Biodegradation Process Research Articles

Arctic's hidden hydrocarbon degradation microbes: investigating the effects of hydrocarbon contamination, biostimulation, and a surface washing agent on microbial communities and hydrocarbon biodegradation pathways in high-Arctic beaches

BackgroundCanadian Arctic summer sea ice has dramatically declined due to global warming, resulting in the rapid opening of the Northwest Passage (NWP), slated to be a major shipping route connecting the Atlantic and Pacific Oceans by 2040. This development elevates the risk of oil spills in Arctic regions, prompting growing concerns over the remediation and minimizing the impact on affected shorelines.ResultsThis research aims to assess the viability of nutrient and a surface washing agent addition as potential bioremediation methods for Arctic beaches. To achieve this goal, we conducted two semi-automated mesocosm experiments simulating hydrocarbon contamination in high-Arctic beach tidal sediments: a 32-day experiment at 8 °C and a 92-day experiment at 4 °C. We analyzed the effects of hydrocarbon contamination, biostimulation, and a surface washing agent on the microbial community and its functional capacity using 16S rRNA gene sequencing and metagenomics. Hydrocarbon removal rates were determined through total petroleum hydrocarbon analysis. Biostimulation is commonly considered the most effective strategy for enhancing the bioremediation process in response to oil contamination. However, our findings suggest that nutrient addition has limited effectiveness in facilitating the biodegradation process in Arctic beaches, despite its initial promotion of aliphatic hydrocarbons within a constrained timeframe. Alternatively, our study highlights the promise of a surface washing agent as a potential bioremediation approach. By implementing advanced -omics approaches, we unveiled highly proficient, unconventional hydrocarbon-degrading microorganisms such as Halioglobus and Acidimicrobiales genera.ConclusionsGiven the receding Arctic sea ice and the rising traffic in the NWP, heightened awareness and preparedness for potential oil spills are imperative. While continuously exploring optimal remediation strategies through the integration of microbial and chemical studies, a paramount consideration involves limiting traffic in the NWP and Arctic regions to prevent beach oil contamination, as cleanup in these remote areas proves exceedingly challenging and costly.

Removal mechanisms of pentachlorophenol in a horizontal-flow anaerobic immobilized biomass reactor (HAIB) inoculated with an indigenous estuarine sediment microbiota: adsorption and biodegradation processes.

Pentachlorophenol (PCP) is a highly toxic and carcinogenic compound with significant environmental impact, necessitating effective treatment technologies. This study evaluates PCP removal mechanisms, including adsorption and biodegradation, during the startup of a horizontal-flow anaerobic immobilized biomass reactor (HAIB), and examines the impact of PCP concentration on microbial diversity using denaturing gradient gel electrophoresis (DGGE). The primary mechanism for PCP removal in the HAIB was adsorption, effectively described by the Freundlich isotherm model. Adsorption efficiency ranged from 86 to 104% for PCP concentrations between 0.2 and 5.0mg/L, and 46% to 64% for concentrations between 0.098 and 0.05mg/L. Additionally, PCP degradation intermediates such as 2,3-DCP and 2,6-DCP were detected, indicating that biodegradation also occurred in the HAIB. Organic matter degradation averaged 81 ± 9%, and methane content in the biogas averaged 46 ± 9%, confirming the anaerobic process. No inhibition of microbial activity was observed due to PCP toxicity, even at a PCP load of 5mg PCP/g STV per day. While the archaeal community showed only slight changes, with similarity coefficients ranging from 88 to 95%, the bacterial community was significantly affected by PCP, with similarity coefficients ranging from 18 to 50%. Bacterial groups were responsible for the initial PCP degradation, while the archaeal community was involved in metabolizing the resulting byproducts. The use of indigenous inoculum from the Santos-São Vicente estuary demonstrated its potential for effective PCP removal. Polyurethane foam proved to be an effective support material, enhancing the adsorption process and reducing PCP toxicity to the microbial consortium. This study provides valuable insights into PCP adsorption and biodegradation mechanisms in HAIB, highlighting the effectiveness of indigenous inoculum and polyurethane foam for PCP removal.

