Process Biochemistry 118 (2022) 215–226 Available online 29 April 2022 1359-5113/© 2022 Elsevier Ltd. All rights reserved. Aspergillus terreus, Penicillium sp. and Bacillus sp. isolated from mangrove soil having laccase and peroxidase role in depolymerization of polyethylene bags Ahmed Mohy Eldin a, * , Sohad Fouad Said Al-Sharnouby a , Khadiga Ibrahim Mohamed ElGabry a , Amal Ibrahim Ramadan a a Department of Microbiology, Soils, Water and Environmental Research Institute - Agricultural Research Center, ARC, SWERI, 9 Cairo Univ. St., Giza 12112, Egypt A R T I C L E INFO Key words: Laccase Peroxidase Aspergillus terreus Polyethylene Depolymerization ABSTRACT Low density polyethylene (LDPE) bags constituting major section in plastic wastes problem, were subjected to depolymerization study using microbial candidates isolated from mangrove soil. Three most promising microbial candidates were identifed by rRNA gene sequencing analysis and uploaded in GenBank as Penicillium sp. [OM760513], Aspergillus terreus [OM760511] and Bacillus sp. [OM760515]. Incubation of the three candidates individually and in permutation and combination with LDPE bags in mineral salt medium broth (MSM) for 105 days revealed possible cooperative mechanism of microbial laccase and peroxidase in depolymerization of LDPE bag in an alternative manner. Weight loss by 24% and scan electron microscopy (SEM) examining surface of LDPE bag samples resulting from treatment with A. terreus OM760511 revealed its superiority. Attenuated Total Refectance (ATR) Fourier Transform Infrared (FTIR) spectroscopy analysis revealed positive correlation between weight loss and changes in LDPE bag structure confrmed by increase in double bonds, shifting in absorption bands and decrease in T% parallel to decrease in both carbonyl index and crystallinity %. 1. Introduction Plastics materials are organic materials that can be either fossil fuel based or bio based. Both types of plastic materials are recyclable and it is possible to produce bio-degradable plastics with both types of feed- stocks. Currently, most plastics materials are derived from fossil feed- stocks such as natural gas, oil or coal. Due to its durability, it found its way into many applications such as packaging, textiles, constructions, insulation, transportation,. etc., from which the expected cumulative waste generation and disposal might reach 25,000 million metric tons on 2050 [1]. In Egypt, 5.4 million tons of plastic wastes were generated annually from which 67% were mismanaged as mentioned by “Plastic Value Chain” in Egypt, according to UNIDO (United Nations Industrial Development Organization 2021). Low density polyethylene (LDPE) widely used as in plastic bags, formed the major plastic wastes worldwide [2] and considered recalci- trant to biodegradation processes [3]. LDPE consisted of methylene polymer backbone (secondary carbon) interrupted with tertiary carbon at branching points. The branch structures occasionally included butene, hexene and octene that made LDPE more susceptible for enzy- matic action [2]. LDPE biodegradation mechanisms recently were revealed through oxidation and hydrolysis done by microbial extracellular enzymes [4,5]. No complete biodegradation was achieved up till now through the work of many researchers who succeeded in partial degradation (depoly- merization) of polyethylene using microbial species, including bacteria such as Bacillus spp. [6–8] and fungi such as Aspergillus spp. [9,10], Penicillium spp. [9,11,12]. Many mangrove ecosystems worldwide were considered through many studies to be reliable sources for microor- ganisms that can partially biodegrade polyethylene [13]. Methods used in previous researches to qualify and quantify the degradation through various analytical approaches. Physical analysis used such as polymer weight loss, surface texture examination by Scan Electron Microscopy (SEM), changes in density, crystallinity, gel permeation chromatography (GPC) analysis that provided number average molecular weight (Mn), weight average molecular weight (Mw), size average weight (Mz) and molecular weight distribution (MWD). Chemical structure analysis used such as Attenuated Total * Corresponding author. E-mail address: ameaefe2006@yahoo.com (A. Mohy Eldin). Contents lists available at ScienceDirect Process Biochemistry journal homepage: www.elsevier.com/locate/procbio https://doi.org/10.1016/j.procbio.2022.04.030 Received 1 December 2021; Received in revised form 25 April 2022; Accepted 26 April 2022