Fungal Pellets Research Articles

Yeast cell vacuum infusion into fungal pellets as a novel cell encapsulation methodology

Immobilized yeast cells are used industrially in winemaking processes such as sparkling wine and Sherry wine production. Here, a novel approach has been explored for the infusion and immobilization of yeast cells into filamentous fungal pellets, which serve as a porous natural material. This was accomplished through vacuum application to force the yeast cells towards the core of the fungal pellets followed by culture in YPD medium to promote their growth from the interior. This method represents an improved variation of a previous approach for the assembly of “yeast biocapsules,” which entailed the co-culture of both fungal and yeast cells in the same medium. A comparison was made between both techniques in terms of biocapsule productivity, cell retention capacity, and cell biological activity through an alcoholic fermentation of a grape must. The results indicated a substantial increase in biocapsule productivity (37.40-fold), higher cell retention within the biocapsules (threefold), and reduction in cell leakage during fermentation (twofold). Although the majority of the chemical and sensory variables measured in the produced wine did not exhibit notable differences from those produced utilizing suspended yeast cells (conventional method), some differences (such as herbaceous and toasted smells, acidity, bitterness, and persistence) were perceived and wines positively evaluated by the sensory panel. As the immobilized cells remain functional and the encapsulation technique can be expanded to other microorganisms, it creates potential for additional industrial uses like biofuel, health applications, microbe encapsulation and delivery, bioremediation, and pharmacy.Key points• New approach improves biocapsule productivity and cell retention.• Immobilized yeast remains functional in fermentation.• Wine made with immobilized yeast had positive sensory differences.

Synchrotron radiation-based microcomputed tomography for three-dimensional growth analysis of Aspergillus niger pellets.

Filamentous fungi produce a wide range of relevant biotechnological compounds. The close relationship between fungal morphology and productivity has led to a variety of analytical methods to quantify their macromorphology. Nevertheless, only a µ-computed tomography (µ-CT) based method allows a detailed analysis of the 3D micromorphology of fungal pellets. However, the low sample throughput of a laboratory µ-CT limits the tracking of the micromorphological evolution of a statistically representative number of submerged cultivated fungal pellets over time. To meet this challenge, we applied synchrotron radiation-based X-ray microtomography at the Deutsches Elektronen-Synchrotron[German Electron Synchrotron Research Center], resulting in 19,940 3D analyzed individual fungal pellets that were obtained from 26 sampling points during a 48 hAspergillus niger submerged batch cultivation. For each of the pellets, we were able to determine micromorphological properties such as number and density of spores, tips, branching points, and hyphae. The computed data allowed us to monitor the growth of submerged cultivated fungal pellets in highly resolved 3D for the first time. The generated morphological database from synchrotron measurements can be used to understand, describe, and model the growth of filamentous fungal cultivations.

Fungal-assisted immobilization of microalgae for simultaneous harvesting and product customization: Effects of geometry, loading, and microalgae concentration

The production of sustainable foods and other bioproducts is expected to increase to achieve key circular bioeconomy goals. In this study, Haematococcus pluvialis microalgae cells were simultaneously harvested and immobilized in the hyphal matrix of the edible fungal strain Aspergillus awamori. The study investigated the impact of fungal loading, pellet geometry, and initial microalgae cell concentration on the immobilization performance and product characteristics. It was found that higher fungal loading and larger fungal pellets contributed to increased immobilization performance. High initial microalgae concentrations led to substantial inhibition of the immobilization behavior, which could be partially overcome by increased specific loading rate of fungi (g/g algae). A proof-of-concept demonstration study of product protein content showed that manipulation of key operational parameters allowed the product composition to be tuned to desired criteria. This study provides new insights to the fungal-assisted microalgae immobilization process and demonstrates a novel application in bioproduct customization.