Biodegradation Study of Food Packaging Materials: Assessment of the Impact of the Use of Different Biopolymers and Soil Characteristics

In this article, the relationship between the properties of different membranes (agar, chitosan, and agar + chitosan) and biodegradability in natural and sterilized soil was investigated. The membranes under investigation exhibited variations in the biodegradation process, a phenomenon closely linked to both the soil microbiota composition and their water affinity. Higher solubility in water and greater swelling tendencies correlated with shorter initiation times for the biodegradation process in soil. Overall, all tested membranes began biodegradation within 14 days, as assessed through thickness and morphological analysis parameters, demonstrating a superior degradation rate compared to low-density polyethylene films.

Analysis of long-term MSW settlement based on field data measured at two closed landfills

Waste settlement characteristics vary depending on waste composition, physical properties, waste management operations, and time. In this study, the post-closure waste settlement behavior was analyzed using field data measured at two closed municipal solid waste landfills in Korea, for 23 and 5 years after landfill closure. The long-term waste settlement data was analyzed to derive a time-varying long-term compression ratio (CLT) that was consistent with modeled biodegradation processes. A statistical assessment of the field data was conducted to examine the relationship between CLT and several factors that may affect the observed settlements. The CLT of Landfill #1 and #2 was found to vary between the two landfills that had differences in the percentage of organic matter (B0), total unit weight (γwaste), and moisture content (w) due to changes in waste management policies.

Increasing LNAPL density and viscosity are indicators of Natural Source Zone Depletion

Natural source zone depletion (NSZD) acts to reduce the mass and/or toxicity of light non-aqueous phase liquids (LNAPL) in the shallow subsurface. Several indirect measurement techniques are commonly used to estimate LNAPL mass depletion based on CO 2 generation by hydrocarbon mineralisation, heat production by exothermic biodegradation processes, and sub-surface gas concentration gradients. This paper presents data on LNAPL density and viscosity and shows changes that result from NSZD processes. Increasing trends in LNAPL density and viscosity were observed that provided a qualitative line-of-evidence for NSZD. When LNAPL density and viscosity were combined with contemporaneous LNAPL chemistry analysis it was possible to correlate changes in the physical properties to depletion of alkanes from the LNAPL in a manner that would inform a quantitative NSZD assessment. LNAPL density and viscosity measurements are relatively cheap and reproducible, and increasing trends in LNAPL density and viscosity provide additional lines-of-evidence for NSZD.

Biodegradation kinetics of petroleum hydrocarbons by composite microbial agents combined with slow release agents in groundwater

Bioremediation of oil-polluted groundwater is often limited by the properties of oil and oligotrophic conditions in the groundwater environment, sometimes causing long biodegradation times and low biodegradation efficiencies. To clarify this issue, dominant oil-degrading bacteria and slow release agents (SRAs) were prepared and mixed to enhance the biodegradation of different oil samples and hydrocarbons in the groundwater environment. The biodegradation efficiencies of diesel oil, Venezuelan crude oil, and Jibei heavy crude oil by the consortia of bacteria increased from 33.66 %–52.21 % to 34.90 %–63.43 % when optimal nitrogen (N) and phosphorus (P) nutrients were added with SRAs. The release kinetics of N and P SRAs (NP-SRAs) followed Fickian diffusion, and the biodegradation processes of the five petroleum hydrocarbons and three oil products were all well approximated by a second-order kinetic model. The half-lives of the five hydrocarbons in the groundwater were shortened from 0.01 to 7.46 d with the NP salt directly added to 0.002–6.67 d when the NP-SRAs and oxygen SRAs were added, and they decreased from 4.85 to 34.00 d to 2.80–28.90 d for the three oil samples. This study provides insights into the biodegradation kinetics of different hydrocarbons, facilitating the development of effective microbial remediation technologies for the oil contaminated groundwater environment.

