Aspergillus Niger Spores Research Articles

High-pressure pulses for Aspergillus niger spore inactivation in a model pharmaceutical lipid emulsion

High hydrostatic pressure (HHP) is a non-thermal process widely used in the food industry to reduce microbial populations. However, rarely its effect has been assessed in products with high oil content. This study evaluated the efficacy of HHP (200, 250, and 300 MPa) at different temperatures (25, 35, and 45 °C) by cycles (1, 2, or 3) of 10 min in the inactivation of Aspergillus niger spores in a lipid emulsion. After treatments at 300 MPa for 1 cycle at 35 or 45 °C, no surviving spores were recovered. All treatments were modeled by the linear and Weibull models. The presence of shoulders and tails in the treatments at 300 MPa at 35 or 45 °C resulted in sigmoidal curves which cannot be described by the linear model, hence the Weibull + Tail, Shoulder + Log-lin + Tail, and double Weibull models were evaluated to elucidate the inactivation kinetics. The tailing formation could be related to the presence of resistance subpopulations. The double Weibull model showed better goodness of fit (RMSE <0.2) to describe the inactivation kinetics of the treatments with the higher spore reductions. HHP at 200–300 MPa and 25 °C did not reduce the Aspergillus niger spores. The combined HHP and mild temperatures (35–45 °C) favored fungal spore inactivation. Spore inactivation in lipid emulsions by HHP did not follow a linear inactivation. HHP at mild temperatures is an alternative to the thermal process in lipid emulsions.

The potential of UVC decontamination to prolong shelf-life of par-baked bread.

The effect of UVC (254 nm) treatment on the mould-free shelf-life of par-baked wholemeal, rye and six-grain bread was examined. Currently, these breads are par-baked, wrapped in high-density polyethylene (HDPE)-foil and transported or stored at room temperature for a couple of days before being full-baked and sold/consumed. Generally, after five days, these breads show signs of mould spoilage. A shelf-life increase in one or more days would already offer immense economical and logistic benefits for the baker or retailer. In this study, the parameters fluence rate (irradiation intensity), fluence (UV dose), distance to the UV-lamp (DTL) and number of layers of a common wrapping HDPE-foil (20 µm) were diversified. The breads were subjected to a UVC treatment (0-2502 mJ/cm²), packed and stored at room temperature for a period of 15 days (21.5 ± 0.8 °C). Similar as for the breads, agar plates with mould spores of Aspergillus niger, Aspergillus montevidensis and Penicillium roqueforti were UVC treated (0-1664 mJ/cm²) and checked daily for visible mould growth during 15 days (25 °C). Aspergillus niger showed the strongest resistance towards UVC, a fluence of 800 mJ/cm² was needed to inhibit growth during 15 days of storage, whereas for P. roqueforti and A. montevidensis, respectively, UV levels of 291 and 133 mJ/cm² were found sufficient. Furthermore, the shelf-life of wholemeal, rye and six-grain bread can be prolonged from 5 to 6, 8 and 9 days, respectively, using 2502 mJ/cm². The effect of higher UVC dosage on shelf-life reached a maximal level and was strongly impacted by the wide spread on data of mould-free shelf-life. The main factors influencing the potential of UV decontamination were the rough bread surface, differences in DTL, the possibility of post-contamination and UV permeability of packaging materials.

Modeling the inactivation of Aspergillus niger spores in a model parenteral emulsion by high hydrostatic pressure and its effect on the emulsion droplet size

ABSTRACT A predictive model based on the Box–Behnken design was developed to determine the effect of high hydrostatic pressure (HHP), temperature, and cycles (each holding time of 10 min) on the inactivation of Aspergillus niger spores and in the droplet size of a model emulsion. The obtained model presented goodness of fit to the data with a high correlation coefficient (R2 = 0.91) and adjusted correlation coefficient value (0.88), with no significant lack-of-fit test (p = 0.6031). The canonical analysis provides the conditions (37.29 °C, 263.33 MPa, and, 1.88 cycles) to reduce 5.0 Log10 CFU/mL of A. nigger. Under such conditions, emulsions exhibited a monomodal distribution of droplet size. However, as temperature and pressure increased, both the PDI, D3,2, and D4,3 values increased (p ≤ 0.05). In conclusion, the proposed model has the potential to predict the reduction of A. niger spores by HHP without causing emulsion destabilization.

