Cell Wall Deformation Research Articles

Morphological, structural, and ultrastructural key features of hyperhydricity in Beta vulgaris L. var. saccharifera

Abstract Hyperhydricity, as a phenomenon specific to in vitro plants, triggers a series of changes at the cell and tissue level, which modify the plants’ physiological processes. For a better understanding of this phenomenon, we found it useful to present here the fundamental research on establishing the steps of structural and ultrastructural degradation of cells and tissues, observed by light microscopy (LM) and transmission electron microscopy (TEM) analyses, in the leaves of Beta vulgaris var. saccharifera, at 30 days of secondary culture, and their correlation with viability in the third culture. Comparative with control (non-hyperhydric plants), three degradation steps of hyperhydricity were identified in plants regenerated on a culture medium with 2.5 mg·L-1 6-benzyladenine. The first step involved cell wall deformation, which lost its rigidity and became sinuous, causing the enlargement of the intercellular spaces. In the second step, these spaces formed gaps through their union, and the whole membrane system suffered: both chloroplasts and tonoplast were broken (the cytoplasm and vacuolar composition were mixed), the nuclear membrane presented undulations, just before the damage to the tonoplast, and the nucleus became pyknotic. In step 3, the cell showed the beginning of lysis, which leads to necrosis, the cell had nothing in common with a normal ultrastructure. For in vitro plants in this final step, there was no chance of surviving but in steps I and II, the viability was 55-75%. These features can be useful to producers to calculate the level of culture damage and start measures to prevent losses.

Unraveling cereal physical barriers composed of cell walls and protein matrix: Insights from structural changes and starch digestion

Physical barriers composed of cell walls and protein matrix in cereals, as well as their cooking changes, play important roles in starch digestion. In this study, the physical barriers of native and cooked highland barley (HB), brown rice (BR), and oats (OA) kernels and their contribution to starch digestion were investigated. The resistant starch content was similar in cereal flours, but varied among cooked kernels (HB > BR > OA: 45.05 %, 10.30 %, and 24.71 %). The water adsorption, gelatinization enthalpy, and decrease in hardness of HB kernels were lower than those of OA and BR kernels. Microstructural observations of native kernels showed that HB had the thickest cell walls. After cooking, the lowest cell wall deformation and a dense continuous network developed from the protein matrix were observed in HB kernels. During digestion, undigested starch granules encapsulated by the stable cell walls and strong protein network were observed in HB kernels, but not in BR or OA kernels. Furthermore, the heavily milled HB kernels still had more resistant starch than the intact OA and BR kernels. Therefore, the physical barriers of HB kernels exhibited stronger inhibition of starch gelatinization and digestion. Differences in cereal physical barriers led to various inhibitory effects.

Chromosome doubling increases PECTIN METHYLESTERASE 2 expression, biomass, and osmotic stress tolerance in kiwifruit

Abstract Chromosome doubling-induced polyploidization is a popular tool for crop breeding. Polyploidy crops commonly have multiple advantages, including increased biomass and stress tolerance. However, little is known about the genes responsible for these advantages. We found kiwifruit (Actinidia chinensis cv. Hongyang) PECTIN METHYLESTERASE 2 (AcPME2)is substantially upregulated in artificially created tetraploid plants that show increased biomass and enhanced tolerance to osmotic stress. Overexpression (OE) of AcPME2 led to increased biomass and enhanced stress tolerance in Arabidopsis (Arabidopsis thaliana), tomato (Solanum lycopersicum), and kiwifruit. Upon short-term osmotic stress treatment, AcPME2-OE plants showed higher levels of demethylesterified pectins and more Ca2+ accumulation in the cell wall than Col-0 plants, which led to increased cell wall stiffness. The stress-induced plasmolysis assays indicated that AcPME2 dynamically mediated the cell wall stiffness in response to osmotic stress, which is dependent on Ca2+ accumulation. Transcriptomic analysis discovered that dozens of stress-responsive genes were significantly upregulated in the AcPME2-OE plants under osmotic stress. Besides, AcPME2-mediated cell wall reinforcement prevented cell wall collapse and deformation under osmotic stress. Our results revealed a single gene contributes to two advantages of polyploidization (increased biomass and osmotic stress tolerance) and that AcPME2 dynamically regulates cell wall stiffness in response to osmotic stress.

