Mycelial Waste Research Articles

The production and biological activity of fungal chitosan from the mycelial waste of Rhizomucor miehei

In this study, waste biomass of industrial enzyme producer Rhizomucor miehei was used as an alternative source for fungal chitosan production. Fungal chitosan was obtained from mycelial waste at the deproteinization and deacetylation stages at different temperatures and times of alkali and acid treatment with different concentrations of sodium hydroxide (1–3 N) and acetic acid (2–4 %), respectively. High chitosan yield (70.6 mg/g) was reached at the optimized conditions when the concentration of NaOH (3 N), the deproteinization time (20 mins) and temperature ( 95℃), the concentration of acetic acid (4 %), the deacetylation time (6 hrs) and temperature (85℃). The fungal chitosan with a molecular weight of 14 kDa showed a deacetylation degree of 78 %. The XRD pattern showed two peaks at 2θ values of 9° and 19°. The antimicrobial activity of the fungal chitosan showed broad spectrum at low concentrations (125–250 µg/mL) against the test microorganisms. As wound healing activity, after five days post-scratching, the HaCaT cells cultured in the presence of fungal chitosan demonstrated a notable 57 % increase in migration rate. These findings underscored the efficacy of the produced fungal chitosan, highlighting its promising biological activities. This is the first report to evaluate the use of waste Rhizomucor miehei biomass as alternative source for chitosan.

High performance biochar derived from mycelium-based leather composites waste for energy storage applications

The mycelial waste generated during the production of mycelium-based leather composites presents both opportunities and challenges in maximizing biomass resource efficiency. In this study, we synthesized mesoporous biochar (AGLM-5) with a specific surface area of 3151.9 m2/g through the KOH activation method using Ganoderma lucidum mycelium waste as the precursor material. AGLM-5 exhibited exceptional performance in a three-electrode system test, demonstrating a specific capacitance of 303.5 F/g. In a two-electrode system test, it achieved an energy density of 45.5 Wh/kg at a power density of 450.7 W/kg. The symmetric supercapacitor assembled using AGLM-5 demonstrated outstanding cycling stability over 10,000 cycles, exhibiting a capacitance loss of less than 4 % throughout the entire testing period. Additionally, we employed a hydrothermal method to synthesize composite electrode sheets (δ-MnO2/AGLM-5), which not only supported the layered structure of δ-MnO2 but also significantly improved the cycling stability and electrical conductivity of aqueous zinc ion batteries (AZIB). This study presents an environmentally friendly and sustainable approach for utilizing Ganoderma lucidum mycelial biomass, with particular emphasis on the potential application of mycelial carbon materials in battery energy storage.

Deletion of the Aspergillus niger Pro-Protein Processing Protease Gene kexB Results in a pH-Dependent Morphological Transition during Submerged Cultivations and Increases Cell Wall Chitin Content.

There is a growing interest in the use of post-fermentation mycelial waste to obtain cell wall chitin as an added-value product. In the pursuit to identify suitable production strains that can be used for post-fermentation cell wall harvesting, we turned to an Aspergillus niger strain in which the kexB gene was deleted. Previous work has shown that the deletion of kexB causes hyper-branching and thicker cell walls, traits that may be beneficial for the reduction in fermentation viscosity and lysis. Hyper-branching of ∆kexB was previously found to be pH-dependent on solid medium at pH 6.0, but was absent at pH 5.0. This phenotype was reported to be less pronounced during submerged growth. Here, we show a series of controlled batch cultivations at a pH range of 5, 5.5, and 6 to examine the pellet phenotype of ΔkexB in liquid medium. Morphological analysis showed that ΔkexB formed wild type-like pellets at pH 5.0, whereas the hyper-branching ΔkexB phenotype was found at pH 6.0. The transition of phenotypic plasticity was found in cultivations at pH 5.5, seen as an intermediate phenotype. Analyzing the cell walls of ΔkexB from these controlled pH-conditions showed an increase in chitin content compared to the wild type across all three pH values. Surprisingly, the increase in chitin content was found to be irrespective of the hyper-branching morphology. Evidence for alterations in cell wall make-up are corroborated by transcriptional analysis that showed a significant cell wall stress response in addition to the upregulation of genes encoding other unrelated cell wall biosynthetic genes.

