Biodegradation最新文献

Cr (VI) is highly toxic, persistent, and non-biodegradable in soil–water systems, while fluoride levels in many aquatic environments are rising to similarly hazardous concentrations. This study investigates the capacity of Bacillus albus strain SSAU-9, isolated from the River Ganges and identified by 16S rRNA gene sequencing- to remove Cr (VI) in both the absence and presence of fluoride. Several parameters (inoculum size, salinity, pH, external electron donor, and initial Cr (VI) and fluoride concentrations) were optimized to maximize removal efficiency. Surface morphological changes were visualized by scanning electron microscopy (SEM), and functional groups involved in adsorption-reduction were identified via FTIR spectroscopy. Kinetic analysis showed that Cr (VI) reduction followed a pseudo-second order model; the Webber-Morris intraparticle diffusion model further described mass-transfer control at 50 ppm Cr (VI) only. The Langmuir and Redlich-Peterson isotherm models provided the best fit to the experimental data, indicating monolayer adsorption behaviour. The Dubinin- Radushkevich (D-R) isotherm also showed a good fit, but only in the absence of fluoride. Phytotoxicity assays with mustard (Brassica juncea) seeds demonstrated that treated effluents were non-inhibitory, confirming the biosafety of the process. These results highlight the Bacillus albus (SSAU9) as an efficient, environment friendly agent for Cr (VI) detoxification even under fluoride co-contamination, offering a practical bioremediation strategy for mixed-pollutant systems.

The actinomycetal consortium plays a key role in lignocellulose degradation and offers promising applications in sustainable biomass conversion and biotechnology. A thermotolerant lignocellulolytic actinobacterial consortium, composed of strains A5 (Streptomyces cavourensis strain QT227), C13 (Streptomyces parvus 5–94 gene), and C17 (Streptomyces cavourensis strain SIF3) isolated from an arid region in Madinah, Saudi Arabia, demonstrates significant potential in sustainable biomass conversion and biotechnology. This consortium effectively degrades various cellulosic substrates, including bagasse (SB), corncob (CC), and palm leaves (PL), making it suitable for biorefinery processes. Specifically, the consortium achieved saccharification percentages of 159% for CC, 96.2% for SB, and 37.02% for PL. Correspondingly, the utilization percentages for these substrates were 37% for CC, 11% for SB, and 17% for PL. The consortium’s crude extract exhibited total cellulase activities of 1.34 U/mL on CC, 1.51 U/mL on SB, and 0.42 U/mL on PL. The kinetic parameters of CMCase activity were determined for individual strains A5, C13, and C17, with affinity (K_m) values of 3.64, 1.28, and 1.56 mM, respectively. Therefore, these strains represent promising candidates for industrial applications, offering the production of thermostable cellulases and efficient lignocellulosic biomass conversion without the need for costly and environmentally impactful chemical or thermal pretreatments.

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In the search for sustainable alternatives and substitutes to overcome plastic pollution, polyhydroxyalkanoates (PHA) stand out as the gold standard. The very fact that PHA are microbially produced from renewable carbon sources, biodegraded by microbial action, and possess the beneficial properties of over 50% of the world’s plastics has caught the attention of a wide range of producers, converters, brand owners, and policy makers with a view to replace conventional fossil-based plastics with these natural materials. PHA are readily biodegraded by the enzymatic toolbox of living organisms, aligning with the principle of natural circularity. Over 150 different monomeric building blocks of PHA have been identified, leading to a wide variety of naturally accessible PHA biopolyesters with diverse properties that include thermoplastic and crosslinkable polymers for single use and durable uses for packaging and personal care and as paints, coatings and adhesives, and as fibers for fabrics and textiles. The type of monomer and microstructure, as well as the environment, play important roles in their production and biodegradation. This comprehensive paper reviews the degradability of commercially available and other PHA types with varying microstructures in fresh water, sea water, soil, as well as in home and industrial composting and anaerobic conditions. Unlike previous reviews the authors integrate information from diverse biodegradation studies and provide a holistic view and understanding of the biodegradability of the PHA biopolymer family in nature and in industrial environments.

