High Degree Of Deacetylation Research Articles

Separation properties and fouling resistance of polyethersulfone membrane modified by fungal chitosan.

This research explores the enhancement of polyethersulfone (PES) membranes through the incorporation of chitosan derived from the lignicolous fungus Ganoderma sp. Utilizing wet phase inversion and solution casting techniques, chitosan was successfully integrated into the PES matrix, as confirmed by Fourier Transform Infrared Spectroscopy (FT-IR), which indicated a high deacetylation degree of 75.7%. The incorporation of chitosan significantly increased the membrane hydrophilicity, as evidenced by a reduction in the water contact angle and a substantial improvement in pure water permeability, from 17.9L m-2 h-1 bar-1 to 27.3L m-2 h-1 bar-1. The membrane anti-fouling properties were also notably enhanced, with the Flux Recovery Ratio (FRR) increasing from approximately 60-80%. Moreover, the chitosan-modified PES/CS membrane, particularly at a 5% chitosan concentration, demonstrated exceptional efficacy in pollutant removal, achieving over 90% elimination of total suspended solids, cadmium (Cd), and lead (Pb), alongside a 79% reduction in color during the treatment of textile wastewater.

Bio synthesis of chitosan from shrimp shell chitin using Streptomyces griseoincarnatus RB7AG:Characterization and application as coating material to enhance shelf life of tomatoes (var. Ruby pusa) in post-harvest storgae condition

In this investigation, chitosan was successfully obtained from shrimp shell chitin through microbial degradation by Streptomyces griseoincarnatus RB7AG. The resulting chitosan showcased remarkable characteristics, including high solubility, a high degree of deacetylation, a well-defined crystalline structure, and a rough surface with minimal pores. The application of chitosan as a coating material for tomatoes demonstrated significant preservation benefits compared to commercially available chitosan. The chitosan coating proved effective in minimizing weight loss, reducing the production of reactive oxygen species (ROS), and preserving essential compounds such as anthocyanin content and antioxidant enzymes in tomatoes. Firstly, the chitosan coating served as a physical barrier, preventing moisture loss and maintaining the tomatoes' structural integrity. Secondly, the antimicrobial properties of chitosan hindered the growth of spoilage-causing microorganisms, extending the shelf life of the tomatoes. Additionally, the chitosan coating exhibited antioxidant properties, scavenging ROS and preserving the natural antioxidants in tomatoes. Furthermore, the chitosan coating facilitated controlled gas exchange, allowing optimal levels of oxygen and carbon dioxide to maintain the freshness of the tomatoes without accelerating the ripening process. With the help of the above-mentioned mechanisms, the potential of the microbially synthesized chitosan to enhance the shelf life of the tomatoes can be explained which was found better than the commercially synthesized chitosan coating. This research underscores the potential of microbially synthesized chitosan as an effective coating material but also provides insights into the intricate mechanisms involved in preserving tomatoes. The findings pave the way for innovative applications of chitosan-based coatings in the food industry, ensuring prolonged freshness and nutritional quality of perishable fruits and vegetables.

Valorization of freshwater crab shell residues to chitosan for postharvest quality of mango (Mangifera indica L.) by fruit coating

Freshwater crab shells (Somanniathelphusa dugasti) are abundant in inland areas and rich in chitosan, which can be extracted and utilized. This study investigated the characteristics of chitosan from freshwater crab shells (FC-chitosan) and its impact on extending the shelf life of Nam Dok Mai mangoes (Mangifera indica L.). The FC-chitosan had a high degree of deacetylation (99.15 %), thereby enhancing solubility and reactivity for a uniform coating, and a low ash content (0.75 %), minimizing the interference effects on mechanical strength and transparency, both of which could contribute to its potential use as a well-adhering coating material. The FC-chitosan film exhibited superior properties as a coating film, with relatively higher transparency (25.09 % T/mm), tensile strength (21.57 MPa), and elongation (76.09 %) compared to commercially available marine crab chitosan. Mango fruits coated with 2.0 % (w/v) FC-chitosan demonstrated appropriate postharvest quality, with lower weight loss and maintained peel color, fruit firmness, titratable acidity, and ascorbic acid during storage at room temperature (30 ± 5 °C) for up to 11 days. The results suggest that FC-chitosan is effective as a coating material for delaying ripening and extending the shelf life of mangoes. The novelty of using chitosan derived from freshwater crab shells lies in its unique properties and its sustainable use of underutilized byproducts.