Functional fungal pellets self-immobilized by mycelium fragments of Irpex lacteus WRF-IL for efficient degradation of sulfamethazine as the sole carbon source

In order to achieve an efficient microbial material with dual functions of self-immobilization and sulfamethazine (SMZ) degradation, this study explored the pelletization technique utilizing mycelium fragments of Irpex lacteus WRF-IL and systematically examined the pellets formation conditions and degradation capability. The Box-Behnken design results demonstrated that pure mycelium fragments, broken by frosted glass beads, could be rapidly self-immobilized to form white rot mycelial pellets (WRMPs) within 24 h, serving as the pelleting core. These WRMPs could completely remove SMZ as the sole carbon source within 20 h. The addition of sucrose expedited this process, achieving complete removal within only 14 h. Kinetic analysis showed that WRMPs could potentially remove SMZ at higher concentrations (>25 mg/L). Biodegradation was the primary pathway of SMZ removal. Seven intermediates were identified by QTOF LC/MS, and three transformation pathways initiated by SO2 overflow, molecular rearrangement, and aniline moiety oxidation were deduced.

Efficient Copper Adsorption from Aqueous Solution by Dictyuchus sterile Pellets

A common heavy metal pollutant of water resources, copper (II), can cause serious health problems or even death. Over the past few years, several filamentous fungi strains have been isolated, identified, and tested for their ability to bio-adsorb heavy metals for potential use in the bio-remediation of copper from wastewater. In this study, variables, including the dosage of fungal pellets, temperature, pH, time, initial copper concentration, and agitation rate, were assessed to select the best conditions for the adsorption of copper by Dictyuchus sterile pellets. To identify the active groups responsible for metal adsorption, microscopic observations were made using a light microscope and scanning electron microscope. The copper adsorbent was then analyzed before and after adsorption using an atomic adsorption spectrophotometer and Fourier transform infrared spectroscopy. The ideal adsorption conditions were: fungal pellets with a wet weight of 1 g.L-1 at a temperature of 25°C, pH 5.5, the initial copper concentration of 100 ppm, and shaking at a speed of about 250 rpm for 72 h to achieve a removal efficiency rate of 95%. Copper adsorbed with the biomass of the fungal pellets was 57 mg.g-1. The use of fungal pellets would be a method that can be used to increase the surface area of adsorption and also is thought to be one of the most cost-effective ways to remove trace metals from polluted water.

Biosorption performance of the multi-metal tolerant fungus Aspergillus sp. for removal of some metallic nanoparticles from aqueous solutions

The wide spread of nanotechnology applications currently carries with it the possibility of polluting the environment with the residues of these nanomaterials, especially those in the metallic form. Therefore, it is necessary to study the possibility of treating and removing various nanoscale metal pollutants in environmentally friendly ways. The present study focused on the isolation of multi-metal tolerant fungi to be applied in the bioremoval of Zn, Fe, Se, and Ag nanoparticles as potential nanoscale metal pollutants. Aspergillus sp. has been isolated as multi-metal tolerant fingus and investigated in the bioremoval of targeted nanometals from their aquoues solutions. The effect of biomass age, pH, and contact time was studied to determine the optimal biosorption conditions for fungal pellets towards metal NPs. The results showed a high percentage of fungal biosorption on the of two-day-old cells, which amounted to 39.3, 52.2, 91.7, and 76.8% of zinc, iron, selenium, and silver, respectively. The pH 7 was recorded the highest percentage of NPs removal for the four studied metals i.e. 38.8, 68.1, 80.4, and 82.0% of Zn-, Fe-, Se- and Ag-NPs, respectively. The contact time required between Aspergillus sp. and the metal nanoparticles to obtain the best adsorption was only 10 min in the case of Zn and Ag, but it was 40 min for both Fe and Se NPs. The efficiency of living fungal pellets in removing the four metallic NPs exceeded that of dead biomass by 1.8, 5.7, 2.5, and 2.5 folds for Zn, Fe, Se and Ag, respectively. However, utilization of dead fungal biomass for metallic NPs removal could be considered more applicable to the actual environmental applications.

