Toxic metal uptake by oyster mushrooms grown in sugarcane bagasse

Fungiculture or Mushroom Cultivation is rapidly expanding throughout the world. It is further catalyzed by its high nutritional value and increased market demand. Additionally, the method of cultivation does not require much space and the per unit production is very high compared to other crops. Bagasse is the byproduct left after extracting the juice from sugarcane. It has been speculated that bagasse can be an excellent substrate due to its high carbohydrate and mineral content (Hoa et al., 2015). In the experiment spawns of Oyster Mushroom were inoculated in bagasse collected from industries. Remarkable growth of mushrooms in short period of time was observed. However, the metal toxicity being our primary concern in this experiment, AAS (Atomic Absorption Spectrometry) Test was used to detect the heavy metal ion concentrations in both the bagasse and the fruiting bodies of mushrooms. The concentrations of metals calculated are as follows, in bagasse (mg/kg): Cadmium - 0.015, Arsenic - 8.56, Copper-12.47, Chromium-9.17, Mercury - less than 0.01, and in mushroom (mg/kg): Cd - 0.022, As - 10.12, Cu - 14.29, Cr - 7.59, Hg - less than 0.01. These results indicated biomagnification of metal ion concentration in the mushrooms up taken from bagasse. These metals, in such high concentrations are lethal and causes many diseases in humans and other animals. Hence, from this experiment it can be deduced, that though bagasse is an excellent substrate for mushroom cultivation, the toxicity of metal ions present in it in such high concentrations overshadow the earlier benefits of bagasse as a good substrate. However, it has been proposed that if such metals are removed or their concentrations are lowered then the earlier mentioned benefits of bagasse are restored.