Alkaline fungal degradation of oxidized polyethylene in black liquor: Studies on the effect of lignin peroxidases and manganese peroxidases

Abstract

High-molecular-weight polyethylene is resistant to natural environmental degradation for its crystalline, hydrophobic structure. In this study, waste polyethylene bags are chemically oxidized at 80 C for 5 days by potassium dichromate solutions of various concentrations along with sulfuric acid. Absorbance peaks of carbonyl and carboxylate ions in the Fourier transform infrared spectroscopy spectra and formation of amorphous phase from crystalline one as indicated in X ray diffraction studies of oxidized polyethylenes indicate the formation of a polar hydrophilic and low-molecular-weight material after oxidation. From the scanning electron microscopy studies, it is observed that reacted polyethylene surface is disintegrated and numerous fissures are formed throughout the surface. The respective weight loss of incubated oxidized polyethylene with Phanerochaete chrysosporium (MTCC-787) after 15 days of incubation is 70%, respectively, in black liquor-glucose-malt extract medium. As both lignin peroxidase (LiP) and manganese peroxidase (MnP) were detected in this media, further degradation of oxidized polyethylene is carried out in four different media with varying amount of N and Mn. The weight loss is observed only in media with excess nitrogen (N) and limited manganese (Mn), the condition which enhances the presence of LiP and MnP. This indicates that these enzymes are essential for degradation of lignin as well as oxidized polyethylene. UV spectroscopic studies indicate 40% decrease in the lignin concentration. This process of fungal degradation of chemically oxidized polyethylene using black liquor is very quick compared to the other related studies, leading to the simultaneous degradation of two waste materials, polyethylene and black liquor.

Microbial enzymes for the recycling of recalcitrant petroleum‐based plastics: how far are we?

“…The concentrated culture supernatants of lignocellulose‐degrading Streptomyces species containing LiP activity were reported to degrade the PE fraction of a heat‐treated plastic blend (Pometto et al ., ). Similarly, the extracellular LiP and MnP of Phanerochaete chrysosporium MTCC‐787 were reported to degrade 70% of a preoxidized high molecular weight PE sample within 15 days of incubation (Mukherjee and Kundu, ).…”

Fungal bioremediation of polyethylene: Challenges and perspectives

“…Comparing weight loss figures in the studies reviewed (Table S1 & Table S2) does, however, indicate increased LDPE biodegradation over HDPE, enhancement of biodegradation following a PT step (Balasubramanian et al, 2014;Sheik et al, 2015), and variation in biodegradative capacity within and between genera (Alsherehrei, 2017;Muhonja et al, 2018;Sáenz et al, 2019). In a small subset of studies, considerable (>40%) weight losses have been reported over 15-90 days (Mukherjee and Kundu, 2014;Raut et al, 2015;Alsherehrei, 2017;Paço et al, 2017).…”

“…This article is protected by copyright. All rights reserved however, the activities of LiP, MnP, and laccase have all been associated with the biodegradation of PE by fungal species (Iiyoshi et al, 1998;Mukherjee and Kundu, 2014;Kang et al, 2019;Zhang et al, 2020) and some efforts at enhancing their action have been made. All three enzymes most typically attack the phenolic subunits of lignin but may also attack non-phenolic subunits -which PE most closely resembleswith the addition of mediators (Datta et al, 2017;Kumar and Chandra, 2020).…”

Chemical-biological degradation of polyethylene combining Baeyer–Villiger oxidation and hydrolysis reaction of cutinase

“…Owing to the higher bond energy of its carbon–carbon single bonds (330–370 kJ mol −1 ), 3 polyethylene requires functionalization before plastic-degrading enzymes can be used to catalyze its degradation reaction. 4 Current pretreatment methods mainly include the use of ultraviolet (UV), 5 strong acid, strong alkali, or inorganic oxidant treatment, 6 and the functional groups hence generated are mainly hydroxyl, carbonyl, and carbon–carbon double bonds. 7 It has been reported that the above pretreatment can lead to some oxidoreductases degrading the polyethylene.…”

“…7 It has been reported that the above pretreatment can lead to some oxidoreductases degrading the polyethylene. For example, laccase (Lac)-degraded UV oxidizes polyethylene, with a loss of M w of about 20%, 8 lignin peroxidase (Lip) and manganese peroxidase (Mnp) degraded K 2 Cr 2 O 7 oxidizes polyethylene in black liquor as medium, 6 and latex cleating protein (Lcp) catalyzed the UV oxidation of polyethylene, with a loss of M w of about 42.02%. 9 Although the above pretreatment methods effectively improve the degradation efficiency of biological enzymes, 10 no research has been conducted to clarify the mechanism by which they degrade polyethylene by using oxygen-containing groups.…”