Oyster Mushroom Grain Spawn: Boiled Wheat with Lime and Gypsum, 121 °C

The "mother seed" of oyster mushroom: wheat boiled, limed to about pH 9, sterilised in litre bottles and overgrown from a piece of agar culture. It is the spawn that starts a straw crop. The figures are those of a 2018 study at the Benemérita Universidad Autónoma de Puebla, Mexico, with their strain CP-50 of Pleurotus ostreatus. Source: Valencia de Ita et al., J. Pure Appl. Microbiol. 12(2) 679-686 (2018), p. 680. The bottle closure, the scalpel and the hood are ours. The picture shows an oyster mushroom culture on agar, the starter.