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

Green synthesis of selenium nanoparticles, and its conjugation with antibacterial proteins for enhancing their antibacterial activity

This study aimed to determine the frequency of multi-drug-resistant bacteria (MDR) found in patients with urinary tract infections (UTIs) and to analyze the antibiotic resistance patterns in these patients. Additionally, Selenium nanoparticles (Se-NPs) were synthesized using eco-friendly methods and conjugated with antibacterial proteins (7S and 11S globulins) from red kidney beans to enhance their antibacterial properties. The highest percentages of resistance were found for Amikacin (AK; 43 %), Cefuroxime (CXM; 42 %), Gatifloxacin (GAT; 38 %), Clindamycin (DA; 38 %), Ciprofloxacin (CIP; 36 %), Ceftriaxone (CRO; 35 %), Cefoperazone/Sulbactam (CES; 34 %), Nitrofurantoin (F; 31 %), Piperacillin (PRL; 26 %), and Amoxicillin/Clavulanic acid (AMC; 23 %). The 10 bacterial isolates resistant to more than or equal to 80 % of selected antibiotics were chosen and then identified. All ten isolates were confirmed to be Acinetobacter spp., Klebsiella pneumoniae, and E. coli. The synthesis of Se-NPs was indicated by colour changes to ruby red and are preliminary substantiated by UV-Vis spectrum high peak absorption spectrum at 388 nm for Se-NPs, while the conjugated Se-NPs with 7S protein were 400 nm as well as Se-NPs with 11S protein were 420 nm. The TEM and DLS confirmed the formation of selenium nanoparticles of several sizes. Results showed that 11S globulin had the highest antibacterial activity of 7S globulin and isolated protein, recording the MIC at 125 μg/mL. Conjugation between Se-NPs with antibacterial proteins (protein isolates, 7S, and 11S) has MBC (125 μg/mL) and MIC (125 μg/mL) values against tested bacteria.

Adaptability assessment of Aspergillus niger and Aspergillus terreus isolated from long-term municipal/industrial effluent-irrigated soils to cadmium stress

Heavy metals (HMs) contamination is a major issue produced by industrial and mining processes, among other human activities. The capacity of fungi to eliminate HMs from the environment has drawn attention. However, the main process by which fungi protect the environment against the damaging effects of these HMs, such as cadmium (Cd), is still unknown. In this study, some fungi were isolated from HMs-polluted soil. The minimum inhibitory concentrations (MICs) and the tolerance indices of the tested isolates against Cd were evaluated. Moreover, molecular identification of the most tolerant fungal isolates (Aspergillus niger and A. terreus) was done and deposited in the GenBank NCBI database. The results showed that the colony diameter of A. niger and A. terreus was decreased gradually by the increase of Cd concentration. Also, all the tested parameters were influenced by Cd concentration. Lipid peroxidation (MDA content) was progressively increased by 12.95-105.95% (A. niger) and 17.27-85.38% (A. terreus), respectively, from 50 to 200 mg/L. PPO, APX, and POD enzymes were elevated in the presence of Cd, thus illustrating the appearance of an oxidative stress action. Compared to the non-stressed A. niger, the POD and PPO activities were enhanced by 92.00 and 104.24% at 200 mg/L Cd. Also, APX activity was increased by 58.12% at 200 mg/L. Removal efficiency and microbial accumulation capacities of A. niger and A. terreus have also been assessed. Production of succinic and malic acids by A. niger and A. terreus was increased in response to 200 mg/L Cd, in contrast to their controls (Cd-free), as revealed by HPLC analysis. These findings helped us to suggest A. niger and A. terreus as the potential mycoremediation microbes that alleviate Cd contamination. We can learn more about these fungal isolates' resistance mechanisms against different HMs through further studies.

