Biodegradation最新文献

Biodegradation using a synergically integrated system of laccase (E.C. 1.10.3.2) and versatile peroxidase (EC 1.11.1.16) co-immobilized on the polyacrylamide (PAM) hydrogel presents a promising solution for removing endocrine disrupting chemicals (EDCs) like bisphenol A (BPA) from wastewater. In this study, we developed a tailored biocatalyst consisting of a fungal laccase from Pleurotus ostreatus IBL-02 and versatile peroxidase, enzyme cascade co-immobilized covalently on a 7% (w/v) PAM hydrogel, offering high catalytic potential across various pH and temperature ranges. The PAM-VP/Lac structure was analyzed using scanning electron microscopy and Fourier-transform infrared spectrophotometry, revealing improved characteristics compared to free counterparts (FLac and FVP). The optimal pH for FLac, FVP, Lac/VP, and PAM-VP/Lac was 4, 5, 6, and 7, respectively. PAM-VP/Lac exhibited optimal activity at 50–60 °C, higher than FLac, FVP, and Lac-VP. PAM-VP/Lac showed superior operational stability, retaining 99.2% of its activity after eight cycles, with an immobilization efficiency of 78.62 ± 1.15% and activity recovery of 33.71 ± 0.2%. It also demonstrated enhanced thermal stability, with a two-fold increase in half-life at 50–70 °C. Thermodynamic analysis showed significant improvements in stability parameters for PAM-VP/Lac. This system achieved complete BPA degradation within two and a half hr, highlighting its potential for industrial-scale environmental remediation.

Emerging contaminants such as persistent organic pollutants, perfluorinated compounds, and microplastics pose unparallel challenges to environmental health and current remediation techniques. Microbial biosurfactants, biodegradable compounds produced by microorganisms, have gained attention as eco-friendly alternatives for degrading recalcitrant pollutants. Unlike traditional chemical surfactants, biosurfactants offer the dual benefit of being derived from renewable resources while enhancing the solubility and bioavailability of hydrophobic contaminants. This review is novel in its comprehensive exploration of microbial biosurfactants as a one-step solution for tackling the most persistent environmental pollutants. It introduces recent advancements in metabolic engineering and alternative fermentation strategies that have significantly improved biosurfactant production. Furthermore, the review critically examines the current limitations, including high production costs and complex downstream processing, and proposes cutting-edge approaches to overcome these barriers, such as the use of low-cost feedstocks and integrated bioprocessing techniques. Beyond their established uses, this review also sheds light on their untapped potential in heavy metal removal and microplastic degradation areas that have received little attention. By emphasizing these novel applications and outlining pathways for large-scale production, this review offers valuable insights into how biosurfactants could play a transformative role in sustainable environmental remediation.

Many herbicides used extensively to manage weeds and protect economically important crops contain glyphosate (GP) as their main ingredient, which contaminates ecosystems when it spreads from the soil into the surrounding environment. This study evaluated the ability of two fungal strains to remove GP at a microcosm scale. The strains, Aspergillus oryzae AM2 and Mucor circinelloides 166, were tested on their own and in mixed cultures. The microcosms were conditioned at 30 or 70% field capacity (FC), and contaminated with 5000 or 15,000 mg kg⁻¹ GP. The native microbial communities played a crucial role in the dissipation of the herbicide. At the end of the incubation (60 days), they had achieved removal percentages above 95% in most treatments. The exceptions were the microcosms subjected to hydric stress (30% FC) and contaminated with 15,000 mg kg⁻¹ GP, in which the co-cultures outperformed the native microbial species (≥ 80 vs 33% removal, respectively). An increase in AMPA (aminomethylphosphonic acid), the main metabolite of GP degradation, was usually detected after 60 days, which indicates that biodegradation may have been one of the main mechanisms involved in the removal of the herbicide. These results provide information about the potential of two mixed fungal cultures (containing species that are native to agricultural soils) to remove GP under stressful conditions.

Urbanization has led to heavy metal contamination of dredged sediments, posing severe environmental and health risks. This study investigated the efficacy of Bacillus subtilis-bioremediation and reuse Heavy Metal contaminated sediment as construction material. Recognizing the limitations of conventional calcium chloride, alternative calcium sources for enhanced remediation were explored. The results demonstrate that utilizing calcium hydroxide (0.625 M) as a cementing reagent resulted in optimal compressive strength while minimizing heavy metal leaching. A substantial reduction in leachability: 97.8% for cadmium, 92% for nickel, and 98% for zinc, was observed as determined by USEPA Method 1311. Sequential extraction procedure analysis revealed the effective immobilization of heavy metals within the sediment matrix, primarily through their conversion to metal carbonates and their association with organic matter. This eco-friendly bioremediation approach, combining bacterial activity with sustainable cement stabilization, presents a promising remediation strategy for contaminated dredged sediments, enabling the safe reuse in engineering applications.

