Use of biogas fluid-soaked water hyacinth for cultivating Pleurotus geesteranus.

Experiments were carried out to test the viability of growing Pleurotus geesteranus on media containing varying amounts of crushed water hyacinth slices, which were soaked in pig farm biogas fluid and dried. The water hyacinth material was utilized to substitute sawdust in the media for mushroom cultivation. Mushroom fruiting bodies harvested were evaluated for yield, amino acid and heavy metal contents. Among the eight treatment groups, the greatest yield and highest amino acid content in the mushrooms were obtained when the proportions of water hyacinth and sawdust in the medium were equal. The concentrations of heavy metals, Hg, Pb and Cd, in most of the present mushroom samples did not exceed the maximum allowed levels according to the limits set forth by the food hygienic and safety regulations for edible mushrooms in China. The proposed waste utilization of water hyacinth could conceivably benefit the environment in various aspects including conservation of forest by reducing the demand on natural woods for mushroom production.

[Effect of exogenous zinc addition on cell protective enzyme activities in the fruit bodies of Lentinus giganteus].

OBJECTIVE: The effects of exogenous Zn addition on cell protective enzyme activities in the fruit bodies of Lentinus giganteus were studied. METHODS: ZnSO4 was used as exogenous Zn and added into culture medium. The final Zn concentrations in culture media were 0, 10, 20, 30, 40, 50 mg/kg respectively. The activities of superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), malondialchehyche (MDA) content and soluble protein content in the fruit bodies were analyzed by spectrophotometry; catalase (CAT) was determined by potassium permanganate titration. RESULTS: The content of soluble protein and SOD, POD and CAT activities in the fruit bodies of L. giganteus were significantly increased (P < 0.01), but PPO activity (P < 0.01) and MDA content (P < 0.05) was significantly decreased in the treatment of 30 mg/kg Zn concentration. The content of soluble protein and SOD, POD and CAT activities showed a decreasing trend with the increase of Zn concentration, but MDA content was significantly increased (P < 0.01 and P < 0.05). CONCLUSION: High Zn concentration caused the increase of MDA contents and the decrease of SOD, POD and CAT activities in the fruit body of L. giganteus. It will destroy the protective enzyme system, cause the accumulation of free radicals and thus intensify membrane lipid peroxidation. Appropriate Zn concentration improved the protective enzyme activities, and lightened the harm of membrane from lipid peroxidation.