Anatomical Studies of Four Pleurotus Species Cultivated on Mansonia altisima Sawdust

Abstract

Pleurotus (Fr.) Quel is a genus of gilled mushrooms, and are one of the most commonly cultivated edible mushrooms in the world. This work was aimed at cultivating and identifying/determining the anatomical features of  Pleurotus species at different developmental stages. Four species of Pleurotus, namely Pleurotus florida, P. ostreatus, P.ostreatus var. F. and P. pulmonarius were cultivated on Mansonia altisima sawdust and supplemented with rice bran. The sawdust was sterilized in an autoclave at 121^oC at 15 ibs pressure for 20 minutes. On cooling, spawn of each of the species were inoculated on the sterilized substrate. The inoculated bottles were incubated in a dark at controlled temperature of 15^oc. Pure cultures of each of the mushroom were grown on PDA to obtain the mycelia stage. After mycelial colonization of the substrate, primordia stage and mature fruit body stage were studied morphologically and samples were harvested in vial bottles. The pinhead formation took 26 and 27 days for Pleurotus florida, P. ostreatus, respectively; and 28 days for P.ostreatus var. F. and P. pulmonarius.  Harvesting of the mature fruiting bodies was done after 30 days for Pleurotus florida, 31 days for P. ostreatus and P.ostreatus var. F, and 33 days for P. pulmonarius. The mature fruit body comprise of the stipe, gills and pileus. Anatomical sections were then taken at 25 micron thickness, stained and mounted on glass slide. Hyphae arrangement, cell polarity, cell density, cell shape, stainability, fruit bodies initials, presence of cuticle, hymenium length, hymenophore structure, cell wall structure, presence of nodulus, presence of copious granules, cell wall structure and cell size were diagnostic and varies among the species. Dendogram of characters produced Pleurotus florida, P. Ostreatus and Pleurotus ostreatus var. F. in a cluster and Pleurotus pulmonarius as an outlier. Classification based on cluster analysis confirmed the original identification of the Pleurotus species studied. Pleurotus pulmonarius was well separated from Pleurotus ostreatus, Pleurotus florida and Pleurotus ostreatus var. f with a taxonomic distance (D=0.90). The study has shown that Mansonia altisima sawdust is a good substrate for the cultivation of Pleurotus species. Pleurotus ostreatus, Pleurotus florida and Pleurotus ostreatus var. f in a cluster demonstrated closer zymographic relationships.  Variations in the characters used are useful in the identification of the four species studied.