Study on cell wall deformation in ultrasonic cutting aluminum honeycomb by straight-blade knife

Aluminum honeycomb sandwich structure has been widely used in the aeronautic and astronautic fields. As the core part, aluminum honeycomb needs to be machined but defects are easily generated. Ultrasonic cutting is an advanced machining technology for honeycomb materials due to improved machining quality. However, ultrasonic cutting aluminum honeycomb by straight-blade knife is usually accompanied by cell wall deformation, which results in poor machining quality. To facilitate the industrial use of ultrasonic cutting aluminum honeycomb with a straight-blade knife, a finite element (FE) model was developed, and experimental studies had been performed. The effects of the blade-inclined angle and lead angle of the straight-blade knife were studied by analyzing the cutting force, the stress and deformation in the cutting zone. Results showed that the cell wall deformation was significantly suppressed when cutting with a corresponding blade-inclined angle and a lead angle. Meanwhile, effects of ultrasonic cutting parameters on the cell wall deformation were also studied, indicating that a well-machined cell wall could be obtained when cutting with large ultrasonic amplitude.

Size/Shape-Controllable Carbonized Wood Electrodes Enabled by an MXene Shell with Spatial Confinement and a Traction Effect on the Wood Cell Wall for Shape-Customizable Energy Storage Devices.

The shrinkage and collapse of wood cell walls during carbonization make it challenging to control the size and shape of carbonized wood (CW) through pre- or postprocessing (e.g., sawing, cutting, and milling). Herein, a shape-adaptive MXene shell (MS) is created on the surface of the wood cell walls. The MS limits the deformation of wood cell walls by spatial confinement and traction effects, which is supported by the inherent dimensional stability of the MS and the formation of new C-O-Ti covalent bonds between the wood cell wall and MS. Consequently, the volumetric shrinkage ratio of CW encapsulated by the MS (CW-MS) is significantly reduced from 54.8% for CW to 2.6% for CW-MS even at 800 °C. The harnessing of this collapse enables the production of CW-MS with prolonged stability and high electric conductivity (384 S m-1). These properties make CW-MS suitable for energy storage devices with various designed shapes, matching the increasingly compact and complex structures of electronic devices.

Effects of oil heat treatment on poplar wood properties: A pilot scale study

Pilot-scale oil heat treatment was conducted to enhance the quality of poplar wood obtained from a fast-growing plantation. Three target temperatures, namely 180, 190, and 200 ˚C, were chosen for the oil heat treatment process. Clear, small specimens were cut from the lumber, following the prescribed standards for assessing wood quality. Light microscopy revealed the ruptures and deformation of the wood cell wall as the treatment temperature increased. The volumetric swelling of the treated specimen decreased proportionally with the increase in treatment temperature. The impact of oil heat treatment on the mechanical properties of wood varied depending on the specific type of mechanical strength and processing temperature. The modulus of rupture, toughness, and hardness of the treated specimens drastically decreased at 200°C. However, the specimens treated at 200°C exhibited much lower mass loss during the fungal decay test. The results of the analytical test showed an increase in the crystalline cellulose content and thermal stability of the treated wood, due to the thermal degradation of hemicelluloses and amorphous regions of cellulose. Overall, it is concluded that oil heat treatment of poplar wood in the optimal temperature is an efficient approach to upgrade its quality with minimal reduction in mechanical strength.

