Influence of Nitrogen Source and Growth Phase on Extracellular Biosynthesis of Silver Nanoparticles Using Cultural Filtrates of Scenedesmus obliquus

Unveiling the silver lining: examining the effects of biogenic silver nanoparticles on the growth dynamics of in vitro olive shoots

The current study aimed to evaluate the effects of biogenic silver nanoparticles (AgNPs) on growth behavior and leaf anatomy of in vitro growing shoots of 'Picual' and 'Dolce' olive cultivars. Biosynthesis of AgNPs was carried out using the cell-free filtrate of Fusarium oxysporum. The dimension and shape of the synthesized AgNPs have been analyzed using spectroscopy and topography analysis tools, confirming that the biosynthesis of AgNPs is a crystalline nanostructure with an average particle size of 37 nm. The shoots of the selected olive cultivars were cultured on Rugini olive medium-supplemented AgNPs at 0, 10, 20, and 30mg L- 1. The effect of genotypes on shoot multiplication was significant, 'Picual' recorded higher values of shoot growth parameters compared with 'Dolce' cultivar. Adding AgNPs to the culture medium significantly affected the growth of in vitro olive shoots. AgNPs at 20 and 30mg L- 1 produced higher values of the number of shoots, shoot length, and leaf number of Picual cv. compared with the control treatments, but the higher AgNPs concentration harmed the growth parameters of Dolce cv. and recorded lower growth values compared with the lower concentration (10mg L- 1). AgNPs had a significant effect on leaf morphology and their anatomical structure. The current results showed that the stimulatory effect of AgNPs on shoot growth of in vitro olive shoots is highly dependent on plant genotype and nanoparticle concentration.

Antibacterial, antibiofilm, and anticancer activity of silver-nanoparticles synthesized from the cell-filtrate of Streptomyces enissocaesilis

Silver nanoparticles (Ag-NPs) have a unique mode of action as antibacterial agents in addition to their anticancer and antioxidant properties. In this study, microbial nanotechnology is employed to synthesize Ag-NPs using the cell filtrate of Streptomyces enissocaesilis BS1. The synthesized Ag-NPs are confirmed by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Also, the effects of different factors on Ag-NPs synthesis were evaluated to set the optimum synthesis conditions. Also, the antibacterial, antibiofilm, and anticancer activity of Ag-NPs was assessed. The X-ray diffraction (XRD) analysis confirmed the crystalline nature of the sample and validated that the crystal structure under consideration is a face-centered cubic (FCC) pattern. The TEM examination displayed the spherical particles of the Ag-NPs and their average size, which is 32.2 nm. Fourier transform infrared spectroscopy (FTIR) revealed significant changes in functionality after silver nanoparticle dispersion, which could be attributed to the potency of the cell filtrate of Streptomyces enissocaesilis BS1 to act as both a reducing agent and a capping agent. The bioactivity tests showed that our synthesized Ag-NPs exhibited remarkable antibacterial activity against different pathogenic strains. Also, when the preformed biofilms of Pseudomonas aeruginosa ATCC 9027, Salmonella typhi ATCC 12023, Escherichia coli ATCC 8739, and Staphylococcus aureus ATCC 6598 were exposed to Ag NPs 50 mg/ml for 24 hours, the biofilm biomass was reduced by 10.7, 34.6, 34.75, and 39.08%, respectively. Furthermore, the Ag-NPs showed in vitro cancer-specific sensitivity against human breast cancer MCF-7 cell lines and colon cancer cell line Caco-2, and the IC50 was 0.160 mg/mL and 0.156 mg/mL, respectively. The results of this study prove the ease and efficiency of the synthesis of Ag-NPs using actinomycetes and demonstrate the significant potential of these Ag-NPs as anticancer and antibacterial agents.