Potent Fungal Chitinase for the Bioconversion of Mycelial Waste.

Aspergillus niger mycelial waste is a good raw material for production of N-acetyl-d-glucosamine (GlcNAc). In this study, AnChiB, an A. niger chitinase which is upregulated during autolysis, was found to degrade A. niger mycelial waste with high efficiency. It could produce 1.45 mM (GlcNAc)2 in 8 h from raw mycelial waste, outperforming other chitinases, including bacterial SmChiA, human HsCht, and insect OfChtI and OfChi-h. The crystal structure of AnChiB was determined, and residues Trp106 and Trp118 were found to be important for the activity of AnChiB toward mycelial waste; mutation of either Trp106 or Trp118 into phenylalanine or alanine resulted in dramatically decreased activity. A recombinant strain of Bacillus subtilis was constructed to extracellularly produce AnChiB, and the culture supernatant was used to treat mycelial waste. This eco-friendly strategy could produce 3.7 mM of GlcNAc from 10 g of mycelial waste in 94 h with a yield of 71.3%.

Insights into the evolution of chemical structures in lignocellulose and non-lignocellulose biowastes during hydrothermal carbonization (HTC)

Insights into evolution pathways of chemical structures during HTC are essential in acquiring the mechanisms controlling the structure-reactivity of biowaste-derived hydrochars. In this study, two types of industrial biowastes were selected for HTC experiments, namely, a lignocellulose one (herbal tea waste, HTW) and a non-lignocellulose one (penicillin mycelial waste, PMW). In addition to their fundamental properties, chemical structures of hydrochars were concurrently identified with the help of XRD and Raman (for crystalline and aromatic structure), XPS and 13C NMR (for carbon skeleton structures), FTIR and 2D-PCIS (for surface functionalities) technologies. Results found that a more condensed and amorphous structures of biowaste-derived hydrochars was obtained, regardless of the differences in biowaste components. The original structures in biowastes were converted from low-energy states (CH/O/O) to high energy states (aromatic CC/C) via hydrolysis, carbonization and polymerization; nevertheless, the evolution pathways of chemical structures were different from each other. Nucleation growing process was the key mechanism for HTW, while the conversion routes of PMW were more complex than HTW due to the self-rearrangement of amino acids, as well as synergistic reactions between amino acids and reduced sugars.

Reutilization potential of antibiotic wastes via hydrothermal liquefaction (HTL): Bio-oil and aqueous phase characteristics

Hydrothermal liquefaction (HTL) technology was employed to investigate the feasibility of recovering energy from penicillin mycelial waste (PMW) with the help of TG, Py-GC/MS and GC-MS techniques; meanwhile, the nutrients in aqueous phase were also analyzed by spectrophotometry methods. The effects of operating conditions, including hydrothermal temperature (240–300 °C), duration time (20–60 min), total solid ratio (5–15%) and their interactive reactions were concurrently evaluated via response surface methodology. Results demonstrated that operating temperature was found to be the dominant variable affecting the HTL of PMW. Based on the optimal conditions of 298 °C, 60 min and 14.85%, heavy oil derived from PMW was comparable with algal-derived bio-oil as it possessed the highest energy recovery efficiency (42.95%) with a calorie value of 32.84 MJ/kg and a yield of 24.93%. GC/MS results indicated that heavy oil mainly consisted of N-containing compounds (36.73%) and aromatic compounds (31.07%), which might be contributed to the hydrolysis of protein and the aromatization of intermediates, respectively. Besides, more than 65% of nitrogen and 40% of carbon were enriched in aqueous phase, suggesting the possibility of further recycling for algae cultivation, fermentation and anaerobic digestion.

