Vol. 8(5), pp. 432-436, 29 January, 2014 DOI: 10.5897/AJMR2013.6410 ISSN 1996-0808 ©2014 Academic Journals http://www.academicjournals.org/AJMR African Journal of Microbiology Research Full Length Research Paper Strain improvement in Pleurotus Ostreatus using UV light and ethyl methyl sulfonate as mutagens Rishu Sharma* and B. M. Sharma Department of Plant Pathology, Centre for Mushroom Research and Training, CSKHPKV, Palampur, Himachal Pradesh, 176062, India. Accepted 13 January, 2014 Oyster mushroom (Pleurotus Ostreatus) is the choicest edible species cultivated in various regions of the world. Strain improvement studies were carried out in three strains of P. Ostreatus spp. Three strains of P. Ostreatus viz. PO-2, PO-6 and PO-7 were used for strain improvement, emphasizing on lower spore count and colour of the sporophore. It is a gymnocarpous genus of mushroom, which continuously release spores in its close vicinity causing various respiratory allergies. Their spores are highly potent allergens which can also cause exogenous allergic alveolitis. Attempts were made to produce low sporing strains of P. Ostreatus through mutagenesis using physical mutagen (UV light) and chemical mutagen (ethyl methyl sulfonate, EMS). Spores of three strains of P. Ostreatus spp. were given different treatments with UV light and EMS. Mutants exhibited appressed mycelial growth and showed slower spawn run and creamish white sporophore in PO 7(U4). A lower spore count was also observed in PO-7(E3) mutant as compared to control. Key words: Pleurotus, UV light, ethyl methyl sulfonate, mutagens. INTRODUCTION Pleurotus spp. constitute 30% and ranks third among the cultivated mushrooms grown widely in temperate, sub- tropical and tropical regions of the world. The species of Pleurotus grow in the forests, attacking both cellulose and lignin components of wood (Zardazil and Kurtzman, 1982). The total world production of mushrooms is 200 thousand lakh tones in 2010. In India, mushroom pro- duction has crossed over 1,00,000 tons in 2010 (Singh et al., 2011). In the last few decades, Pleurotus cultivation has accelerated in India. It being a predo-minantly agriculture based country, holds a vast potential and stock of lignocellulosic waste, its adaptability to a wide range of subtropical climate temperature (20-30°C), ease of its cultivation, having good culinary and medicinal properties has attracted various farmers, entrepreneurs for its commercial production in the Indian sub continent. The sporophores of Pleurotus are gymnocarpous and continuously release spores in the atmosphere causing of immunologic lung diseases like hay fever and farmer’s lung disease among workers (Obatake et al., 2003) The antigens present on the walls of the spores cause the allergy. Also, during cultivation these spores settle on fruit bodies forming a velvety film after germination and thus giving an unpleasant appearance to mushroom (Ravishanker et al., 2006). The importance of fungal spores in causing air borne respiratory allergies has been well established (Hegde et al., 2002). A strict environ- mental control of Basidiomycetes spores is important to reduce the high risk of sensitization and possible deve- lopment of various allergic diseases. A reliable spore extraction method has been devised, and a reasonable number of available patients showed positive results with *Corresponding author. E-mail: rishupath12@gmail.com. Tel: 091-9419295531.