Technology optimization of chitosan production from Aspergillus niger biomass and its functional activities

Development of hydrogels from cell wall of Aspergillus oryzae containing chitin-glucan and wet spinning to monofilaments

Fungal mycelium is emerging as a source for sustainable bio-based materials. Fungal biomass of Aspergillus oryzae was prepared by cultivation on bread waste hydrolysate to valorize this abundant food waste. Chitin-glucan-rich alkali-insoluble material (AIM) was isolated from fungal biomass, formed into hydrogels, and wet spun into monofilaments. AIM in the form of fungal microfibers containing 0.09 g polymer of glucosamine (GlcN)/g AIM was subjected to freeze-thaw and deacetylation treatments to increase the amount of GlcN. The GlcN fraction was 0.19 and 0.34 g polymer of GlcN/g AIM, for AIM subjected to deacetylation (AIM-DAC) and freeze-thaw cycles and deacetylation (AIM-FRTH-DAC), respectively. The increased GlcN fraction enabled the formation of hydrogels via the protonation of amino groups after the addition of lactic acid. Morphological differences in the hydrogels included aggregation of the fungal microfibers in the AIM-DAC hydrogel, whereas the microfibers in the AIM-FRTH-DAC hydrogel had a porous and interconnected network. Rheological assessment revealed shear thinning behavior and gel properties of the produced hydrogels. Wet spinning of the hydrogels resulted in monofilaments with tensile strengths of up to 70 MPa and 12 % elongation at break. This demonstrates promising avenues for biomaterial development from fungal cell walls containing chitin-glucan via food waste valorization.

Extraction of chitin from flammulina velutipes waste: A low-concentration acid pretreatment and aspergillus Niger fermentation approach

In recent years, with the booming of the edible mushroom industry, chitin production has become increasingly dependent on fungi and other non-traditional sources. Fungal chitin has advantages including superior performance, simpler separation processes, abundant raw materials, and the absence of shellfish allergens. As a kind of edible mushroom, flammulina velutipes (F. velutipes) also has the advantages of wide source and large annual yield. This provided the possibility for the extraction of chitin. Here, a procedure to extract chitin from F. velutipes waste be presented. This method comprises low-concentration acid pretreatment coupled with consolidated bioprocessing with Aspergillus niger. Characterization by SEM, FTIR, XRD, NMR, and TGA confirmed that the extracted chitin was β-chitin. To achieve optimal fermentation of F. velutipes waste (80 g/L), ammonium sulfate and glucose were selected as nitrogen and carbon sources (5 g/L), with a fermentation time of 5 days. The extracted chitin could be further deacetylated and purified to obtain high-purity chitosan (99.2 % ± 1.07 %). This chitosan exhibited a wide degree of deacetylation (50.0 % ± 1.33 % - 92.1 % ± 0.97 %) and a molecular weight distribution of 92-192 kDa. Notably, the yield of chitosan extracted in this study was increased by 56.3 % ± 0.47 % compared to the traditional chemical extraction method.

Isolation and Structure Analysis of Chitin Obtained from Different Developmental Stages of the Mulberry Silkworm (Bombyx mori)

Chitin, a ubiquitous biopolymer, holds paramount scientific and economic significance. Historically, it has been primarily isolated from marine crustaceans. However, the surge in demand for chitin and the burgeoning interest in biopolymers have necessitated the exploration of alternative sources. Among these methods, the mulberry silkworm (Bombyx mori) has emerged as a particularly intriguing prospect. To isolate chitin from Bombyx mori, a chemical extraction methodology was employed. This process involved a series of meticulously orchestrated steps, including Folch extraction, demineralization, deproteinization, and decolorization. The resultant chitin was subjected to comprehensive analysis utilizing techniques such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), 13C nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray scattering (WAXS). The obtained results allow us to conclude that the Bombyx mori represents an attractive alternative source of α-chitin.