Removing Toxic Dyes from Aqueous Medium by Trichoderma-Graphain Oxide Aerogel

Toxic dyes are commonly discharged into waste waters and dyes are extensively used in the textile industry so it is necessary to find out efficient and eco-friendly method for treating waste waters resulting from industrial effluences. To achieve this aim the fungus Trichoderma sp. is employed into two lines: first line was self – immobilized fungal pellets in (Czapek – Dox medium) to adsorbs two dyes crystal violet, congo red by concentrations 0.01, 0.02, 0.03, 0.04, 0.05, 0.06 mg/L to both dyes, PH 2, room temperature with shaker in ( hrs.2,hrs.4,hrs.24) , by Uv- Visible spectrum . the removal efficiency of 0.05 mg/L crystal violet by Trichoderma sp was 96%. but there was no removal by congo red. The second line was immobilizing fungal mycelium to Graphain oxide free – standing aerogel to increase efficiency of adsorption. The decolorization of toxic dyes solution was detected by the change in the adsorption Uv- Visible spectrum and scanning microscopy analysis which revealed that there was dye adsorption on fungal mycelium surface. After treatment of crystal violet with 20 mg Graphain oxide -fungi aerogel in the condition PH 2, room temperature with shaker in time (hrs.2 ,hrs.4 , hrs.24 ) removal percentage to crystal violet was increasing with to raise concentrations the dye crystal violet until reaching the maximum removal percentage 97% in hrs.4 in 0.05mg/L concentrate , and it increased the efficiency of other concentrations . In contrast, according to congo red there was no color removal in any concentration within treatment time since congo red surface carries both negative and positive charges and causes electrostatic attraction, therefor, the adsorption reduced or does not occur.Trichoderma sp. is considered a selective removal to basic dyes and could be employed to remove dyes from industrial effluents.

Potential of direct granulation and organic loading rate tolerance of aerobic granular sludge in ultra-hypersaline environment

Salt-tolerant aerobic granular sludge (SAGS) technology has shown potentials in the treatment of ultra-hypersaline high-strength organic wastewater. However, the long granulation period and salt-tolerance acclimation period are still bottlenecks that hinder SAGS applications. In this study, “one-step” development strategy was used to try to directly cultivate SAGS under 9% salinity, and the fastest cultivation process was obtained under such high salinity compared to the previous papers with the inoculum of municipal activated sludge without bioaugmentation. Briefly, the inoculated municipal activated sludge was almost discharged on Day 1–10, then fungal pellets appeared and it gradually transitioned to mature SAGS (particle size of ∼4156 μm and SVI30 of 57.8 mL/g) from Day 11 to Day 47 without fragmentation. Metagenomic revealed that fungus Fusarium played key roles in the transition process probably because it functioned as structural backbone. RRNPP and AHL-mediated systems might be the main QS regulation systems of bacteria. TOC and NH4+-N removal efficiencies maintained at ∼93.9% (after Day 11) and ∼68.5% (after Day 33), respectively. Subsequently, the influent organic loading rate (OLR) was stepwise increased from 1.8 to 11.7 kg COD/m3·d. It was found that SAGS could maintain intact structure and low SVI30 (< 55 mL/g) under 9% salinity and the OLR of 1.8–9.9 kg COD/m3·d with adjustment of air velocity. TOC and NH4+-N (TN) removal efficiencies could maintain at ∼95.4% (below OLR of 8.1 kg COD/m3·d) and ∼84.1% (below nitrogen loading rate of 0.40 kg N/m3·d) in ultra-hypersaline environment. Halomonas dominated the SAGS under 9% salinity and varied OLR. This study confirmed the feasibility of direct aerobic granulation in ultra-hypersaline environment and verified the upper OLR boundary of SAGS in ultra-hypersaline high-strength organic wastewater treatment.