Enhancement of mechanical and flame-retardant properties of Acacia hybrid through the treatment of a combination of styrene-acrylic copolymer and sodium silicate

The mechanical and flame-retardant properties of Acacia hybrid wood were studied through the treatment of an aqueous solution containing a styrene-acrylic copolymer (SC) and sodium silicate (SS). The results showed a significant increase in the mechanical properties of SC/SS-treated wood. Specifically, the modulus of rupture (MOR) and modulus of elasticity (MOE) improved by up to 71.54% and 53.65%, respectively. The surface hardness of the cross-section and radial section also increased by 37.24% and 46.65%, respectively. The treated wood’s weight percentage gain (WPG) reached up to 23.31%. The largest leaching rate (LR) of treated wood was only 8.01%, suggesting this treatment has obvious effects in fixing the SS in the wood. However, it did not cause positive bulking efficiency (BE) and anti-swelling efficiency (ASE). The incorporation of SS with SC resulted in the decomposition of polysaccharides at a lower temperature while increasing the limiting oxygen index (LOI), which was 34.95% higher than that of untreated wood, making it more difficult to ignite. Scanning electron microscopy (SEM) results showed that the SC/SS deposited in the cell lumina after polymerization, but significant structural changes occurred, including vessel and cell wall deformation due to the partial dissolution of hemicellulose and lignin from the cell wall in the alkaline solution. The results of this study demonstrate the feasibility of applying the SC/SS combination treatment to wood in practical applications.

Effect of thermo-mechanical treatment with different initial moisture content on bamboo cell walls

Thermo-hydro-mechanical (THM) treatment is an effective way to improve the performance of bamboo. However, to date, research on the impact of moisture content (MC) on THM treatment has been relatively little. This study examined the microstructure and physical and chemical properties of bamboo treated with THM under different initial moisture content conditions. The interaction and influencing relationships among the three were explored to provide a reference for THM in the bamboo industry. According to the results of the Three-point Bending test and Nanoindentation test, it is indicated that humidity has a relatively minor impact on the mechanical performance and micro-mechanical properties of compressed samples. However, Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP) tests have shown that an increase in moisture content effectively improves the uneven deformation of bamboo cell walls during compression, thereby reducing their porosity. However, appropriate moisture content in the experiment affected the softening effect of bamboo and caused slight cracking of the fiber tube during compression. With respect to Fourier Transform Infrared Spectrometer (FTIR) spectroscopy, differences in the initial moisture content can also affect the chemical composition. The X-ray diffraction (XRD) analysis has also shown that the crystallinity of the treated samples was higher than that of the untreated samples. Moisture content has a significant impact on the hygroscopicity and dimensional stability of compressed samples by influencing changes in the chemical composition, microstructure, and crystallinity during thermo-hydro-mechanical treatments. In this experiment, bamboo with a moisture content of 12% had a pronounced softening effect during the hot-pressing process while exhibiting the dimensional stability and low moisture absorption required.

Antifungal and Plant-Growth Promotion Effects of Bacillus velezensis When Applied to Coastal to Pine (Pinus thunbergii Parl.) Seedlings

Fungal diseases such as root rot and leaf blight cause substantial losses in coastal pine (Pinus thunbergii Parl.) seedling production, which hinders afforestation/forest restoration programs. We isolated and identified Fusarium oxysporum and Alternaria alternata as the causal agents of root rot and needle blight diseases and investigated the biocontrol efficacy against the fungal pathogens and growth promotion of coastal pine seedlings using Bacillus velezensis CE 100. The bacterium produced the hydrolytic enzymes chitinase, β-1,3-glucanase, and protease enzymes, and the crude enzyme fraction of the biocontrol strain caused the deformation of the fungal cell wall and antagonized F. oxysporum and A. alternata, causing respective inhibition of spore germination by 91.0% and 85.9% and mycelial growth by 58.3% and 54.3%, at a concentration of 1000 µL/mL. Consequently, the bacterial treatment improved the survival rate of seedlings 1.9 times relative to the control group. The bacterium secreted indole-acetic acid (IAA) phytohormone and enhanced root growth and absorption of nutrients, which notably enhanced the biomass production of coastal pine seedlings. Therefore, these results provide evidence that B. velezensis CE 100 is an effective antifungal and growth-promoting bacterium that can facilitate the production of high-quality coastal pine seedlings for the restoration and establishment of coastal forests.