Characteristics of NOx precursors and their formation mechanism during pyrolysis of herb residues

Based on two herb residues-herbal tea waste (HTW) and penicillin mycelial waste (PMW), characteristics of NOx precursors during their pyrolysis were investigated in a horizontal tubular reactor with the help of XPS and TGA technologies. Effects of thermal conditions and physicochemical properties of fuels were discussed and compared. The results demonstrate that protein-N is the main nitrogen form for both HTW and PMW, determining the dominance of NH3 among NOx precursors at any operational conditions. Thermal conditions would still change the ratio and total yield by intrinsically influencing their formation pathways. Subsequently, the effects could be sequenced as follows: high temperatures with rapid pyrolysis > high temperatures with slow pyrolysis > low temperatures with rapid pyrolysis ≈ low temperatures with slow pyrolysis. Moreover, at high temperatures with rapid pyrolysis, increase in particle size or decrease in moisture content would result in reduction of total yield by 5%–11% and 4%–6%, respectively. In addition, NH3 yield is produced at low temperatures or slow pyrolysis with sequence of PMW > HTW and vice versa, depending on components in the fuels. Consequently, analyses on nitrogen forms in char and nitrogen distribution indicate that total yield of 20%–45% is observed to be independent of fuel type under typical pyrolysis conditions, which may provide helpful guidance for the clean reutilization of herb residues.

DEVELOPMENT OF ECOLOGICALLY SAFE TECHNOLOGY OF WASTE MYCELIA RECYCLING

Chitosan is a cationic polymer derived by deacetylation of chitin obtained from crustaceans. Biodegradable and mucoadhesion properties of chitosan have recently led to increasing the interest. Chitosan can be used as raw material for the manufacture of films, membranes and fibers, in such branches as medicine, agriculture, veterinary medicine, biotechnology, cosmetics and pulp, and paper industry. Previously it was investigated that in Aspergillus Niger cell wall constituents, chitin comprises of 42 % and also researchers confirmed that the chitosan content of fungi depends on fungal strains, mycelial age, cultivation medium and conditions [1]. In the paper the results of the study of physical and chemical properties of obtained samples of chitosan are shown. The influence of initial parameters of the process on the quality of chitosan is investigated. Use of the biomass to produce chitosan on the basis of the developed methodology is shown. It is found that the resulting chitosan is characterized by low values of ash content, moisture content and the value is within 75–82 %. A further development of the scientific basis for the creation of an efficient, competitive and environmentally safe technologies for utilization mycelial biomass of the fungus Aspergillus Niger with the production of a valuable product is chitosan, which is in contrast to the known allows to reduce production costs by 10–80 % (by using not concentrated solutions of chemicals and low temperature process. This leads to reducing the cost of reagents and electricity. The calculation was performed on indicators such as net present value, internal rate of return and payback period.) The use of the developed technological schemes in practice allows utilization of mycelial waste with the aim of obtaining from them valuable product of chitosan, and to ensure the improvement of ecological situation in the region.

Production of N-Acetyl-d-glucosamine from Mycelial Waste by a Combination of Bacterial Chitinases and an Insect N-Acetyl-d-glucosaminidase.

N-Acetyl-d-glucosamine (GlcNAc) has great potential to be used as a food additive and medicine. The enzymatic degradation of chitin-containing biomass for producing GlcNAc is an eco-friendly approach but suffers from a high cost. The economical efficiency can be improved by both optimizing the member and ratio of the chitinolytic enzymes and using new inexpensive substrates. To address this, a novel combination of bacterial and insect chitinolytic enzymes was developed in this study to efficiently produce GlcNAc from the mycelia of Asperillus niger, a fermentation waste. This enzyme combination contained three bacterial chitinases (chitinase A from Serratia marcescens (SmChiA), SmChiB, SmChiC) and one insect N-acetyl-d-glucosaminidase from Ostrinia furnacalis (OfHex1) in a ratio of 39.1% of SmChiA, 26.7% of SmChiB, 32.9% of SmChiC, and 1.3% of OfHex1. A yield of 6.3 mM (1.4 mg/mL) GlcNAc with a purity of 95% can be obtained from 10 mg/mL mycelial powder in 24 h. The enzyme combination reported here exhibited 5.8-fold higher hydrolytic activity over the commercial chitinase preparation derived from Streptomyces griseus.