Effect of varying volumes of anaerobic microbial inoculum on biodegradation and biogas production from black water

Unfettered discharge of untreated black water is one of the raging environmental issues which needs to be addressed especially in many developing and third-world countries. Black water is rich in organic compounds, elements such as nitrogen and phosphorous, and harmful faecal coliforms which makes it a major threat to the environment. The present study focuses on the use of an inhouse anaerobic microbial inoculum for the treatment of black water with an emphasis on decentralized treatment systems. The effects of varying volumes of inoculum (5 %, 10 %, 20 % & 30 %) for the treatment of black water was studied. Various parameters such as pH, total solids (TS), volatile solids (VS), chemical oxygen demand (COD) and biogas production were recorded. 10 % inoculum yielded the maximum amount of biogas. The biogas volume varied from 1046 mL–1180 mL depending on the experiments carried out using either fresh inoculum or acclimatized old inoculum. The inoculum could also be reused for sustained biodegradation and biogas production process which makes its use economic and apt as inoculum for reactors used in decentralized treatment processes. An attempt was also made in this work to reduce the input COD imparted via the inoculum itself by letting the larger and heavier solids to settle. Nevertheless, it was observed that the best working inoculum was the 10 % whole inoculum in terms of biogas production and COD removal.

Aqueous-based assembly of plant-derived proteins yields a crosslinker-free biodegradable bioplastic consistent with green chemistry principles.

Plastics are an indispensable part of modern life. Due to the harmful environmental consequences of petroleum-based plastic usage, there is an urgent need to replace them with biodegradable bioplastics that meet the sustainability standards required for a low environmental footprint. Here, we use plant-derived proteins to produce bioplastics. Since most plant-derived proteins are not water-soluble, there has always been a need to use acidic or basic solutions or organic solvents with plasticizers and crosslinkers to produce bioplastic. Here, we present a counterintuitive approach for using water-insoluble plant-derived soy and pea proteins to manufacture large-scale bioplastics using only water as a solvent without common plasticizers or crosslinkers. We show that bioplastics can form via a self-assembly process initiated by a small molecular initiator while maintaining favourable mechanical properties. The lack of crosslinking and the protein nature of the bioplastic leads to a rapid biodegradation process under various conditions. Overall, the approach we present is highly attractive in terms of cost and time, and most importantly, it obeys all the relevant principles of green chemistry in bioplastics production.

Rapid Degradation Of Dye Effluents With A SnS Catalyst: A Sustainable Approach Using Natural Light Under Ambient Conditions.

Dye degradation presents a persistent challenge in addressing water pollution. While several methods, including adsorption, biodegradation, and advanced oxidation processes, have been extensively explored, photocatalysis remains one of the most effective techniques. Conventional photocatalytic dye degradation processes often rely on expensive light sources and are time-intensive. Herein, we synthesized a SnS catalyst using solvated metal atom dispersion (SMAD) method, using Sn foil and sulfur powder. The catalyst exhibited remarkable performance, achieving complete degradation of methylene blue within 2 minutes under ambient room light, without the need for any external light source. Similar degradation efficiency was achieved for methyl orange. To evaluate the role of light for the degradation, control experiments were conducted in the dark using methylene blue as a model dye. Although the degradation rate was slightly reduced, the catalyst still facilitated dye degradation in the absence of light. Additionally, the catalytic performance was tested with four other dyes under natural light, all of which yielded promising results, demonstrating the versatility and effectiveness of the SnS catalyst in dye degradation. This work highlights the potential of the SnS catalyst for efficient and rapid dye degradation under both light and dark conditions, offering an energy-efficient solution for wastewater treatment.