The mineral element levels in avocado oil processing byproducts were evaluated to make inferences about these byproducts’ biodegradability behaviour. The mineral assays were determined using ICP-OES methods. Literature was also reviewed to understand how different mineral elements detected in substrates could impact biogas production under anaerobic digestion (AD) conditions. It was noted that there is no consensus among scholars on absolute mineral requirement levels for optimal digester performance since digesters use different substrates operating under varying conditions in most cases. When mineral elements are below certain values, the digester operates sub-optimally. When certain mineral levels are exceeded in digesters, the minerals become toxic to the AD microorganisms and destabilise the biogas digester. Only Zn levels across all avocado oil processing byproducts and K levels in cold-pressed decanter wastewater (CDW) exceeded the toxic level limits pegged at 1 mg/L and 3000 mg/L respectively. These may therefore need corrective action to avoid potential inhibition of the AD process. Mineral assays that seemed adequate and required no supplementation or detoxification were K, P, Fe, Cu, Se and Cr across the studied byproducts. All the other elements (excluding the Hg, As and Cd which are toxic) may require supplementation for optimal digester performances when using avocado oil processing byproducts as biogas digester substrates. However, these inferences may be affected by issues of mineral bioavailability which is a substrate-dependent phenomenon. Mercury cadmium and arsenic are naturally toxic to microorganisms and must be removed or detoxified if detected in substrates. The current study indicates the significance of mineral elements’ characterisation in explaining and potentially guiding the optimisation of substrate biodegradation to biogas.

The biocompatibility and degradability of poly hydroxybutyrate (PHB) make it an important material for food packaging. Poly hydroxybutyrate (PHB) is less flexible than typical polymers and more brittle due to its strong crystalline structure and low melting temperature. Furthermore, while poly hydroxybutyrate (PHB) does not have antibiotic capabilities, the inclusion of additional materials such as phycocyanin can boost its antibiotic and antifungal effects. This research focuses on increasing the yield of phycocyanin from the microalgae Spirulina and selecting an optimal green extraction method, and on the other hand, on the synthesis of biodegradable polymers derived from poly hydroxybutyrate in combination with phycocyanin for food packaging applications. This study shows that higher wavelengths of light, an optimal temperature of about 33 degrees Celsius, pH adjustments using changing the composition of the culture medium by increasing metal compounds and using non-invasive, green and inexpensive extraction methods significantly increase biomass production and phycocyanin yield, which in previous research only one to two of the above parameters were considered for protein extraction, which this study has addressed more comprehensively. Also, the synthesis of biodegradable polymers with special properties for packaging applications, including green polymer poly hydroxybutyrate, phycocyanin and beeswax, which has not been done in previous research on modifying the properties of poly hydroxybutyrate using these two research materials, so that with 60% phycocyanin in combination with poly hydroxybutyrate, they show promising properties for food packaging applications. By examining the physical and chemical properties, thermal strength and degradability of the polymer compared to pure poly hydroxybutyrate, it shows further improvement in addition to antibiotic and antifungal properties.

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Chromium (Cr⁶⁺) waste poses a hazard as it leads to imbalanced ecosystems and severe health issues. Although, it is widely associated with many industries. Chromium (Cr⁶⁺) reduction by the immobilized cells of Paenibacillus taitungensis strain MAHA-MIE was optimized using response surface methodology (RSM) and artificial neural networks (ANN). The RSM-Box-Behnken Design (BBD) was selected to investigate the effects of chromium (Cr⁶⁺) concentration, alginate concentration, gellan gum concentration, bead size, and the number of beads on chromium (Cr⁶⁺) reduction rate. Experimental data from the BBD was used to train a feed-forward, multilayer artificial neural network (ANN). Results show that the ANN model outperformed the response surface methodology (RSM) based on actual and predicted data, with lower errors and a higher R² value. The ANN model predicted the optimum points as follows: 155 ppm chromium (Cr⁶⁺), 0.32% alginate, 0.65% gellan gum, 0.5 cm beads, and 27 beads. The validation confirmed a high agreement of chromium (Cr⁶⁺) reduction rate between the validation value (99.00%) and the predicted value (99.99%), with the lowest deviation at 0.1%. Modeling abilities were compared using statistical criteria, including Root Mean Square Error (RMSE), Standard Error of Prediction (SEP), Relative Percent Deviation (RPD), and regression coefficients (R²). The ANN analysis showed the high predictive performance, with high R² (0.9911), low SEP (0.45%), RPD (1.88), and RMSE (1.37%). The results of this study approved that alginate-gellan gum immobilized cells of Paenibacillus taitungensis strain MAHA-MIE could be effectively used for the handling of chromium (Cr⁶⁺).

