Environmental friendly synthesis of silver nanomaterials from the promising Streptomyces parvus strain Al-Dhabi-91 recovered from the Saudi Arabian marine regions for antimicrobial and antioxidant properties

Construction of a domestic wastewater disinfection filter from biosynthesized and commercial nanosilver: a comparative study

Purpose

Biosynthesis of nanoparticles is an eco-friendly process and considered one of the most significant aspects of nanotechnology. Silver nanoparticles (Ag NPs) have a better bactericidal activity due to its high surface area to volume ratio. In this paper, Streptomyces sp. U13 (KP109813) was used to biosynthesize silver nanoparticles (Ag NPs) to construct wastewater disinfection filter.

Methods

The biosynthesized nanosilver and a commercially available ink nanosilver were characterized, and their wastewater disinfection efficiency was compared. The nanometrological characteristics of both nanosilver such as structure, shape, and size were investigated using the X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), high-resolution transmission electron microscope (HR-TEM), and UV-visible spectroscopy.

Result

The results revealed that the biosynthesized and ink Ag NPs were well dispersed and had a spherical shape, with sizes ranged from 5 to 37 nm and from 2 to 26 nm, respectively. To examine the disinfection capabilities, Ag NPs were loaded on two substrates, foam and limestone gravel, and packed into a glass column receiving domestic wastewater. Results showed that Ag NPs attached to limestone gravel eliminate 100% of the coliform bacteria better than foam. Comparing to control columns (without silver), only 50 and 10% reduction of the total coliform in gravel and foam column were achieved, respectively.

Conclusion

This work concluded that the type of substrate controls the amount of Ag NPs loaded on it and thus controls the disinfection process. No significant difference between biosynthesized and ink nanosilver in wastewater disinfection was observed. Using limestone gravel filter loaded with 200 mg/l Ag NPs with contact time of 150 min achieves a complete eradication of coliform bacteria.

Streptomyces rochei MS-37 as a Novel Marine Actinobacterium for Green Biosynthesis of Silver Nanoparticles and Their Biomedical Applications

Periodontitis, as one of the most common diseases on a global scale, is a public health concern. Microbial resistance to currently available antimicrobial agents is becoming a growing issue in periodontal treatment. As a result, it is critical to develop effective and environmentally friendly biomedical approaches to overcome such challenges. The investigation of Streptomyces rochei MS-37's performance may be the first of its kind as a novel marine actinobacterium for the green biosynthesis of silver nanoparticles (SNPs) and potentials as antibacterial, anti-inflammatory, antibiofilm, and antioxidant candidates suppressing membrane-associated dental infections. Streptomyces rochei MS-37, a new marine actinobacterial strain, was used in this study for the biosynthesis of silver nanoparticles for various biomedical applications. Surface plasmon resonance spectroscopy showed a peak at 429 nm for the SNPs. The SNPs were spherical, tiny (average 23.2 nm by TEM, 59.4 nm by DLS), very stable (-26 mV), and contained capping agents. The minimum inhibitory concentrations of the SNPs that showed potential antibacterial action ranged from 8 to 128 µg/mL. Periodontal pathogens were used to perform qualitative evaluations of microbial adhesion and bacterial penetration through guided tissue regeneration membranes. The findings suggested that the presence of the SNPs could aid in the suppression of membrane-associated infection. Furthermore, when the anti-inflammatory action of the SNPs was tested using nitric oxide radical scavenging capacity and protein denaturation inhibition, it was discovered that the SNPs were extremely efficient at scavenging nitric oxide free radicals and had a strong anti-denaturation impact. The SNPs were found to be more cytotoxic to CAL27 than to human peripheral blood mononuclear cells (PBMCs), with IC50 values of 81.16 µg/mL in PBMCs and 34.03 µg/mL in CAL27. This study's findings open a new avenue for using marine actinobacteria for silver nanoparticle biosynthesis, which holds great promise for a variety of biomedical applications, in particular periodontal treatment.

