The potential use of rice waste lignocellulose and its amendments as substrate for the cultivation of Pleurotus eous Strain P-31in Ghana

Abstract

The use of mushroom for the bioconversion of low quality lignocellulosic agricultural waste into nutritional food and animal feed rich in protein and minerals offers an alternative food and feed supplement. The genus Pleurotus comprises of edible lignolytic mushrooms capable of selective delignification of lignocellulolytic crop residue converting into edible protein and mineral salts. The effect of raw untreated rice straw and pre-treated (composted for 0, 4, 8 and 12 days supplemented with either 5, 10 and 15% rice bran 1% CaCO3 on growth rate, yield performance and Biological Efficiency (BE) of Pleurotus eous Strain P-31 was investigated using the conventional pasteurized bagged technique. The traditional ‘‘wawa’’ (Triplochiton scleroxylon) sawdust was used for comparison purposes only. The growth parameters (pH, moisture, spawn running time, fruit body formation, interval between flushes, total number of fruiting bodies during the cropping time and mushroom yield (Biological Efficiency) as well as the nutrient and mineral profiles of the fruiting bodies were determined by the conventional techniques. It was observed that amendment or supplementation of the substrate (rice straw) did not significantly (p≤0.05)enhance mushroom yield of Pleurotus eous such that growth on the composted substrates (4 - 8 days) gave the best yield with BE 67.1 – 75.1%. Yield on the unfermented rice straw was comparatively good (BE = 53.3 - 72.8)%. Both the pH and moisture content for all the substrates were within the optimum range of 6.0 - 8.0, 60 – 70% RH respectively. The standard substrate, ‘‘wawa’’ sawdust, currently in use for cultivation of Pleurotus spp. gave BE of 55.6 – 64.8%. The fruiting body contained high fat, protein, crude fibre and carbohydrates but differed depending on the type of substrate used. The carpophore contained mineral elements Ca, Mg, K, Na, and P in appreciable amounts useful for good health. Although heavy metals such as Cu, Fe, Mn, Pb and Zn were detected they were far below the WHO stipulated safe limits. The presence of high potassium over sodium makes P. eous fruiting body suitable for therapeutic treatment of hypertension