Stress distribution and microstructural response of radiata pine under high-intensity microwave (HIMW) treatment

ABSTRACT In this study, the stress distribution within the cell wall layers and the microstructural response under high-intensity microwave (HIMW) treatment were investigated. Finite-element models were developed for both single tracheid and multicellular structures, considering the influence of the saturated vapour pressure. The findings showed uniform vapour pressure caused expansion and deformation of the tracheid layers, with the radial wall deforming slightly more than the tangential wall due to differences in microfibril angle (MFA) and elastic properties. Despite its thinness, the S3 layer, with a wide MFA, played a pivotal role in supporting the saturated vapour pressure within the cell lumen under HIMW treatment, effectively constraining lateral cell-wall deformation. In contrast, the S2 layer, being the thickest, exhibited lower lateral elasticity and sustained damage at the interfaces with the S3 and S1 layers during the expansion and recovery stages. The multicellular simulation demonstrated that earlywood cells experienced larger deformations than latewood cells and revealed a negative correlation between the cell-wall thickness and deformation. The simulation results were validated through the microscopic analysis of the wood topography after HIMW treatment. The findings of this study provide significant insights into understanding the microstructural deformation of wood under HIMW treatment.

The compressive response of the filled Kelvin foam

Periodic unit-cell solutions are obtained for the finite-strain, elasto-plastic response of a filled closed-cell Kelvin foam in uniaxial compression. The closed-cell Kelvin foam has edges of equal length, and attention is focussed on the regular Kelvin foam with faces comprising regular hexagons and squares. The elongated Kelvin foam is also studied: its faces comprise elongated hexagons and quadrilaterals. Both the cell walls and core of the Kelvin foam are treated as elastic, ideally plastic von Mises solids. In the first part of the study, the core modulus and strength are sufficiently small for the core to behave as an inviscid, incompressible fluid. Filling of the closed-cell Kelvin foam, in regular or elongated form, with an inviscid, incompressible core elevates its yield strength slightly and stabilises the post-yield response against softening. In the second part of the study, the macroscopic modulus and strength of a filled closed-cell foam are determined as a function of core modulus and deviatoric strength. The deformation mode of the cell edges switches from a bending mode to an affine stretching mode when the core is sufficiently stiff and strong; an analytical model is derived for affine deformation of cell walls and core. Finally, the response of a finite specimen containing an edge imperfection is in good agreement with the periodic, unit cell response of the filled Kelvin foam.

Combined effects of alkaline pH and high Ca concentration on root morphology, cell-wall polysaccharide concentrations and blueberry plant performance

The appropriate soil pH for blueberry production is <5.5. However, the exact factors involved in the retardation of blueberry growth at higher pH levels have not yet been completely identified. In this study, we examined the short- and long-term combined effects of pH level and Ca concentrations on root morphology and development in relation to blueberry plant performance. Southern highbush blueberry (Vaccinium corymbosum, cv. Windsor) plants were grown in solutions of pH 4.5 or 7.5 that contained 0, 5, 10, 50 or 100 mg L-1 of Ca. The dimensions of the epidermal cell walls of the roots and the levels of pectin and hemicellulose 1 and 2 in those cells were determined after 1 and 3 days. Concentrations of essential macro and micro-elements in the plant organs, chlorophyll concentrations in the leaves and whole-plant biomass production were measured after 12 weeks. The results demonstrate a rapid (3 days) negative response of root tips at pH 7.5 expressed as reduced dimensions and deformation of the epidermal cell walls. This response was accompanied by reduced concentrations of pectin and hemicellulose 1 in those cell walls. These negative effects of pH 7.5 were amplified by a 100 mg L-1 of Ca over the long term (12 weeks), where the concentrations of P and Ca on the epidermal cell of the root were increased. Additionally, the translocation of Mn from the root to the shoot was retarded. The negative effect of the pH level on roots development and on the Mn translocation were associated with significant reductions in chlorophyll concentrations and biomass production. The results presented in this study demonstrate, for the first time, the negative effect of the combination of slightly alkaline pH and a high Ca concentration on root development, which associated with retarding blueberry plants performance.

