Spent bleaching clay (SBC) from oil refining as a substrate for the spawn production of shiitake mushroom (Lentinula edodes)

Abstract

While no effective (both in a technical and economic sense) methods exist so far to handle large quantities of untreated spent bleaching clay (SBC) in China, there are indeed great demands for low-cost alternatives for mushroom substrate. Hence, it is in the interest of both edible-oil-refining industries and mushroom producers to explore how partially substituting traditional shiitake substrate by SBC would influence the mycelial growth in shiitake spawn production. This paper conducted a comparative shiitake spawn production experiment with a conventional shiitake substrate formula comprising of 78% sawdust, 20% wheat bran, 1% magnesium sulfate, and 1% gypsum (percentage by weight, the same thereafter) as the control and substrate formulae with the substitution of SBC for part of sawdust or wheat bran as treatments to observe the mycelial growth. The results indicated that formulae with SBC had lower incidence of microbial contamination and higher mycelial growth speed, and the optimal formula was 15% SBC, 78% coarse sawdust, 5% wheat bran, 1% magnesium sulfate and 1% gypsum. Therefore, the utilization of SBC in shiitatke spawn production not only considerably reduces the costs of shiitake production but also bring about substantial environmental benefits.