Green Synthesis of Silver Nanoparticles Using the Cell-Free Supernatant of Haematococcus pluvialis Culture

The green synthesis of silver nanoparticles (AgNPs) using the cell-free supernatant of a Haematococcus pluvialis culture (CFS) was implemented in the current study, under illumination conditions. The reduction of Ag+ to AgNPs by the CFS could be described by a pseudo-first-order kinetic equation at the temperature range tested. A high reaction rate during synthesis and stable AgNPs were obtained at 45 °C, while an alkaline pH (pH = 11.0) and a AgNO3 aqueous solution to CFS ratio of 90:10 (v/v) proved to be the most effective conditions in AgNPs synthesis. A metal precursor (AgNO3) at the concentration range tested (1-5 mM) was the limited reactant in the synthesis process. The synthesis of AgNPs was accomplished under static and agitated conditions. Continuous stirring enhanced the rate of reaction but induced aggregation at prolonged incubation times. Zeta potential and polydispersity index measurements indicated stable AgNPs and the majority of AgNPs formation occurred in the monodisperse phase. The X-ray diffraction (XRD) pattern revealed the face-centered cubic structure of the formed AgNPs, while TEM analysis revealed that the AgNPs were of a quasi-spherical shape with a size from 30 to 50 nm. The long-term stability of the AgNPs could be achieved in darkness and at 4 °C. In addition, the synthesized nanoparticles showed antibacterial activity against Escherichia coli.

Microalga Broths Synthesize Antibacterial and Non-Cytotoxic Silver Nanoparticles Showing Synergy with Antibiotics and Bacterial ROS Induction and Can Be Reused for Successive AgNP Batches

The era of increasing bacterial antibiotic resistance requires new approaches to fight infections. With this purpose, silver-based nanomaterials are a reality in some fields and promise new developments. We report the green synthesis of silver nanoparticles (AgNPs) using culture broths from a microalga. Broths from two media, with different compositions and pHs and sampled at two growth phases, produced eight AgNP types. Nanoparticles harvested after several synthesis periods showed differences in antibacterial activity and stability. Moreover, an evaluation of the broths for several consecutive syntheses did not find relevant kinetics or activity differences until the third round. Physicochemical characteristics of the AgNPs (core and hydrodynamic sizes, Z-potential, crystallinity, and corona composition) were determined, observing differences depending on the broths used. AgNPs showed good antibacterial activity at concentrations producing no or low cytotoxicity on cultured eukaryotic cells. All the AgNPs had high levels of synergy against Escherichia coli and Staphylococcus aureus with the classic antibiotics streptomycin and kanamycin, but with ampicillin only against S. aureus and tetracycline against E. coli. Differences in the synergy levels were also dependent on the types of AgNPs. We also found that, for some AgNPs, the killing of bacteria started before the massive accumulation of ROS.

A comprehensive review on soft rot disease management in ginger (Zingiber officinale) for enhancing its pharmaceutical and industrial values

Zingiber officinale L. Roscoe is a significant herb that possesses many medicinal and ethnomedicinal properties. Due to the presence of various bioactive compounds, it has immense healing capacity. However, ginger as a crop is susceptible to several fungal pathogens. Among all the fungal pathogens, Pythium and Fusarium spp. are of most concern, causing soft rot (rhizome rot) disease, majorly responsible for the downfall in its production by 50-90%. Pesticides and fungicides spray is generally recommended for the control of soft rot. Ample use of chemicals not only affects the quality of the crop but also disturbs ecological integrity. Therefore, biological methods of disease management involving suitable microbial agents such as Trichoderma harzianum, Pseudomonas spp., Bacillus subtilis, Streptomyces spp. and plant extracts are attracting and gaining importance as a part of integrated approaches (IPM) to manage the soft rot and sustainably enhance the production and improve the medicinal and pharmaceutical values of ginger. The present review is aimed to discuss various means of controlling soft rot disease by physical, chemical, biological, and nanotechnology-based methods. Moreover, various bioactive constituents of ginger and their pharmaceutical importance have been also discussed.

Nanoparticles from Microalgae and Their Biomedical Applications

Over the years, microalgae have been a source of useful compounds mainly used as food and dietary supplements. Recently, microalgae have been used as a source of metabolites that can participate in the synthesis of several nanoparticles through inexpensive and environmentally friendly routes alternative to chemical synthesis. Notably, the occurrence of global health threats focused attention on the microalgae application in the medicinal field. In this review, we report the influence of secondary metabolites from marine and freshwater microalgae and cyanobacteria on the synthesis of nanoparticles that were applied as therapeutics. In addition, the use of isolated compounds on the surface of nanoparticles to combat diseases has also been addressed. Although studies have proven the beneficial effect of high-value bioproducts on microalgae and their potential in medicine, there is still room for understanding their exact role in the human body and translating lab-based research into clinical trials.

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.