Photo-sterilization of groundwater by tellurium and enhancement by micro/nano bubbles

In rural areas where low-temperature groundwater is used as a drinking water source, cost-effective sterilization techniques are needed to prevent groundwater consumers from the disease risks triggered by pathogenic microorganisms like Escherichia coli and fungal spores. In this study, micro/nano bubbles (MNBs) coupled with the tellurium (Te)-based catalysts were used to considerably enhance the solar disinfection (SODIS) efficiency while overcoming the intrinsic defects of SODIS, particularly in low-temperature. Sterilization tests showed that 6.5 log10 cfu/mL of E. coli K-12 and 4.0 log10 cfu/mL of Aspergillus niger spores were completely inactivated within 5 min while applying this novel process for disinfection of raw groundwater, even in low-temperature. The underlying mechanisms of the extraordinary sterilization efficiency were revealed through comprehensive characterization of the catalysts and the physiological changes of the microorganisms. The localized surface plasmon resonance (LSPR) effect of the Te catalysts was identified to take advantage of photothermal synergism to achieve cell death. The integration of MNBs with the facet-engineered Te catalysts improved the photothermal catalytic effect and extracellular electron transfer, which substantially strengthened disinfection efficiency. This study provides a targeted solution into microbial inactivation in groundwater and emphasizes a cost-effective groundwater sterilization process.

Effect of membrane depolarization against Aspergillus niger GM31 resistant by ultra nanoclusters characterized by Ag2+ and Ag3+ oxidation state

To date, the impossibility of treating resistant forms of bacteria and fungi (AMR) with traditional drugs is a cause for global alarm. We have made the green synthesis of Argirium silver ultra nanoclusters (Argirium-SUNCs) very effective against resistant bacteria (< 1 ppm) and mature biofilm (0.6 ppm). In vitro and preclinical tests indicate that SUNCs are approximately 10 times less toxic in human cells than bacteria. Unique chemical-physical characteristics such as particle size < 2 nm, a core composed of Ag0, and a shell of Ag +, Ag2+ , Ag3+ never observed before in stable form in ultra pure water, explain their remarkable redox properties Otto Cars (Lancet Glob. Health 9:6, 2021). Here we show that Argirium-SUNCs have strong antimicrobial properties also against resistant Aspergillus niger GM31 mycelia and spore inactivation (0.6 ppm). The membrane depolarization is a primary target leading to cell death as already observed in bacteria. Being effective against both bacteria and fungi Argirium-SUNCs represent a completely different tool for the treatment of infectious diseases.

