İstiridye mantarı: Pleurotus ostreatus kullanılarak mikoremediasyon yöntemi ile topraktan ağır metal giderimi

According to fossil records, fungi diverged from other life around 1.5 billion years ago and probably fungi colonised on Earth during the Cambrien, which is long before human beings evolved on it. The term "mycology" is derived from Greek word "mykes", meaning mushroom which is a branch of life science that refers the study of fungi. In general, mushrooms are responsible for decomposing of organic molecules to provide continuance of life by recycling organic wastes and returning of nutrients back into the ecosystem. These features of fungi reveal a term called as "mycoremediation". Increasing human population and supporting unconscious consumerism by a politics of capitalist world economy caused the pollution of the environment with synthetic compounds which has become a major problem all around the world. These synthetic compounds are called as xenobiotics which do not occur naturally in the biosphere so are not easily degraded by the natural microflora and fauna. Biological approaches based on the environmental biotechnology are focusing on the development of "environmentalist technologies". Further, these clean technologies focus on the use of metabolic pathways of organisms for the remediation of waste. One such biological method is mycoremediation (fungal remediation). The mushrooms and other fungi act as enzymatic machinery for degradation of a wide variety of waste/pollutant. However mushrooms, basidiomycetous fungi, are becoming more popular nowadays for remediation purposes as a bioremediation tool. The white rot fungi in all the fungi species, are known to degrade polyaromatic hydrocarbons (PAHs), chlorinated aromatic hydrocarbons (CAHs), polycyclic aromatics, polychlorinated biphenyls, polychlorinated dibenzo(p)dioxins, the pesticides and some azo dyes. White-rot fungi are also used in bioremediation of polluted soils and accumulation of heavy metals and involved in mineralization, biodeterioration, biodegradation, transformation and co-metabolism. Phanerochaete chrysosporium, Pleurotus ostreatus, Pleurotus pulmonarius, Pleurotus tuber-regium, Lentinus squarrosulus etc. are white-rot fungi, so far used in bioremediation researches. Heavy metals are natural constituents of the earth crust. Their non- biodegradable, non-thermodegradable features contribute to environmental pollution mainly and show toxic effects on organisms. The most common heavy metals found at contaminated sites, in order of abundance are Pb, Cr, As, Zn, Cd, Cu and Hg. Those metals are important since they are capable of decreasing crop production due to the risk of bioaccumulation and biomagnification in the food chain. There is also the risk of superficial and groundwater contamination. Cadmium, mercury and lead can describe as three big poisinous metals which are not known essential role for living organisms. Cadmiums chemical similarity to Zn which is an essential micronutrient for plants and animals, probably responsible of its toxicity. Mercury, Hg, is the only liquid metal at standard temperature, and major source of Hg contamination is caused by coal combustion. Mostly Pb contamination in nature arises during the improper disposal of Pb storage batteries. The aim of this study is to remediate contaminated soils from three most toxic heavy metals using Pleurotus ostreatus mycelium. Soil and mycelium heavy metal analysis were performed by Bureau Veritas Mineral Laboratories, in Canada. Soil Pb and Cd analyses were performed using ICP-MS analysis. In this study, bioaccumulation percentage of was studied with three different concentration of Pb, Cd and Hg for two different incubation period. The results showed that bioaccumulation percentage increased by incubation period for lead, cadmium and mercury. While SET I mycelium analyses showed that increasing concentration of lead caused a decrease for its bioaccumulation, in SET II bioaccumulated concentration of Pb did not showed a significant difference for all concentrations. According to bioaccumulation percentage calculations for Pb, it showed a decrease in order of 2.5 ppm, 5 ppm and 10 ppm. Cadmium showed the lowest bioaccumulation percentage in Content 2, comparison to Content 1 and Content 3, both SET I and SET II. Heavy metal analyses of mycelium samples showed that the most bioaccumulated heavy metal by Pleurotus ostreatus was mercury. The mycelium samples belonged to 10 ppm mercury contained soil samples showed 54 % Hg bioaccumulation and 85 %, in SET I and SET II, respectively. The heavy metals which were used in this experiment in order of bioaccumulation percentages were Hg > Cd> Pb.