Effect of spent mushroom compost tea on mycelial growth and yield of button mushroom (Agaricus bisporus)

Preliminary studies suggested that the use of compost tea made from spent mushroom substrate (SMS) may be regarded as a potential method for biologically controlling dry bubble disease in button mushroom. The aim of this study was to assess the effect of SMS compost tea on the host, the button mushroom, to ascertain whether the addition of these water extracts has a toxic effect on Agaricus bisporus mycelium growth and on mushroom yield. In vitro experiments showed that the addition of SMS compost tea to the culture medium inoculated with a mushroom spawn grain did not have an inhibitory effect on A. bisporus mycelial growth. The effect of compost teas on the quantitative production parameters of A. bisporus (yield, unitary weight, biological efficiency and earliness) was tested in a cropping trial, applying the compost teas to the casing in three different drench applications. Quantitative production parameters were not significantly affected by the compost tea treatments although there was a slight delay of 0.8-1.4 days in the harvest time of the first flush. These results suggest that compost teas have no fungitoxic effect on A. bisporus so that they can be considered a suitable biocontrol substance for the control of dry bubble disease.     

Effects of spawn,supplement and phase II compost additions and time of re-casing second break compost on mushroom (Agaricus bisporus) yield and biological efficiency

Three cropping experiments (0710, 0803 and 0805) were conducted to determine the effect of adding spawn, various levels of delayed release nutrient, and phase II compost to 2nd break mushroom compost (2BkC) on mushroom yield and biological efficiency (BE). We also investigated the effect of delaying time of re-casing non-supplemented and supplemented 2BkC on mushroom yields and BEs. The addition of 14.6% spawn to nutrient-supplemented 2BkC (w.w./d.w) increased yield by 11.1% over the control (no spawn) but did not affect BE. The addition of delayed release supplements to 2BkC increased maximum yields by 29–54%, depending on the treatment. Substitution of 15% phase II compost in 2BkC (15/85) did not significantly affect mushroom yields. However, use of 15% phase II compost in 2BkC increased the response of the mixture to delayed release supplement. Yield response to increasing levels of supplement was greater in the 15/85 mixture compared to 100% 2BkC. Yields also increased as time of re-casing was delayed up to 10 days. Mushroom yields increased approximately 2.1% for each day re-casing was delayed. Overall yields were generally higher from commercial 2BkC compared to 2BkC originating from the Penn State Mushroom Research Center (MRC) probably due to nitrogen (N) content of the 2BkC. Nitrogen content in commercial 2BkC (Crop 0805) was 3% while N content in 2BkC from Crops 0710 and 0803 was 2.2% and 2.1%, respectively. By optimizing supplement levels and adding 15% phase II compost to commercial 2BkC, or by delaying casing by 5–10 days, it was possible to obtain BEs that were equivalent to supplemented phase II compost.     

Improvement of yield of Pleurotus eryngii var. eryngii by substrate supplementation and use of a casing overlay

Improved yield and biological efficiency (BE) of Pleurotus eryngii var. eryngii were achieved by supplementation of substrate with a commercial delayed-release nutrient and use of a casing overlay. Yield increases of 14% were achieved from cased substrates that were supplemented at time of casing with delayed-release nutrient (Remo’s). Use of a casing layer enhanced yield by 141% over non-cased substrates. When casing and substrate supplementation were combined, yield increased 179% over non-cased/non-supplemented substrates. Mushrooms harvested from cased substrates were darker in color and solids contents were lower compared to non-cased substrates. An additional break of mushrooms was harvested from non-cased “spent” substrate by fragmenting and re-supplementing the substrate prior to the application of a casing overlay. Three production methods were compared for their effect on mushroom yield: “standard”, “casing” and “casing after first break”. Casing of the substrate before first break (“casing” production method) resulted in the highest yield and biological efficiency.     

