Polyethylene (PE) has been considered nonbiodegradable for decades. Although the biodegradation of PE by bacterial cultures has been occasionally described, valid evidence of PE biodegradation has ...remained limited in the literature. We found that waxworms, or Indian mealmoths (the larvae of Plodia interpunctella), were capable of chewing and eating PE films. Two bacterial strains capable of degrading PE were isolated from this worm’s gut, Enterobacter asburiae YT1 and Bacillus sp. YP1. Over a 28-day incubation period of the two strains on PE films, viable biofilms formed, and the PE films’ hydrophobicity decreased. Obvious damage, including pits and cavities (0.3–0.4 μm in depth), was observed on the surfaces of the PE films using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The formation of carbonyl groups was verified using X-ray photoelectron spectroscopy (XPS) and microattenuated total reflectance/Fourier transform infrared (micro-ATR/FTIR) imaging microscope. Suspension cultures of YT1 and YP1 (108 cells/mL) were able to degrade approximately 6.1 ± 0.3% and 10.7 ± 0.2% of the PE films (100 mg), respectively, over a 60-day incubation period. The molecular weights of the residual PE films were lower, and the release of 12 water-soluble daughter products was also detected. The results demonstrated the presence of PE-degrading bacteria in the guts of waxworms and provided promising evidence for the biodegradation of PE in the environment.
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•Persistent organic pollutants beget adverse effects on environment and ecosystem.•Conventional organic wastewater treatment is highly complex and expensive.•Microalgae-bacteria ...synergy shows several advantages to the economy and environment.•Microalgae-bacteria consortia is a latent wastewater treatment to remove POPs.•Mechanisms involved mainly via biosorption, bioaccumulation and biodegradation.
The litter of persistent organic pollutants (POPs) into the water streams and soil bodies via industrial effluents led to several adverse effects on the environment, health, and ecosystem. For the past decades, scientists have been paying efforts in the innovation and development of POPs removal from wastewater treatment. However, the conventional methods used for the removal of POPs from wastewater are costly and could lead to secondary pollution including soil and water bodies pollution. In recent, the utilization of green mechanisms such as biosorption, bioaccumulation and biodegradation has drawn attention and prelude the potential of green technology globally. Microalgae-bacteria consortia have emerged to be one of the latent wastewater treatment systems. The synergistic interactions between microalgae and bacteria could proficiently enhance the existing biological wastewater treatment system. This paper will critically review the comparison of conventional and recent advanced wastewater treatment systems and the mechanisms of the microalgae-bacteria symbiosis system.
The occurrence and fate of endocrine disrupting compounds (EDCs) in a sewage treatment plant and two industrial wastewater treatment plants from textile and tannery factories were investigated. EDCs ...of interest are 4-nonylphenol, 4-octylphenol, their ethoxylate oligomers (mono- and di-ethoxylates of nonylphenol and octylphenol), bisphenol A, triclosan and steroid estrogens. Target compounds were determined in dissolved fraction, total suspended solids and sludge by employing solid phase extraction and ultrasonication followed by gas chromatography-mass spectrometry. Nonylphenols and oligomers with one or two ethoxy groups were the most abundant compounds in raw wastewater as well as in effluents from all the treatment stages of sewage treatment plant, followed by triclosan and bisphenol A. Steroids were found at very low concentrations. Almost all phenolic EDCs compounds were predominantly associated to suspended solids in influents whereas the dissolved fraction dominated the treated effluents. High removal rates, ranging from 86% to 99%, were observed throughout the whole treatment process. Biodegradation was the main removal pathway of EDCs. Tannery wastewaters exhibited high concentrations of nonylphenolic compounds. This type of wastewaters could pose a significant risk to the aquatic and terrestrial environment.
Landfill leachate concentrate is a type of refractory organic wastewater with high environmental risk. Identification of refractory components and insights into the molecular transformations of the ...organics are essential for the development of efficient treatment process. In this report, molecular compositions of dissolved organic matter (DOM) in leachate concentrate, as well as changes after anaerobic/aerobic biodegradation and coagulation with salts, were characterized using electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). DOM in leachate concentrate were more saturated and less oxidized with more nitrogen and sulfur-containing substances (accounting for 50.0%), comparing with natural organic matter in Suwannee River. Selectivity for different classes of organics during biodegradation and coagulation processes was observed. Substances with low oxidation degree (O/C < 0.3) were more reactive during biodegradation process, leading to the formation of highly oxidized molecules (O/C > 0.5). Unsaturated (H/C < 1.0) and oxidized (O/C > 0.4) substances containing carboxyl groups were preferentially removed after coagulation with Al or Fe sulfate. The complementary functions of biodegradation and coagulation in the treatment of DOM in leachate concentrate were verified at the molecular level. Lignin-derived compounds and sulfur-containing substances in leachate concentrate were resistant to biodegradation and coagulation treatments. To treat leachate concentrate more effectively, processes aimed at removal of such DOM should be developed.