Advances in chitosan and chitosan derivatives for biomedical applications in tissue engineering: An updated review

In recent years, chitosan (CS) has received much attention as a functional biopolymer for various applications, especially in the biomedical field. It is a natural polysaccharide created by the chemical deacetylation of chitin (CT) that is nontoxic, biocompatible, and biodegradable. This natural polymer is difficult to process; however, chemical modification of the CS backbone allows improved use of functional derivatives. CS and its derivatives are used to prepare hydrogels, membranes, scaffolds, fibers, foams, and sponges, primarily for regenerative medicine. Tissue engineering (TE), currently one of the fastest-growing fields in the life sciences, primarily aims to restore or replace lost or damaged organs and tissues using supports that, combined with cells and biomolecules, generate new tissue. In this sense, the growing interest in the application of biomaterials based on CS and some of its derivatives is justifiable. This review aims to summarize the most important recent advances in developing biomaterials based on CS and its derivatives and to study their synthesis, characterization, and applications in the biomedical field, especially in the TE area.

Aspergillus niger fermentation residues application to produce biochar for the anode of lithium-ion batteries

Aspergillus niger is widely applied in the fermentation industry, but produce abundant mycelium residues every year. As a kind of solid waste, mycelium residues seriously affect the environment. How to manage and utilize this solid waste is a problem for the fermentation industry. It was reported that many kinds of biomass could be utilized to produce carbon materials, which would be further used to produce lithium-ion rechargeable batteries (LIBs). Here, porous biochar was prepared from A. niger mycelial residues and further used as an anode for LIBs. Since the A. niger mycelium contains abundant nitrogen (5.29%) from its chitosan-dominated cell wall, and silicon (9.63%) from perlite filter aid, respectively, the biochar presented an excellent cycle stability and rate performance when applied as the anode of LIBs. The conclusion of this research shows the wide application prospect of fungal fermentation residues as carbon precursors in energy storage devices. Meanwhile, this investigation provides an alternative management method for A. niger mycelium residues, with which the mycelium residues could be effectively recycled to avoid resource waste and environmental pollution.

Chemical extraction, characterization, and inspection of the antimicrobial and antibiofilm activities of shrimp chitosan against foodborne fungi and bacteria

Nowadays, the exploitation of biopolymers in the industrial sector has become a trend. Chitosan is considered one of the most investigated biopolymers due to its abundance and antibacterial, antifungal, and antibiofilm activities. In this work, chitosan was chemically extracted from shrimp shells. Solutions of HCl 1 M, NaOH 4 M, and NaOH 15 M were used for the demineralization, deproteinization, and deacetylation process, respectively. The utilized methods of characterization (FTIR, 1 H NMR, 13 C NMR, and SEC-MALS) revealed that the obtained chitosan has a moderate degree of deacetylation and low molecular weight (DDA = 74% and Mw = 72.14 kDa). The microdilution method and inoculation of solid medium were carried out to assess the antibiofilm action of chitosan against Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus hirae, Escherichia coli, Rhizopus sp., and Aspergillus sp. which are known as foodborne microorganisms. Results showed that the produced chitosan at 1 g/L inhibits between 63.44 and 99.75% of the microbial biofilm depending on the tested strains. These promising results confirm the potential deployment of the obtained chitosan in the food industry as a replacement for synthetic antimicrobial agents.

Essential characteristics improvement of metallic nanoparticles loaded carbohydrate polymeric films - A review

Petroleum-based films have contributed immensely to various environmental issues. Developing green-based films from carbohydrate polymers is crucial for addressing the harms encountered. However, some limitations exist on their property, processibility, and applicability that prohibit their processing for further developments. This review discusses the potential carbohydrate polymers and their sources, film preparation methods, such as solvent-casting, tape-casting, extrusion, and thermo-mechanical compressions for green-based films using various biological polymers with their merits and demerits. Research outcomes revealed that the essential characteristics improvement achieved by incorporating different metallic nanoparticles has significantly reformed the properties of biofilms, including crystallization, mechanical stability, thermal stability, barrier function, and antimicrobial activity. The property-enhanced bio-based films made with nanoparticles are potentially interested in replacing fossil-based films in various areas, including food-packaging applications. The review paves a new way for the commercial use of numerous carbohydrate polymers to help maintain a sustainable green environment.