Biosorption performance toward Co(II) and Cd(II) by irradiated Fusarium solani biomass

Fusarium solani biomass plays a significant role in water pollution remediation due to its ability to sequester heavy metals, particularly cobalt (Co(II)) and cadmium (Cd(II)), which pose severe environmental and health risks. This study aimed to identify fungi from sewage-contaminated sites and evaluate their efficiency in absorbing and reducing Co(II) and Cd(II) ions. The biosorption potential of irradiated Fusarium solani biomass for removing Co(II) and Cd(II) ions from aqueous solutions was investigated. Six fungal isolates were screened, and the most promising isolate, identified as F. solani, was selected for further research. The biomass was exposed to different gamma irradiation doses (0, 1, 3, and 5 kGy), and its biosorption efficiency was assessed. The highest biosorption efficiencies were observed with the biomass exposed to 5 kGy (FS-5), achieving 37% for Co(II) and 90% for Cd(II) removal within 25 min. The surface area of the biosorbent increased from 13.12 m2 g-1 for unexposed biomass (FS-0) to 34.87 m2 g-1 for FS-5, enhancing the biosorption capacity. The adsorption kinetics followed a pseudo second order model with high correlation coefficients (R2 > 0.993), indicating chemisorption as the rate-limiting step. Isotherm studies showed that the Langmuir model provided a better fit to the experimental data, with maximum adsorption capacities of 4.44 mg g-1 for Co(II) and 21.00 mg g-1. This study provides valuable insights into the effective removal of Cd and Co from polluted sites, underscoring the potential of developing eco-friendly and cost-effective bioremediation approaches.

Development of nanocomposite-selenium filter for water disinfection and bioremediation of wastewater from Hg and AgNPs

Selenium nanoparticles (SeNPs) are used in several sectors as antitumor, antimicrobial, and environmental adsorbents. Thus, the present research objective was the production of bacterial-SeNPs as an active and environmentally-friendly antibacterial and adsorbent agents and application into novel nanocomposite filter. From a total of 25 samples (soil, wastewater, and water) obtained from different locations in Egypt, 60 selenium-resistant bacterial isolates were obtained (on a mineral salt medium supplemented with selenium ions). After screening (based on the conversion of selenium from ionic form to nanoform), a superior bacterial isolate for SeNPs formation was obtained and molecular identified as Bacillus pumilus isolate OR431753. The high yield of SeNPs was noted after optimization (glucose as carbon source, pH 9 at 30 °C). The produced SeNPs were characterized as approximately 15 nm-diameter spherical nanoparticles, in addition to the presence of organic substances around these particles like polysaccharides and aromatic amines (protein residues). Also, they have antibacterial activity increased after formation of nanocomposite with nano-chitosan (SeNPs/NCh) against several pathogens. The antibacterial activity (expressed as a diameter of the inhibitory zone) averaged between 2.1 and 4.3, 2.7 and 4.8 cm for SeNPs and SeNPs/NCh, respectively compared with 1.1 to 1.8 cm for Amoxicillin. The produced nanoselenium/chitosan was used as a biofilter to remove mercury (Hg) and AgNPs as model chemicals with serious toxicity and potential pollutant for water bodies in many industries. The new SeNPs/NCh biofilter has proven highly effective in individually removing mercury and AgNPs from their synthetic wastewaters, with an efficiency of up to 99%. Moreover, the removal efficiency of AgNPs stabilized at 99% after treating them with the syringe filter-Se nanocomposite for 4 cycles of treatment (5 min each).

Bioremoval of tannins and heavy metals using immobilized tannase and biomass of Aspergillus glaucus

BACKGROUND

The presence of inorganic pollutants and heavy metals in industrial effluents has become a serious threat and environmental issues. Fungi have a remarkable ability to exclude heavy metals from wastewater through biosorption in eco-friendly way. Tannase plays an important role in bioconversion of tannin, a major constituent of tannery effluent, to gallic acid which has great pharmaceutical applications. Therefore, the aim of the current study was to exploit the potential of tannase from Aspergillus glaucus and fungal biomass waste for the bioremediation of heavy metals and tannin.

