The Research On Control Method Of Accumulation Of Heavy Metals In Fruit Body Of Edible Fungus

Edible fungus, which contain a lot of nutritions such as protein, amino acids, vitamins, are a delicious and healthy food. However, as the emission of industrial waste, the use of pesticides and herbicides containing different heavy metals, the sources diversification of cultivation materials of edible fungi, the problem of the excessive content of heavy metal ions in edible fungus increasingly outstanding.Therefore, we need to control the content of heavy metals in edible fungi to enhance the food safety of edible fungi which has far-reaching significance to the edible fungus industry in China.In this paper, we studied the effects of heavy metals on mycelium growth and colonial morphology of Lentinus edodes and Pleurotus ostreatus. The results showed that the toxicity of mercury to mycelium growth of Pleurotus ostreatus is more serious than that of lead, the significant differences of mean growth diameter of basic medium and medium contaminated by heavy metals appeared, when the concentrations of lead and mercury were 50mg/L,15mg/L;the mycelium growth and colonial morphology of Lentinus edodes were seriously affected when the concentrations of mercury and cadmium in medium were 10.0mg/L,1.0mg/L.When the medium were added on alkaline earth elements, trace elements under the condition that the concentrations of the heavy metal seriously restrained the mycelium growth, we found that calcium and Ammonium Dihydrogen Phosphate could well mitigated the poisonous effect of heavy metals on Lentinus edodes mycelium, particularly the calcium; when adding pectin and phytic acid into medium, they were able to alleviate the toxic effects of heavy metal to mycelium of Pleurotus ostreatus, the detoxification of phytic acid was better than that of pectin, and when concentration of phytic acid was 0.1-2.0g/L, the detoxification to mercury added into medium was the best, when concentration was 3.0g/L, the best to lead; in the experiment about rice bran and Swida Wilsoniana Oilcake, we found that the detoxification of rice bran was better than Swida Wilsoniana Oilcake, when the content of rice bran and Swida Wilsoniana Oilcake were 20.0g/L, the detoxification to heavy metals was obvious.The research about Lentinus edodes told us that rice bran and Swida Wilsoniana Oilcake also had very significantly effects on restraining the toxicity to mercury and cadmium. Their detoxification to Hg2+ was apparent, but the Swida Wilsoniana Oilcake's detoxification to Cd2+ was better than the that of rice bran.In the absorption tests of phytic acid and pectin to heavy metals, the absorption ability of the phytic acid is much higher than the pectin. Especially at the condition of PH was 10, in which the absorption capacity of heavy metal to phytic acid was 84.7% (0.85mg/g) and 67.7%(0.68mg/g) compared with the blank sample solution respectively; in the absorption tests of rice bran and Swida Wilsoniana Oilcake to heavy metals, the absorption ability of rice bran to lead and mercury was significantly better than that of Swida Wilsoniana Oilcake,the average absorption contents of rice bran to lead and mercury were 3.11mg/g,1.05mg/g respectively, Swida Wilsoniana Oilcake were 2.94mg/g,0.96mg/g.The result of the experiment of cultivation materials using straw showed that the calcium could significantly reduce the richment ability of mercury in fruiting bodies of Pleurotus ostreatus. Compared with the accumulation content of mercury in fruiting bodies of Pleurotus ostreatus cultivated by Formula 1, Formula 4 was decreased by 39.87%, and the yield of Pleurotus ostreatus also increased by 26.03%; for cultivation materials dealing with two methods (Formula 3,6), the accumulation content of mercury in fruiting bodies of Pleurotus ostreatus cultivated by Formula 6 was at only 61.01% of Formula 1's.However, the accumulation content of lead in fruiting bodies of Pleurotus ostreatus cultivated by Formula 5 was decreased by 20.6% comparing with that of Formula 2, and the qualification yield of concentration of lead in fruiting bodies increased by 20.0%.The results of the experiment of cultivation materials using sawdust revealed that the production of Pleurotus ostreatus increased when the rice bran, Swida Wilsoniana Oilcake and Ammonium dihydrogen phosphate were added into cultivation materials which were contaminated by heavy metals,and detoxification of rice bran and Swida Wilsoniana Oilcake to heavy metals were very distinct, especially the rice bran's,when it added into cultivation materials which was contaminated by heavy metals,there was significant differences about the content of mercury in fruiting bodies of Pleurotus ostreatus between it and the contaminated cultivated material, in contrast with Formula 1, the accumulation content of mercury in fruiting bodies cultivated by Formula 3 was 3.64mg/kg,and decreased by 56.05%; when rice bran and Swida Wilsoniana Oilcake were added into the cultivation materials which were contaminated by lead, the accumulation contents of lead in fruiting bodies of Pleurotus ostreatus were 7.19mg/kg,8.16mg/kg respectively, compared with the contaminated cultivation materials,they decreased by 55.86%,49.91%,especially there was significant differences about the content of lead in fruiting bodies of Pleurotus ostreatus between different cultivation materials (Formula 7 and Formula 2),therefore,the rice bran was the best at the detoxification to lead.