Modification of Chitosan Isolation Method from Pearl Oyster Shell (Pinctada maxima sp) as A Source of Natural Polymer

Abstract Chitosan is natural polymer with abundant availability and unique characteristics. The purpose of this study was to investigate the effects of various isolation methods on chitosan properties. Chitosan was obtained by isolation method using oyster pearl shell (Pinctada maxima sp.). The parameters of the deacetylation process are the comparison of heating method with microwave method and the comparison of microwave power. Chitosan was characterized for degree of deacetylation (DD) and functional groups by FTIR, and viscosity by Brookfield viscometer. The microwave method was faster than the heating method. Then, the larger mass of shell and %NaOH produced a higher DD of 89.75%. However, the use of 60g mass and 60% NaOH resulted in an already high DD of 81.96%. Furthermore, variation microwave power showed the highest DD at high power. FTIR spectrum analysis showed the appearance of chitosan functional groups, OH and NH2 groups. The viscosity value decreased as the microwave power increased. Based on this study, different isolation methods affect the quality of chitosan. However, it’s necessary to conduct more detailed research related to changes in chemical structure. Therefore, oyster shells can produce chitosan as a source of natural polymers with different characteristics.

Characterization of a Novel Acid-Stable Chitosanase from Lentinula edodes Suitable for Chitooligosaccharide Preparation

As high-value chitosan derivatives, chitooligosaccharides (COSs) with biodegradable, biocompatible, nontoxic, antimicrobial, and antioxidant activities have been widely applied in food-related fields. Chitosanases can hydrolyze chitosan to produce COSs. Herein, a chitosanase (LeCho1) from Lentinula edodes was successfully expressed in Escherichia coli and was then purified and characterized. LeCho1 had a low sequence identity with other chitosanases reported from the GH75 family. The recombinant protein showed a molecular mass of 27 kDa on SDS-PAGE. LeCho1 preferentially hydrolyzed chitosan with a high degree of deacetylation (DDA) and exhibited maximal activity (71.88 U/mg) towards 95% DDA chitosan at pH 3.0 and 50 °C. It possessed good stability at pH 2.0–6.0 and temperatures below 45 °C. Its hydrolytic activity was remarkably enhanced by the metal ion Mn2+ at 1 mM, while it was totally inhibited by 1 mM Fe3+ or 10 mM EDTA. Its Km and Vmax values were 0.04 μM and 76.81 μmol·min−1·mg−1, respectively, indicating good substrate affinity. LeCho1 degraded chitosan into COSs with degrees of polymerization (DPs) of 2–5, while it had no action on COSs with DPs of less than 5, revealing its endo-chitosanase activity. This study proved that chitosanase LeCho1 is a promising candidate in the industrial preparation of COSs due to its excellent properties.

Statistical physics insights in the Allura Red adsorption on chitosan: Effects of adsorbents features, and experimental conditions

This study presents an innovative approach using statistical physical modeling to analyze the effect of experimental conditions and adsorbent features on removing Allura Red dye by chitosan. Five models based on statistical physics were employed to understand the removal mechanism under different experimental conditions, including variations in pH, particle sizes, chitosan deacetylation degrees, and temperatures. The best models were determined through rigorous statistical analysis and a detailed evaluation of the estimated parameters, considering their physical meaning and standard deviations. The models demonstrated high predictive capacity (coefficients of determination greater than 0.9 and low mean squared error values < 110). Analysis of the effects of experimental conditions revealed that a pH of 6.6, particles smaller than 0.10 mm, a high degree of deacetylation (84 %), and temperatures of 298 K and 308 K present the greatest potential for dye removal by chitosan. Furthermore, it was observed that, in general, the dye removal mechanism involves the formation of a double layer with two adsorption energies under the best experimental conditions, and the process occurs predominantly by physical forces (adsorption energy below 35 kJ/mol). This work contributes significantly to understanding how experimental conditions influence the mechanism of dye adsorption by chitosan, offering valuable and new insights for future applications and optimizations in the treatment of effluent-containing dyes.

