The wastewater that originates from the widespread usage of synthetic dyes in the industry have become a severe environmental problem. Several efforts have been made to develop new types of treatment which are capable of performing the degradation of the dyes from the environment. Within this scope, much attention has been drawn to enzymatic approaches, mainly the ones applying oxidative enzymes, such as peroxidases. A recently discovered superfamily of peroxidases, the so called dye-decolorizing peroxidases (DyPs) is a promising alternative to further improve the efficiency of these processes. In this work, two of these peroxidases (Saccharomonospora viridis (SviDyP) and Thermobifida fusca (TfuDyp)) were tested together with twelve different reactive dyes in order to evaluate the efficiency of degradation and decolorization, leading to good results. When applying the SviDyP enzyme in experiments carried out for 12 h in pH 3, the degradation efficiencies were above 80% for some dyes. The biodegradation efficiency data and cyclic voltammograms were recorded to obtain the redox potential of the chosen dyes and enzymes. In addition, an electrochemical biosensor was used to gauge the genotoxicity of the generated bioproducts. This analysis showed that bioproducts from dye degradation mostly present a lower degree of genotoxicity when compared to the control reactions.

ABSTRACT Several enzymatic reactions of heteroatom-containing compounds have been explored as unnatural substrates. Considerable advances related to the search for efficient enzymatic systems able to support a broader substrate scope with high catalytic performance are described in the literature. These reports include mainly native and mutated enzymes and whole cells biocatalysis. Herein, we describe the historical background along with the progress of biocatalyzed reactions involving the heteroatom(S, Se, B, P and Si) from hetero-organic substrates.

In this study, lipase from Candida antarctica B (Lipozyme CaLB-L) was successfully immobilized on SiO2 through adsorption and used to obtain (R)-(+)-esters derived from (R,S)-1-phenylethanol. The new immobilized enzyme was compared with commercially immobilized lipases (Novozyme 435, Lipozyme 435 and Pseudomonas cepacia (PSC-II and PSD-I)). Lipozyme CaLB-L adsorbed onto SiO2 was found to be a good catalyst and, under optimal conditions, esters could be obtained with conversion 44%, enantiomeric excess of product (eep) > 99%, enantiomeric excess of substract (ees) 77% and enantiomeric ratio (E) > 200. The lipase maintained enantioselectivity under adverse conditions, such as in organic solvents, with an excess of substrate and at different temperatures. The immobilized lipase could be reused five times with no significant loss of the activity.