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•Superworms can eat and live well with Styrofoam as sole diet.•Depolymerization of ingested Styrofoam occurred within the superworms’ guts.•Up to 36.7% of ingested Styrofoam was ...mineralized into CO2.•Gut microbiota plays a key role in the biodegradation of PS within the guts.
Polystyrene (PS) is one of the major plastic debris accumulated in environment. Previously, we reported that mealworm (Tenebrio molitor) was capable of degrading and mineralizing Styrofoam (PS foam). This finding arouses our curiosity to explore whether more other insect species have the same capability as mealworms. Here, an insect larva, superworm (Zophobas atratus), was newly proven to be capable of eating, degrading and mineralizing PS. Superworms could live with Styrofoam as sole diet as well as those fed with a normal diet (bran) over a 28-day period. The average consumption rate of Styrofoam for each superworm was estimated at 0.58 mg/d that was 4 times more than that of mealworm. Analyses of frass, using gel permeation chromatography (GPC), solid-state 13C cross-polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy, and thermogravimetric interfaced with Fourier transform infrared (TG-FTIR) spectroscopy, demonstrated that the depolymerization of long-chain PS molecules and the formation of low molecular-weight products occurred in the larval gut. A respirometry test showed that up to 36.7% of the ingested Styrofoam carbon was converted into CO2 during a 16-day test period. The PS-degrading capability of superworm was inhibited by the antibiotic suppression of gut microbiota, indicating that gut microbiota contributed to PS degradation. This new finding extends the PS-degrading insects beyond the species within the Tenebrio genus and indicates that the gut microbiota of superworm would be a novel bioresource for pursuit of plastic-degrading enzymes.
With the benefits of coming at low-cost, being light-weight and having a high formability and durability, conventional plastics are widely used in both industry and daily life. However, because of ...their durability and extensive half-life with poor degradability and the low recycling rate, large amounts of plastic waste are accumulated in various environments, posing a significant threat to organisms and ecosystems. Compared to conventional physical and chemical degradation, biodegradation of plastic might become a promising and environmentally friendly solution for this problem. One of the aims of this review is to briefly describe the impact of plastics (especially microplastics). To facilitate rapid advancements in the area of plastic biodegradation, this paper provides a comprehensive review of the candidate organisms capable of biodegrading plastics and originating from four categories including natural microorganisms, artificially derived microorganisms, algae and animal organisms. In addition, the potential mechanism during plastic biodegradation and associated driving factors are summarized and discussed. Furthermore, the recent biotechnological progress (e.g. synthetic biology, systems biology, etc.) is highlighted as being key for future research. Finally, innovative research avenues for future studies are proposed. Concluding, our review is addressing the practical application of plastic biodegradation and the plastic pollution, thus necessitating more sustainable developments.
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•Plastic pollution poses a huge threat to the environment and organisms.•Biodegradation is a promising disposal method for plastic waste.•Candidate organisms capable of biodegrading plastics were summarized.•Mechanisms of biodegradation of representative conventional plastics were reviewed.•Biotechnology, bioinformatics and computational biology are vital tools for research.
Microplastics (MPs) have been gaining the attention of environmental researchers since the 1960s anecdotal reports of plastic entanglement and ingestion by marine creatures. Due to their increasing ...accretion in aquatic environments, as well as resistance towards degradation, marine litter research has focused on microplastics more recently. In the present study, a relatively new method of biodegradation was implemented for the biodegradation of three structurally different MPs i.e. polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET). Periphytic biofilm was used for this purpose in various backgrounds of carbon sources (glucose, peptone, and glucose and peptone). Biodegradation of MPs was estimated in terms of weight loss. It was observed that the addition of glucose enhanced the biodegradation of MPs by periphyton biofilm for all MPs (from 9.52%–18.02%, 5.95%–14.02% and 13.24–19.72% for PP, PE and PET respectively) after 60 days compared to natural biofilm alone. To the contrary, peptone, and glucose and peptone together, were inhibitory. Biodegradation was further confirmed by morphological changes observed using SEM, FTIR spectra and GPC lent further support to the results whereby new peaks appeared along with reduction in old peaks and decrease in peak intensities. MiSeq sequencing shows that Deinococcus-thermus > Proteobacteria > Cyanobacteria are the dominant phyla in natural biofilms, and their relative abundances increase after the addition of glucose. However, the abundances shifted to Deinococcus-thermus > Cyanobacteria > Firmicutes > Bacteroidetes, when the biofilms were treated with either peptone alone, or with glucose and peptone together. Therefore, the change in biodegradation capability might also be due to the change in the microbial community structures after addition of the C-sources. These experiments provide an innovative approach towards effective biodegradation of MPs using a relatively new environment-friendly method.
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•Immobilized periphytic biofilms were implemented for the biodegradation of MPs.•Glucose proved to be the most effective C-source for effectual MPs' biodegradation.•SEM and FTIR confirm biodegradation showing morphological and structural changes.•MiSeq sequencing shows that C-sources affects microbial community structure.•Periphytic biofilms are eco-friendly entities effectual for MP biodegradation.
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