Obtaining chitosan from chitine-containing uzbekistan raw materials and research of antimicrobial properties

The optimal conditions for the isolation of valuable natural biopolymers were revealed. chitosan from cysts of Artemia parthenogenetia in the Aral Sea and from pupae of the silkworm Bombyx mori. Chitosan (Chs) was obtained from cysts of A. parthenogenetia with a molecular weight of 89 kDa, degree of deacetylation (DDA)— 72% and solubility— 81.62%. It has been shown that it is possible to isolate Chs from silkworm pupae of sufficient purity with different molecular weights and DDA depending on the synthesis conditions and the degree of purification. Bombyx mori Chs has a higher molecular weight of 100–160 kDa, a high DDA— up to 90% and a solubility of 88%. IR spectroscopy, X-ray diffraction and elemental analysis have shown the purity of the isolated Chs from various sources. In chitin from A. parthenogenetia cysts of the Aral Sea, two types of modifications α and β with corresponding syngonies are observed, which confirms its polymorphic structure. The antibacterial activity of B. mori Chs has been shown, which tends to expand the spectrum of suppressed bacteria with increasing concentration and have a bactericidal effect on both gram-negative and gram-positive bacteria. Chs B. mori had an immunostimulating effect on living organisms, which allows us to recommend drugs based on Chs to strengthen the immune system.

Synthesis and Characterization of Low Molecular Weight Irradiated Chitosan in Various Water Levels and Gamma-Ray Doses

Chitosan is a biopolymer derived from marine animal shell waste that exhibits numerous pharmacological activities. However, its high molecular weight limits the application in various fields due to its low solubility. Therefore, this study aims to synthesize low molecular weight chitosan using varying water content and doses of gamma irradiation. To initiate chitosan degradation, H2O (5 and 10 mL) was added, followed by gamma ray irradiation at doses of 5 and 10 kGy. The Molecular Weight (MW) of degraded chitosan was determined using Gel Permeation Chromatography (GPC), while Fourier Transform Infrared Spectroscopy (FTIR) was used to characterize the functional groups and degree of deacetylation of chitosan. The study found that the molecular weight of irradiated chitosan decreased as the irradiation dose and H2O addition increased. The addition of 10 mL of water and gamma irradiation at a dose of 10 kGy has been found to reduce the molecular weight of chitosan to 118 kDa, with a high deacetylation degree of 86.78%. The FTIR analysis showed no significant changes in the functional groups, indicating that gamma irradiation did not affect the structure of chitosan.

Optimization of Chitosan Synthesis Process Parameters to Enhance PES/Chitosan Membrane Performance for the Treatment of Acid Mine Drainage (AMD).

Acid mine drainage (AMD) is an environmental issue linked with mining activities, causing the release of toxic water from mining areas. Polyethersulphone (PES) membranes are explored for AMD treatment, but their limited hydrophilicity hinders their performance. Chitosan enhances hydrophilicity, addressing this issue. However, the effectiveness depends on chitosan's degree of deacetylation (DD), determined during the deacetylation process for chitosan production. This study optimized the chitin deacetylation temperature, alkaline (NaOH) concentration, and reaction time, yielding the highest chitosan degree of deacetylation (DD) for PES/chitosan membrane applications. Prior research has shown that high DD chitosan enhances membrane antifouling and hydrophilicity, increasing contaminant rejection and permeate flux. Evaluation of the best deacetylation conditions in terms of temperature (80, 100, 120 °C), NaOH concentration (20, 40, 60 wt.%), and time (2, 4, 6 h) was performed. The highest chitosan DD obtained was 87.11% at 80 °C, 40 wt. %NaOH at 4 h of chitin deacetylation. The PES/0.75 chitosan membrane (87.11%DD) showed an increase in surface hydrophilicity (63.62° contact angle) as compared to the pristine PES membrane (72.83° contact angle). This was an indicated improvement in membrane performance. Thus, presumably leading to high contaminant rejection and permeate flux in the AMD treatment context, postulate to literature.