Production of Agaricus bisporus on substrates pre-colonized by Scytalidium thermophilum and supplemented at casing with protein-rich supplements

The objective of this study was to evaluate performance of Agaricus bisporus (Ab) on substrates pre-colonized by Scytalidiumthermophilum (St), a thermophilic fungus known to enhance yields of Ab and increase selectivity of the substrate. The radial extension rate (RER) of the mycelium of three strains of St and their influence on the growth of a brown strain of Ab were evaluated. We also determined the time required for colonization of pangola grass by St in a compost pile and the influence of three protein-rich supplements on yield of Ab on pangola grass (Digitaria decumbens) colonized by St. RER of St ranged from 10.1 mm/d on grass to 18.9 mm/d on potato dextrose yeast extract agar, with significant differences among substrates and among strains. Ab grew faster on substrate colonized for 1, 2, or 3 days by St (RER of 3.31, 3.29, 3.23 mm/d, respectively) compared to non-colonized substrate (1.85 mm/d). Ab was cultivated on substrate samples selected daily from the St-inoculated pile, with biological efficiencies (BE) ranging from 4% (day 0) to 73.9% (day 2). Protein-rich supplements (soybean, black beans and cowpeas) added at casing significantly stimulated mushroom yield on St-colonized substrate compared to the non-supplemented control. BE varied from 26.1% on substrate non-supplemented to 73.1% on compost supplemented with ground soybean. There were no significant differences in mushroom yield observed among supplements evaluated.     

The influence of spawn type and strain on yield, size and mushroom solids content of Agaricus bisporus produced on non-composted and spent mushroom compost

Two crops of Agaricus bisporus (J. Lange) Imbach were grown on mixtures of non-composted substrate (NCS)/spent mushroom compost (SMC) or pasteurized Phase II compost (control). NCS consisted of oak sawdust (28% oven dry wt), millet (29%), rye (8%), peat (8%), ground alfalfa (4%), ground soybean (4%), wheat bran (9%), and CaCO3 (10%). Substrates included 25/75 NCS/SMC, 50/50 NCS/SMC, and 75/25 NCS/SMC, NCS and Phase II compost. Spawn types and strains were evaluated for their effects on yield, biological efficiency (BE), size and mushroom solids content. Spawn types included millet, casing inoculum (CI), 50/50 CI/millet, or NCS while mushroom strains were of the brown or hybrid off-white variety (U1 type). Mushroom yields and BEs on substrate mixtures of NCS and SMC were comparable to non-supplemented Phase II compost. The highest yield (12.8 kg/m2) and BE (70.9%) were produced on a substrate mixture of 50/50 NCS/SMC and spawn type NCS. Mushroom solids content (7.1%) was highest from the brown strain produced on a 50/50 mixture of NCS/SMC.     

Ground wheat straw as a substitute for portions of oak wood chips used in shiitake (Lentinula edodes) substrate formulae

Oak woodchips, used for production of shiitake Lentinula edodes (Berk) Pegler, are increasingly difficult to obtain due to dwindling supplies. We investigated the effect of adding ground wheat straw as a substitute for portions of oak woodchips in substrate formulae on mushroom yield and size. We also determined the effect of mushroom cropping on relative feed value (RFV) by chemical analysis of the substrate at spawning (AS) and after cropping (AC). Three formulae containing 0%, 8% and 16% ground wheat straw and 52%, 44% and 36% oak sawdust, respectively, were bulk pasteurized (111 degrees C for 20 min) in an autoclaving mixer, subjected to spawn run (21 d), browning (28 d) and a production cycle of three breaks (38 d). Mean (4 crops) mushroom yields were 11% higher when 8% wheat straw was used in the medium and 19% higher when 16% wheat straw was substituted for portions of oak sawdust. There were no significant differences in mushroom sizes between any of the treatments. Relative feed values of shiitake substrates AC increased more dramatically as more wheat straw was added to the formulae. Using mature alfalfa (full bloom) as a base value of 100%, RFVs for substrate AS were 98%, 92%, and 92% for 0%, 8% and 16% straw, respectively; RFVs AC were 118%, 120% and 133%, respectively. Substrate AC containing 16% straw had a RFV comparable to corn silage (well-eared). Fat contents of the substrates decreased by 50-62% AC, whereas potassium contents decreased by 40%. Use of ground wheat straw in synthetic medium would not only increase mushroom yield by up to 19%, but may help alleviate periodic shortages of oak sawdust. In addition, growers would avoid the added expense of aging the wheat straw (for 8-12 week) as is typically done for oak sawdust in the industry. This is the first report of RFVs for spent shiitake substrate (SSS) predicting its excellent potential for use as animal feed.     