Characterization of pulsed light for microbial inactivation

Pulsed light is an emerging technology that can serve as an alternative to current antimicrobial interventions in the food industry. The first objective of this study was to define the spectrum and energy characteristics of pulsed light. The second objective was to establish the germicidal response of Escherichia coli , Salmonella enterica subsp. enterica ser. Typhimurium, Listeria monocytogenes , Bacillus cereus (vegetative cells and endospores), Aspergillus niger spores, and Penicillium roqueforti spores were evaluated following pulsed light treatments. Microorganisms were treated using three different broad-spectrum xenon gas flashlamps (Type A: 380–1100 nm, Type B: 235–1100 nm, and Type C: 190–1100 nm) for up to 15 pulses. All microorganisms experienced a significant interaction of flashlamp type × treatment duration (P < 0.0001). Additionally, E. coli was treated with pulsed light with flashlamp type B using light filters to block ultraviolet light and selectively deliver visible (VIS; 380–740 nm), near-infrared (NIR; 700–1080 nm), and VIS-NIR (400–1080 nm) radiation to the cells. The filter type × treatment duration interaction was significant (P < 0.0001). The VIS, NIR, and VIS-NIR filter treatments achieved modest reductions of 0.72, 0.19, and 0.83 Log 10 CFU/mL, respectively, after 75 consecutive pulses. To visualize physical effects on cell structures, transmission electron microscopy (TEM) images were obtained for E. coli following 15 pulse treatments of the three flashlamp types and the type B flashlamp with VIS-NIR filter placement. TEM imaging indicated that damage to cell morphology following treatment by broad-spectrum radiation was negligible. These results indicate that microbial sensitivity to pulsed light treatment differs for species and is predominantly attributed to the ultraviolet portion of the spectrum. • Pulsed light treatment susceptibility differs for Gram -, Gram +, and spores/fungi. • Microbial inactivation by pulsed light is predominantly attributed to UV light. • Visible and near-infrared radiation contribute negligibly to microbe inactivation. • Pulsed light treatment imparts negligible effects to Escherichia coli morphology.

A Detection Method for Crop Fungal Spores Based on Microfluidic Separation Enrichment and AC Impedance Characteristics.

The timely monitoring of airborne crop fungal spores is important for maintaining food security. In this study, a method based on microfluidic separation and enrichment and AC impedance characteristics was proposed to detect spores of fungal pathogens that cause diseases on crops. Firstly, a microfluidic chip with tertiary structure was designed for the direct separation and enrichment of Ustilaginoidea virens spores, Magnaporthe grisea spores, and Aspergillus niger spores from the air. Then, the impedance characteristics of fungal spores were measured by impedance analyzer in the enrichment area of a microfluidic chip. The impedance characteristics of fungal spores were analyzed, and four impedance characteristics were extracted: absolute value of impedance (abs), real part of impedance (real), imaginary part of impedance (imag), and impedance phase (phase). Finally, based on the impedance characteristics of extracted fungal spores, K-proximity (KNN), random forest (RF), and support vector machine (SVM) classification models were established to classify the three fungal spores. The results showed that the microfluidic chip designed in this study could well collect the spores of three fungal diseases, and the collection rate was up to 97. The average accuracy of KNN model, RF model, and SVM model for the detection of three disease spores was 93.33, 96.44 and 97.78, respectively. The F1-Score of KNN model, RF model, and SVM model was 90, 94.65, and 96.18, respectively. The accuracy, precision, recall, and F1-Score of the SVM model were all the highest, at 97.78, 96.67, 96.69, and 96.18, respectively. Therefore, the detection method of crop fungal spores based on microfluidic separation, enrichment, and impedance characteristics proposed in this study can be used for the detection of airborne crop fungal spores, providing a basis for the subsequent detection of crop fungal spores.

Efficacy of Ultraviolet Radiations against Coronavirus, Bacteria, Fungi, Fungal Spores and Biofilm

Ultra-violet (UV) C (200–280 wavelength) light has long been known for its antimicrobial and disinfecting efficacy. It damages DNA by causing the dimerization of pyrimidines. A newly designed technology (MUVi-UVC; Mobile UV Innovations Pty Ltd., Melbourne, VIC, Australia) that emits UVC at 240 nm is composed of an enclosed booth with three UVC light stands each with four bulbs, and has been developed for disinfecting mobile medical equipment. The aim of this project was to examine the spectrum of antimicrobial activity of this device. The experiments were designed following ASTM E1052-20, EN14561, BSEN14476-2005, BSEN14562-2006 and AOAC-Official-Method-966.04 standards for surface disinfection after drying microbes on surfaces. The disinfection was analyzed using Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (6294), Candida auris (CBS 12373), spores of Aspergillus niger (ATCC 16404), coronavirus (SARS-CoV-2 surrogate ATCC VR-261) as well as a methicillin-resistant Staphylococcus aureus (SA31), a carbapenem- and polymyxin-resistant Pseudomonas aeruginosa (PA219), Escherichia coli K12 (ATCC 10798) and Salmonella typhi (ATCC 700730). The parameters of time, the number of lights and direction of the sample facing the lights were examined. The MUVi-UVC was able to kill 99.999% of all of the tested bacteria, fungi, coronavirus and bacteria in the biofilms if used for 5 min using all three lights in the setup with the glass slides in a vertical position. However, for fungal spores, 30 min were required to achieve 99.999% killing. There was a small but insignificant effect of having the surface horizontally or vertically aligned to the UV lights. Therefore, this UVC device is an effective technology to disinfect medical devices.