Mechanical deviation in 3D-Printed PLA bone scaffolds during biodegradation

Large or carcinogenic bone defects may require a challenging bone tissue scaffold design ensuring a proper mechanobiological setting. Porosity and biodegradation rate are the key parameters controlling the bone-remodeling process. PLA presents a great potential for geometrically flexible 3-D scaffold design. This study aims to investigate the mechanical variation throughout the biodegradation process for lattice-type PLA scaffolds using both experimental observations and simulations. Three different unit-cell geometries are used for creating the scaffolds: basic cube (BC), body-centered structure (BCS), and body-centered cube (BCC). Three different porosity ratios, 50 %, 62.5 %, and 75 %, are assigned to all three structures by altering their strut dimensions. 3-D printed scaffolds are soaked in PBS solution at 37 °C for 15, 30, 60, 90, and 120 days both unloaded and under dead load. Water absorption, weight loss, and compression stiffness are measured to characterize the first-stage degradation and investigate the possible influences of these parameters on the whole biodegradation process. The strength reduction stage of biodegradation is simulated by solving pseudo-first-order kinetics-based molecular weight change equation using FEA with equisized cubic (voxel-like) elements.For the first stage, mechanical load does not have a statistically significant effect on biodegradation. BCC with 62.5 % porosity shows a maximum water absorption rate of around 25 % by the 60th day which brings an advantage in creating an aquatic environment for cell growth. Results indicate a significant water deposition inside almost all scaffolds and water content is determined to be the main reason for the retained or increased compression stiffness. A distinguishable stiffness increase in the initial degradation process occurs for 75 % porous BC and 50 % porous BCC scaffolds. Following the quasi-stable stage of biodegradation, almost all scaffolds lost their rigidity by around 44–48 % within 120 days based on numerical results. Therefore, initial stiffness increase in the quasi-stable stage of biodegradation can be advantageous and BCC geometry with a porosity between 50% and 62 % is the optimum solution for the whole biodegradation process.

3D structural analysis of the biodegradability of banana pseudostem nanocellulose bioplastics

X-Ray micro-computed tomography (XCT) is used to reveal the micro-structural changes of banana pseudostem nanocellulose bioplastic due to a biodegradation process initiated in a formulated composting media that allowed the growth of aerobic microflora. The bioplastic itself was made of nanocellulose, which was isolated from banana pseudostem using the 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) mediated oxidation method, and polyethylene glycol (PEG) as plasticiser. XCT provided insights into the 3D structural change of the bioplastic identifying the degradation process at two scales. The results showed that the local thickness and roughness of the bioplastic increased after degradation, while the density of the material decreased. Enlarged voids and tunnels were observed in the material after degradation. The formation of these tunnels is attributed to the popping of internal PEG-containing voids because of the generation of gases, which after forming may further accelerate biodegradation by microbial activity.

The influence of Cu2+ and Pb2+ on the characteristics of extracellular polymeric substances (EPSs) from Mucor mucedo and its relationship with pyrene biodegradation

The bioremediation of polycyclic aromatic hydrocarbons (PAHs) may be facilitated by the presence of heavy metals (HMs) via extracellular polymeric substances (EPSs). However, the variability of EPS characteristics influenced by HMs in relation to PAHs degradation remains uncertain, particularly in the case of fungi. It is therefore crucial to elucidate the impact of HMs on the characteristics of EPSs and their interaction in the process of PAHs biodegradation. The present study observed the cell membrane of Mucor mucedo under conditions of Cu2+ and Pb2+ stress, as well as determining the characteristics of EPSs. The findings demonstated that the presence of HM ions led to a disruption of the fungal cell membrane. The production of EPSs, the content of their main components and EPS property exhibited changes in accordance with the increasing concentration of HMs. It is noteworthy that the degradation of pyrene was enhanced as the concentration of HMs within the range of 0–80 mg L−1, particularly in the presence of EPSs. A positive correlation was observed between pyrene degradation and the total organic carbon, total nitrogen, polysaccharides, proteins, and surface tension of EPSs. It was thus demonstrated that pyrene biodegradation was enhanced under the stress of HMs (less than 80 mg L−1) by varying the characteristics of EPSs. The conceptual framework outlines the pyrene biodegradation process by EPSs under HM stress. This study provides new insights into the potential mechanism by which HMs influence the biodegradation of PAHs through the involvement of EPSs.