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.     

Performance of olive mill solid waste as a constituent of the substrate in commercial cultivation of Agaricus bisporus

The feasibility of using olive mill waste (OMW) as an ingredient in the substrate used for cultivation of Agaricus bisporus (Lange) Sing. was studied in a large-scale cultivation trial, concerning 2500 m² of mushroom growing area, at a specialized mushroom farm. Standard commercial cultivation technique involving compost preparation, spawning, casing and harvesting was used. The performance indicators such as mushroom yield, biological efficiency, market quality as well as horticultural value of the spent compost showed that the compost prepared with OMW was superior to the control compost in all the categories. The OMW-amended substrate supported higher populations of beneficial microorganisms especially, actinomycetes which enabled the breakdown of the compost ingredients. It is suggested that OMW is a suitable ingredient for the preparation of mushroom substrate. We have demonstrated that conversion of OMW (a liability) into value-added mushroom substrate (an asset) is an effective waste management tool in oleaculture.     

Recycling spent larval food of Corcyra cephalonica Stainton for preparing spawn and sporophore of Pleurotus sajor-caju (Fr.) Singer

Large scale production of the rice moth, Corcyra cephalonica Stainton in pearl millet grain medium leads to a huge accumulation of spent larval medium in commercial insectaries. We attempted bioconversion of spent larval medium of C. cephalonica (CLM) for cultivation of the mushroom Pleurotus sajor-caju (Fr.) Singer, to increase the usage of these residues. Maximum efficiency limits of CLM for spawn run, sporophore cropping and as bed substrate were assessed with varying combinations of sorghum and rice straw. Sorghum grains and rice straw were the best substrates for spawn run and sporophore yield respectively. Having been crushed, macerated, heated and sterilized, CLM could also become a suitable substrate along with sorghum or rice straw. Sorghum and CLM at 16.7% + 83.3% and 33.3% + 66.7% combinations were very effective in supporting mycelial growth and quicker colonization of fungus, and mother spawn yield. The spawn that was obtained from these combinations yielded higher sporophore as well. The fungus did not rapidly colonize on other combinations (50% + 50%, 66.7% + 33.3% and 83.3% + 16.7%), and was completely unable to grow on CLM 100%. Combination of rice straw and CLM at 75% + 25% and 50% + 50% as bed substrate contributed higher sporophore yield. Analysis of the substrates indicated variation in their chemical and mineral composition, but they were good sources of N, P and Ca. The prospects of exploring CLM for the mushroom cultivation are discussed.     

Effects of bendiocarb and diflubenzuron on mushroom cropping

When mixed into the casing or compost layers of a mushroom bed in the absence of pests, bendiocarb decreased yield and number of mushrooms according to concentration. The most severe effects were on mushroom number at the two highest rates used (100 and 1000 μg/g), and there were large increases in mushroom size. Effects of bendiocarb incorporation in the compost diminished with time, and there was partial compensation in yield and numbers at the fourth flush. The action of bendiocarb persisted when it was mixed into the casing. Diflubenzuron showed some opposite effects at lower concentrations. When either mixed into, or drenched onto the casing at the commercial rate (30 μg/g), yield and size were both increased and the timing of the flushes was unaffected. At the two higher concentrations (180 and 1080 μg/g), reductions in yield and number and an increase in mushroom size were shown. However, these effects became more severe with time, especially those on mushroom number, possibly due to the accumulation of a toxic breakdown product.     