Microorganisms are very well known potential sources of many novel metabolites and biosurfactants (green molecules). Biosurfactants are biobased molecules which are synthesized by bacteria, yeasts, fungi and actinomycetes. These biomolecules have emerged as multifunctional biomolecules of the 21st century due to their remarkable functional properties like low toxicity, enhanced effectiveness, selectivity, stability, high biodegradability and eco-friendly nature. These characteristics enable them to remain high effective under extreme conditions and play a significant role in environmental protection. Biosurfactants play a pivotal role in bioremediation technologies, offering an environmentally sustainable alternative for cleaning up contaminants. Their unique ability to reduce interfacial tension in liquids enables them to perform crucial functions such as biodegradation, emulsification, foam formation, surface activity, washing performance and detergent formulation. These versatile properties make biosurfactants invaluable across various industries, including environmental remediation, pharmaceuticals, agriculture and cosmetics. This review discusses the microbial production, characterization, industrial applications and ecological significance of biosurfactants. By highlighting their impact in the bioremediation of contaminants, this article underscores the potential of biosurfactants in advancing green technologies and addressing global environmental challenges.

Polystyrene (PS), a substance that constitutes a significant portion of plastic waste, has resulted in environmental pollution and adverse health effects. Biodegradation and chemical transformation of PS are limited. However, biodegradation is one alternative way to reduce plastic pollution. This research aims to select plastic-degrading bacteria and produce exopolysaccharides (EPS) from plastic waste. Among the marine plastic waste at Chala tat Beach (Songkhla, Thailand), 35 rod-shaped and Gram-positive bacteria were found. The selected strains that exhibited the highest optical density (OD) at 600 nm were CHB1.5, CHD2.2, and CHC3.2. The efficiency of EPS production was tested and showed that CHB 1.5 could produce the maximum amount of EPS (13.47 ± 0.10 g/L) with a significant difference. After four weeks of plastic breakdown, CHB 1.5 had the highest total count (4.03 ± 0.02 Log CFU/mL), followed by CHD2.2 and CHC3.2 (3.99 ± 0.12 and 3.96 ± 0.02 Log CFU/mL, respectively). CHB 1.5 was also examined to use PS foam as a carbon source in modified Mineral Salt Medium for EPS production, with an EPS yield of 1.36 ± 0.08 g/L in week 4. The presence of amides I, polysaccharides, benzene rings, and hydroxyl groups (O–H) was detected by Fourier transform infrared spectroscopy. The Scanning Electron Microscope images confirmed the adherence of the CHB1.5 strain and EPS formation on the plastic sheet. In conclusion, the strain CHB1.5 showed promising potential for degrading PS plastic and producing EPS. Its qualities could be utilized in the future, as well as contribute to the reduction of plastic pollution in the environment in an eco-friendly way.

Iron minerals and the coupling of electron shuttle media can effectively overcome the problem of the insolubility of iron minerals and the higher cross-medium resistance consequently to enhance the bio-reduction rate of Cr(VI) by dissimilatory metal-reducing bacteria (DMRB). This study explored the potential synergistic enhancement of Cr(VI) bio-reduction by Shewanella putrefaciens CN32 in combination with three iron minerals (ferrihydrite, goethite and hematite) and riboflavin (RF). The addition of RF accelerates the transfer of electrons from bacterial cells to Fe minerals, which in turn promotes the production of large amounts of Fe(II). The results indicated that compared to the control group, the Cr(VI) reduction rates in the CN32/RF/hematite, goethite, ferrihydrite systems increased to 93.03%, 91.07%, and 86.83%, hematite was capable of generating 2.24 mM Fe(II) due to its stable structure and efficient synergy with riboflavin. Enhancement factor(EF) was used to quantify the synergistic effect of RF and iron minerals on the bio-reduction of Cr(VI). At all three reaction times, the F_EF (K_CN32+RF+Fe/K_CN32) of three Fe(III) minerals were all greater than 1. XPS analysis revealed that the primary reduction products of Cr(VI) were identified as Cr(CH₃C(O)CHC(O)CH₃)₃, Cr₂O₃ and Fe(II)-Cr(III) hydroxide, were predominantly deposited on both bacterial and mineral surfaces, thereby influencing their synergistic interactions. This study unveiled the dynamic synergistic mechanism changes of Cr(VI) reduction in different iron minerals environment,which offers new ideas for the remediation of Cr(VI) pollution.

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