Mycoremediation (bioremediation with fungi) – growing mushrooms to clean the earth

Abstract

Some of the prospects of using fungi, principally white-rot fungi, for cleaning contaminated land are surveyed. That whiterot fungi are so effective in degrading a wide range of organic molecules is due to their release of extra-cellular ligninmodifying enzymes, with a low substrate-specificity, so they can act upon various molecules that are broadly similar to lignin. The enzymes present in the system employed for degrading lignin include lignin-peroxidase (LiP), manganese peroxidase (MnP), various H 2 O 2 producing enzymes and laccase. The degradation can be augmented by adding carbon sources such as sawdust, straw and corn cob at polluted sites.

The fungal ability for biobleaching/biopulping/bioremediation of lignin-like compounds of agro-industrial raw material

“…129 The effect of inoculation of soil microcosms with T. versicolor and P. chrysosporium on wood chips on differential degradation of pesticides (simazine, trifluralin and dieldrin, 10 mg kg −1 soil) at two water potentials (−0.7 and −2.8 MPa, at 15 °C) was studied through soil microcosms destructively sampled after 6/12 weeks for determination of four extracellular enzymes, respiration and content of the pesticides. 158 It was found that fungal treatments increased extracellular enzymes cellulase/dehydrogenase and laccase (mainly with T. versicolor), respiratory activity and degradation of the three pesticides by wood chip addition alone (20-30%) in inoculated soil containing higher contents of pesticide mixtures. T. versicolor increased degradation of simazine (27-46%), trifluralin (5-17%) and dieldrin (5-11%) after 12 weeks and P. chrysosporium by 34-48%, 0-30% and 40-46%, respectively, when compared with controls, even at −2.8 MPa water potential, suggesting that effective bioremediation of xenobiotic mixtures using wood chips and fungal inoculants is achievable over a relatively wide water potential range when compared with that allowing plant growth (−1.4 MPa).…”

“…Such preparation methods enhance the likelihood of success in the first phase. 158 The are many studies using mycoremediation in artificially contaminated sites spiked with organic pollutants, but the importance of researches under nonsterile conditions, with real contaminated soils/effluents, became more common in the last twenty years and made their results potentially transferable to a field scale, using biostimulation, bioaugmentation or, more recently, both technologies. This process depends on nutrient availability and the optimum presence of other factors that support biological functions, such as the concentration of the contaminants and their bioavailability, site characteristics, moisture, temperature, redox potential and oxygen content.…”

“…163,164 P. chrysosporium has been known to degrade many types of organo-pollutants, such as polycyclic aromatic hydrocarbons (PAH's), polychlorinated biphenyls and dioxines, chlorophenols, chlorolignins, nitrocranditics, synthetic dyes and different pesticides, being a model for mycoremediation, since it is more efficient than other fungi or microorganisms in degrading toxic or insoluble materials because it presents simultaneous oxidative and reductive mechanisms, which permit its use in many different situations, both regarding the type of contamination, its degree, and the nature of the site itself. 158 Biotreatment of bagasse effluent with high content of lignin using P. chrysosporium has shown that the best conditions of temperature, biomass concentration, pH and duration for this remediation were 35 °C, 552 mg l −1 , 6 and 5 to 9 days, respectively. Under these conditions, a 9 days long treatment reduced by 98.7% the original biochemical oxygen demand (of 2,780 mg l −1 ) and by 98.5% the dissolved chemical oxygen demand (initial 4,200 mg l −1 ).…”

“…159 Based on the literature about mycoremediation, whiterot basidiomycetes accounts for at least 30% of the total research on fungi used in this process, and P. chrysosporium, A. bisporus, Irpex lacteus, T. versicolor and Pleurotus ostreatus, P. tuberregium and P. pulmonarius, amongst many other basidiomycetes, have been reported in the decontamination of polluted sites. 5,158 The biodegradation of vinasse by ligninolytic enzymes has been reviewed previously. 160 Assays for vinasse decolorization were performed using the fungus Pleurotus sajor-caju CCB020 in vinasse biodegradation study, in which occurred reductions of 82.8% in COD, 75.3% in BOD, 99.2% in the coloration and 99.7% in turbidity.…”

“…This process depends on nutrient availability and the optimum presence of other factors that support biological functions, such as the concentration of the contaminants and their bioavailability, site characteristics, moisture, temperature, redox potential and oxygen content. 158 Basidiomycetes are amongst nature's most powerful decomposers, secreting strong and low specificity catabolic extracellular enzymes from mycelium due to their aggressive growth and biomass production (they form extended mycelial networks to expand their surface area, what makes easier to contact the pollutant). Besides this, they are known due to their efficiency in producing food protein in the mycelia or fruiting bodies using different wastes as nutrients.…”