Factors affecting entomophilic activity of Neoaplectana feltiae in mushroom compost

The host-searching ability of Neoaplectana feltiae Filipjev (= S. bibionis Bovien) (Nematoda: Steinernematidae) in response to larvae of a mushroom fly, Lycoriella solani Winn. was examined in a mushroom substrate. Individuals of L. solani were less attractive for the parasite than larvae of Galleria mellonella L. The nematode juveniles penetrated a 22 cm layer of casing mixture within 2–4 days. In the casing alone nematode effectiveness was better than in mushroom compost or in compost and casing together. In the casing mixture parasite dosages of 20 and 100 juveniles per cm² led to 22% and 45% parasitization of L. solani respectively, while all G. mellonella larvae were parasitized at both dosages. The prevalence of nematode infection depended on the content of water in the mushroom substrate. The highest N. feltiae infectivity was observed, when the ratio of the dry casing weight to the weight of water content was 1: 2.5. The practical aspects of the observed phenomena, essential for the use of N. feltiae in the protection of commercial mushroom cultivation are discussed.     

Pseudomonas tolaasi in Mushroom Crops: A Note on Primary and Secondary Sources of the Bacterium on a Commercial Farm in England

Primary sources of Pseudomonas tolaasi Paine on a mushroom farm were the peat and limestone used in the casing process. The pathogen could not be detected in the farm soil, water supply, the mushroom spawn used, or in compost after spawning, but was isolated from the casing (peat/limestone mixture) layer of symptom-free mushroom beds and both the casing layer and compost of beds bearing diseased mushrooms. Secondary sources were numerous once the pathogen was present in mushroom beds. These included symptomless and diseased mushrooms, the fingers and shoes of people handling the crop, their baskets, knives and ladders. Ps. tolaasi could be isolated from dust in the air in infected houses and also from floors. Spores of infected mushrooms may transport the bacterium, as did sciarid flies and mites which are common pests of mushroom crops.     

Holistic assessment of the microbiome dynamics in the substrates used for commercial champignon (Agaricus bisporus) cultivation

Microorganisms strongly influence and are required to generate the selective substrate that provides nutrients and support for fungal growth, and ultimately to induce mushroom fructification under controlled environmental conditions. In this work, the fungal and bacterial microbiota living in the different substrates employed in a commercial crop (compost phase I, II and III, flush 1 and 2, and casing material on day 1, 6 and 8 after compost casing and during flush 1 and 2) have been characterized along the different stages of cultivation by metataxonomic analysis (16S rRNA and ITS2), analysis of phospholipid fatty acid content (PLFAs) and RT-qPCR. Additionally, laccase activity and the content of lignin and complex carbohydrates in compost and casing have been quantified. The bacterial diversity in compost and casing increased throughout the crop cycle boosted by the connection of both substrates. As reflected by the PLFAs, the total living bacterial biomass appears to be negatively correlated with the mycelium of the crop. Agaricus bisporus was the dominant fungal species in colonized substrates, displacing the pre-eminent Ascomycota, accompanied by a sustained increase in laccase activity, which is considered to be a major product of protein synthesis during the mycelial growth of champignon. From phase II onwards, the metabolic machinery of the fungal crop degrades lignin and carbohydrates in compost, while these components are hardly degraded in casing, which reflects the minor role of the casing for nourishing the crop. The techniques employed in this study provide a holistic and detailed characterization of the changing microbial composition in commercial champignon substrates. The knowledge generated will contribute to improve compost formulations (selection of base materials) and accelerate compost production, for instance, through biotechnological interventions in the form of tailored biostimulants and to design environmentally sustainable bio-based casing materials.     

Kinetic mechanism and catalysis of Trypanosoma cruzi dihydroorotate dehydrogenase enzyme evaluated by isothermal titration calorimetry