Insights into differences between spore-assisted and pellet-assisted microalgae harvesting using a highly efficient fungus: Efficiency, high-value substances, and mechanisms

To achieve efficient and low-cost microalgae harvesting, investigations were conducted on the harvesting efficiency and potential mechanisms of Chlorella sp. HQ by filamentous fungi using two strategies, fungal spore-assisted harvesting (FSH) and fungal pellet-assisted harvesting (FPH). Five of the 19 fungal species isolated from domestic sewage could form pellets, and Aspergillus niger HW8-1 comprised the highest harvesting efficiencies of 99.17 % and 88.70 % for FPH and FSH, respectively. FSH had 2–3 times more lipids and polysaccharides in fungus-alga pellets and caused richer saturated and monounsaturated fatty acids compared with FPH. Moreover, by optimizing the microalgae preculture time, glucose concentration, and microalgae initial density, the contents of high-value substances, such as lipids, polysaccharides, and proteins of fungus-alga pellets after FPH were improved from 5.96 %, 5.67 %, and 7.27 % to 20.18 %, 24.34 % and 10.48 %, respectively. Furthermore, fungal pellets secreted more extracellular polymeric substances (EPS) during FPH than those by FSH, which could chemisorb algal cells by lowering the surface potential of fungal pellets. FPH caused algal cells to cover the outside, which increased the light exposure area of algae, thereby increasing the photosynthesis rate, whereas FSH mainly captured microalgae physically through mycelium entanglement.

The interplay between (−)-epigallocatechin-3-gallate (EGCG) and Aspergillus niger RAF106, an EGCG-biotransforming fungus derived from Pu-erh tea

Although (−)-epigallocatechin-3-gallate (EGCG) exhibits various bioactivities, its low bioavailability and toxicity at high concentrations limit its application. Microbial biotransformation of EGCG could improve its bioavailability and bioactivities, but the interplay between EGCG and EGCG-transforming microbes was little known. Here, 50 g/L or less of EGCG was completely degraded at 48 h when co-incubated with Aspergillus niger RAF106 in potato dextrose broth. The degradation was accompanied by an unchanged radical-scavenging activity and increase in the production of (−)-epigallocatechin and gallic acid, which were degraded as the fermentation time increased. According to the compound structure, (−)-epicatechin and (−)-catechin were discovered after 120 h. When co-incubated with EGCG, RAF106 formed dispersed mycelia and grew faster. The inhibition of conidial agglomeration and changes in the ultrastructure of hyphal wall coincided with the inhibition of pellet formation. Additionally, the addition of EGCG increased the cellulase and pectinase activities and altered the transcripts of 1394 genes, including those associated with carbohydrate metabolism and fungal growth and development. Conclusively, co-incubation of EGCG and RAF106 resulted in EGCG conversion into smaller molecules, inhibition of fungal pellet formation, increased fungal growth and production of cellulases and pectinases, and significant changes in hyphal morphology and transcripts of several phenotype-related genes.

A microfluidic device for simultaneous detection of enzyme secretion and elongation of a single hypha.

Filamentous fungi grow through elongation of their apical region by exocytosis and secrete enzymes that can be of commercial or industrial importance. Their hyphae exhibit extensive branching, making it difficult to control hyphal growth for observation and analysis. Therefore, although hyphal morphology and productivity are closely related, the relationship between the two has not yet been clarified. Conventional morphology and productivity studies have only compared the results of macro imaging of fungal pellets cultured in bulk with the averaged products in the culture medium. Filamentous fungi are multicellular and their expression differs between different hyphae. To truly understand the relationship between morphology and productivity, it is necessary to compare the morphology and productivity of individual hyphae. To achieve this, we developed a microfluidic system that confines hyphae to individual channels for observation and investigated the relationship between their growth, morphology, and enzyme productivity. Furthermore, using Trichoderma reesei, a potent cellulase-producing fungus, as a model, we developed a cellulase detection assay with 4-MUC substrate to detect hyphal growth and enzyme secretion in a microfluidic device in real time. Using a strain that expresses cellobiohydrolase I (CBH I) fused with AcGFP1, we compared fluorescence from the detection assay with GFP fluorescence intensity, which showed a strong correlation between the two. These results indicate that extracellular enzymes can be easily detected in the microfluidic device in real time because the production of cellulase is synchronized in T. reesei. This microfluidic system enables real-time visualization of the dynamics of hypha and enzymes during carbon source exchange and the quantitative dynamics of gene expression. This technology can be applied to many biosystems from bioenergy production to human health.