Numerous physical, chemical, and biological treatment strategies for removing pollutants from wastewater have been studied for several decades. Nevertheless, these methodologies possess some constraints. Since the early 2000s, membrane-based hybrid technology has been increasingly recognized and adopted due to advancements in manufacturing and casting methods, as well as membrane modification techniques. Membrane-based treatment technology, coupled with other semi-renewable treatment technologies such as advanced oxidation processes (photocatalysis), bioreactors, and hybrid membrane bioreactors, is adopted as an substitute to conventional wastewater treatment due to its ease of operation and superior performance. In this study, a thorough examination of these attractive hybrid technologies is conducted. Additionally, this study also assorted the stand-alone methods and techniques associated with membrane reactors, photocatalytic membrane reactors (PCMRs), and membrane bioreactors (MBRs). MBRs and PCMRs deliver effective and sustainable wastewater treatment by integrating biological processes or photocatalysis with membrane filtration, yielding high-quality effluents suitable for reuse. The benefits of these renewably derived integrations include their compact design, diminished sludge generation, and capacity for water recycling. However, fouling remains significant challenges, primarily resulting from foulant adherence, pore clogging, creation of a cake layer, and the temporal alogn with spatial changes in the structure of foulants are identified as key processes that contribute to fouling in PCMRS. The interaction of bacteria, membrane surfaces, and the secretion of extracellular polymeric substances are responsible for biofouling in MBRs. Incorporating AOP (photocatalysts) into MBR membranes presents a novel approach to mitigate fouling. The integration of catalysis and membrane filtration systems can stretch membrane lifespan, eliminate membrane surface contamination, and decompose organic pollutants simultaneously, thereby enhancing wastewater treatment efficiency. This study offers a thorough examination of contemporary research regarding membrane modification utilizing photocatalysts in MBR systems, emphasizing the prevailing challenges and future opportunities in this domain. Notwithstanding these possible benefits, studies aimed at enhancing MBR membrane effectiveness via photocatalysis are limited. To preserve the sustainability of this technology, it is imperative to consider key factors, including reactor configuration, kinetics, fouling processes, economic viability, and scaling challenges.

Chlorpyrifos is an organophosphorus pesticide which is most widely used in agricultural farmlands to control insect pests. Besides protecting crops from pests, chlorpyrifos enters into soil and water bodies, and pose serious health hazards to living organisms. Biodegradation involves the use of microorganisms to degrade pesticides into non-toxic substances. In the present study Aspergillus niger TC1 showed maximum degradation of chlorpyrifos. The isolate was able to tolerate 500 ppm concentration of chlorpyrifos and substantially degraded 400 ppm concentration of chlorpyrifos. Based on GC–MS analysis, Aspergillus niger TC1 degraded chlorpyrifos into 2,4 Bis (1,1 dimethyl ethyl) phenol, a fuel additive compound. Based on HPLC analysis, the percentage of chlorpyrifos degradation was calculated to be 95.2%. A temperature of 27 ℃ and pH 7 were identified as optimum conditions for maximum degradation of chlorpyrifos. The isolate showed positive results for Indole-3-Acetic Acid and ammonia production, along with phosphate and zinc solubilizing plant growth-promoting assays. Also, the isolate showed increased seed germination along with increased shoot and root length in the seed germination and pot assay. Further, Aspergillus niger TC1 showed significant biocontrol potential against Rhizoctonia solani and Fusarium oxysporum. The isolate showed significant degradation of chlorpyrifos along with plant growth promotion and biocontrol potential. While chlorpyrifos degradation by Aspergillus niger has been previously reported, this study is the first to comprehensively assess a single strain for its combined abilities in chlorpyrifos degradation, plant growth promotion, and biocontrol potential. The study shows that Aspergillus niger TC1 can be efficiently used for sustainable agriculture.

Graphical Abstract

The conversion of “linear” conventional wastewater treatment plants (WWTP) into “circular” biorefineries offers an eco-friendly and cost-effective method of extracting valuable resources from waste. Microbiome of sewage sludge (SS) enable the fermentation of organic contaminants, producing volatile fatty acids that can be further used to produce polyhydroxyalkanoates (PHAs)—essential bioplastic precursors that can replace petroleum-based plastics. Optimizing PHA production requires understanding the relationships between SS microbiota structure and the operational parameters. Thus, this study examines how organic loading rate (OLR) influences PHA production in a selection sequencing batch reactor (S-SBR) within a pilot-scale WWTP collecting wastewater from various facilities at the University of Palermo campus. The S-SBR, enriched with PHA-producing microorganisms, was fed by a synthetic VFA mixture under two OLR conditions and subjected to a feast-famine (F/F) cycle. The results demonstrated that high OLR level increased PHA yield and promoted the selection of bacteria involved in organic matter degradation and PHA production. Specifically, a OLR of 1.3 g COD L⁻¹ d⁻¹ resulted in PHA productivity reaching 20% of biomass content, compared to 15% at a lower OLR of 0.8 g COD L⁻¹ d⁻¹. Indeed, metaxonomics revealed structural changes in the SS microbiota, with higher OLR driving a selection for PHA-producing bacteria belonging to Proteobacteria phylum, mainly the Rhodocyclaceae family—whose members are known for PHA production capabilities—showing increased abundance in comparison to the starting and the lower OLR conditions. Thus, shifts in microbiota structure linked to OLR variation may account for the differences in PHA yields observed under realistic conditions, thereby supporting future research toward the development of full-scale biorefinery systems.