Nano-bioremediation of textile industry wastewater using immobilized CuO-NPs myco-synthesized by a novel Cu-resistant Fusarium oxysporum OSF18

Currently, bionanotechnologies are attracting great interest due to their promising results and potential benefits on many aspects of life. In this study, the objectives was to biosynthesis CuO-NPs using cell-free extract(s) of copper-resistant fungi and use them in bioremediation of textile industry wastewater. Out of 18 copper-resistant fungal isolates, the novel fungus strain Fusarium oxysporum OSF18 was selected for this purpose. This strain showed a high efficiency in extracellular reducing copper ions to their nano-form. The myco-synthesized CuO-NPs were characterized using UV-Vis spectroscopy, HRTEM, FTIR, and XRD and were found to be spherical nanocrystals with the size range of 21-47 nm. The bio-synthesized CuO-NPs showed promising antimicrobial activity as well as high efficiency in removing heavy metals and textile dye from industrial wastewater. The myco-synthesized CuO-NPs immobilized in alginate beads exhibited superior microbial disinfection (99.995%), heavy metals removal (93, 55, and 30 % for Pb, Cr, and Ni, respectively), and dye decolorization (90%). Such results represent a promising step to produce an eco-friendly, cost-effective, and easy-to handle tool for the bioremediation of textile industry wastewater.

Improving the antioxidant and anticancer potential of Cinnamomum cassia via fermentation with Lactobacillus plantarum

This study designed to investigate effect of fermentation by Lactobacillus plantarum on antioxidant and anticancer properties of Cinnamomum cassia aqueous solution. The optimum condition to produce high antioxidant activity was 10⁷ CFU L. plantarum/10 g cinnamon at pH6 after 3 days of incubation at 35 °C. Fermented cinnamon showed an increase in ABTS, DPPH and H₂O₂ by 24.63, 58.31 and 60.27%, respectively over the control. Also, the total phenolic and flavonoid contents were increased, 8.15 to 11.40 mg GAE/g and 0.43 to 2.61 mg QE/g, respectively. The gallic acid, p-hydroxybenzoic acid, catechin and chlorogenic acid were increased by 37, 404, 11 and 98%, respectively. Also, anticancer activity was developed after fermentation. The increased antioxidant activity of fermented cinnamon could be attributed to the increase of some phenolics and flavonoids. Hence, cinnamon fermentation using L. plantarum is able to enhance its antioxidant and anticancer activities without producing toxic substances.

Synthesis and characterization of functionalized modified PVC-chitosan as antimicrobial polymeric biomaterial

Amino acetic acid modified poly(vinyl chloride), MPVC, was obtained by chemical modification of PVC using glycine methyl ester. MPVC was used as a precursor to prepare some functionalized MPVC conjugates to be used in biomedical applications. MPVC-Cs was prepared by the chemical reaction of MPVC with chitosan as a natural polymer in absence and presence of epichlorohydrin (Ech) as a crosslinking agent. Further chemical modification was performed by the reaction of MPVC with Cs and salicylic acid in the absence in presence of Ech via one-pot reaction. The chemical structure of the formed MPVC, MPVC-Cs, MPVC-Cs/POH, MPVC-Cs/SA and MPVC-Cs/POH/SA was confirmed by the FTIR spectroscopic analysis, scanning electron microscopy, and thermogravimetric analysis (TGA). The antibacterial activity of the prepared MPVC and its conjugates was investigated against two Gram +ve bacteria (Staphylococcus aurous and Listeria monocytogenes) and (Escherichia coli and Salmonella typhi) as Gram −ve bacteria in addition to the Catondida albicans as yeast. Minimum inhibition concentration (MIC) was also determined for the prepared materials.

Highly effective enzymes immobilization on ceramics: Requirements for supports and enzymes