Production and physicochemical properties of fungal chitosans with efficacy to inhibit mycelial growth activity of pathogenic fungi

In order to enable the applicability of chitosan as an antifungal, soil fungi were isolated and identified, then used in its production. Fungal chitosan has several advantages, including lower toxicity, low cost, and high degree of deacetylation. These characteristics are essential for therapeutic applications. The results indicate high viability of the isolated strains to produce chitosan, obtaining a maximum yield of 40.59 mg chitosan/g of dry biomass. M. pseudolusitanicus L. was reported for the first time for production by chitosan. The chitosan signals were observed by ATR-FTIR and ¹³C SSNMR. Chitosans showed high degrees of deacetylation (DD), ranging from 68.8% to 88.5%. In comparison with the crustacean chitosan, Rhizopus stolonifer and Cunninghamella elegans presented lower viscometric molar masses (26.23 and 22.18 kDa). At the same time, the molar mass of chitosan Mucor pseudolusitanicus L. showed a value coincident with that assumed as low molar mass (50,000-150,000 g mol^-1). Concerning the in vitro antifungal potential against the dermatophyte fungus Microsporum canis (CFP 00098), the fungal chitosans showed satisfactory antifungal activities, inhibiting mycelial growth by up to 62.81%. This study points to the potential of chitosans extracted from fungal cell walls for applications in the inhibition of the growth of (Microsporum canis) human pathogenic dermatophyte.

Optimization of Chitosan Extraction Process from Rapana venosa Egg Capsules Waste Using Experimental Design

New green and sustainable sources were chosen to obtain chitosan, an important material, with many applications in different fields. The present study is focused on egg capsules of Rapana venosa waste as raw material for chitosan oligomers. As previous studies revealed that chitosan extraction from this material takes place with a low yield, the present research aimed to optimize this step. A 2² experimental plan, with three replicates in the center, was proposed to investigate the influence of NaOH concentration and temperature on the yield extraction. After a primary analysis of the experimental data, a favorable temperature value was selected (90 °C) at which the total dissolution of the egg capsules was obtained. Then, at this temperature, the experimental plan was extended exploring the influence of the NaOH concentration on three levels (5, 6, and 7%) and the extraction duration on two levels (60 and 85 min). Based on all experimental data, a neural model was obtained and validated. The neural model was used to maximize the yield, applying Genetic Algorithm (GA) implemented in Matlab^®. The resulting optimal solution is: NaOH concentration 6.47%, temperature 90 °C, duration 120 min, with a yield value of 7.05%.

Improved Metal Cation Optosensing Membranes through the Incorporation of Sulphated Polysaccharides

Optosensing chitosan-based membranes have been applied for the detection of heavy metals, especially in drinking water. The novelty of this study is based on the use of sulphated polysaccharides, in such optosensing membranes, aiming at an improved analytical performance. The sulphated polysaccharides, such as ulvan, fucoidan and chondroitin sulfate, were extracted from by-products and wastes of marine-related activities. The membranes were developed for the analysis of aluminum. The variation in the visible absorbance of the sensor membranes after the contact between the chromophore and the aluminum cation was studied. The membranes containing sulphated polysaccharides showed improved signals when compared to the chitosan-only membrane. As for the detection limits for the membranes containing ulvan, fucoidan and chondroitin sulfate, 0.17 mg L⁻¹, 0.21 mg L⁻¹ and 0.36 mg L⁻¹ were obtained, respectively. The values were much lower than that obtained for the chitosan-only membrane, 0.52 mg L⁻¹, which shows the improvement obtained from the sulphated polysaccharides. The results were obtained with the presence of CTAB in analysis solution, which forms a ternary complex with the aluminum cation and the chromophore. This resulted in an hyperchromic and batochromic shift in the absorption band. When in the presence of this surfactant, the membranes showed lower detection limits and higher selectivity.

Chitosan Production by Fungi: Current State of Knowledge, Future Opportunities and Constraints

Conventionally, the commercial supply of chitin and chitosan relies on shellfish wastes as the extraction sources. However, the fungal sources constitute a valuable option, especially for biomedical and pharmaceutical applications, due to the batch-to-batch unsteady properties of chitin and chitosan from conventional ones. Fungal production of these glycans is not affected by seasonality enables accurate process control and, consequently, more uniform properties of the obtained product. Moreover, liquid and solid production media often are derived from wastes, thus enabling the application of circular economy criteria and improving the process economics. The present review deals with fungal chitosan production processes focusing on waste-oriented and integrated production processes. In doing so, contrary to other reviews that used a genus-specific approach for organizing the available information, the present one bases the discussion on the bioprocess typology. Finally, the main process parameters affecting chitosan production and their interactions are critically discussed.