Mechanisms of manganese-tolerant Bacillus brevis MM2 mediated oxytetracycline biodegradation process

Addressing the environmental threat of oxytetracycline (OTC) contamination, this study harnesses the bioremediation capabilities of Bacillus brevis MM2, a manganese-oxidizing bacterium from acid mine drainage. We demonstrate the strain's exceptional efficiency in degrading OTC under high manganese conditions, with complete removal achieved within 24 h. The degradation is facilitated by the production of Bio-MnOx, utilizing their high redox potential and large specific surface area, which significantly enhance the adsorption and oxidation of OTC. Advanced characterization techniques, including X-ray diffraction, scanning electron microscopy, High Resolution-Transmission Electronic Microscope and X-ray photoelectron spectroscopy, provide a detailed analysis of the structural and functional properties of Bio-MnOx. The study also reveals the crucial role of Mn(III) intermediates and reactive oxygen species in the OTC degradation process, with quenching experiments validating their substantial impact on efficiency. Laccase activity, a key manganese-oxidizing enzyme, is assessed spectrophotometrically, further highlighting the enzymatic contribution to Mn(II) oxidation and OTC breakdown. This research contributes valuable insights and approaches for the targeted bioremediation of OTC-contaminated aquatic environments, offering a promising strategy for combating pollution from antibiotics and analogous compounds.

Assessing the impact of weathered polystyrene collected from the marine environment on oxidative stress responses in Zophobas morio larvae: A preliminary study

Foamed polystyrene (PS) is a prevalent material in consumer products and thus represents one of the largest constituents of marine litter. PS may interact with and be ingested by various organisms, including insects, which are starting to be used in biodegradation of plastic wastes. This study examines the physiological performances and the potential oxidative stress related to dietary environmental PS exposure of Z. morio larvae. Experimental groups were fed different diets: bran and oatmeal (control), weathered PS collected from the marine environment, and virgin PS. Over a 30-day feeding period, larvae growth, survival, and PS consumption were measured, together with antioxidant enzymatic activities and gene expression profiles. Results showed that PS ingestion supports larval growth similarly to bran, but the two PS-fed groups consumed a different amount of plastic, suggesting that weathered PS might affect the patterns of PS consumption by larvae. We denoted that PS consumption was associated with a decline in total antioxidant capacity, which showed the highest decrease in the environmental PS group. Marked increases in oxidative stress biomarkers such as superoxide dismutase (SOD) activity/mRNA levels and malondialdehyde content were also observed in the environmental PS-fed group, indicating an elevated oxidative stress response, probably due to pollutants adsorbed/absorbed on PS. Differently to SOD, catalase at both mRNA and enzyme activity levels was found to be significantly reduced by PS digestion, regardless of PS type. The mRNA levels of glutathione s-transferase (GST) were significantly higher in the environmental PS-fed larvae compared to the virgin PS-fed group. In addition, Principal Component Analysis clearly distinguished between larvae fed different PS types, highlighting the enhanced oxidative stress caused by the ingestion of PS collected from marine environments. These results support the potential of insects in plastic biodegradation processes but also demonstrate the health hazards of using environmental PS as principal dietary component in Z. morio larvae, thus questioning their use in downstream productions.

Характеристика нового штамма гриба Schizophyllum commune EO22 и его способности разлагать полиэтилен

