EFFECTS OF VARIATION IN COMPOSTING MATERIALS ON THE CULTIVATION AND NUTRITIONAL QUALITY OF EDIBLE TROPICAL MUSHROOM (PLEUROTUS OSTREATUS) EX. JACQ.FR

Abstract

Mushroom cultivation is a worldwide practice which utilizes almost all agricultural and agroindustrial residues as substrates. Many genera off mushrooms are edible and rich in essential nutrients. In this study, the effects of variation in composting materials on the cultivation of the mushroom, Pleurotus ostreatus was investigated. Compost and vermicompost preparations were made from different proportions of wood dust and organic wastes from livestock at 28±2oC for 70 days. Wood dusts from Pycnanthus angolensis and Spondias mombin were mixed with cow, goat, sheep dung and poultry droppings as substrates for cultivation of mushroom. The wood:organic matter were prepared at proportion of 9:1, 8:2, 7:3, 6:4 and 5:5 while using 100% wood dust served as the control. Vermicomposted samples reduced in pH to neutral, while the highest temperature ranging from 25.8-42.50C were observed in substrates with cow dung. The proximate and mineral analysis of compost/vermicompost substrates showed increase in protein content but decrease in the fiber as wood dust:organic waste ratio increased. Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Fusarium oxysporum, Rhizopus stolonifer, Curvularia lunata, Cladosporium sp Alternaria alternata, Aspergillus ochraceous Trichoderma sp. Scopulariopsis sp. were the fungi isolated within the first 10 weeks of experiment. While the bacteria isolated were Pseudomonas aeruginosa, Acitnomyces bovis, Actinomyces eriksonii, Pediococcus cerevisiae, Bacillus polymyxa, Enterobacter aerogene, Citrobacter freundii, Clostridium perfringes, Escherichia coli. Fungi diversity and population were more in composting and vermicomposting containing cow dung with both wood dust of P. angolensis and S. mombin, but least in the control sample (100% wood dust). Fungal population increased from 7.64 x 104 at the initial stage to 25.9 x 104 at the final stage in composting and 43.5 x 104 SFU/ml in vi vermicomposting for samples of P. angolensis and cow dung. Aspergillus spp had the highest occurrence of 45.0%, while Scopulariopsis sp. had the least occurrence of 3.0% at both initial and final stages of composting and vermicomposting. Pleurotus ostreatus cultivated on the substrates showed highest ramification on ratio 9:1 substrate mix for both wood types. All substrates at this proportion support the growth of both mycelial and fruit bodies of the mushroom. Composted substrate of Spondias mombin with cow dung at ratio 9:1 produced the highest mushroom harvest of 208.85 g/kg and biological efficiency of 59.67% (P<0.05). Potassium was higher in Pleurotus ostreatus compared to other minerals in all substrates. The phytochemical screening revealed the presence of tannins, phytates, saponins, oxalate and alkaloid at varying quantities that are safe for dietary intake. Composting reduced the quantity of phytochemical and antinutrients in the mushroom. There was an increase in protein, ash, and calcium content of used substrates after mushroom cultivation. The cultivation of P. ostreatus on different substrates increased the protein and ash content of the spent substrates. The result of the animal bioassay showed that rats fed with mushroom from composted substrates resulted to increase in Packed Cell Volume (PCV). The highest lymphocyte and neutrophils was observed on rats fed with vermicomposted substrate of P. angolensis (P≤0.05). The histopathological analyses of the vital organs of the rats fed with mushroom and the control showed no form of haemorrhage, necrosis and infiltration. However, kidneys of rat fed with mushroom cultivated on composted wood dust of S. mombin and sheep dung was poorly formed. In this study Pleurotus ostreatus was cultivated on various compost and vermicompost substrates made from waste materials from wood dust and livestock manure. The best compost preparation for maximum mushroom yield. Vermicomposting has further reduced antinutritional factors of all the mushroom.