Respond surface optimization of bioflocculation of Chlorella vulgaris using filamentous fungus Aspergillus niger pellets to improve harvesting efficiency

Chlorella vulgaris is a microalga with a high lipid content ranging from 2 to 77 % of its dry weight, making it a potential source of renewable fuel. Due to the very small size of 2–10 m and the low solubility in culture, the harvesting process is a major problem in the algae industry. The objective of this research was to investigate the use of fungal pellets of Aspergillus niger as bioflocculants in microalgae harvesting. Chlorella sp. was harvested using fungi at a variety of bioflocculant dosages (2.5–4.5 ppm), cationic inducers (0.05–0.07 M), and agitation speeds (150–170 rpm), and a response surface methodology has been employed to optimize the bioflocculation process. The result showed that a harvesting efficiency of 98 % had been achieved under optimum conditions: pH 8, cationic inducer concentration of 0.06 mM, bioflocculant dose of 3.5 % w/v, and agitation at 160 rpm.

Chitosan-coated oleaginous microalgae-fungal pellets for improved bioremediation of non-sterile secondary effluent and application in carbon dioxide sequestration in bubble column photobioreactors

Oleaginous microalga Scenedesmus sp. SPP was rapidly immobilized in oleaginous fungal pellets by their opposite-surface-charges. Microalgae-fungal (MF) pellets were more effective in bioremediation of non-sterile secondary effluent than mono-culture. The optimal hydraulic retention time for dual bioremediation in semi-continuous mode was 72 h. The MF pellets coated with 0.4 %-chitosan improved removal efficiencies of COD, total nitrogen (TN), and total phosphorus (TP) up to 96.2±0.0 %, 88.2±2.8 % and 71.5±0.7 %, respectively, likely because of better cell retention and more nutrient adsorption and assimilation. Dual bioremediation by coated MF pellets was also successfully scaled up in 30-L bubble-column photobioreactors with improved COD, TN, and TP removal efficiencies of 98.5±0.0 %, 90.2±0.0 % and 79.5±2.1 %, respectively. This system also effectively removed CO2 from simulated flue gas at 71.2±0.4 % and produced biomass with high lipid content. These results highlight the effectiveness of bio-immobilization by fungal pellets; chitosan coating; and their practical applications in bioremediation and CO2 sequestration.

Indium removal by Aspergillus niger fungal pellets in the presence of selenite and tellurite

The feasibility of simultaneous removal of indium, selenite and tellurite using biological reduction by Aspergillus niger fungal pellets is explored. Initially, batch experiments were conducted to study the capability of A. niger pellets to remove indium, selenium and tellurium in different combinations. The indium removal efficiency ranged between 52.3 and 65.6 % at 10 mg/L, with a maximum removal (~65 %) in incubations with only indium or indium with tellurite. The tellurium removal efficiency was maximum (76.7 %) in experiments with indium, but dropped drastically to 47.2 and 33.7 %, respectively, when selenite and indium were incubated together. The selenite removal efficiencies of the A. niger pellets were more consistent (50.2–59.5 %) for different experimental combinations and were not affected by either indium or tellurium. Further characterization of fungal biomass showed accumulation of mainly elemental Se and Te nanoparticles within the pellets. In addition, XRD analysis showed the formation of indium selenide and indium telluride during their simultaneous removal. The EPS production by A. niger increased in the presence of these elements along with changes in the polysaccharide and protein content of the EPS. The fluorescence EEM spectra revealed that the EPS produced by A. niger during pollutant removal was mostly composed of soluble microbial products and humic acid like substances. This study demonstrated recovery of elemental chalcogen and indium chalcogenide nanoparticles can be achieved using fungal pelleted systems.