A Chitosan Scaffold Supports the Enhanced and Prolonged Differentiation of HiPSCs into Nucleus Pulposus-like Cells.

Intervertebral disc degeneration (IDD) is a progressive condition and stands as one of the primary causes of low back pain. Cell therapy that uses nucleus pulposus (NP)-like cells derived from human induced pluripotent stem cells (hiPSCs) holds great promise as a treatment for IDD. However, the conventional two-dimensional (2D) monolayer cultures oversimplify cell-cell interactions, leading to suboptimal differentiation efficiency and potential loss of phenotype. While three-dimensional (3D) culture systems like Matrigel improve hiPSC differentiation efficiency, they are limited by animal-derived materials for translation, poorly defined composition, short-term degradation, and high cost. In this study, we introduce a new 3D scaffold fabricated using medical-grade chitosan with a high degree of deacetylation. The scaffold features a highly interconnected porous structure, near-neutral surface charge, and exceptional degradation stability, benefiting iPSC adhesion and proliferation. This scaffold remarkably enhances the differentiation efficiency and allows uninterrupted differentiation for up to 25 days without subculturing. Notably, cells differentiated on the chitosan scaffold exhibited increased cell survival rates and upregulated gene expression associated with extracellular matrix secretion under a chemically defined condition mimicking the challenging microenvironment of intervertebral discs. These characteristics qualify the chitosan scaffold-cell construct for direct implantation, serving as both a structural support and a cellular source for enhanced stem cell therapy for IDD.

Synthesis and comprehensive characterization with anticancer activity assessment of salicylaldehyde and 2-acetylphenol based chitosan thiosemicarbazones and their copper(II) complexes

Functionalization of chitosan as salicylaldehyde and 2-acetylphenol-based chitosan thiosemicarbazone involving amino group at C2 position of pyranose ring was confirmed by comprehensive characterization by spectroscopic and analytical ways. Both the low molecular weight (Mw) chitosan oligosaccharide (CS) (Mw < 3000 Da, degree of deacetylation (DDA) = 87 %) and the crab shell chitosan (CCS) (Mw = 350 kDa, DDA = 67 %) functionalized thiosemicarbazones behaved as ONS tridentate ligand to form the square planar copper(II) complexes with a chloride ion as an additional ligand to satisfy the co-ordination sphere. All the derivatives were found thermally stable till the commencement of chitosan backbone disruption at 200 °C. The MTT assay profiles showed a conspicuous enhancement in the in vitro antitumorigenic and anticancer activity of native chitosan upon its functionalization as phenolic carbaldehyde chitosan thiosemicarbazones. Further, the assays more often revealed a further lowering of cell viability with chitosan oligosaccharide derivatives in comparison to high molecular weight chitosan derivatives, and a lower viability of the MCF-7 cancer cells than the tumorigenic MDCK cells. Both the low Mw chitosan with high DDA and high Mw chitosan with low DDA, the chitosan-functionalized salicylaldehyde based thiosemicarbazones, and their copper(II) chitosan thiosemicarbazone complexes were found to have minimal toxicity with IC50 >600 μgmL−1 against the mouse embryonic normal fibroblast NIH3T3 cells. These results were indicatives of more protonation and enhanced anticancer activity of chitosan oligosaccharide derivatives, and preferential cytotoxicity of chitosan biomaterials against the tumorigenic and cancer cells with more negatively charged cell surfaces.

Simultaneous Optimization of Deacetylation Degree and Molar Mass of Chitosan from Shrimp Waste.

