Non-composted Substrates Research Articles

Organic residue valorization for Ethiopian agriculture through vermicomposting with native (Eudrilus eugeniae) and exotic (Eisenia fetida and Eisenia andrei) earthworms

Vermicomposting has recently been shown to be an efficient recycling technology that would improve the quality of the final product by stimulating the microbial community. However, the efficacy of vermicomposting process, as well as the microbial biomass and community structure during this bioconversion process, depend on earthworm species and type of substrate ingested. Therefore, this study investigated the potential of native (Eudrilus eugeniae) and exotic (Eisenia fetida and Eisenia andrei) earthworms in Ethiopia on nutrient transformation and microbial dynamics and enzymatic activity during vermicomposting of substrates from mixed agricultural wastes. Earthworm inoculation transformed the wastes into a nutrient-rich humified vermicompost with a significant reduction in pH, TOC and C:N ratios (twofold reduction compared to non-composted substrates). An increase in worm growth and cocoon production were shown in substrates of cow manure mixed with soybean and banana residues (CM + SB) after gut transit through Eudrilus eugeniae and Eisenia fetida. Cow manure mixed with maize and soybean residues (CM + MS) were found suitable for Eisenia andrei. The same substrate and earthworm species resulted in the highest nutrient concentrations (N, P, K, and S) and higher C loss (up to 77% of the initial C) with lower N loss (<9%) compared to non-composted substrates. A considerable increase in microbial biomass, β-glucosidase and dehydrogenase activity (two times more than control) was obtained in substrates of CM + SB using Eudrilus eugeniae. The PLFA analysis indicated that earthworms increased Gram-positive and Gram-negative bacteria, actinomycetes, AMF, fungi18:1, and protozoan population, while they reduced fungal community (fungi18:2 and fungi18:3) compared to uninoculated control. In conclusion, vermicomposting earthworms could potentially valorize substrates from agricultural wastes into nutrient-rich and microbially improved vermicomposts.

Agaricus blazei production on non-composted substrates based on sunflower seed hulls and spent oyster mushroom substrate.

Agaricus blazei Murrill is usually cultivated using the same biphasic composting method employed for A. bisporus. Because cultivation of A. blazei on traditional A. bisporus composts poses some disadvantages, non-composted substrates were studied for A. blazei cultivation. Mycelial growth rate and productive performance of A. blazei were evaluated on substrates containing sunflower seed hulls, Pleurotus spp. spent mushroom substrate, or their combination, in the absence or in the presence of different supplements (vermicompost, peat or brewery residues). Substrates were prepared by initially soaking them and then they were sterilized (1atm for 120min). In addition, each substrate's degradation was measured after cultivation by obtaining the lignin, cellulose, hemicellulose, organic matter, total fiber, ash, carbon and nitrogen contents before spawn-run and at the end of two flushes of A. blazei. The cultivation of A. blazei on non-composted substrates is possible and with a low rate of contamination when using the spent mushroom substrate as the main component or combined 50:50 with sunflower seed hulls. In addition, the best yields were obtained on those substrates containing spent Pleurotus mushroom substrate with supplements and those mixtures with sunflower seed hulls and vermicompost. These yields were similar to those reported on composted substrates. Substrate changes in composition measured at the end of two flushes indicate that the lignin-hemicellulose fraction was preferentially used and that the substrates exhibiting the best yield showed greater biodegradation of lignin-hemicellulose fraction than the others did.

Enhanced Production of Agaricus bisporus Using Non-Composted Substrate in the Presence of Delayed-Release Supplements and Control Agents for Water Release

Non-composted substrates composed of commercial grain spawn and delayed-release nutrient supplements were tested for mushroom production as alternatives to the environmentally problematic composting process associated with conventional commercial mushroom (Agaricus bisporus) cultivation. The effect of casing type, thiophanate-methyl (fungicide) use, delayed-release supplement type (S41 and S44) and level, and perlite addition were tested on mushroom production. Use of a non-sterile casing overlain on grain spawn/supplement substrate produced mushrooms comparable to a steam-treated casing with 25% activated carbon, yielding 6.4 and 7.6 kg m-2, respectively. Thiophanate-methyl severely reduced mushroom yield when used. Average mushroom yield from treatments with S41 supplement was greater than that of S44, and when commercial grain spawn substrate was underlain with a layer of perlite (2000 mL over 0.048 m2) to absorb and release excess water, mushroom yield increased two-fold, producing 13 kg m-2, compared to 7.6 kg m-2 for treatments without perlite.