The widespread and possessing extensive biotechnological potential xylotrophic basidiomycete Schizophyllum commune Fr. has a significant genetic variability. This actualizes the study of the fungus various strains to solve a complex of environmental problems, in particular, the disposal of plastic waste. The S. commune strain EO22 used in the work was isolated from rotting Acer negundo wood in the southern taiga subzone of the European Northeast (N58о35´, E49о69´, vicinity of Kirov). It is maintained in mycelial culture in laboratory conditions. The species identification was performed based on the morphology and sequencing result of the ITS1–5.8S–ITS2 fragment nucleotide sequence. The features of the growth and fruiting of mycelial culture EO22 on potato-sucrose and malt agar are described. The degradation potential of the S. commune strain EO22 was established in the experiment on co-incubation with low-pressure polyethylene (HDPE) film. HDPE is one of the most common environmental pollutants (64% of the total plastics production). The process of HDPE biodegradation was carried out exclusively by the dikaryotic type of mycelium and was accompanied by the forming of the fungus fruiting bodies. The results obtained are of interest in connection with the development of technologies for food protein production in the process of plastic waste utilization.

Testing the ability of water hyacinth for wastewater treatment and methane biogas production

This study aims to assess the potential of water hyacinth (WH) in treating wastewater and its viability for co-digestion with municipal solid waste to achieve zero waste treatment by generating methane biogas. A batch flow reactor treated wastewater, evaluating nine parameters (NO3, PO4, BOD5, Turbidity, Chromium, Cadmium, Lead, Calcium, and Magnesium). The highest removal efficiencies were observed for NO3 (94.13%), PO4 (75.85%), BOD5 (100%), Turbidity (93.86%), Chromium (94.3%), Cadmium (94.93%), Lead (91.33%), Calcium (41.42%), and Magnesium (43.13%). The pH ranged from 7.82 to 7.44. Methane biogas production was examined using anaerobic digesters with varying ratios of carbon-based waste and WH, along with pH, temperature, and total solid content variations. The optimal methane biogas production ratio was found to be 1:3 for WH and solid waste at 35°C, 10% total solids, and a pH of 7.5, resulting in the highest cumulative methane generation of 1039.80 mL/gm vs. The Gompertz model accurately described methane biogas generation with a yield of 1083.088 mL/gm vs., supported by a coefficient of determination (R2) of 0.999. The kinetics of the biodegradation process were evaluated using a first-order kinetic model. The negative value of k (-0.2364) suggests a rapid solid waste biodegradation, with a high correlation coefficient (R2) of 0.9971. Numerous correlations were employed to enhance the production of methane, yielding a correlation coefficient of 91.36%.

Proteome Changes Induced by Iprodione Exposure in the Pesticide-Tolerant Pseudomonas sp. C9 Strain Isolated from a Biopurification System

Iprodione is a pesticide that belongs to the dicarboximide fungicide family. This pesticide was designed to combat various agronomical pests; however, its use has been restricted due to its environmental toxicity and risks to human health. In this study, we explored the proteomic changes in the Pseudomonas sp. C9 strain when exposed to iprodione, to gain insights into the affected metabolic pathways and enzymes involved in iprodione tolerance and biodegradation processes. As a result, we identified 1472 differentially expressed proteins in response to iprodione exposure, with 978 proteins showing significant variations. We observed that the C9 strain upregulated the expression of efflux pumps, enhancing its tolerance to iprodione and other harmful compounds. Peptidoglycan-binding proteins LysM, glutamine amidotransferase, and protein Ddl were similarly upregulated, indicating their potential role in altering and preserving bacterial cell wall structure, thereby enhancing tolerance. We also observed the presence of hydrolases and amidohydrolases, essential enzymes for iprodione biodegradation. Furthermore, the exclusive identification of ABC transporters and multidrug efflux complexes among proteins present only during iprodione exposure suggests potential counteraction against the inhibitory effects of iprodione on downregulated proteins. These findings provide new insights into iprodione tolerance and biodegradation by the Pseudomonas sp. C9 strain.