Deciphering the adaption of bacterial cell wall mechanical integrity and turgor to different chemical or mechanical environments

Bacteria adapt the mechanical properties of their cell envelope, including cell wall stiffness, turgor, and cell wall tension and deformation, to grow and survive in harsh environments. However, it remains a technical challenge to simultaneously determine these mechanical properties at a single cell level. Here we combined theoretical modelling with an experimental approach to quantify the mechanical properties and turgor of Staphylococcus epidermidis. It was found that high osmolarity leads to a decrease in both cell wall stiffness and turgor. We also demonstrated that the turgor change is associated with a change in the viscosity of the bacterial cell. We predicted that the cell wall tension is much higher in deionized (DI) water and it decreases with an increase in osmolality. We also found that an external force increases the cell wall deformation to reinforce its adherence to a surface and this effect can be more significant in lower osmolarity. Overall, our work highlights how bacterial mechanics supports survival in harsh environments and uncovers the adaption of bacterial cell wall mechanical integrity and turgor to osmotic and mechanical challenges.

Automated quantification of fluorescence and morphological changes in pretreated wood cells by fluorescence macroscopy

BackgroundLignocellulosic biomass is a complex network of polysaccharides and lignin that requires a pretreatment step to overcome recalcitrance and optimize valorisation into biobased products. Pretreatment of biomass induces chemical and morphological changes. Quantification of these changes is critical to understand biomass recalcitrance and to predict lignocellulose reactivity. In this study, we propose an automated method for the quantification of chemical and morphological parameters through fluorescence macroscopy, which was applied on wood samples (spruce, beechwood) pretreated with steam explosion.ResultsResults in fluorescence macroscopy highlighted the impact of steam explosion on spruce and beechwood: fluorescence intensity of samples was highly altered, especially for the most severe conditions. Morphological changes were also revealed: shrinkage of cells and deformation of cell walls manifested as the loss of rectangularity or circular shape, for tracheids in spruce and vessels in beechwood respectively. Quantification of fluorescence intensity of cell walls and quantification of morphological parameters related to cell lumens were carried out accurately by applying the automated method onto the macroscopic images. The results showed that lumens area and circularity could be considered as complementary markers of cell deformation, and that fluorescence intensity of the cell walls could be related to morphological changes and to the conditions of pretreatment.ConclusionsThe developed procedure allows simultaneous and effective quantification of morphological parameters and fluorescence intensity of the cell walls. This approach can be applied to fluorescence macroscopy as well as other imaging techniques and provides encouraging results towards the understanding of biomass architecture.

Study on Machining Quality of Aluminum Honeycomb in Ultrasonic Cutting by Disc Cutter

Abstract Aluminum honeycomb has been highlighted in aeronautics and astronautics in the form of the sandwich structure, but defects are easily generated during machining. Ultrasonic cutting for honeycomb material has received growing attention over the past years for improved machining quality and efficiency. In order to support the industrial application of the ultrasonic cutting for aluminum honeycomb by disc cutter, a finite element (FE) model is established and experimental investigations are conducted to study the influencing factors of the machining quality. The proposed FE model is verified by the comparison of cutting forces obtained from simulations and experiments. Based on the FE model and experiments, influences of tool orientation precisions, including lead angle and runout of disc cutter, are analyzed first. Moreover, cutting force, honeycomb morphology, the stress in the cutting zone, and cell wall deformation at different cutting parameters are investigated. Results show that the lead angle should be set as a slightly positive value, and the axial runout of the disc cutter should be controlled to an extremely small value to avoid machining defects. Meanwhile, the cutting forces decrease significantly with the application of the ultrasonic vibration and increase with the increases in the feed speed and the cutting depth. Therefore, a well-machined surface can be obtained by applying ultrasonic vibration, cutting at a lower feed speed, and a smaller cutting depth.

