면증, 사지마비, 소아마비, 간질 등에 효과가 있는 것으로 알려져 있으므로, 뽕나무 버섯 균사체의 고농도 배양을 위한 최적 조건확립 하고자 하였다. 뽕나무 버섯균사체 생산의 최적배지 선정을 위하여 7종의 배지를 대상으로 수행한 결과 맥아즙배지가 뽕나무 버섯 균사체 생산에 가장 우수하였다. 맥아즙 배지에서 뽕나무 버섯균 균사체 생산을 위한 적정조건은 맥아즙 농도 <TEX>$15\;Brix^{\circ}$</TEX>이었으며 온도, pH, 배양기간의 조건을 반응표면 분석법에 의해서 실행한 결과, <TEX>$25.9^{\circ}C$</TEX>, pH 5.72, 15.22일의 배양에서 3,40 g/50 ml의 최대 예측치를 나타내었다. 이는 실제 실험결과치와도 대체로 일치하는 경향이었다. Armillaria mellea, honey mushroom is well known as a symbiotic fungus with Gastodia elata, The mycelial yields of the fungus were compared when cultured with various broth media. The highest yield of cell mass, 2.31 g dry weight/50mL, was obtained on germinated-malt extract broth (GMEB). The optimal broth concentration which was measured hand refractometer for mycelium production was <TEX>$15\;Brix^{\circ}$</TEX>. The optimal conditions estimated with response surface methodology under temperature, pH and incubation period were <TEX>$25.9^{\circ}C$</TEX>, pH 5.72, 15.22 days, respectively, on GMEB having <TEX>$15\;Brix^{\circ}$</TEX> concentration for mycelial production of A. mellea.

Submerged production of edible mushroom Agaricus bisporus mycelium in ram horn hydrolysate

The production of the fungus Agaricus bisporus ATTC 10893 was studied in submerged fermentation with horn hydrolysate as the main substrate source. First, horns were ground and 35 g of the horn powder were chemically hydrolyzed (acid hydrolysis). As a result of this process, 30 of the 35 g horn powder (85.7%) could be hydrolyzed. Hydrolyzed material was completed to 400 ml with deionized water and this resulting solution was termed as crude horn hydrolysate (CHH). The contents of protein, nitrogen, ash, some minerals, total sugars, total lipids and amino acids of CHH were determined. It was found that it has both organic and inorganic materials sufficient for use as a substrate in the production of Agaricus bisporus mycelium. The CHH was enriched by addition of glucose and KH 2PO 4. The effects of different concentrations (1–7% v/v) of CHH on the growth of A. bisporus were investigated and 2% of the CHH (Horn Broth=HB) was found to be optimal. The HB contains 20 g of glucose, 20 ml of CHH and 1 g of KH 2PO 4 per liter of laboratory quality water. The optimum growth conditions for the A. bisporus in HB were as follows: Initial pH: 6; temperature: 26 °C; fermentation time: 8 days and agitation: 150 rpm. Under these optimal conditions, initial carbohydrate content of HB was reduced from 2.02 to 0.2% and the biomass yield was 10.8 g l −1. The biomass contained about 47.1% of protein, 5.8% of fat and 7.9% of ash (on a dry-weight basis). Amino acid content of biomass was compared with both the FAO standard and fruiting body. The biomass contained all of the essential amino acids but the amounts of the essential amino acids were somewhat lower than that of the FAO standard, while it was comparable with that of fruiting body. The results with HB were also compared with previously reported data on edible mushroom mycelium grown on some substrates. It was found that HB could be used as a substrate for the production of Agaricus bisporus mycelium.

Fruit-body production of an ectomycorrhizal fungus in genus Boletus in pure culture

Mycelial growth and fruit-body production of an ectomycorrhizal Boletus sp. were examined in pure culture. Mycelia of the strain Bo1 grew well on a medium consisting of sawdust and barley grains. Mature fruit bodies bearing basidiospores were produced after incubation at 22°C for 90 days in the dark, followed by incubation at 26°C for 30–46 days under conditions of high humidity and illumination. The addition of porous stone as a casing on the medium increased fruit-body yield. Deposited spores germinated well on an agar medium and formed mycelial colonies, thus completing the life cycle of Bo1 without a host plant and under axenic conditions. The ability of Bo1 to form ectomycorrhizas was confirmed by axenic resynthesis of mycorrhizas on Quercus serrata. Cultured fruit bodies of Bo1 resembled Gyroporus castaneus and Boletus subcinnamomeus, but its taxonomic position was not elucidated at the species level.