Turbidity reduction in palm oil mill effluent (POME) by submerged fermentation with immobilized Aspergillus niger spores using coconut husk

Increasing production of palm oil in Malaysia has been releasing an alarming rate of palm oil mill effluent (POME). POME must be treated prior to release into the environment. Turbidity reduction by fermentation in palm oil mill effluent (POME) reduces the chemical oxygen demand (COD) which improves the effectiveness of downstream treatment. Aspergillus niger is a promising decomposer but as a filamentous fungus, its performance could be enhanced when it is supported with fibrous surface to provide a larger surface area for growth. Waste material from agroindustry constituted from lignocellulose have been widely used in the immobilization process to reduce costs. In the present study, sterile coconut husk was used to immobilize A.niger cells. POME, the fermentation media was prepared at concentrations ranging from 0-100%. Post fermentation slurry was filtered. Turbidity for every concentration were recorded. A free cell fermentation was conducted for comparison. The immobilized cell fermentation shows turbidity reduction between 95% and 98% while the free cell fermentation shows reduction between 87% and 95%. The immobilized cell produced a better turbidity reduction percentage.

Numerical Simulation of Aspergillus Niger Spore Deposition in Nasal Cavities of a Population in Northwest China

Background: As common pathogens in the human respiratory tract, fungal-spore-related health risks have been challenging to evaluate properly. This paper presents numerical simulations of particle deposition of Aspergillus niger spores in human nasal cavities. Methods: 30 healthy adults (including 60 nasal chambers) who lived in northwest China were recruited to conduct a nasal cavity numerical simulation using computational fluid dynamics–discrete phase model (CFD-DPM). The deposition rate in each anatomic area and its influencing variables, such as body position and respiratory flow rate, were analyzed. Results: (1) Under a resting condition, only about 5.57% ± 1.51% Aspergillus niger spores were deposited in the nasal cavity, while most of them escaped from the nasopharynx, and 0.31% ± 0.20% spores entered the maxillary sinus; (2) under an exercising condition, spores deposited in the nasal cavity were about 2.09 times as many as that in the resting state; (3) in a lying position, the A. niger spores deposited evenly on the lateral wall of the nasal cavity and the sinus when compared with a standing position. However, the deposition rate in each anatomic area did not change significantly.

Antifungal Activity of NP20 Derived from Amphioxus Midkine/Pleiotrophin Homolog Against Aspergillus niger and Aspergillus fumigatus.

With the emergence of antifungal resistance, systematic infections with Aspergillus are becoming the major cause of the clinical morbidity. The development of novel antifungal agents with high efficacy, low drug tolerance, and few side effects is urgent. In response to that need, we have identified NP20. Here we demonstrate clearly that NP20 has antifungal activity, capable of killing the spores of Aspergillus niger and Aspergillus fumigatus as well as causing direct damage to the surface, membrane, cytoplasm, organelle, and nucleus of the fungal spores. Interestingly, NP20 is active under temperature stress and a wide range of pH. Subsequently, MTT assay, assay for binding of NP20 to fungal cell wall components, membrane depolarization assay, confocal microscopy, ROS assay, DNA replication, and protein synthesis assay are performed to clarify the mechanisms underlying NP20 against Aspergillus. The results show that NP20 can bind with and pass through the fungal cell wall, and then interfere with the lipid membrane. Moreover, NP20 can induce intracellular ROS production, DNA fragmentation, and protein synthesis inhibition of the fungal cells. These together indicate that NP20 is a novel antifungal peptide, which has considerable potential for future development as novel peptide antibiotics against Aspergillus.