Bandgap and visible-light-induced photocatalytic performance and dye degradation of silver doped HAp/TiO2 nanocomposite by sol-gel method and its antimicrobial activity

Silver doped hydroxyapatite and titanium oxide nanocomposites have been obtained by sol-gel techniques with novel antimicrobial activities for biomedical applications. The synthesis of Ca_10-X Ag_X (PO₄)₆(OH)₂ along with titanium oxide nanoparticles with X_Ag = 0 (HAp/TiO₂), 0.1, 0.25 and 0.5 (Ag:HAp/TiO₂-NCS) was performed. The developed crystalline phase was characterized via X-ray diffraction (XRD), and the morphological features were executed via scanning and transmission electron microscopy (SEM/TEM). The HAp/TiO₂ and silver doped HAp/TiO₂ nanocomposites were spherical grains, with needle and flower-like structures. XRD examination revealed the crystalline phases of HAp/TiO₂ and Ag-doped HAp/TiO₂ nanocomposites. The crystallite size of HAp/TiO₂ and Ag-doped HAp/TiO₂ nanocomposites determined from the XRD pattern was ranged between 16 nm and 20 nm. The FTIR analysis confirms the presence of stretching and vibrational peaks for the presence of silver doped HAp/TiO₂. The EDAX analysis showed the existence of major elements of HAp/TiO₂ and Ag-HAp/TiO₂ nanostructured composites. HAp/TiO₂ and silver doped HAp/TiO₂ were active against both Gram-positive and Gram-negative bacteria such as, E. coli (MTCC 443), S. typhi (MTCC 733), and S. aureus (MTCC 3160). The photocatalytic absorption spectrum implied an increased absorption rate of methylene blue by HAp/TiO₂ and silver doped HAp/TiO₂ nanocomposites. The photocatalytic activity revealed that 50% Ag doped HAp/TiO₂ optimally improved photocatalytic activity.

Green synthesis of Silver nanoparticles using Streptomyces hirsutus strain SNPGA-8 and their characterization, antimicrobial activity, and anticancer activity against human lung carcinoma cell line A549

The current study described the systematic and detailed extracellular synthesis method of silver nanoparticles (AgNPs) using Streptomyces hirsutus strain SNPGA-8 by green synthesis method. The AgNPs were subjected for characterizations using UV-Vis, FTIR, TGA, TEM, EDX, XRD, and zeta-potential analyses. The antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli, Candida albicans, Alternaria alternata, Candida glabrata and Fusarium oxysporum was determined by the agar well diffusion technique. The cytotoxicity of AgNPs against human lung cancer (A549) was studied by MTT and ROS assays and capping of proteins of AgNPs from SDS-PAGE. In the UV-Vis., absorption peak was found at 418 nm, FTIR analysis revealed the infrared bands of specific functional groups from 3273 cm-1 to 428 cm-1; TEM data confirmed the spherical shape, smallest size of particle as 18.99 nm, while EDX analysis confirmed the elemental composition of AgNPs with 22.24% Ag. The XRD pattern confirmed the nature of AgNPs as crystalline, and zeta potential peak was found at -24.6 mV indicating the higher stability. The AgNPs exhibited increased antimicrobial activity with increase in dosage volume and considerable MIC and MBC values against microbial pathogens. In the MTT cytotoxicity assay, the IC50 value of 31.41 μg/mL is obtained against A549 cell line, suggesting the potential of AgNPs to inhibit the tumour cells; and ROS assay displayed increased ROS production with increase in treatment time. Based on the results, it is evident that Streptomyces hirsutus strain SNPGA-8 AgNPs are potentially promising to be applied for biomedical uses.