Use of stillage grain from a rice-spirit distillery in the solid state fermentation of Ganoderma lucidum

The feasibility of reusing stillage grain as a substrate for the cultivation of Ganoderma lucidum in solid-state fermentation is evaluated. Cultures were carried out in test tubes or propylene bags and G. lucidum was cultivated on stillage grain supplemented with wheat bran, ground rice or sawdust at different ratios. The effect of mixed ratios on the production of mycelia and fruit body was investigated. The compositions of fruiting body were also analyzed and compared. The additions of NH 4H 2PO 4 and CaCO 3 favored mycelial growth in the test-tube cultures. Due to its high content of carbohydrate and nitrogen, stillage grain was considered as a nutritive substrate for mycelial growth. However, too much addition of stillage grain might result in the diminution of compost voidage and had an adverse effect on mycelial growth in propylene-bag cultures. The results obtained from propylene-bag cultures reveal that the substrate type altered not only the shape of fruiting bodies but also their constituents. Sawdust supplemented with stillage grain at a ratio 4:1 at a water content of 60% was optimal for the production of fruiting body. High ratios of stillage grain might lead to an increase of total dry weight of fruit body, but also caused the formation of antler branches and smaller fruiting body, which contained higher amounts of reducing sugars and lower amounts of polysaccharide than those of the control.

Production of external mycelium by ectomycorrhizal fungi in a norway spruce forest was reduced in response to nitrogen fertilization

Summary A field study was carried out to evaluate the influence of N fertilization on the growth of the external mycelium of ectomycorrhizal (EM) fungi in a Norway spruce forest in SW Sweden. Nylon mesh bags filled with sand were buried in the soil for 6–18 months and the ingrowth of mycelium was used as an estimate of EM mycelial growth. Root‐isolated, trenched plots were used to estimate background growth of saprotrophic fungi. Mycelial growth of EM fungi in N‐treated plots was reduced to c. 50% of that in nonfertilized plots. Local addition of apatite stimulated the EM mycelial growth in N‐treated plots. The negative influence of N on the growth of external EM mycelium observed earlier in laboratory studies was confirmed in the present field study. The growth of EM mycelia was not directly related to N concentration in the soil but rather to the N status of the trees, although other factors induced by the N treatment may also have influenced EM mycelial growth.

Early events in the Fusarium verticillioides-maize interaction characterized by using a green fluorescent protein-expressing transgenic isolate.

The infection of maize by Fusarium verticillioides can result in highly variable disease symptoms ranging from asymptomatic plants to severe rotting and wilting. We produced F. verticillioides green fluorescent protein-expressing transgenic isolates and used them to characterize early events in the F. verticillioides-maize interaction that may affect later symptom appearance. Plants grown in F. verticillioides-infested soil were smaller and chlorotic. The fungus colonized all of the underground parts of a plant but was found primarily in lateral roots and mesocotyl tissue. In some mesocotyl cells, conidia were produced within 14 to 21 days after infection. Intercellular mycelium was detected, but additional cells were not infected until 21 days after planting. At 25 to 30 days after planting, the mesocotyl and main roots were heavily infected, and rotting developed in these tissues. Other tissues, including the adventitious roots and the stem, appeared to be healthy and contained only a small number of hyphae. These results imply that asymptomatic systemic infection is characterized by a mode of fungal development that includes infection of certain tissues, intercellular growth of a limited number of fungal hyphae, and reproduction of the fungus in a few cells without invasion of other cells. Development of visibly rotted tissue is associated with massive production of fungal mycelium and much less organized growth.

Production of Ganoderma lucidum mycelium using cheese whey as an alternative substrate: response surface analysis and biokinetics

A novel approach to utilize cheese whey, cultivating mycelium of an edible mushroom Ganoderma lucidum using cheese whey as a substrate, was introduced. Response surface analysis (RSA) with central composite in cube design was successfully applied to determine the optimal conditions where the maximum mycelial production occurred, which was at pH 4.2 and 28.3 °C. The high extract ratio as well as high content of polysaccharide (i.e., 1.2 g/l) indicated that the whey could be an alternative substrate for the mycelial production. Soluble chemical oxygen demand (SCOD) removal ranged from 80.7 to 93.1% within the design boundary. Therefore, cultivation of G. lucidum mycelia using cheese whey can provide a unique solution to solve the dual problems of an alternative utilization of the whey and waste management. The substrate inhibition biokinetics at the optimal conditions were also evaluated using a method of fourth-order Runge–Kutta approximation. The nonlinear least-squares (NLLS) method with 95% confidence interval was used. The maximum microbial growth rate, μ max, and half saturation coefficient, K s, for lactose and SCOD were determined to be 2.28±0.11 and 2.27±0.15 per day, and 95.5±9.1 and 128.0±12.1 g/l, respectively. The microbial yield coefficient, Y, and microbial decay rate coefficient, k d, for lactose and SCOD were determined to be 0.49±0.03 and 0.39±0.03 g VSS/g of each substrate, and 0.05±0.01 and 0.05±0.01 per day, respectively. Inhibition coefficients were 37.6±2.9 and 49.3±3.3 g/l for lactose and SCOD, respectively.