Biodegradation最新文献

1,2,3-Trichloropropane (1,2,3-TCP) is a suspected human carcinogen and a persistent emerging contaminant in groundwater and drinking water. 1,2,3-TCP was historically used as a solvent for cleaning and maintenance, paint and varnish removal, and degreasing, but its sources also include chemical manufacturing processes and application of soil fumigants. The California Department of Public Health (CDPH) has established a state maximum contaminant level (MCL) of 0.005 µg/L for 1,2,3-TCP in drinking water and a public health goal (PHG) of only 0.0007 µg/L. The primary research question addressed herein was whether aerobic or anaerobic cultures can potentially be applied for treatment of 1,2,3-TCP, and whether bacteria are capable of biodegrading 1,2,3-TCP to below the California MCL. During this study, we identified cultures capable of biodegrading 1,2,3-TCP via reductive dehalogenation as well as through aerobic cometabolic processes. Follow-on studies with organisms capable of aerobically degrading 1,2,3-TCP included kinetic modeling and assessment of concentrations of 1,2,3-TCP achievable via biodegradation. 1,2-Dichloropropane (1,2-DCP) is sometimes found co-mingled with 1,2,3-TCP, so studies also were conducted to quantify rates of 1,2-DCP biodegradation alone and when present together with 1,2,3-TCP. The dehalogenating consortium CPD-2, which was isolated from sewage sludge and includes Dehalococcoides, Dehalobacter and Dehalobium spp., biodegraded both 1,2,3-TCP and 1,2-DCP. Anaerobic 1,2,3-TCP degradation resulted in a transient production of 1,2-DCP followed by 1-chloropropane (1-CP), which accumulated nearly stoichiometrically and then slowly degraded, indicating complete dechlorination of 1,2,3-TCP by this mixed culture. Two different cometabolic pure cultures, Rhodococcus ruber ENV425 and Rhodococcus aetherivorans ENV493 degraded 1,2,3-TCP after growth on propane or isobutane. Importantly, both bacteria were capable of degrading 20 µg/L of 1,2,3-TCP to < 0.005 µg/L after growth on isobutane. Experiments conducted with ENV425 and ENV493 to quantify relevant kinetic parameters after growth on isobutane suggested that ENV425 facilitated more rapid 1,2,3-TCP degradation than ENV493. Both strains were observed to degrade 1,2-DCP much faster than 1,2,3-TCP when present individually or in mixtures. The data from this study suggest that cometabolic treatment of 1,2,3-TCP, or mixtures of 1,2-DCP and 1,2,3-TCP, is feasible and that relevant regulatory concentrations are achievable using this process. Similarly, anaerobic treatment may be possible at locations with higher concentrations or where 1,2,3-TCP occurs with other chlorinated solvents.

The current research explores the microbial synthesis of manganese oxide nanoparticles from Stenotrophomonas sp. their characterization, and subsequent application against the degradation of fluorene hydrocarbon. There are several physical and chemical strategies to treat polycyclic aromatic hydrocarbons. But Nano-bioremediation is most effective and economical in degrading the polycyclic aromatic hydrocarbons. Various structural, crystalline, and optical characteristics of manganese oxide nanoparticles were investigated. Manganese oxide nanoparticle formation is indicated by a distinctive peak at 248 nm with a 3.5 eV band gap. X-ray diffraction demonstrated that manganese oxide nanoparticles had a crystalline grain size of 6.3 nm. Scanning and high-resolution transmission electron micrographs reveal the agglomerated spherical form. Manganese and oxygen existence and purity were validated with EDAX analysis. This study investigated the optimizational degradation of fluorene hydrocarbon using response surface methodology. The degradation of fluorene hydrocarbon was examined using Fourier Transform Infrared Spectroscopy and Gas chromatography–mass spectrometric analysis. Trigonella foenum-graecum was used in the phyto-toxicity study of fluorene degradation by microbial-synthesized manganese oxide nanoparticles.

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Current humic substances (HSs) production for bioremediation suffers from low yields and inconsistent functionality. The present work examined humic acid (HA) and fulvic acid (FA) extraction from compost treated with (1) molasses alone (CK), (2) Pseudomonas aeruginosa (T1), (3) Bacillus firmus (T2), and (4) a synergistic combination of molasses and both microbes (T3). The humic substances (HSs) were extracted using the standard alkaline extraction followed by the acid precipitation method. HSs were characterized over a period of 75 days using inductively coupled plasma mass spectrometry (ICP-MS) for heavy metals, Fourier-transform infrared spectrophotometer (FTIR), UV–Vis spectrophotometer, and X-ray photoelectron spectroscopy (XPS) for functional groups, along with elemental analysis. Results demonstrated that T3 significantly enhanced HA yield (4.76 g/kg) with optimal C/N (1.06) and E4/E6 (4.33) ratios, while T1 yielded the highest FA (2.18 g/kg) by day 60. In the HA fraction, T3 significantly reduced HM concentrations of Cd by 73%, Zn by 68%, and Fe by 45% in HA fractions, while revealing Cu and Mn bioavailability, providing a novel insight for targeted remediation indicating enhanced stabilization. Functional group engineering was validated by XPS, which indicated that T3 is uniquely enriched with redox-active groups, specifically carbonyl (C = O, 531.99 eV) and hydroxyl (C–OH, 532.96 eV). These groups facilitate the binding of nitrogen/sulfur species (amide: 400.24 eV; thiol: 163.45 eV), thereby enhancing bioremediation processes. Elemental analysis revealed enriched carbon (HA: 55.04%; FA: 56.24%) and oxygen (HA: 31.87%; FA: 31.73%), alongside elevated nitrogen, sulfur, and hydrogen. The T3 synergy demonstrates immediate applicability in the rehabilitation of contaminated soil.

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.

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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.