Shrimp waste is a valuable source for chitin extraction and consequently for chitosan preparation. In the process of obtaining chitosan, a determining step is the chitin deacetylation. The main characteristic of chitosan is the degree of deacetylation, which must be as high as possible. The molar mass is another important parameter that defines its utilizations, and according to these, high or low molar masses are required. The present study is an attempt to optimize the deacetylation step to obtain chitosan with a high degree of deacetylation and high or low molar mass. The study was carried out based on experimental data obtained in the frame of a central composite design where three working parameters were considered: NaOH concentration, liquid:solid ratio, and process duration. The regression models defined for the degree of deacetylation (DD) and for the mean molar mass (MM) of chitosan powders were used in the formulation of optimization problems. The objectives considered were simultaneous maximum DD and maximum/minimum MM for the final chitosan samples. For these purposes, multiobjective optimization problems were formulated and solved using genetic algorithms implemented in Matlab®. The multiple optimal solutions represented by trade-offs between the two objectives are presented for each case.

Avanços na extração e atividades biológicas da quitosana de lagostim e sua aplicação na descoloração de corantes sintéticos

ABSTRACT An eco-friendly method of extraction for chitin and chitosan extracted from crawfish was our goal. Chitin is always present with proteins, minerals, and other components. This study used an eco-accommodating, novel technique for chitin and chitosan extraction. Lactobacillus lactis was used for the deproteinization and demineralization of chitin in a single stage by Saccharomyces cerevisiae (BB: biological-biological extraction) to convert chitin into chitosan. BB is a more environmentally friendly method of producing chitosan than deacetylation with NaOH (BC: biological-chemical extraction). Chitosan was characterized by FTIR. A high degree of deacetylation (%) was observed. The UV spectrum for chitosan was similar at 0.788, 0.415, and 1.150 for CC, BC, and BB, respectively. The results show that chitosan (BB) has potential applications in the biomedical fields such as antioxidant activity, anticancer activity against human liver cancer (HepG2), breast cancer (MCF-7) and human hepatocellular carcinoma (HCT) cell lines. The results in terms of water treatment and removal of dyes using chitosan (BB) are valuable in terms of its application in industrial wastewater treatment and demonstrate that it can be used as a biosorbent.

Synthesis and characterization of chitosan-copper nanocomposites and their catalytic properties for 4-nitrophenol reduction

Biopolymer-based copper nanoparticles (CuNPs) have become an area of significant interest due to their wide-ranging applications in a variety of fields. However, there remains a challenge in tailoring their morphologies and improving their properties. In this study, CuNPs were synthesized via wet chemical reduction using sodium hypophosphite monohydrate (NaH2PO2·H2O), l-ascorbic acid and chitosan. The effect of different synthesis conditions, including reaction pH, temperature, time, concentration of NaH2PO2·H2O, l-ascorbic acid and chitosan, as well as the deacetylation degree (DD) of chitosan, on the synthesis of CuNPs was investigated. The synthesized CuNPs were characterized by various analytical techniques. The catalytic properties of synthesized CuNPs were investigated for the reduction of 4-nitrophenol (4-NP) in the presence of sodium borohydride. The synthesis-morphology-catalytic activity relationship of CuNPs was discussed. The results suggested that the morphology of CuNPs could be adjusted by controlling the synthesis conditions. Chitosan DD significantly impacts the morphology of the synthesized CuNPs. As the chitosan DD decreased from 91.8 % to 52.3 %, the average particle size of synthesized CuNPs decreased from 43.9 ± 10.6 to 17.7 ± 5.9 nm and the shape changed from anisotropy to near-sphere. CuNPs synthesized using low DD (53.2 %) chitosan (CuNPs-N3) demonstrated the highest 4-NP conversion rate of 99.1 % and reaction rate constant of 0.3540 min−1. CuNPs-N3 was thermodynamically and kinetically more feasible than CuNPs synthesized with high DD chitosan. These findings provide important insights for further designing and developing hierarchical nanostructured CuNPs catalysts for broader applications.

