A large number of enzymes from bacteria, fungi, and plants have been reported to be involved in the biodegradation of toxic organic pollutants. Bioremediation is a cost effective and nature friendly biotechnology that is powered by microbial enzymes. The research activity in this area would contribute towards developing advanced bioprocess technology to reduce the toxicity of the pollutants and also to obtain novel useful substances. The information on the mechanisms of bioremediation-related enzymes such as oxido-reductases and hydrolases have been extensively studied. This review attempts to provide descriptive information on the enzymes from various microorganisms involved in the biodegradation of wide range of pollutants, applications, and suggestions required to overcome the limitations of their efficient use.

/pdf/role-of-microbial-enzymes-in-the-bioremediation-of-2uov3ks5gc.pdf

Role of microbial enzymes in the bioremediation of pollutants: a review.

The ability of peroxidases and laccases enzymes to treat organic pollutants is reviewed. Enzymatic methods generally have low energy requirements, are easy to control, can operate over a wide range of conditions and have a minimal environmental impact. Peroxidases and laccases have broad substrate specificities and can catalyze the oxidation of a wide range of toxic organic compounds. The results show that an enzymatic oxidation can diminish the toxicity of some polycyclic aromatic hydrocarbons (PAHs), phenols, organophosphorus pesticides and azo dyes in laboratory and some field conditions. Due to the hydrophobicity and low aqueous solubility of these substrates, reactions are usually performed in the presence of organic solvents. However, it was detected that organic solvents can provoke enzyme denaturation, unfavorable substrate partition, inhibition or stabilization of enzyme–substrate complexes, depending on the enzyme, substrate and organic solvent used. Strategies to overcome these problems are proposed. Additionally, the low stability of heme-containing peroxidases to hydrogen peroxide, the low reaction rates of laccases, the mediators toxicity, the limited availability and high costs of these enzymes are other limitations detected for commercial applications. Due to field reaction conditions are more complex than laboratory conditions efforts have to be made to achieve the cheap overproduction of these biocatalysts in heterologous hosts and also their modification by chemical means or protein engineering to obtain more robust and active enzymes.

Potential use of oxidative enzymes for the detoxification of organic pollutants

Degradation of 2,2-Bis(4-hydroxyphenyl)propane (bisphenol A, BPA), an endocrine-disturbing chemical, by the growing mycelia of the white-rot basidiomycete, Pleurotus ostreatus, was examined. About 80% of BPA initially present decreased in 12 days of culture with this fungus. By in vitro experiments using the lignin-degrading enzyme manganese peroxidase (MnP), BPA was metabolized to phenol, 4-isopropenylphenol, 4-isopropylphenol, and hexestrol. The degradation products of BPA were assumed to be formed by the one-electron oxidation of the substrate.

https://www.tandfonline.com/doi/pdf/10.1271/bbb.64.1958

Degradation of bisphenol A by the lignin-degrading enzyme, manganese peroxidase, produced by the white-rot basidiomycete, Pleurotus ostreatus

Purification of a new manganese peroxidase of the white-rot fungus Irpex lacteus, and degradation of polycyclic aromatic hydrocarbons by the enzyme.

1 Preparation and Characterization of Lignin-Carbohydrate Complexes.- 2 Location of Lignin Moieties Along Polysaccharide Chains in Lignin-Carbohydrate Complexes.- 3 Formation of Lignin-Carbohydrate-Complex Micelles and Pectin/Lignin/Hemicelluloses.- 4 Analysis of Native Bonds Between Lignin and Carbohydrate by Specific Chemical Reactions.- 5 Residual Lignin in Alkaline Pulps.- 6 Functions of Lignin-Carbohydrate Complexes.- 7 Microbial Degradation of Lignin-Carbohydrate Complexes.- 8 Condensation of Lignins with Carbohydrates in Concentrated Sulfuric Acid.- References.

Association Between Lignin and Carbohydrates in Wood and Other Plant Tissues

The reaction of manganese peroxidase (MnP) of the white-rot fungusBjerkandera adusta with synthetic lignin dehydrogenation polymer, DHP) in acetone medium was investigated. Gel-permeation chromatography of the DHP treated by MnP demonstrated depolymerization of syringyl DHP in the reaction mixture containing 70% acetone; moreover, concomitant repolymerization occurred to give highly polymerized products. Guaiacyl DHP was only repolymerized by MnP in the same acetone solution without giving degradation products. Addition of ascorbic acid to reaction mixtures containing acetone resulted in preferential depolymerization of syringyl DHP.

/pdf/reaction-of-manganese-peroxidase-of-bjerkandera-adusta-with-3nd16gnkv4.pdf

Reaction of manganese peroxidase of Bjerkandera adusta with synthetic lignin in acetone solution

This paper describes preparation and characterization of dehydrogenation polymers using MnP of Bjerkandera adusta in reaction mixtures containing organic solvents.

Preparation of synthetic lignin by manganese peroxidase of Bjerkandera adusta in organic solvents

The oxidation of various phenolics and aromatic amines by manganese-dependent peroxidase (MnP) of Bjerkandera adusta was examined in aqueous organic media. MnP retained its activities in several 70% (v/v) aqueous solutions of water-miscible organic solvents including ethylene glycol, diethylene glycol, acetone and acetonitrile. The absorption spectra of MnP in these aqueous organic media were similar to that observed in the reaction without solvent addition, indicating that the heme of MnP was little affected by the addition of these water-miscible organic solvents. MnP was also found to oxidize Mn(II) to Mn(III) in these 70% (v/v) aqueous organic media. The oxidation of Mn(II) by MnP was correlated with the Dimroth–Reichardt parameter, ET(30), of the solvents. Furthermore, MnP catalyzed the oxidation of anisidines, aminophenols, phenylenediamines and phenolics in aqueous 70% (v/v) acetone, acetonitrile and diethylene glycol media. Aromatic amines that have high hydrophobicity were shown to be suitable for the reaction of MnP in aqueous water-miscible organic media.

Akinobu Chatani

Papers

Reaction of manganese peroxidase of Bjerkandera adusta with synthetic lignin in acetone solution

Preparation of synthetic lignin by manganese peroxidase of Bjerkandera adusta in organic solvents

Reaction of manganese-dependent peroxidase from Bjerkandera adusta in aqueous organic media

Reaction of Manganese-dependent Peroxidase from Bjerkandera adusta in Organic Solvents