RESULTS

Tannase from A. glaucus was partially purified 4.8-fold by ammonium sulfate precipitation (80%). The enzyme was optimally active at pH 5.0 and 40 °C and stable at this temperature for 1 h. Tannase showed high stability at different physiological conditions, displayed about 50% of its activity at 60 °C and pH range 5.0-6.0. Immobilization of tannase was carried out using methods such. as entrapment in Na-alginate and covalent binding to chitosan. The effects of Na-alginate concentrations on the beads formation and enzyme immobilization revealed that maximum immobilization efficiency (75%) was obtained with 3% Na-alginate. A potential reusability of the immobilized enzyme was showed through keeping 70% of its relative activity up to the fourth cycle. The best bioconversion efficiency of tannic acid to gallic acid by immobilized tannase was at 40 °C with tannic acid concentration up to 50 g/l. Moreover, bioremediation of heavy metal (Cr3+, Pb2+, Cu2+, Fe3+, and Mn2+) from aqueous solution using A. glaucus biomass waste was achieved with uptake percentage of (37.20, 60.30, 55.27, 79.03 and 21.13 respectively). The biomass was successfully used repeatedly for removing Cr3+ after using desorbing agent (0.1 N HCl) for three cycles.

CONCLUSION

These results shed the light on the potential use of tannase from locally isolated A. glaucus in the bioremediation of industrial tanneries contained heavy metals and tannin.

Small particles, big effects: How nanoparticles can enhance plant growth in favorable and harsh conditions

By 2050, the global population is projected to reach 9 billion, underscoring the imperative for innovative solutions to increase grain yield and enhance food security. Nanotechnology has emerged as a powerful tool, providing unique solutions to this challenge. Nanoparticles (NPs) can improve plant growth and nutrition under normal conditions through their high surface-to-volume ratio and unique physical and chemical properties. Moreover, they can be used to monitor crop health status and augment plant resilience against abiotic stresses (such as salinity, drought, heavy metals, and extreme temperatures) that endanger global agriculture. Application of NPs can enhance stress tolerance mechanisms in plants, minimizing potential yield losses and underscoring the potential of NPs to raise crop yield and quality. This review highlights the need for a comprehensive exploration of the environmental implications and safety of nanomaterials and provides valuable guidelines for researchers, policymakers, and agricultural practitioners. With thoughtful stewardship, nanotechnology holds immense promise in shaping environmentally sustainable agriculture amid escalating environmental challenges.

Removing Heavy Metals: Cutting-Edge Strategies and Advancements in Biosorption Technology

This article explores recent advancements and innovative strategies in biosorption technology, with a particular focus on the removal of heavy metals, such as Cu(II), Pb(II), Cr(III), Cr(VI), Zn(II), and Ni(II), and a metalloid, As(V), from various sources. Detailed information on biosorbents, including their composition, structure, and performance metrics in heavy metal sorption, is presented. Specific attention is given to the numerical values of the adsorption capacities for each metal, showcasing the efficacy of biosorbents in removing Cu (up to 96.4%), Pb (up to 95%), Cr (up to 99.9%), Zn (up to 99%), Ni (up to 93.8%), and As (up to 92.9%) from wastewater and industrial effluents. In addition, the issue of biosorbent deactivation and failure over time is highlighted as it is crucial for the successful implementation of adsorption in practical applications. Such phenomena as blockage by other cations or chemical decomposition are reported, and chemical, thermal, and microwave treatments are indicated as effective regeneration techniques. Ongoing research should focus on the development of more resilient biosorbent materials, optimizing regeneration techniques, and exploring innovative approaches to improve the long-term performance and sustainability of biosorption technologies. The analysis showed that biosorption emerges as a promising strategy for alleviating pollutants in wastewater and industrial effluents, offering a sustainable and environmentally friendly approach to addressing water pollution challenges.