Trypanosoma cruzi dihydroorotate dehydrogenase (TcDHODH) catalyzes the oxidation of l-dihydroorotate to orotate with concomitant reduction of fumarate to succinate in the de novo pyrimidine biosynthetic pathway. Based on the important need to characterize catalytic mechanism of TcDHODH, we have tailored a protocol to measure TcDHODH kinetic parameters based on isothermal titration calorimetry. Enzymatic assays lead to Michaelis-Menten curves that enable the Michaelis constant (K_M) and maximum velocity (V_max) for both of the TcDHODH substrates: dihydroorotate (K_M = 8.6 ± 2.6 μM and V_max = 4.1 ± 0.7 μM s^-1) and fumarate (K_M = 120 ± 9 μM and V_max = 6.71 ± 0.15 μM s^-1). TcDHODH activity was investigated using dimethyl sulfoxide (10%, v/v) and Triton X-100 (0.5%, v/v), which seem to facilitate the substrate binding process with a small decrease in K_M. Arrhenius plot analysis allowed the determination of thermodynamic parameters of activation for substrates and gave some insights into the enzyme mechanism. Activation entropy was the main contributor to the Gibbs free energy in the formation of the transition state. A factor that might contribute to the unfavorable entropy is the hindered access of substrates to the TcDHODH active site where a loop at its entrance regulates the open-close channel for substrate access.     

Comparative effects of three insect growth regulator insecticides and a dipteran-active strain of Bacillus thuringiensis on cropping of the cultivated mushroom Agaricus bisporus

Three insect growth regulator insecticides and an entomopathogenic strain of Bacillus thuringiensis (GC327), products effective against the mushroom sciarid, Lycoriella auripila, were compared for their effect on mushroom cropping. Cyromazine and diflubenzuron were applied as a surface drench to mushroom compost before or after pasteurisation (at filling or spawning, respectively); admixed into casing material (at casing); or at a combination of these times. Hexaflumuron and GC327 were applied only at filling and casing, respectively. The presence of the target pest, L. auripila, had no effect on treatment trends, although it was accounted for in the analysis by use of a yield model. The trial was notable for the disparate effects that cyromazine and diflubenzuron casing treatments had on mushroom cropping. Cyromazine treatments that included application at casing resulted in increases in yield, compared to the untreated control whereas, with diflubenzuron, the opposite was true, with treatment at casing alone causing the greatest reduction overall (10%). GC327 applied at casing was also conspicuous for giving a 13% increase in yield. Treating the crop at casing with either cyromazine or GC327, therefore, resulted in a 15% or 24% increase in yield, respectively, compared to a similar treatment with diflubenzuron. Hexaflumuron applied at filling caused increases in yield compared to application of cyromazine at filling and cyromazine or diflubenzuron at spawning. There were also effects on crop timing. The addition of a cyromazine casing treatment normally caused the distinct flushes of mushrooms to be produced significantly earlier than the untreated control (up to 2.5 days), as did GC327. With diflubenzuron, the earlier flushes were only produced by those treatments that did not include a casing application. The combinations that included a casing treatment with diflubenzuron initially produced mushroom flushes earlier than the untreated control. They became either synchronous with the control or they were delayed. From the crop tolerance perspective, therefore, cyromazine and GC327 would be the sciarid control products of choice for a commercial mushroom grower.     

Biological control of sciarid and phorid pests of mushroom with predatory mites from the genus Hypoaspis(Acari: Hypoaspidae) and the entomopathogenic nematode Steinernema feltiae

In small-scale experiments, the predatory mites, Hypoaspis aculeifer (Canestrini) and H. miles Berlese, applied at 700 mites m(-2), and the entomopathogenic nematode, Steinernema feltiae (Filipjev) applied at 3 x 10(-6) nematodes m(-2) controlled sciarids and phorids in mushroom compost and casing substrates. For both mite species, earliest application to the growing substrate following sciarid infestation reduced sciarid emergence. In contrast, later application of each biological control agent provided more effective control of phorid emergence. The behaviour of adult mites suggested that H. aculeifer were more positively geotactic than H. miles although both species could penetrate compost and casing substrates to a depth of 2-12 cm. A majority of S. feltiae nematodes resided at a depth of 2-4 cm in both substrate types. Independent application of H. aculeifer provided more comprehensive control of sciarids and phorids than the other biological agents studied, owing to its better dispersal within compost and casing, and ability to attack larvae of differing ages.     