Biosorption of ketoprofen and diclofenac by living cells of the green microalgae Chlorella sp

There is a growing interest for the removal of different pharmaceuticals from water owing to their toxicity to various organisms. The present study investigated the use of living cells of the green alga Chlorella sp. in the short-term adsorption of ketoprofen (KET) and diclofenac (DIF) from aqueous solutions. The bioremoval efficiency of both KET and DIF was highly dependent on various parameters such as time, pH, algal dosage, and drug concentration. The adsorption efficiencies of both KET and DIC were maximized at pH 6. The biosorption of KET was better described by pseudo-first-order kinetics, while DIC obeyed the pseudo-second-order model. The maximum adsorption capacities of KET and DIF were attained as 0.328 and 0.429 mg g^-1, respectively. The equilibrium data of the investigated drugs showed a better fit to the Freundlich model than the Langmuir model. The Elovich and Temkin models indicated that the algal surface was heterogeneous with different binding energies, while the intraparticle diffusion model assumed a boundary layer effect. Additionally, the Dubinin-Radushkevich isotherm indicated that the adsorption process was predominantly physisorption. FT-IR analysis revealed that H-bonding and n-π interactions were prominent in the biosorption process of the investigated pharmaceuticals on the surface of microalgae. The results of the present study showed that microalgae living cells could be applied as an eco-friendly and cost-effective biosorbent for the removal of KET and DIF at low concentrations.

Insect Chitin-Based Nanomaterials for Innovative Cosmetics and Cosmeceuticals

Chitin and its derivatives are attracting great interest in cosmetic and cosmeceutical fields, thanks to their antioxidant and antimicrobial properties, as well as their biocompatibility and biodegradability. The classical source of chitin, crustacean waste, is no longer sustainable and fungi, a possible alternative, have not been exploited at an industrial scale yet. On the contrary, the breeding of bioconverting insects, especially of the Diptera Hermetia illucens, is becoming increasingly popular worldwide. Therefore, their exoskeletons, consisting of chitin as a major component, represent a waste stream of facilities that could be exploited for many applications. Insect chitin, indeed, suggests its application in the same fields as the crustacean biopolymer, because of its comparable commercial characteristics. This review reports several cosmetic and cosmeceutical applications based on chitin and its derivatives. In this context, chitin nanofibers and nanofibrils, produced from crustacean waste, have proved to be excellent cosmeceutical active compounds and carriers of active ingredients in personal care. Consequently, the insect-based chitin, its derivatives and their complexes with hyaluronic acid and lignin, as well as with other chitin-derived compounds, may be considered a new appropriate potential polymer to be used in cosmetic and cosmeceutical fields.

Shellfish Chitosan Potential in Wine Clarification

Chitosan is a chitin-derived fiber, extracted from the shellfish shells, a by-product of the fish industry, or from fungi grown in bioreactors. In oenology, it is used for the control of Brettanomyces spp., for the prevention of ferric, copper, and protein casse and for clarification. The International Organisation of Vine and Wine established the exclusive utilization of fungal chitosan to avoid the eventuality of allergic reactions. This work focuses on the differences between two chitosan categories, fungal and animal chitosan, characterizing several samples in terms of chitin content and degree of deacetylation. In addition, different acids were used to dissolve chitosans, and their effect on viscosity and on the efficacy in wine clarification were observed. The results demonstrated that even if fungal and animal chitosans shared similar chemical properties (deacetylation degree and chitin content), they showed different viscosity depending on their molecular weight but also on the acid used to dissolve them. A significant difference was discovered on their fining properties, as animal chitosans showed a faster and greater sedimentation compared to the fungal ones, independently from the acid used for their dissolution. This suggests that physical–chemical differences in the molecular structure occur between the two chitosan categories and that this significantly affects their technologic (oenological) properties.

In depth investigation of the retention behavior of structurally related β-blockers on RP-HPLC column: Quality by design and quantitative structure-property relationship complementary approaches for optimization and validation

