Differential Degradation and Detoxification of an Aromatic Pollutant by Two Different Peroxidases

Abstract

Enzymatic degradation of organic pollutants is a new and promising remediation approach. Peroxidases are one of the most commonly used classes of enzymes to degrade organic pollutants. However, it is generally assumed that all peroxidases behave similarly and produce similar degradation products. In this study, we conducted detailed studies of the degradation of a model aromatic pollutant, Sulforhodamine B dye (SRB dye), using two peroxidases—soybean peroxidase (SBP) and chloroperoxidase (CPO). Our results show that these two related enzymes had different optimum conditions (pH, temperature, H2O2 concentration, etc.) for efficiently degrading SRB dye. High-performance liquid chromatography and liquid chromatography –mass spectrometry analyses confirmed that both SBP and CPO transformed the SRB dye into low molecular weight intermediates. While most of the intermediates produced by the two enzymes were the same, the CPO treatment produced at least one different intermediate. Furthermore, toxicological evaluation using lettuce (Lactuca sativa) seeds demonstrated that the SBP-based treatment was able to eliminate the phytotoxicity of SRB dye, but the CPO-based treatment did not. Our results show, for the first time, that while both of these related enzymes can be used to efficiently degrade organic pollutants, they have different optimum reaction conditions and may not be equally efficient in detoxification of organic pollutants.

Purification and enzymatic properties of a textile dye-decolourizing peroxidase from Moringa oleifera roots

“…5). In particular, the absence of ascorbic acid oxidation by MoPOX corroborates other works reporting this behavior as characteristic of peroxidases (Alneyadi et al, 2017;Baumer et al, 2018). Similar results were reported for a peroxidase from Withania somnifera, which readily catalyzed the oxidation of phenolic substrates like guaiacol and o-dianisidine, but not ascorbic acid [24].…”

Comparative Degradation of a Thiazole Pollutant by an Advanced Oxidation Process and an Enzymatic Approach

“…The materials produced after the enzymatic and the photolytic treatments were analyzed using LC-MS, as previously described [ 18 , 19 ]. Briefly, all ThT samples were filtered using a 0.45 µm CA syringe filter prior to injection.…”

“…The toxicity of ThT before and after the UV + H 2 O 2 and CPO + H 2 O 2 treatments was measured using the lettuce seed growth inhibition assay, similar to a previously described method but with slight modifications [ 19 ]. Briefly, 20 Lactuca sativa seeds were placed on sterilized Whatman filter paper, No.…”

“…Our research group and others have used this enzyme for the efficient and rapid degradation of various organic pollutants [ 17 , 18 , 19 , 20 , 21 ]. Although a tremendous amount of research has been published on the use of AOPs [ 22 , 23 , 24 ] and enzymatic [ 18 , 19 , 25 , 26 ] approaches to the degradation of organic pollutants, including some “combination approaches” [ 27 , 28 , 29 , 30 , 31 ], to date there have been no detailed studies published that compare the degradation of a specific organic compound by these two different methods. Many questions remain about the pollutant degradation pathways, the types of intermediates generated, and the residual toxicity of the pollutants when using these two very different methods.…”

Never let a crisis go to waste: Repurposing independent research projects to enhance students' critical thinking skills

“…Based on Scheme 1, students are asked to read a paper that shows dramatic differences in thermal stabilities of two related proteins (e.g., soybean peroxidase and chloroperoxidase). 5 (If they have access to labs, they are asked to test the activities of chosen enzymes after incubation at different temperatures.) At this stage, students are guided to identify a question, that is, "what is the molecular basis of enzyme thermostability?"…”