Energy recycling from sewage sludge by producing solid biofuel with hydrothermal carbonization

The hydrothermal (HT) conversion has been proposed to produce nitrogen, chlorine free solid biofuel or liquid fertilizer from high moisture and nitrogen content bio-wastes, such as municipal solid waste (MSW), mycelial waste, sewage sludge and paper sludge. However, the energy and economic efficiency of this process has not been fully investigated yet. This work focuses on energy recycling from sewage sludge by producing solid biofuel with HT carbonization, in order to optimize the operating parameters and evaluate the energy efficiency of this fuel production process. The effect of the HT temperature and holding time on the biofuel recovering ratio, calorific value and energy recovery rate was investigated. This evaluation fully considered the effect of the HT conditions, mechanical dewatering, thermal drying, and biofuel recovery ratio. Moreover, the energy consumption of sludge thermal drying was introduced to illustrate the economic efficiency of the HT biofuel production process more intuitively. The results show that the HT biofuel production process was more cost-effective than the conventional thermal drying. The HT temperature was the most important parameter to affect the biofuel properties. The carbon content of solid biofuel kept increasing both with HT temperature and holding time, resulting in an increase in the calorific value of biofuel; whereas, the biofuel recovering ratio α, defined as the mass ratio of solid biofuel to raw sludge, also dropped causing a reduction in the energy recovery rate. After the HT temperature was above 200°C, the energy recovery rate was around 40%. A moderate condition–HT temperature of 200°C and holding time of 30min was suggested to produce solid biofuel from sewage sludge with an energy recovery rate of 50%. Practically, it is better to improve the intensity of mechanical dewatering to remove more water from the HT products in order to improve thermal efficiency.

Fuel-N Evolution during the Pyrolysis of Industrial Biomass Wastes with High Nitrogen Content

In this study, sewage sludge and mycelial waste from antibiotic production were pyrolyzed in a batch scale fixed-bed reactor as examples of two kinds of typical industrial biomass wastes with high nitrogen content. A series of experiments were conducted on the rapid pyrolysis and the slow pyrolysis of these wastes in the temperature range from 500–800 °C to investigate the Fuel-N transformation behavior among pyrolysis products. The results showed that Fuel-N conversion to Char-N intimately depended on the pyrolysis temperature and the yield of Char-N reduced with the increase of the pyrolysis temperature. Under the same pyrolysis conditions, Tar-N production mainly depended on complex properties of the different biomasses, including volatile matter, nitrogen content and biomass functional groups. HCN was the predominant NOx precursor in the rapid pyrolysis of biomass, whereas in the slow pyrolysis of mycelial waste, more NH3 was produced than HCN due to the additional NH3 formation through the hydrogenation reaction of Char-N, HCN and H radicals. At the same time, some part of the char was analyzed by Fourier Transform infrared spectroscopy (FTIR) to get more information on the nitrogen functionality changes and the tar was also characterized by Gas Chromatography and Mass Spectrometry (GCMS) to identify typical nitrogenous tar compounds. Finally, the whole nitrogen distribution in products was discussed.

Antimicrobial textile treated with chitosan from Aspergillus niger mycelial waste

The waste biomass of Aspergillus niger, following citric acid production, was used as a source for fungal chitosan extraction. The produced chitosan was characterized with deacetylation degree of 89.6%, a molecular weight of 25,000 dalton, 97% solubility in 1% acetic acid solution and comparable FT-IR spectra to standard shrimp chitosan. Fungal chitosan was applied as a cotton fabric finishing agent using pad-dry-cure method. The topographical structure of chitosan-treated fabrics (CTF) was much improved compared with control fabrics. CTF, after durability tests, exhibited a powerful antimicrobial activity against both E. coli and Candida albicans, the captured micrographs for E. coli cells contacted with CTF showed a complete lysis of cell walls with the prolonging contact time. The produced antimicrobial CTF could be proposed as a suitable material for many medical and hygienic applications.