Immobilization of Diatom Phaeodactylum tricornutum with Filamentous Fungi and Its Kinetics.

Immobilizing microalgae cells in a hyphal matrix can simplify harvest while producing novel mycoalgae products with potential food, feed, biomaterial, and renewable energy applications; however, limited quantitative information to describe the process and its applicability under various conditions leads to difficulties in comparing across studies and scaling-up. Here, we demonstrate the immobilization of both active and heat-deactivated marine diatom Phaeodactylum tricornutum (UTEX 466) using different loadings of fungal pellets (Aspergillus sp.) and model the process through kinetics and equilibrium models. Active P. tricornutum cells were not required for the fungal-assisted immobilization process and the fungal isolate was able to immobilize more than its original mass of microalgae. The Freundlich isotherm model adequately described the equilibrium immobilization characteristics and indicated increased normalized algae immobilization (g algae removed/g fungi loaded) under low fungal pellet loadings. The kinetics of algae immobilization by the fungal pellets were found to be adequately modeled using both a pseudo-second order model and a model previously developed for fungal-assisted algae immobilization. These results provide new insights into the behavior and potential applications of fungal-assisted algae immobilization.

Batch adsorption and process optimization for sequestration of Cr(VI) from aqueous solution using biofilm forming filamentous fungus Aspergillus niger BSC-1

Chromium (Cr) contamination in an aquatic environment is one of the greatest concerns nowadays. However, biosorption by various microorganisms is proven to be an environmentally sustainable method. The present study investigated fungal biofilm-mediated sorption of hexavalent chromium [Cr(VI)] using manglicolous filamentous fungus Aspergillus niger BSC-1 obtained from the Indian Sundarban mangrove ecosystem. Biosorbents, such as fungal pellet and fungal biofilm, were utilized for Cr(VI) sequestration. The result showed significantly higher removal of Cr(VI) by fungal biofilm (97.81 ± 2.5 %) than the fungal pellet (79.14 ± 2.4 %) (P < 0.05; two-way ANOVA). Batch adsorption study showed that the highest removal efficiency was attained at 40 °C and pH 3 with 3 g/L of fungal biofilm. The adsorption isotherms, kinetics and thermodynamic analysis suggested monolayer, endothermic and chemisorption of Cr(VI) on the fungal biofilm biosorbent. The adsorption process was further optimized using response surface methodology (RSM) - Central Composite Design (CCD), suggesting the quadratic model for Cr adsorption with high significance (P < 0.0001). The 3D surface plots among the three key variables, i.e., pH, temperature and Cr concentration, revealed that maximum sequestration (92.39 %) was achieved at 40 °C, pH 3 and 30 mg/L of Cr(VI) using 3 g/L of fungal biofilm. Regeneration study demonstrated that fungal biofilm retained 87.19 ± 3.23 % of Cr(VI) sorption with no significant reduction in Cr(VI) removal after five successive adsorption-desorption cycles. X-ray photoelectron spectroscopic analysis showed that adsorption, reduction and complexation mechanisms were involved in Cr(VI) detoxification. Furthermore, the fungal biofilm biosorbent efficiently removed approximately 100 % of Cr(VI) from leather effluent within 90 min of reaction time.

Assessing Edible Filamentous Fungal Carriers as Cell Supports for Growth of Yeast and Cultivated Meat.

The growth and activity of adherent cells can be enabled or enhanced through attachment to a solid surface. For food and beverage production processes, these solid supports should be food-grade, low-cost, and biocompatible with the cell of interest. Solid supports that are edible can be a part of the final product, thus simplifying downstream operations in the production of fermented beverages and lab grown meat. We provide proof of concept that edible filamentous fungal pellets can function as a solid support by assessing the attachment and growth of two model cell types: yeast, and myoblast cells. The filamentous fungus Aspergillus oryzae was cultured to produce pellets with 0.9 mm diameter. These fugal pellets were inactivated by heat or chemical methods and characterized physicochemically. Chemically inactivated pellets had the lowest dry mass and were the most hydrophobic. Scanning electron microscope images showed that both yeast and myoblast cells naturally adhered to the fungal pellets. Over 48 h of incubation, immobilized yeast increased five-fold on active pellets and six-fold on heat-inactivated pellets. Myoblast cells proliferated best on heat-treated pellets, where viable cell activity increased almost two-fold, whereas on chemically inactivated pellets myoblasts did not increase in the cell mass. These results support the use of filamentous fungi as a novel cell immobilization biomaterial for food technology applications.