The persistent introduction of new β-blockers motivates the demand for optimizing RP-HPLC well-designed analytical procedures that could be applied to this structurally related and commonly prescribed pharmacological group in order to reduce time and chemicals consumption in quality control units. Betoxolol HCl (BEX) and Carvidolol (CAR) were selected as representative examples to conduct predictive studies based on two complementary approaches, Quality by design (QBD) and Quantitative structure property relationship (QSPR). In concern QBD, a Box-Behnken design was adopted at variable chromatographic parameters to achieve the most proper conditions that might be applied for efficient analysis of the majority of group members. On the other hand, the retention time was chosen as the target property in the QSPR study that was conducted onto seven β. blockers (the two investigated drugs in addition to five other β. blockers) to find the best correlated molecular descriptors to the retention behavior. Both external and internal validation studies have comparable quality with training levels. Hence a simple selection algorithm of conventional features provides robust confirmatory predictive QBD and QSPR models. Derringer's desirability function as as a multi-criteria approach was applied for getting the optimum chromatographic analysis conditions. Efficient analysis of BET and CAR was achieved at column temperatures of 26.00 and 27.50 °C, respectively using acetonitrile and phosphate buffer (pH 4.55) 70:30 v/v as a mobile phase with a flow rate of 1.00 mL/min, and UV detection at 220 nm. The method was validated in accordance to ICH guidelines, and had exhibited acceptable precision, accuracy, linearity, and robustness.

Development of Stimuli-Responsive Chitosan/ZnO NPs Transdermal Systems for Controlled Cannabidiol Delivery

One of the most common neurological diseases is epilepsy, which not only negatively affects the quality of people's life but also may lead to life-threatening situations when its symptoms such as seizures cannot be controlled medically. A very serious problem to be overcame is the untreatable form of this disease, which cannot be cured by any currently available medicines. Cannabidiol, which is a natural product obtained from Cannabis Sativa, brings a new hope to people suffering from drug-resistant epilepsy. However, the hydrophobic character of this compound significantly lowers its clinical efficiency. One of the promising methods of this substance bioactivity increase is delivery through the skin tissue. In this article, a new type of advanced transdermal systems based on chitosan and ZnO nanoparticles (NPs) has been developed according to Sustained Development principles. The chemical modification of the biopolymer confirmed by FT-IR method resulted in the preparation of the material with great swelling abilities and appropriate water vapor permeability. Obtained nanoparticles were investigated over their crystalline structure and morphology and their positive impact on drug loading capacity and cannabidiol controlled release was proved. The novel biomaterials were confirmed to have conductive properties and not be cytotoxic to L929 mouse fibroblasts.

Preparation and characterization of various chitin-glucan complexes derived from white button mushroom using a deep eutectic solvent-based ecofriendly method

Deep eutectic solvents (DESs) have gained great interests as ecofriendly and safe solvents in diverse areas. Herein, various chitin-glucan complexes (CGCs) were prepared from white button mushroom (Agaricus bisporus) using DESs. Ultrasonication of mushroom in five DESs yielded two types of CGCs from each DES, one from the DES-insoluble residue (DES_P) and another from the DES-soluble extract (DES_S). The ten resulting CGCs with varying chitin-to-β-glucan ratios were compared with alkali-insoluble matter (AIM), chemically prepared using NaOH. BU_S and BU_P, prepared using BU comprising betaine and urea, were obtained in the highest yields with reasonably low protein and mineral contents. Despite different acetylation degrees (77.3% and 57.3%, respectively), BU_S and BU_P both degraded at 318 °C and showed remarkably low crystallinity (32.0% and 37.0% for BU_S and BU_P, respectively) compared to AIM, commercial chitin, and the reported CGCs. The surface of BU_S and BU_P was very porous and rough compared with AIM as a result of reduced H-bonds and lowered crystallinity. The DES-based method can potentially enable the preparation of advanced biomaterials from mushrooms under mild and ecofriendly conditions.

Production of peptides and amino acids from microbial biomass in food and feed industries: biotechnological aspects

Introduction. Microbial biomass is a popular source of food ingredients and feed additives. Its high use has made it focus of many relevant studies. Yeast and fungal biomasses proved to be useful substrates that improve the quality and biological value of functional products. They differ in the content and composition of proteins and polysaccharides. The present research dealt with the enzymatic decomposition of proteins found in a novel fungal and yeast biomass. The research objective was to describe the peptide and amino acid composition of their enzymatic hydrolysates. Study objects and methods. The research featured a new fungal and yeast biomass mix. Aspergillus oryzae is a mycelial fungus and a popular industrial producer of hydrolytic enzymes in food industry. As for the yeast, it was the Saccharomyces cerevisiae strain, which is often used in baking. Results and discussion. The total content of identified amino acids in the fungal and yeast biomass was 306.0 mg/g, which was 1.5 times higher than in the fungal biomass alone. The biomass mix demonstrated a higher biological value of proteins than the yeast biomass. A set of experiments made it possible to compile a scheme for the biocatalytic destruction of polymers in the fungal and yeast biomass under the effect of fungal intracellular and endogenous enzymes. The article also contains a thorough description of the obtained enzymatic hydrolysates with various fractional compositions of peptides and free amino acids. Peptides with the molecular weight in the range of up to 29.0 kDa decreased by 2.1 times after 5 h of hydrolysis and by 10.7 times after 18 h. The designed conditions doubled the release of amino acids and increased the content of low-molecular-weight peptides up to 75.3%. Conclusion. The research provided a new algorithm for the biocatalytic conversion of microbial biomass. Regulating the conditions of enzymatic hydrolysis made it possible to obtain enzymatic hydrolysates with a desired degree of protein degradation. They could serve as peptides and amino acids in functional food and feed products.