UTILIZATION OF MANGROVE ENDOPHYTIC FUNGI AS A SUSTAINABLE AND ENVIRONMENTALLY FRIENDLY SOURCE OF CHITOSAN

Chitosan is an important biopolymer that is used as a raw material in several industries, but the manufacturing process has the potential to harm the environment. This study aimed to exploit chitosan in mangrove endophytic fungi and to characterize it. The four fungi isolates used were 20BB0501, 20CB07, 20BA04, and 20BA0502. Fungi were obtained from mangrove plants and identified macroscopically and microscopically using the coverslip method. After performing fungal maintenance on MEA media, fungi cultivation was done on rice media for 14 days. A chitosan extract was made by isolating and extracting the chitosan from the fungal biomass. FTIR was used to characterize the isolated chitosan extract. Macroscopic examinations revealed that each of the four strains had a delicate structure and was white. According to the extraction results, the yield of chitosan from the fungal biomass was 7.5%, 16.7%, 1.6%, and 11%, respectively. According to the FTIR data, showed the degree of deacetylation reached 85.02%, 97.78%, 88.7%, and 85.02%. It can be concluded that mangrove endophytic fungi can be used in the manufacture of chitosan, which produces a high degree of deacetylation using a more environmentally friendly process. The results of this study indicate that marine fungal strains can be used as a source of chitosan. This basis can be developed for the production of bio surfactants, enzymes, and the discovery of new bioactive compounds has pharmacological and biotechnological potential.

High quality, low molecular weight shrimp and crab chitosans obtained by short-time holistic high-power microwave technology

The study sought to investigate the impact of a holistic high-power microwave technology during all stages of the extraction on the quality, time of extraction, and degree of deacetylation (DD) of shrimp chitosan (SC) and crab chitosan (KC). The demineralization and deproteinization stages took 7 and 8 min, at 750 and 875 W, respectively. The deacetylation process was conducted at two powers, 875 W and 1250 W, for 10, 15, and 20 min. It only took 25 min at 875 W to successfully prepare chitosan with a high DD and 30 min to reach the maximum DD. The highest DDs by the potentiometric titration method, FTIR, and 1H NMR of SC were 86.6%, 86.7%, and 83%, compared to 83.8%, 82.7%, and 80% for KC, respectively. Extracted SC had 79% solubility, 14.125 kDa, a 46.57% crystallinity index, 705.40% WBC, and 434.60% FBC, against 74.5%, 16.982 kDa, 74.14%, 689.82%, and 413.20% for KC, respectively. The study proved that 30 min of holistic high-power microwave at 875 W produced low-molecular-weight chitosan with relatively high deacetylation and low content of viscosity, crystallinity, and protein residue. The technique can provide a feasible alternative to the commercial production of low-molecular-weight chitosan in less time and energy.

Solid-state mechanochemical synthesis of chitosan from mud crab (Scylla serrata) chitin

This study presents a method for solvent-free mechanochemical synthesis of chitosan from chitin, sourced from the shells of mud crabs (Scylla serrata). The procedure involves a sequence of demineralization and deproteinization to extract chitin from the crab shells, followed by mechanochemical deacetylation. The chitin was deacetylated by grinding it as a solid blend with sodium hydroxide (NaOH) using a stainless steel mortar and pestle. After grinding, chitosan is isolated from the blend by repetitive washing and centrifugation. The chitosan product is then characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. These characterization techniques confirm the successful deacetylation of chitin to form chitosan. A high degree of deacetylation (DD) is achieved when the weight ratio of NaOH to chitin is 1:1 or higher, implying that the DD value can be enhanced by increasing this weight ratio. The mechanochemical reaction mechanism involves the hydroxyl groups on the NaOH particles reacting with the acetamide groups of the chitin strands, yielding solid chitosan and sodium acetate. This mechanochemical deacetylation approach is more practical than the conventional heterogeneous deacetylation in strong basic solutions, since it could suppress depolymerization of the resulting chitosan and requires significantly less base. This makes it a promising method for large-scale industrial applications.

Green preparation of β-chitins from squid pens by using alkaline deep eutectic solvents

Based on the assumption that protein could be removed by the combined mechanism of alkaline induced degradation and strong hydrogen bond interactions of deep eutectic solvents (DESs), β-chitins were successfully prepared from squid pens by using alkaline DESs formed by potassium carbonate and glycerol. The chemical structures of the DESs were investigated by 1H nuclear magnetic resonance (1H NMR), attenuated total reflection Fourier transform infrared (ATR-FTIR) and molecular modeling, and the physicochemical property of the prepared β-chitins were characterized. The preparation yields was about 32 %, and DESs with K2CO3/glycerol of 1/10 could be reused for three times while maintaining high preparation yields (31 %–32 %) and degree of deacetylation of 66.9 %–76.9 %. The mechanisms of deproteinization and demineralization by the alkaline DESs were proposed to follow the degradation and dissolution steps, and proteins and minerals were removed from squid pens through the synergistic actions of alkaline degradation and hydrogen bonding interactions. This alkaline DESs are promising to be used as a green and efficient approach for commercial production of β-chitin.