Antimicrobial activity of water-soluble tetra-cationic porphyrins on Pseudomonas aeruginosa

This manuscript presents the cytotoxicity, antimicrobial activity, antibiofilm preliminary properties, and associated therapy with commercial drugs using water-soluble tetra-cationic porphyrins against Pseudomonas aeruginosa. Two commercial tetra-cationic porphyrins were tested against a standard strain of P. aeruginosa 01 (PA01) in antibacterial activity assays under dark conditions and irradiated with white light for 120 min. Porphyrin 4-H2TMePor showed better antimicrobial activity and was chosen for further tests. Increased minimum inhibitory concentration was observed in the presence of reactive oxygen species, suggesting that photooxidation was mediated by the singlet oxygen production. In the time-kill curve assay, 4-H2TMePor inhibited bacterial growth in 90 min of irradiation. The checkerboard assay revealed synergistic interactions. Biofilms of the standard PA01 strain and three clinical isolates were formed. The biofilm destruction assay was more efficient for PA01, significantly reducing the biofilm biomass formed compared to the positive control. The associated treatment to destroy the biofilm potentiated a significant decrease in the biofilm biomass compared to the positive control. The photosensitizer did not damage human keratinocytes or mouse fibroblasts in the cytotoxicity assays, demonstrating the safety of using 4-H2TMePor. Atomic force microscopy indicated lower adhesion force, higher cell wall deformation, and higher dissipation energy in the treated control compared to untreated PA01. Given our findings, it is evident that water-soluble tetra-cationic porphyrins have excellent antimicrobial and a preliminary antibiofilm activity against Gram-negative bacteria, proving to be a potential photosensitizer for clinical use.

Accelerated weathering performance of plantation-grown juvenile poplar and Chinese fir woods

Abstract Plantation-grown juvenile wood species are extensively used as raw materials in the Chinese wood industry. The weathering performances of the wood are crucial for outdoor application. Two of the most important plantation-grown juvenile woods, poplar (Populus × euramericana cv. ‘74/76ʼ) and Chinese fir (Cunninghamia lanceolata Hook), were sliced into thin veneers and compared in this study to observe their weathering performance during exposure to UV alone for 504 h and UV/water for 168 h. The color difference, weight loss, and tensile strength loss of both veneers all increased with exposure time. Scanning electron microscopy showed that the initial structural deterioration originates from the corner of the middle lamella and pit, followed by cell separation, cell wall thinning, deformation, and collapse. Fourier transmission infrared spectroscopy, electron resonance spectrometry and X-ray photoelectron spectroscopy revealed a decrease in lignin-based infrared absorption intensity and radical generation, as well as an increase in O/C ratio throughout the exposure. Water spray considerably accelerated deterioration by washing away the degraded fragments, thereby exposing the fresh substrate underneath. Compared to poplar wood, Chinese fir showed durable structural integrity but more darkening during weathering. These findings reveal the anatomically structural weak phase and photo-degradation performance of two plantation-grown woods during weathering. The results of this work may facilitate the proper external use and further photo-stabilization treatment of plantation-grown juvenile wood products.

Fungicidal activities and molecular docking of the marine alga Ulva lactuca and Punica granatum peel extracts on Alternaria tomato spot disease.