Enzyme immobilization is a well-known method for the improvement of enzyme reusability and stability. To achieve very high effectiveness of the enzyme immobilization, not only does the method of attachment need to be optimized, but the appropriate support must be chosen. The essential necessities addressed to the support applied for enzyme immobilization can be focused on the material features as well as on the stability and resistances in certain conditions. Ceramic membranes and nanoparticles are the most widespread supports for enzyme immobilization. Hence, the immobilization of enzymes on ceramic membrane and nanoparticles are summarized and discussed. The important properties of the supports are particle size, pore structure, active surface area, volume to surface ratio, type and number of reactive available groups, as well as thermal, mechanical, and chemical stability. The modifiers and the crosslinkers are crucial to the enzyme loading amount, the chemical and physical stability, and the reusability and catalytical activity of the immobilized enzymes. Therefore, the chemical and physical methods of modification of ceramic materials are presented. The most popular and used modifiers (e.g. APTES, CPTES, VTES) as well as activating agents (GA, gelatin, EDC and/or NHS) applied to the grafting process are discussed. Moreover, functional groups of enzymes are presented and discussed since they play important roles in the enzyme immobilization via covalent bonding. The enhanced physical, chemical, and catalytical properties of immobilized enzymes are discussed revealing the positive balance between the effectiveness of the immobilization process, preservation of high enzyme activity, its good stability, and relatively low cost.

Improving the bioremediation technology of contaminated wastewater using biosurfactants produced by novel bacillus isolates

Biosurfactants have many advantages outside chemical one, led for application it through different sectors. So, the present study aimed for improving the bioremediation technology of contaminated wastewater using biosurfactants produced by novel bacillus isolates. In this regard, Bacillus thuringiensis and Bacillus toyonensis strains were obtained as most producing isolates of highly active biosurfactants. The optimized conditions for high biosurfactants yield production were established. Also, the stability of the produced biosurfactants at various conditions, pH, temperature and salinity was studied. The biosurfactant has been reported up to 120 °C, pH 12 and 10% of NaCl. The identified biosurfactants, decanoic acid and oleamide were applied for wastewater remediation from oil residues and pathogens contamination. The biosurfactant was had high antibacterial activity compared with references antimicrobial drugs, as well as it is enhanced bioremediation technology for petroleum oil residues contaminating sites. Thus, we can say, these biosurfactants could achieve the objectives of sustainable development.

Isolation and Optimization of Monascus ruber OMNRC45 for Red Pigment Production and Evaluation of the Pigment as a Food Colorant

The color of food is a critical factor influencing its general acceptance. Owing to the effects of chemical colorants on health, current research is directly aimed at producing natural and healthy food colorants from microbial sources. A pigment-producing fungal isolate, obtained from soil samples and selected based on its rapidity and efficiency in producing red pigments, was identified as Monascus ruber OMNRC45. The culture conditions were optimized to enhance pigment production under submerged fermentation. The optimal temperature and pH for the highest red pigment yield were 30 °C and 6.5, respectively. The optimum carbon and nitrogen sources were rice and peptone, respectively. The usefulness of the pigment produced as a food colorant was evaluated by testing for contamination by the harmful mycotoxin citrinin and assessing its biosafety in mice. In addition, sensory evaluation tests were performed to evaluate the overall acceptance of the pigment as a food colorant. The results showed that M. ruber OMNRC45 was able to rapidly and effectively produce dense natural red pigment under the conditions of submerged fermentation without citrinin production. The findings of the sensory and biosafety assessments indicated the biosafety and applicability of the red Monascus pigment as a food colorant.

Statistical optimization of photo-induced biofabrication of silver nanoparticles using the cell extract of Oscillatoria limnetica: insight on characterization and antioxidant potentiality

Silver nanoparticles were successfully fabricated through a very simple, rapid, one-step photo-induced green approach. The formation of silver nanoparticles was accomplished using the bioactive compounds in the aqueous extract of fresh Oscillatoria limnetica biomass, which acted as a reducing and capping agent at the same time. The biosynthesis of Oscillatoria-silver nanoparticles (O-AgNPs) was investigated under the influence of different light intensities 57.75, 75.90 and 1276.51 μmol m-2 s-1 (bright sunlight). UV-Vis (UV) and Fourier transform infrared (FT-IR) spectroscopy were applied to approve the synthesis of AgNPs. Further, the synthesis process under the exposure to sunlight was adjusted via utilizing one factor at a time, and 0.5 mM AgNO3 concentration, 5 mL O. limnetica solution, pH 6.7 and 30 min sunlight (1276.51 μmol m-2 s-1) were applied. Furthermore, the central composite design (CCD) was applied to boost the biosynthesis process of O-AgNPs (manufactured at light intensity 75.90 μmol m-2 s-1). The maximum production of O-AgNPs was attained with 4 detected variables: initial pH level (6.7), AgNO3 concentration (0.3 mM), O. limnetica extract concentration (3.50 mL) and incubation time (48 h). Moreover, TEM, in addition to SEM, images exposed that the biosynthesized AgNPs were quasi-spherical in shape with a small monodisperse nature, and the size range was between 6.98-23.48 nm in the case of light-induced synthesis (75.90 μmol m-2 s-1) and 11.58-22.31 nm with sunlight (1276.51 μmol m-2 s-1).

