Optimization of Mycelial Culture Conditions for Six Isolates of Paddy Straw Mushroom from the Philippines

Abstract

This study evaluated the mycelial growth requirements of six Volvariella volvacea isolates. Three commercial isolates, San Jose, Nueva Ecija (SJ), Tarlac City (TC), and La Union (LU), and three wild isolates, Brgy. Rang-ayan, Muñoz, Nueva Ecija (VVA), CLSU (VVB), and San Mateo, Rizal (SP), were collected from Luzon Island, Philippines. Two isolates (SJ and VVA) showed the greatest mycelial growth and the highest mycelial density on PDA. The other four isolates (TC, LU, VVB, and SP) showed significant growth on CGDG with the shortest incubation period. The optimum pH for most isolates tested on PDA and CGDG was between pH 5.0 and 8.0. For the SJ isolate, the thickest mycelial growth was observed at pH 5, while both LU and SP isolates showed significant mycelial growth at pH 7. Efficient mycelial growth was recorded at pH 8 for TC, VVA, and VVB. All isolates showed maximum mycelial growth when incubated at room temperature (30-32 °C). The TC isolate showed maximum mycelial growth in the dark, while five isolates showed maximum growth under light conditions. For aeration, the SJ isolate showed maximum mycelial growth under unsealed conditions, while the remaining five isolates showed maximum growth under sealed conditions. Nonetheless, the efficient growth of all isolates at room temperature indicates that V. volvacea grows well in tropical countries at room temperature of 30-32 °C. Optimizing cultivation conditions for wild isolates may improve mycelial growth and potentially yield performance comparable to the commercial SJ isolate.