Introduction
The mushroom species of interest in this investigation are
Lentinula edodes and Auricularia auricula. Cultivation of L. edodes
(Shiitake), which is locally known as Xiang Gu, began in the Zhejiang
Province of China over 900 years ago (Ito, 1978). This mushroom
species is currently the second most cultivated edible mushroom
species in the world and the largest producer worldwide is China
(Shen et al., 2008). A. auricular is commonly known as Wood Ear
mushroom and in China the common name for this mushroom is
Hei Mu Er. In China these mushroom species are popular sources of
food and reputed to have medicinal properties. L. edodes can be
purchased either fresh or dried, but A. auricular can only be
purchased in dried form and these mushroom species are produced
both on a cottage and commercial scale (Chang, 2006).
Spores of Clostridiumbotulinumare ubiquitous in soil and sediments,
albeit often at a low concentration, although one survey reported
25,000 spores/kg in soil in China (Peck, 2010). The closeness of
mushrooms to the ground can result in contamination with spores of
C. botulinum. Indeed, surveys have reported spores of C. botulinum in
fresh Agaricus campestris mushroom samples purchased in Canada at a