In this study, we utilized pomegranate peel and marine algae Ulva lactuca (U. lactuca) as rich and sustained sources of bioactive compounds to combat tomato-black spot disease. n-Hexane extracts from the peel of pomegranate (Punica granatum) (PPE) and the marine algal biomass U. lactuca (ULE) were used alone and in combinations to verify their impact against Alternaria alternata (A. alternata). The applied extracts exhibited severe destructive effects on both fungal growth and structure such as mycelia malformation, underdeveloped conidia, cell wall deformation, and shrinkage. Moreover, increased deformations and protrusions, and notch-like structures, were noticed in A. alternata mycelia treated with mixed extracts (PPE and ULE) compared to all other treatments. The protein and reduced sugar contents in tomato fruits were significantly increased in the infected fruits with A. alternata. The highest enzyme activities of pectinase, cellulase, catalase (CAT), and ascorbate peroxidase (APX) were recorded in infected tomatoes in comparison with the healthy ones. Molecular docking studies showed that each extract is rich with bioactive compounds that have a promising inhibition effect on A. alternata cellulases. Pomegranate and Ulva extract showed promising antifungal activity against A. alternata which revealed their feasibility and applicability as biocontrol agents in postharvest disease management and food preservation against fungal pathogens.

Investigation into the deterioration of Castanopsis hystrix buried wood by anatomical, chemical and thermal analysis

Comparative studies of the anatomy and composition had been investigated to learn about the degradation characteristics of Castanopsis hystrix wood. Its chemical degradation was analyzed with wet chemical analysis, Fourier-transform infrared analysis, x-ray diffraction analysis, and thermogravimetric analysis. Its morphology was observed with light microscopes and scanning electron techniques. It was found that the deformation and separation of cell walls have no effect on the identification of C. hystrix wood. The degradation of polysaccharides leads to the mechanical properties of C. hystrix buried wood decreased. The inclusions exist in cells of C. hystrix buried wood increased, and the dark color is related to the inclusions and ferric oxide. Furthermore, the hemicellulose was heavily degraded but there was no obvious degradation of crystalline cellulose. Large amounts of inorganic elements such as Fe and S were detected in the ash of C. hystrix buried wood.

Improving the sound absorption of a highly deformable nanocomposite foam based on ethylene-propylene-diene-monomer (EPDM) infused with multi-walled carbon nanotubes (MWCNTs) to absorb low-frequency waves

In this study, an elastomeric nanocomposite foam was fabricated on the basis of ethylene-propylene-diene-monomer (EPDM) rubber filled with multi-walled carbon nanotubes (MWCNTs) to absorb low-frequency acoustic waves. The effects of adding MWCNTs on the cellular structure, viscoelastic behavior, and sound absorption characteristics were studied. Samples containing slight loadings of MWCNTs with increased damping factor and decreased pore sizes showed high viscose motions with superior sound absorption characteristic. The results revealed that the nanocomposite foam sample with only 0.1 phr (parts per hundred rubber) MWCNTs offered the best sound absorption coefficient with a sharp peak (0.98) within the frequency range of 500–1000 Hz. This can be justified by the dissipation of acoustic energy through vibration and deformation of the flexible cell walls due to the highly elastic matrix, high porosity and airflow resistivity of the fine partially reticulated cellular structure. With further MWCNTs loadings beyond the optimum level, the cell size was reduced dramatically, leading to reduction in porosity and excessive increase in air flow resistivity. These factors resulted in poor sound absorption feature. Moreover, the sound insulation performance of the nanocomposite foams was characterized, and it revealed the improving effect of MWCNTs, especially in high loading, by yielding a sound reduction index equal to 27–33 dB. According to the obtained results, the potential role of MWCNTs in the improvement of the acoustic absorption and sound insulation performance of EPDM foam can be inferred. Thus, a lightweight sound absorber with high resistance to harsh environmental conditions and excellent low-frequency sound absorption can be achieved by the infusion of nanoparticles.