Low Molecular Weight and High Deacetylation Degree Chitosan Batch Alleviates Pathogenesis, Toxin Accumulation, and Fusarium Gene Regulation in Barley Leaf Pathosystem.

Fusarium graminearum is a cosmopolitan fungal pathogen that destroys cereal production, in terms of loss of yield and grain contamination with mycotoxins, worldwide. Chitosan is a natural biopolymer abundant in the environment with proven antifungal properties that also acts as a plant immunity elicitor. Despite a number of articles, there is a lack of systematic comparison of antifungal activity of diverse batches of chitosan. The current study aimed to test the inhibitory effects of a collection of diverse chitosan samples on the growth and production of F. graminearum toxins, validated by changes in the Fusarium transcriptome. Experiments included testing antifungal activity of different chitosan samples, the application of the best performing one in vitro to investigate the impact on F. graminearum growth, followed by analyzing its effect on Fusarium toxins accumulation, and Fusarium transcriptomics in the barley leaf pathosystem. Confirmatory antifungal assays revealed that CS_10, a specific batch of chitosan, retarded Fusarium growth with an application concentration of 200 ppm, significantly reducing toxin synthesis and disease symptoms in Fusarium-inoculated barley leaves. RNA-Seq analysis of F. graminearum in barley leaf pathosystem exposed to CS_10 showed a list of differentially expressed genes involved in redox balance, cell respiration, nutrient transport, cell wall degradation enzymes, ergosterol biosynthesis, and trichothecenes production. The genes functioning in these essential pathways are discussed and assigned as critical checkpoints to control Fusarium infections. The results suggest some important molecular targets in F. graminearum that may be suitable in gene-specific targeting or transgene-free methods, such as spray-induced gene silencing during host-pathogen interactions.

Effects of deacetylation degree of chitosan on the structure of aerogels

Chitosan aerogels, obtained by (supercritical) CO2 drying of hydrogels, are novel adsorbents because of their large surface area and high porosity. Intrinsic properties of chitosan such as molecular weight (MW) and degree of deacetylation (DDA) had large impacts on the characteristics of chitosan aerogels. Although there are a few studies about the effects of solely DDA or MW on aerogel structure, none of them has focused on the mutual effects. The study aims to investigate the combined effects of MW and DDA of chitosan on aerogel properties. Hydrogels were produced in beads form by physical gelation of the chitosan solutions (2 % w/v in acetic acid of 1 %, v/v) in an alkaline environment (NaOH, 4 N). Supercritical CO2 dried aerogels were examined with respect to the bulk density, diameter as well as pore characteristics, and surface area by Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) methods, respectively. Morphologies of aerogels were also examined by Scanning Electron Microscopy (SEM) images and structural changes of aerogels were observed by Fourier Transform Infrared (FTIR) Spectroscopy. Additional to BET-BJH analysis, proton relaxation dispersion was measured by Fast Field Cycling NMR (FFC-NMR) to determine the pore volume of the aerogels. Compact structures were obtained for higher MW chitosan and lower MW chitosans with higher DDA increasing the aerogel diameters. All types of aerogels obtained by different chitosan characteristics (MW and DDA) showed a porous structure and the highest DDA with the lowest MW caused the minimum bulk density with the highest water absorption rate. Although different N2 adsorption-desorption profiles were obtained in terms of pore volumes; all aerogels had Type IV isotherms with Type H1 hysteresis curve. FFC-NMR experiments showed that the coherence length values were associated with the pore volumes and FFC-NMR experiments were found to be meaningful as supportive experiments for the characterization of aerogels.