Intraspecific variability in heat resistance of fungal conidia

Microbial species are inherently variable, which is reflected in intraspecies genotypic and phenotypic differences. Strain-to-strain variation gives rise to variability in stress resistance and plays a crucial role in food safety and food quality. Here, strain variability in heat resistance of asexual spores (conidia) of the fungal species Aspergillus niger, Penicillium roqueforti and Paecilomyces variotii was quantified and compared to bacterial variability found in the literature. After heat treatment, a 5.4- to 8.6-fold difference in inactivation rate was found between individual strains within each species, while the strain variability of the three fungal species was not statistically different. We evaluated whether the degree of intraspecies variability is uniform, not only within the fungal kingdom, but also amongst different bacterial species. Comparison with three spore-forming bacteria and two non-spore-forming bacteria revealed that the variability of the different species was indeed in the same order of magnitude, which hints to a microbial signature of variation that exceeds kingdom boundaries.

Water-based Fe3O4 magnetic fluid-coated Aspergillus niger spores for treating liquid contaminated with Cr(VI)

The use of magnetic biosorbents for the remediation of heavy metals has attracted increasing attention due to their ease of separation and reusability. We developed a method for preparing superparamagnetic biosorbent materials using water-based magnetic fluids. Water-based magnetic fluid-spores (WMFSs) were obtained by combining water-based magnetic fluid (WMF) with Aspergillus niger spores at ratios of 0.6:1 (WMFS1), 0.8:1 (WMFS2), 1:1 (WMFS3), 1.2:1 (WMFS4), and 1.4:1 (WMFS5). A magnetic composite material was prepared from magnetic nanoparticles and spores in a ratio of 1:1 as a control. The adsorption efficiency and separation effect of WMFS3 were significantly better than those of the magnetic composite material. The morphology and structure of WMFS3 were characterized by performing transmission electron microscopy. The results showed that Fe3O4 magnetic particles were uniformly coated on the spore surface. The superparamagnetism of WMFS3 was tested using a vibrating sample magnetometer. At pH 2.0, the maximum adsorption capacity of WMFS3 for Cr(VI) was 105 mg/g; in the pH range of 2.0–3.0, the adsorption equilibrium time of WMFS3 was 60 min. Thus, the adsorption process conformed to the pseudo-second-order kinetic model and Freundlich isotherm. Thermodynamic studies showed that the process was spontaneous and endothermic. The adsorption mechanisms of WMF3 for Cr(VI) included electrostatic, reduction, and complexation adsorption. This biosorbent material showed excellent adsorption performance for Cr(VI) and is promising for wastewater resource applications.

STABILITY STUDIES OF SOME ANTIFUNGAL AGENTS ACTIVITIES AGAINST SELECTED PHYTOPATHOGENIC FUNGI SPORES

Fungi infections have been implicated as one source of yam tuber spoilage. The effects of temperature, pH and storage duration on antifungal activities of selected combined antifungal agents were investigated using the agar-well diffusion and agar dilution method against Aspergillus niger spores. The test combine antifungal agents are: Fluconazole/Sodium propionate (5000/5000?g/ml), Terbinafine Hcl/ Sodium propionate (500/5000?g/ml), ketoconazole / Sodium propionate (2000/5000?g/ml), Fluconazole / Griseofulvin (5000/5000?g/ml), ketoconazole / Griseofulvin (2000/5000?g/ml) and Terbinafine Hcl/ Griseofulvin (500/5000?g/ml). The combined antifungal agents activities at 25 - 70 ºC varies while at neutral &amp; alkaline pH the antifungal activities of the chemical agents remained relatively unaffected. There was no significant changes in the antifungal activities of the test combined agents against Aspergillus niger spores at p&gt;0.05 throughout the period of the six months of investigation. The significant of these finding with relation to stability of the chemical for preserving yam tubers is discussed in this work.