Effect of Delayed-Release Supplements in Grain-Based Substrate on Yield of the Mushroom Agaricus bisporus

Non-composted grain-based substrates mixed with delayed-release supplements were used as a mushroom substrate to test suitability for mushroom production as a replacement for the environmentally problematic composted substrate. Five delayed-release supplements (S41, S44, Promycel Target, T6, and T7) were added at seven levels (0%, 5%, 10%, 15%, 20%, 25%, and 30%) to a non-composted substrate composed of commercial millet grain spawn. Overall, mushroom yield, substrate bioefficiency (fresh weight of mushrooms / dry weight of substrate), and mean mushroom weight increased with the addition of the supplements when compared to the 0% supplement treatment. The highest mushroom yield and substrate bioefficiency were observed for the 20% S41 treatment, which produced 13.7 kg m-2 of mushrooms with a corresponding substrate bioefficiency of 133.7%. The observed yield and substrate bioefficiency were considerably higher for S41 than for Promycel Target, S44, T6, and T7. Mean mushroom weight was highest for the 20% T6 treatment (34 g), and higher mean mushroom weights typically corresponded to treatments with lower mushroom yield. Substrate temperatures for the different treatments were either similar to or lower than the ambient air temperature. Hence, substrate overheating as encountered in compost-based substrate was ruled out as being the reason for lower yields observed at the higher rates of supplementation.

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 CaCO 3 (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 (U 1 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/m 2) 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.

Pangola grass colonized with Scytalidium thermophilum for production of Agaricus bisporus

This work had the dual objective of selecting a substrate for rapid mycelial growth of Scytalidium thermophilum and then comparing the growth and production of a brown variety of Agaricus bisporus on substrate non-colonized and colonized with S. thermophilum. Mycelial growth of S. thermophilum at 45 °C was significantly greater on potato dextrose yeast extract agar (0.58 mm/h) as compared to malt extract glucose agar (0.24 mm/h) and yeast extract glucose agar (0.44 mm/h). On cereal grain, S. thermophilum grew significantly faster on rice (0.31 mm/h) compared to sorghum (0.22 mm/h) and millet (0.18 mm/h). It also grew faster on Pangola grass (0.49 mm/h) compared to corncobs (0.30 mm/h) and sawdust (0.18 mm/h). Colonization of Pangola grass with S. thermophilum was influenced by the addition of calcium salts in the form of gypsum, hydrated lime and ground limestone. For production of A. bisporus, biological efficiency (BE) on pasteurized Pangola grass pre-colonized by S. thermophilum for 4 days at 45 °C was more than twice (26.4%) that on grass non-colonized by S. thermophilum (11.0%). The addition of 2% hydrated lime to Pangola grass prior to colonization by S. thermophilum resulted in an additional doubling of BE of mushroom production (48.1%). These results show the possibility of developing a non-composted substrate method for producing A. bisporus without autoclaving the substrate.

Yield, size, and mushroom solids content of Agaricus bisporus produced on non-composted substrate and spent mushroom compost

Three crops of Agaricus bisporus were grown on non-composted substrate (NCS), spent mushroom compost (SMC), a 50/50 mixture of NSC/SMC, or pasteurized Phase II compost. 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 were non-supplemented or supplemented with Target® (a commercial delayed release nutrient for mushroom culture) or soybean meal at spawning or casing, or with Micromax® (a mixture of nine micronutrients) at spawning. Mushroom yield (27.2 kg/m2) was greatest on a 50/50 mixture of NCS/SMC supplemented with 10% (dry wt) Target® at casing. The same substrate supplemented with Target® at spawning yielded 20.1 kg/m2. By comparison, mushroom yield on Phase II compost supplemented at casing or at spawning with Target® was 21.6 kg/m2 and 20.6 kg/m2, respectively. On NCS amended with 0.74% or 0.9% Micromax® at spawning, yields increased by 51.8% (12.9 kg/m2) and 71.8% (14.6 kg/m2), respectively, over non-amended NCS (8.5 kg/m2). Conversely, mushroom yields were not affected when Micromax® was added to a 50/50 mixture of NCS/SMC. Mushroom solids content was higher in mushrooms harvested from NCS amended with 0.74% Micromax® (9.6%) compared to non-amended NCS (8.3%).