Plastics are synthetic materials that have transformed society in a lot of ways, yet widespread use of these materials has caused a staggering amount of pollution in the environment. Among these plastics, polypropylene and low-density polyethylene are two of the most used plastics for packaging globally. Currently, only two enzymes were characterized for low density polyethylene degradation while no specific enzymes have been confirmed to degrade polypropylene. In this study, one bacterial isolate from landfill soil was assessed for potential polypropylene and low-density polyethylene degradation abilities using gravimetric methods by measuring the initial and final weight of plastic films. Results showed that after 60 days of incubation, a total decrease of 8.04% was observed for polypropylene plastics and 3.13% for low density polyethylene plastics. Whole genome sequencing using Illumina Nextseq™ 1000 generated a total number of 3,746,011 assembled base pairs for Isolate 1 using SPAdes. Phylogenetic tree construction using the Bacterial Pan-Genome Analysis (BPGA) tool revealed close relation of the isolate to Arthrobacter sp. Analysis of the annotated whole genome sequence against the Plastic database revealed 11 putative protein coding genes that encode enzymes with potential to break down plastics.

In bacteria, the biodegradation of glyphosate involves the aminomethylphosphonic acid (AMPA) pathway and the C-P lyase pathway. In the present study, the pathway involved in biodegradation of glyphosate by isolate Stenotrophomonas maltophilia GP-1 was elucidated. Sarcosine and glycine were detected in the cell-free extracts of S. maltophilia GP-1 using thin layer chromatography and LC–MS/MS indicating the role of a glyphosate-specific C-P lyase. However, aminomethylphosphonic acid (AMPA); the key intermediate of glyphosate degradation was found to be absent. The C-P lyase activity (0.4 U) was determined in terms of the release of Pi from glyphosate breakdown. The key genes involved in C-P lyase and AMPA pathway are (i) phnJ and sox, and (ii) goxB (glyphosate oxidoreductase), respectively. Using polymerase chain reaction, amplicons of expected sizes for individual genes encoding for components of C-P lyase were obtained suggesting the presence of phn operon. Subsequently, in the genome sequence of S. maltophilia GP-1, the entire phn operon and sox gene were found to be present. When the expression of key genes of C-P lyase pathway phnJ and sox was studied using qRT-PCR, higher expression of phnJ (tenfold) was observed in the absence of phosphate, while the expression of sox (5.5 fold) remained unaffected. Thus, the presence of phosphate in the environment affects the catabolism of glyphosate through the interplay between phn operon and Pho regulon. The present study, is the first report on the existence of the C-P lyase pathway and the genes encoding the components of the above pathway in a strain of S. maltophilia.

The persistent inefficiency of landfill operations and plastic waste management in South Africa has intensified environmental contamination, underscoring the urgent need for innovative bioremediation strategies. This study aimed to identify and evaluate fungal isolates from landfill soils for their ability to biodegrade polyethylene (PE), thereby contributing to sustainable plastic waste management solutions. A total of eighteen fungal isolates were recovered from local landfill soils using plastic-enriched soil dilution techniques. These isolates were screened for PE biodegradation by incubating pre-weighed polyethylene strips with each fungal culture for 45 days at ambient temperature. Biodegradation efficiency was assessed through gravimetric weight loss, while structural alterations in the polymer matrix were examined using fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Several isolates demonstrated significant PE degradation, including the novel PE degraders Arthrographis kalrae SP5INT, Lecanicillium coprophilum SP7MK, and Didymosphaeria variabile SP11INT, reported here for the first time. Penicillium chrysogenum SP17MK and Engyodontium album SP3MK showed the highest degradation rates, achieving over 20% weight loss. FTIR analysis revealed the appearance of carbonyl groups (~ 1700 cm⁻¹) and a reduction in characteristic PE peaks at 719 and 1472 cm⁻¹, suggesting oxidative degradation. SEM imaging further confirmed surface erosion and structural disintegration of the polymer, supporting the biochemical evidence of degradation. These findings represent the first report of novel fungal species capable of degrading PE in South African landfill soils and significantly expand the known diversity of plastic-degrading fungi. This work highlights South Africa's emerging role in microbial bioremediation research and provides a foundation for the development of locally relevant, biologically based plastic waste management strategies.