Degradation of wheat straw/polylactic acid composites by Aspergillus niger

AbstractPolylactic acid has good biodegradability and it is dosage is increasing. Therefore, the degradation of PLA has become a new problem that needs serious management. In this study, the spores of Aspergillus niger were inoculated onto wheat straw/PLA composites containing different contents of sodium alginate, and the mass loss and characterization (microstructure, fourier transform infrared spectroscopy, thermal properties, and X‐ray diffraction) of the composites were detected. The objective was to explore the possibility of degradation of PLA composites by A. niger and the effect of sodium alginate on the degradability of PLA composites. The results showed that when the amount of sodium alginate was 3% and 6%, the mass loss rate of the composites only increased at the initial stage of degradation. However, when the amount of sodium alginate was 9%, the mass loss rate of the composites was significantly increased. It was found that A. niger could colonize the surface of the composites and cause cracks and depressions on the surface by morphological observation. The infrared spectral curve showed that the number of hydroxyl and carbonyl groups in the composites increased after degradation. According to the thermogravimetric curve of the composites, the pyrolysis temperature of the composites with sodium alginate content of 9% increased and the residual mass decreased after degradation. When the amount of sodium alginate was 9%, the crystallinity of the composites was greatly reduced, and it is crystallization zone was easier to degrade compared with other treatments. The results would provide a theoretical support for the rapid degradation of PLA composites.

Studies on the Amylolytic Enzyme Associated with the Black Mould Deterioration of Eko, a Nigerian Fermented Food

Aims: To characterize amylase enzymes responsible for the spoilage of Eko, a Nigerian fermented food and to provide the best way to preserve it.&#x0D; Study Design: The experiment was carried out to extract the enzyme involved in the deterioration of Eko, it was partially purified using ion-exchange chromatography.&#x0D; Place and Duration of Study: Department of Microbiology, Obafemi Awolowo University, Ile Ife, between 1994 and 1996.&#x0D; Methodology: Eko was obtained from the new market Ile Ife and cut into slices, the slices were inoculated with spores of Aspergillus niger, on the eleventh day after inoculation, the enzyme was extracted, partially purified using ion-exchange chromatograpghy and characterized.&#x0D; Results: Within eleven days of inoculation, the Eko slices were extensively covered by the fungal spores, the amylase secreted by the Aspergillus niger was harvested and characterized. Its molecular weight was 70,000 Da, the optimum pH and temperature were 6 and 35 0C respectively, enzyme activity increased with increase in starch concentration with optimum activity at 0.9 mg/ml, the apparent Km for starch hydrolysis was 0.4 mg/ml. Cations such as Na+ and K+ stimulated amylase activity but was inhibited by EDTA and HgCl2&#x0D; Conclusion: The result of this work showed that amylase enzyme was produced by Aspergillus niger in the infected Eko slices also that the enzyme contributed to the degradation process, therefore, keeping Eko in conditions that will hinder the secretion of amylase enzyme or hinder its activity and the subsequent growth of A. niger will prolong the shelf life of Eko.