NON-COMPOSTED GRAIN-BASED SUBSTRATES FOR MUSHROOM PRODUCTION (AGARICUS BISPORUS)

Non-composted grain-based substrates were evaluated for the cultivation of mushrooms (Agaricus bisporus) withthe goal of eliminating the need for the lengthy and often malodorous composting process. Millet grain, millet grain mixedwith soybean, and commercial rye grain spawn were used as substrates. Treatments included different proportions (100%,75%, 50%, and 25%) of millet grain, or grain spawn with perlite as an inert bulking material. For the millet and soybeanmixtures, the biological matter (millet and soybean) was set at 75% by volume, while the ratios of millet to soybean werevaried. To induce fructification, all substrates were overlain with a sterilized mixture of peat and calcium carbonate (casing)containing 25% activated charcoal (v/v), which was shown to be as effective as a commercial non-sterile casing. Among thevarious treatments, the highest mushroom yield among all three grain treatments was recorded for the 100% millet/0% perlitetreatment (8.7 kg/m2), which was comparable to that of compost (7.7 kg/m2). In contrast, the millet/soybean mixtures failedto produce any mushrooms when soybean was added to the substrate. The highest recorded mushroom yield for commercialgrain spawn was 5.3 kg/m2 for the 100% spawn/0% perlite treatment. This yield was lower when compared to the millet grainand compost substrates. However, biological efficiency (fresh weight of mushroom divided by dry weight of substrates 100)was 117% for the 25% spawn/75% perlite treatment, while that of compost and the 75% millet/25% perlite treatment were98% and 55%, respectively. The results suggest that mushrooms can be grown in a non-composted substrate, but furthereconomic analysis will need to be performed to determine economic viability of alternative substrates.

Modern aspects of mushroom culture technology.

The production and culture of new species of mushrooms is increasing. The breeding of new strains has significantly improved, allowing the use of strains with high yield and resistance to diseases, increasing productivity and diminishing the use of chemicals for pest control. The improvement and development of modern technologies, such as computerized control, automated mushroom harvesting, preparation of compost, production of mushrooms in a non-composted substrate, and new methods of substrate sterilization and spawn preparation, will increase the productivity of mushroom culture. All these aspects are crucial for the production of mushrooms with better flavor, appearance, texture, nutritional qualities, and medicinal properties at low cost. Mushroom culture is a biotechnological process that recycles ligninocellulosic wastes, since mushrooms are food for human consumption and the spent substrate can be used in different ways.

Adapting substrate formulas used for shiitake for production of brown Agaricus bisporus

A pasteurized, non-composted substrate (basal mixture) consisting of oak sawdust (28%), millet (29%), rye (8%), peat (8%), alfalfa meal (4%), soybean flour (4%), wheat bran (9%), and CaCO 3 (10%) was adapted from shiitake culture to produce the common cultivated mushroom (brown; portabello), Agaricus bisporus. Percentage biological efficiency (ratio of fresh mushroom harvested/oven-dry substrate weight, %BE) ranged from a low of 30.1% (when wheat straw was substituted for sawdust) to 77.1% for the basal mixture. Special, high gas-exchange bags were required to optimize mycelial growth during spawn run. Our formula may allow specialty mushroom growers to produce portabello mushrooms on a modified, pasteurized (110°C for 20 min) substrate commonly used for shiitake production without the added expense of compost preparation.

Cultivating mushrooms: Making composted and non-composted substrates

Cultivating mushrooms: Making composted and non-composted substrates