Validation of thermal composting process using olive mill solid waste for industrial scale cultivation of Agaricus bisporus

The production of a substrate containing destoned olive mill solid waste for the cultivation of Agaricus bisporus (Lange) Imbach on an industrial scale was studied. A standard mushroom compost (C) mainly made from straw and poultry manure was compared with the experimental compost (EC) containing the same ingredients as (C) but with added olive mill solid waste (10.6% w/w). Microbial indicators such as counts of heterotrophic microbes and actinomycetes were higher in EC than in C. In addition, compost selectivity as indicated by higher mushroom yield and biological efficiency of EC was higher than that of C. Market quality of the mushrooms produced in both C and EC were comparable. These findings support our work that olive mill solid waste can be used safely in thermal composting process to produce a selective substrate for industrial-scale cultivation of A. bisporus. This study also demonstrates an environmentally sustainable system to manage solid waste from olive oil extraction processes thus overcoming environmental pollution brought about by irrational disposal of the waste on farm lands.     

Scytalidium thermophilum-colonized grain, corncobs and chopped wheat straw substrates for the production of Agaricus bisporus

We examined the possibility of cultivating Agaricus bisporus (Ab) on various grains and agricultural by-products, with the objective of improving yield capacity of substrate pre-colonized by Scytalidium thermophilum (St). Radial growth rate (RGR) of St at 45 degrees C ranged from no growth on sterile wheat grain to 14.9 mm/d on whole oats. The linear extension rate (LER) of Ab, grown on St-colonized substrate (4 days at 45 degrees C), ranged from a low of 2.7 mm/d on 100% corncobs to 4.7 mm/d on a 50/50 mixture of ground corncobs/millet grain. Several other substrates containing wheat straw+ground corncobs+boiled millet and pre-colonized by St (4 days at 42+/-3 degrees C), were evaluated for production of Ab. The biological efficiency (BE) of production increased linearly with the addition of millet to the formula. However, substrates with millet levels 84% often were contaminated before mushroom harvest. Maximum BE (99%) and yield (21.6 kg/m(2)) were obtained on St-colonized wheat straw+2% hydrated lime supplemented with 9% commercial supplement added both at spawning and at casing.     

Abundance and distribution of <Emphasis Type="Italic">Microdispus lambi</Emphasis> (Acari: Microdispidae) in Spanish mushroom crops

The myceliophagous mite Microdispus lambi has become a veritable plague since 1996, when it was first observed in Spanish mushroom crops, and is now causing substantial economic losses, particulary in spring and summer. This study looks at seasonal variation of the pest, its distribution on commercial farms and the population development during the crop cycle of the common white mushroom, Agaricus bisporus. Over a period of 18 months, 24 consecutive mushroom crop cycles were monitored and a total of 24 spawn and 960 substrate samples were analysed. We found that it is usually the substrates in the growing rooms that are infested, most commonly the compost. In many cases, the pest can be detected when the first ‘flush’—i.e., mushroom growth surge, with weekly periodicity—is harvested, although damage does not become evident until the third flush. Mites were detected at the back of the mushroom growing room and, to a lesser extent, near the access door.     

Production of (R)-3-hydroxybutyric acid by fermentation and bioconversion processes with Azohydromonas lata

Feasibility of producing (R)-3-hydroxybutyric acid ((R)-3-HB) using wild type Azohydromonas lata and its mutants (derived by UV mutation) was investigated. A. lata mutant (M5) produced 780 mg/l in the culture broth when sucrose was used as the carbon source. M5 was further studied in terms of its specificity with various bioconversion substrates for production of (R)-3-HB. (R)-3-HB concentration produced in the culture broth by M5 mutant was 2.7-fold higher than that of the wild type strain when sucrose (3% w/v) and (R,S)-1,3-butanediol (3% v/v) were used as carbon source and bioconversion substrate, respectively. Bioconversion of resting cells (M5) with glucose (1% v/w), ethylacetoacetate (2% v/v), and (R,S)-1,3-butanediol (3% v/v), resulted in (R)-3-HB concentrations of 6.5 g/l, 7.3 g/l and 8.7 g/l, respectively.