Using Flammulina velutipes derived chitin-glucan nanofibrils to stabilize palm oil emulsion:A novel food grade Pickering emulsifier

We herein report chitin-glucan nanofibrils from edible mushroom Flammulina velutipes (CGNFs) as a novel stabilizer for palm oil Pickering emulsion (o/w, 30:70, v:v). Generally, these CGNFs being composed of glucose and glucosamine, are threadlike with 4.9 ± 1.2 nm wide and 222.6 ± 91.9 nm long. They were easily absorbed on the oil-water interface to form a compact layer around the oil droplets referring to Pickering emulsion. This emulsion presented shear-thinning and gel-like behaviors, wherein CGNFs concentration had a profound influence on the emulsion volume, droplet size, and stabilization index. Moreover, CGNFs showed an ability to stabilize the emulsion with a minimum of surface coverage approximately 30%. It indicated that moderate concentration of NaCl improved the emulsification effect, and the emulsion were stable in a large range of pH. These CGNFs are easy to prepare, eco-friendly and sustainable, which provides a potential for large-scale application of Pickering emulsion in food and nutraceuticals fields.

Economic microbiological conversion of agroindustrial wastes to fungi chitosan

To investigate the simultaneous influence of different non-nutritional factors in production and physical-chemical characteristics of chitosan obtained by Syncephalastrum racemosum we used individually agroindustrial wastes as the only nutritional sources for fungus growth. The growth conditions were evaluated according to Factorial Design, 24 with three central points in order to determine the mainly factors for maximum production of microbiological chitosan in submerged culture. Syncephalastrum racemosum grown in corn steep liquor and yield up to 7.8 g chitosan/kg of substrate in the best condition by factorial design. The microbiological chitosan obtained has deacetilation degree 88.14%, crystallinity rate of 55.96%, mass decomposition process at 304.43 ºC, and low molecular weight. To fast production we performed a kinetic study and confirmed that at 36 h the chitosan production is higher and the physical-chemical characteristics were maintained. This research describes, for the first time, the factorial study of chitosan production by Syncephalastrum racemosum in agroindustrial wastes and its economic potential for commercialization.

Use of algal biorefinery waste and waste office paper in the development of xerogels: A low cost and eco-friendly biosorbent for the effective removal of congo red and Fe (II) from aqueous solutions

The present study investigated the use of algae biorefinery waste and wastepaper in the preparation of cost-effective and eco-friendly xerogels for the removal of congo red (CR) and Fe²⁺. The xerogel properties such as density, swelling degree and porosity were modified by incorporating alginate extracted from the brown seaweed Cystoseira trinodis. The developed biosorbents exhibited a light and porous network structure and were characterized by a fast uptake of CR and Fe²⁺ and adsorption efficiency was increased at pH 6-8. The equilibrium adsorption capacity was found to be 6.20-7.28 mg CR g^-1 biosorbent and 8.08-8.39 mg Fe²⁺ g^-1 biosorbent using different xerogels. The adsorption of CR obeyed first-order kinetics, while, Fe²⁺ followed second-order kinetics. Intraparticle diffusion model suggested a boundary layer effect. The adsorption capacity was maximally obtained as 41.15 mg g^-1 and 169.49 mg g^-1 for CR and Fe²⁺ using wastepaper/Spirulina and wastepaper/alginate/Spirulina xerogel, respectively. Temkin isotherm fitted better to the equilibrium data of CR adsorption than Langmuir and Freundlich models. While, equilibrium data of Fe²⁺ exhibited a best fit to both Langmuir and Freundlich models. Additionally, the Dubinin-Radushkevich isotherm suggested that adsorption mechanism of CR or Fe²⁺ is predominately physisorption. Investigation of thermodynamic parameters such as ΔH° and ΔS° and ΔG° confirmed the feasibility, spontaneity, randomness and endothermic nature of the adsorption process. Electrostatic attraction, H-bonding and n-π interactions were mainly involved in the biosorption process of CR. The results of this study showed that the developed xerogels could be effectively applied for dye and heavy metal removal at low concentrations.