Exploitation of Trichoderma harzianum mycelial waste for the removal of rhodamine 6G from aqueous solution

The harvested mycelial waste of Trichoderma harzianum was used as an adsorbent for the removal of rhodamine 6G and was studied in batch mode. The effects of agitation time and initial dye concentration, adsorbent dosage and pH were examined. The study revealed that the amount of dye adsorbed (mg g −1) increased with increase in agitation time and reached equilibrium after 120 min, for dye concentrations of 10–50 mg L −1. The adsorbent dosage of 1.0 g/50 mL and pH of 8.0 were found to be optimum for maximum dye removal. The batch mode adsorption data followed both the Langmuir and Freundlich isotherms. The pseudo first- and second-order rate kinetics were applied to the adsorbent system. The adsorption kinetics of rhodamine 6G showed that the pseudo-second-order kinetic model provided the best correlation of the equilibrium data. The study implies that it is possible to develop a dye removal system by using T. harzianum biomass, which occurs as sludge in waste stream of fermentation industries.

Fermentation waste of Aspergillus terreus: a potential copper biosorbent

Aspergillus terreus mycelial waste produced during lipase production showed good copper biosorption capacity (160–180 mg Cu2+ biosorbed/g dry biomass). The sorption process followed fast kinetics and the absorption behaviour could be explained by a Freundlich isotherm model. The process was temperature independent and unaffected by the presence of many competing ions in a multi-ion situation. Maximum biosorption occurred between pH 4 and 5. The biomass could efficiently remove copper from mine effluents. Moreover the loaded biomass could easily be desorbed by a simple acid wash and could be reused a number of times without a decline in its biosorbing potential, thus making the process cost-effective.

Properties and characterization of Au3+-adsorption by mycelial waste ofStreptomyces aureofaciences

Mycelial waste ofStreptomyces aureofaciences procured from the aureomycin fermentation industry is used as biosorbent for Au3+. The properties of Au3+ adsorption by the mycelial waste are studied. The results indicate that the optimum pH value of Au3+ adsorption is 3.5. The biosorption is a rapid and non-temperature-dependent process. The biosorptive capacity with 45.6 mg/g and efficiency with 91.2% are achieved under the conditions of pH 3.5 and 30° C for 45 min, in which the ratio is 50 mg/g dry weight for the concen trations of initial Au3+ and the mycelial waste. The Au3+ ions adsorbed on the mycelial waste can be eluted. The observation in a transmission electron microscope shows that the Au3+ ions can be reduced to Au particles by the mycelial waste and the Au° can become gold crystals with different forms and sizes. X-ray photoelectron spectroscopy analysis further proves that the Au3+ can be reduced to Au° by the mycelial waste.

New metal-binding ethyldiamino- and dicarboxy-products from Aspergillus niger industrial wastes.

The metal-binding ability of Aspergillus niger mycelial waste was improved by chemical modification. The latter was performed by introducing additional carboxy groups using oxidation methods or the introduction of the ethyldiamino group first by chlorination of A. niger using mesyl chloride and subsequent reaction of the product with ethylene diamine. Metal binding abilities of the products for Cd2+, Co2+, Ni2+ and Zn2+ were determined according to the Langmuir model, whereby pKD*-values of 3.88 up to 5.02 were revealed. Maximum capacities for the metals were found to be in the range 172 to 1064 mmol/kg.

An installation for rendering harmless the mycelial waste products from the manufacture of antibiotics with simultaneous regeneration of the filtering powder

An installation for rendering harmless the mycelial waste products from the manufacture of antibiotics with simultaneous regeneration of the filtering powder