Maximizing diclofenac bioremoval efficiency using Chlorella vulgaris strain H1 and Chlorella sorokiniana strain H2: Unveiling the impact of acetic acid on microalgae

BackgroundDiclofenac (DFC) is a commonly detected pharmaceutical pollutant in wastewater, posing environmental risks. Microalgae have emerged as potential candidates for bioremediation due to their ability to degrade pollutants. This study focuses on investigating the biodegradation potential of two newly isolated microalgae strains, Chlorella vulgaris strain H1 and Chlorella sorokiniana strain H2, towards DFC removal. The optimization of pH is crucial for enhancing the efficiency of bioremediation processes. Therefore, in addition to assessing the biodegradation potential of microalgae, this study also investigates the impact of adjusting the pH of the culture medium using acetic acid as an additional carbon source on the biodegradation process. MethodsThrough genetic analysis using 18S rDNA sequencing, the microalgae strains were identified. Various parameters including growth dynamics, chlorophyll content, cell proliferation, photosynthetic activity, and DFC biodegradation efficiency were comprehensively assessed. Additionally, the impact of incorporating acetic acid as an additional carbon source in the culture medium on the biodegradation process was examined. Significant FindingsC. sorokiniana strain H2 demonstrated superior biodegradation rates compared to C. vulgaris strain H1 across varying DFC concentrations. Specifically, C. sorokiniana strain H2 exhibited remarkable biodegradation rates of 84 %, 83.72 %, and 29.57 % for DFC concentrations of 12.5 mg L−1, 25 mg L−1, and 100 mg L−1, respectively. In contrast, C. vulgaris strain H1 showed lower biodegradation rates of 66.64 %, 29.24 %, and 1.83 % for the corresponding DFC concentrations. The study highlights the potential of C. sorokiniana strain H2 as a promising candidate for the removal of pharmaceutical pollutants like DFC from wastewater. Furthermore, the use of acetic acid as a supplementary carbon source enhanced the biodegradation efficiency, suggesting a potential strategy for optimizing bioremediation processes.

Evaluating the removal of the tetra-azo dye direct black-22 in Chlorella vulgaris closed-cultivation systems

ABSTRACT The removal of the tetra-azo dye Direct Black 22 (DB22) using the microalga Chlorella vulgaris was evaluated in the present study, aiming to understand the contribution of different processes (biodegradation, photodegradation, and adsorption) in the removal of this contaminant. The growth and morphological characteristics of C. vulgaris were not affected by the presence of the dye in the reaction medium. The efficiency of dye removal was 62.6 ± 1.46%, 47.7 ± 7.2% of which was attributed to photodegradation, while 13.2 ± 6.5% were associated with the contribution of the microalga by an enzymatic route and 1.7 ± 9.6% with an adsorption process. Additionally, tests with the organism Allium cepa as a bioindicator revealed that DB22 and its byproducts did not induce toxicity, but cytotoxicity and genotoxicity were induced. We observed that genotoxicity was reduced after the remediation process. Our results establish photodegradation as the primary mechanism and biodegradation as the secondary mechanism driving the removal of DB22 within a Chlorella culture. Researchers must carefully consider all aspects involved in the removal process, including photodegradation, biodegradation, and adsorption processes.

Impacts of post-operation loading and fixation implant on the healing process of fractured tibia.

Healing of tibia demonstrates a complex mechanobiological process as it is stimulated by the major factor of strains applied by body weight. The effect of screw heads and bodies as well as their pressure distribution is often overlooked. Hence, effective mechanical conditions of the healing process of tibia can be categorized into the material of the plate and screws, post-operation loadings, and screw type and pressure. In this paper, a mathematical biodegradation model was used to simulate the PGF/PLA plate-screw device over 8 weeks. The effect of different post-operation loading patterns was studied for both locking and non-locking screws. The aim was to reach the best configuration for the most achievable healing using FEA by computing the healing pattern, trend, and efficiency with the mechano-regulation theory based on deviatoric strain. The biodegradation process of the plate and screws resulted in 82% molecular weight loss and 1.05 GPa decrease in Young's modulus during 8 weeks. The healing efficiency of the cases ranged from 4.72% to 14.75% in the first week and 18.64% to 63.05% in the eighth week. Finally, an optimal case was achieved by considering the prevention of muscle erosion, bone density reduction, and nonunion, according to the obtained results.