Chitosan Composites in Packaging Industry-Current Trends and Future Challenges

Chitosan-based composites play an important role in food packaging applications and can be used either as films or as edible coatings. Due to their high costs and lower performance (i.e., lower barrier against water vapor, thermal, and mechanical properties) when compared to the traditional petroleum-based plastics, the use of such biopolymers in large-scale is still limited. Several approaches of chitosan composites in the packaging industry are emerging to overcome some of the disadvantages of pristine polymers. Thus, this work intends to present the current trends and the future challenges towards production and application of chitosan composites in the food packaging industry.

Chitosan Nanocomposite Coatings for Food, Paints, and Water Treatment Applications

Worldwide, millions of tons of crustaceans are produced every year and consumed as protein-rich seafood. However, the shells of the crustaceans and other non-edible parts constituting about half of the body mass are usually discarded as waste. These discarded crustacean shells are a prominent source of polysaccharide (chitin) and protein. Chitosan is a de-acetylated form of chitin obtained from the crustacean waste that has attracted attention for applications in food, biomedical, and paint industries due to its characteristic properties, like solubility in weak acids, film-forming ability, pH-sensitivity, biodegradability, and biocompatibility. We present an overview of the application of chitosan in composite coatings for applications in food, paint, and water treatment. In the context of food industries, the main focus is on fabrication and application of chitosan-based composite films and coatings for prolonging the post-harvest life of fruits and vegetables, whereas anti-corrosion and self-healing properties are the main properties considered for antifouling applications in paints in this review.

Statistical Optimization of Culture Variables for Enhancing Agarase Production by Dendryphiella arenaria Utilizing Palisada perforata (Rhodophyta) and Enzymatic Saccharification of the Macroalgal Biomass

Agarase is a promising biocatalyst for several industrial applications. Agarase production was evaluated by the marine fungus Dendryphiella arenaria utilizing Palisada perforata as a basal substrate in semi-solid state fermentation. Seaweed biomass, glucose, and sucrose were the most significant parameters affecting agarase production, and their levels were further optimized using Box-Behnken design. The maximum agarase activity was 7.69 U/mL. Agarase showed a degree of thermostability with half-life of 99 min at 40 °C, and declining to 44.72 min at 80 °C. Thermodynamics suggested an important process of protein aggregation during thermal inactivation. Additionally, the enzymatic saccharification of the seaweed biomass using crude agarase was optimized with respect to biomass particle size, solid/liquid ratio, and enzyme loadings. The amount of biosugars obtained after optimization was 26.15 ± 1.43 mg/g. To the best of our knowledge, this is the first report on optimization of agarase in D. arenaria.

Technological Microbiology: Development and Applications

Over thousands of years, modernization could be predicted for the use of microorganisms in the production of foods and beverages. However, the current accelerated pace of new food production is due to the rapid incorporation of biotechnological techniques that allow the rapid identification of new molecules and microorganisms or even the genetic improvement of known species. At no other time in history have microorganisms been so present in areas such as agriculture and medicine, except as recognized villains. Currently, however, beneficial microorganisms such as plant growth promoters and phytopathogen controllers are required by various agricultural crops, and many species are being used as biofactories of important pharmacological molecules. The use of biofactories does not end there: microorganisms have been explored for the synthesis of diverse chemicals, fuel molecules, and industrial polymers, and strains environmentally important due to their biodecomposing or biosorption capacity have gained interest in research laboratories and in industrial activities. We call this new microbiology Technological Microbiology, and we believe that complex techniques, such as heterologous expression and metabolic engineering, can be increasingly incorporated into this applied science, allowing the generation of new and improved products and services.

Biodegradable, pH-responsive chitosan aerogels for biomedical applications

Biodegradable chitosan aerogels with advanced properties for biomedical applications are obtained in a two-step process using biotolerant chemicals, MW irradiation and lyophilisation.