Menthoxytriazine modified poly (ethylene terephthalate) for constructing anti-adhesion surface

Polyethylene terephthalate (PET) is powerless against microbial contamination, which poses a threat to human health. Thus, endowing PET with anti-adhesion surface, but without releasing germicide, is currently still a challenge. To address this issue, a menthoxytriazine modified PET (PMET) was developed based on stereochemistry strategy, through inserting the menthoxytriazine block into the chain of PET. Antibacterial adhesion test and antifungal landing test were employed to verify the anti-adhesion performances of PMET. Compared with PET, PMET possessed better anti-adhesion capacity, achieving 90.2% and 87.7% resistance to Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), and a clear surface without any spores of Aspergillus niger (fungi). In-depth analysis revealed that the exposure of menthoxy group on PMET skeleton is crucial for antimicrobial adhesion, otherwise the wind of menthoxy group in the control polymer shows less effect. Furthermore, PMET has no cytotoxicity, thus showing excellent potential for enhancing the anti-adhesive surface of PET.

Potential application of graphene oxide and Aspergillus niger spores with high adsorption capacity for recovery of europium from red phosphor, compact fluorescent lamp and simulated radioactive waste

The recovery of rare earth elements (REEs) is a global challenge and the mining of rare earths has serious environmental implications due to the toxic waste released post mining. Hence, the rising demand for rare earths and their far reaching electronic applications necessitates an effective strategy to recover the REEs from more viable sources. In this work, the graphene oxide–Aspergillus niger spores (GO–A. niger spores) blend was utilized for adsorptive recovery of a precious rare earth Eu(III) and the adsorption variables like pH of the medium, adsorbent dosage, sorption kinetics, thermodynamics, and isotherm were optimized for the developed biosorbent. The adsorption process suits the Langmuir isotherm model with a maximum adsorption capacity of 147.3 mg/g. The pseudo–second–order kinetics is a perfect fit to describe the adsorption process. The results obtained through the Van't Hoff plot show negative free energy change (ΔG0) which implies the spontaneity of the adsorption process. The negative standard enthalpy change (ΔH0) values show that the nature of the adsorption process is exothermic. The analytical characterizations including Fourier transform infrared spectroscopy (FTIR), Raman, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), thermal gravimetric analysis (TGA), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) were employed to study the biosorbent. The features of GO–A. niger spores biosorbent were applied to recover Eu(III) from real samples such as fluorescent lamp phosphor, red phosphor powder, and a simulated radioactive waste solution.

Enhanced Cr(VI) adsorption using chemically modified dormant Aspergillus niger spores: Process and mechanisms

Adsorption materials based on Aspergillus niger spores were synthesized with chemically modified surfaces, and the CTAB surface modification adsorbent was the best. Zeta potential was in the range of pH 1 to pH 4.38, and CTAB-modified spores (CMS) surface had a positive charge, leading to adsorption of negatively charged chromic acid ions. The biosorption capacity of CMS was also markedly increased. The maximum biosorption capacity reached 177 mg/g following CTAB modification. XPS and FTIR confirmed the importance of secondary amine in the reduction adsorption process. Secondary amine (-NH-) transfer electrons to unoccupied orbit of the Cr(VI) for the reduction of hexavalent chromium. At the same time, chromium(III) is coordinated with OC-O functional group and (NH+/N+) and adsorbed on the modified spores. The fungal biological adsorbent can adsorb and desorb hexavalent chromium for five consecutive times without a clear decrease.

Application of palladium-based oxygen scavenger to extend the mould free shelf life of bakery products

An oxygen scavenging film based on a catalytic system with palladium (CSP) was combined with modified atmosphere (MA) packaging to extend the mould free shelf life (MFSL) of bakery products. Par-baked buns, toast bread and gluten-free bread inoculated with Aspergillus niger spores were packed in normal atmosphere (NA) and under MA (with 2 vol.-% of O2) with or without CSP. Mould growth was detected after 2–3 days on all products packed under NA as well as under MA without CO2 and CSP. Use of CO2 in MA extended the MFSL by 8–10 days, 16–18 days and 3–4 days for par-baked buns, toast and gluten-free bread, respectively. Use of CSP with MA reduced the oxygen concentration in headspace from 2 vol.-% to < 0.01 vol.-% within 105–190 min with all bakery products. This led to a further increase in MFSL of bakery products by 3–9 days.