Prospecting for New Antibiotics: Extracting and Cultivating Fungi from Globally Sourced Beans

Introduction: One of the greatest health threats to society is the emergence of antibiotic resistant bacteria. There are many on-going research efforts to find new antibiotics that can overcome bacterial resistance. Our research has uncovered a novel method for discovering new anti-biotics and streamlining current prospecting methods. We discovered that beans sourced from various geographic locations contain residual fungus that can be cultivated and screened for anti-biotic properties. In the present report we sourced beans from global locations and cultivated fungal pellets from beans by confining them in a new form of Non-Thermal Plasma (NTP); Hybrid-Plasma (HP). Methods: The agar plate method was used to evaluate fungal growth for antibacterial properties. The fungus from each of the fungal pellets was collected and sub-cultured in a glass tube with liquid growth media. Bacterial lawns of Staphlococcus. aureus and Eschericia coli grown on tryptic soy agar media plates were prepared and the fungal growth enrichment added to the plate to test for areas of growth inhibition. Results: Testing confirmed measurable zones of inhibition in the agar plates that contained Staphcoccus aureus for 3 of the 4 beans tested. There was no effect on the plates with Eschericia coli. Conclusion: These new methods for producing fungi from various geographic locations is more efficient for discovering and developing of new antibiotics.

Synergism and mutualistic interactions between microalgae and fungi in fungi-microalgae symbiotic system

The method of collecting microalgae using fungal mycelium pellets has attracted widespread attention because of its high efficiency and simplicity. In this study, the interaction in FMSS was explored using Aspergillus fumigatus and Synechocystis sp. PCC6803. Under the conditions of 25–30 °C, pH of 5.0, 160 rpm, a light intensity of 1000 lx, light to darkness ratio of 6:18 h, and glucose concentration of 1.5 g/L, the FMSS had the highest biomass and recovery efficiency. SEM, TEM, and Zeta analysis showed that microalgae can be fixed on the surface of fungal mycelium pellets by the electrostatic attraction (amino, amide, phosphate, hydroxyl, and aldehyde groups) of EPS. The N cycling and CO2–O2 cycling promoted the synthesis of amino acids and provided a guarantee for gas exchange, and the intermediate metabolites (CO32− and HCO3−/H2CO3) satisfied the metabolic activities. The microalgae and fungi worked in coordination each other, which was the mutualistic symbiosis.

Effect of fungal pellets on denitrifying bacteria at low carbon to nitrogen ratio: Nitrate removal, extracellular polymeric substances, and potential functions

This research aims to elucidate the effect of fungal pellets (FP) on denitrifying bacteria regarding nitrate (NO3−-N) removal, extracellular polymeric substances (EPS), and potential functions at a low carbon to nitrogen (C/N) ratio. A symbiotic system of FP and denitrifying bacteria GF2 was established. The symbiotic system showed 100% NO3−-N removal efficiency (4.07 mg L−1 h−1) at 6 h and enhanced electron transfer capability at C/N = 1.5. The interactions between FP and denitrifying bacteria promoted the production of polysaccharides (PS) in EPS. Both the increased PS and the PS provided by FP as well as protein and humic acid-like substances in EPS could be consumed by denitrifying bacteria. FP acted as a protector and provided habitat and nutrients for denitrifying bacteria as well as improved the ability of carbohydrate metabolism, amino metabolism, and nitrogen metabolism of denitrifying bacteria. This study provides a new perspective on the relationship between FP and denitrifying bacteria.