Enhancing physico-mechanical and antibacterial properties of natural rubber using synthesized Ag-SiO2 nanoparticles

The incorporation of the prepared Ag-SiO₂ core-shell particles in natural rubber matrix was investigated on antibacterial and mechanical properties of resulting composites. Significant antibacterial effect against S. aureus (Gram positive) and P. aeruginosa (Gram negative) was observed and achieved inhibition growth up to 85 and 90%, respectively, after 24 h depending on the amount of Ag-SiO₂ core-shell. It was found that SiO₂ acted as crosslinking agent and controlling the amount of silver release. UV-vis spectra and TEM, XRD showed Ag-SiO₂ core-shell particles formation. SEM, FTIR, XRD and mechanical analysis showed uniform distribution of Ag-SiO₂ core-shell into rubber matrix with enhanced tensile strength.

Enzymes immobilization onto magnetic nanoparticles to improve industrial and environmental applications

Enzymes as specific natural biocatalysts are present in all living organisms and they play a key role in the biochemical reactions inside, as outside the cell. Despite the wide range of environmental, medical, agricultural, and food applications, the high cost, non-reusability, and limited stability of soluble (non-immobilized) enzymes are considered barriers to their commercial application. Immobilization techniques are an effective strategy for solving problems associated with free enzymes in terms of improving the efficiency and stability of catalytic enzymes, as well as enhancing their separation and reusability in continuous industrial applications. Out of different supporting materials, magnetic nanoparticles are considered as the future trend for enzyme immobilization due to their exceptional properties regarding stabilization, easy recovery and reuse. Some recent techniques of enzyme immobilization on magnetic nanoparticles will be detailed hereafter in the chapter.

Evaluation of cytotoxicity, biochemical profile and yield components of groundnut plants treated with nano-selenium

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Preparation and Characterization of selenium nanoparticles.

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Foliar application of the prepared nano-selenium on 3 different groundnut (Arachis hypogaea L.) cultivars.

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Evaluation of the effect of nanoselenium on Growth parameters, lipid peroxidation, antioxidants enzymes.

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Evaluation of prepared nano-selenium cytotoxicity.

Knowledge about the risks of the nanoparticles application on the plant development and human health is still limited. Different concentrations of nano-selenium (0, 20 and 40 ppm) were applied to three different Egyptian groundnut (Arachis hypogaea l.) cultivars; (NC, Gregory and Giza 6) under sandy soil conditions at vegetative growth stage to investigate their effects on yield components, protein profile, fatty acids composition, total antioxidant content and cytotoxicity of yielded seeds. The results indicate that the tested Nano-Selenium (Nano-Se) concentrations improved yield components and seeds oil. However, Nano-Se altered protein signatures as well as fatty acids composition by increasing unsaturated fatty acids and/or decreasing saturated fatty acids as compared with control, the cytotoxicity assessments proved safety of the yield for human health.

Flocculation Harvesting Techniques for Microalgae: A Review

Microalgae have been considered as one of the most promising biomass feedstocks for various industrial applications such as biofuels, animal/aquaculture feeds, food supplements, nutraceuticals, and pharmaceuticals. Several biotechnological challenges associated with algae cultivation, including the small size and negative surface charge of algal cells as well as the dilution of its cultures, need to be circumvented, which increases the cost and labor. Therefore, efficient biomass recovery or harvesting of diverse algal species represents a critical bottleneck for large-scale algal biorefinery process. Among different algae harvesting techniques (e.g., centrifugation, gravity sedimentation, screening, filtration, and air flotation), the flocculation-based processes have acquired much attention due to their promising efficiency and scalability. This review covers the basics and recent research trends of various flocculation techniques, such as auto-flocculation, bio-flocculation, chemical flocculation, particle-based flocculation, and electrochemical flocculation, and also discusses their advantages and disadvantages. The challenges and prospects for the development of eco-friendly and economical algae harvesting processes have also been outlined here.