Silver nanoparticles biosynthesized from secondary metabolite producing marine actinobacteria and evaluation of their biomedical potential

Biosynthesis of silver nanoparticles (AgNPs) from marine actinobacteria offers a promising avenue for exploring bacterial extracts as reducing and stabilizing agents. We report extracellular extracts of Rhodococcus rhodochrous (MOSEL-ME29) and Streptomyces sp. (MOSEL-ME28), identified by 16S rRNA gene sequencing for synthesis of AgNPs. Ultrafine silver nanoparticles were biosynthesized using the extracts of R. rhodochrous and Streptomyces sp. and their possible therapeutic applications were studied. The physicochemical properties of nanoparticles were established by HR-SEM/TEM, SAED, UV-Vis, EDS, XRD, and FTIR. UV-Vis spectra displayed characteristic absorption at 430 nm and 412 nm for AgNPs from Streptomyces sp. (S-AgNPs) and Rhodococcus sp. (R-AgNPs), respectively. HR-SEM/TEM, XRD, EDS analysis confirmed the spherical shape, crystalline nature, and elemental formation of silver. Crystallite or grain size was deduced as 5.52 nm for R-AgNPs and 35 nm for S-AgNPs. Zeta-potential indicated electrostatic negative charge for AgNPs, while FTIR revealed the presence of diverse functional groups. Disc diffusion assay indicated the broad-spectrum antibacterial potential of S-AgNPs with the maximum inhibition of B. subtilis while R-AgNPs revealed potency against P. aeruginosa at 10 µg/mL concentration. Biogenic AgNPs revealed antileishmanial activity and the IC₅₀ was calculated as 164 µg/mL and 184 µg/mL for R-AgNPs and S-AgNPs respectively. Similarly, the R-AgNPs and S-AgNPs revealed anti-cancer potential against HepG2 and the IC₅₀ was calculated as 49 µg/mL and 69 µg/mL for R-AgNPs and S-AgNPs, respectively. Moreover, the antioxidant activity showed significant results. MTT assay on RD cells, L20B cells, and Hep-2C indicated intensification in viability by reducing the concentration of R-AgNPs and S-AgNPs. The R-AgNPs and S-AgNPs inhibited sabin-like poliovirus (1TCID₅₀ infection in RD cells). Furthermore, hemocompatibility at low concentrations has been confirmed. Hence, it is concluded that biogenic-AgNPs has the potential to be used in diverse biological applications and that the marine actinobacteria are an excellent resource for fabrication of AgNPs.

In vitro biological properties of Streptomyces cangkringensis isolated from the floral rhizosphere regions

This context was investigated to determine in vitro antimicrobial, antioxidative, and anticancer traits of crude ethyl acetate extract of Streptomyces cangkringensis strain TSAS 04 isolated from soil sample of rhizosphere regions. The antimicrobial activity of ethyl acetate extract of strain TSAS 04 was determined against indicator pathogens using disc diffusion assay which exhibited maximum zones of inhibition of 20.6 ± 0.3 and 16.3 ± 0.6 mm against Bacillus subtilis and Trichoderma viride, respectively. In vitro antioxidant properties of the crude ethyl acetate extract were performed using standard methodologies. The extract revealed maximum DPPḢ and ABTS^•+ radical scavenging activities of 51.1 ± 0.39 and 81.25 ± 0.33%, respectively. Likewise, maximum phosphomolybdenum reduction and Fe³⁺ reduction of the crude ethyl acetate extract of strain TSAS 04 were estimated 76.18 ± 0.10 and 89.01 ± 0.44%, respectively. In vitro anticancer trait of the extract was determined against HeLa cell line using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay which showed anticancer activities in a dose dependent manner with an IC₅₀ value of 410.5 µg/mL. Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography–mass spectrometry (GC-MS) analyses indicated the presence of distinct functional groups and bioactive components in the extract, respectively. In conclusion, S. cangkringensis strain TSAS 04 showed its effectiveness as ideal bioactive agent by exhibiting substantial antimicrobial, antioxidant, and anticancer properties.

Bactericidal and In-Vitro Cytotoxic Efficacy of Silver Nanoparticles (Ag-NPs) Fabricated by Endophytic Actinomycetes and Their Use as Coating for the Textile Fabrics

An endophytic strain of Streptomyces antimycoticus L-1 was isolated from healthy medicinal plant leaves of Mentha longifolia L. and used for the green synthesis of silver nanoparticles (Ag-NPs), through the use of secreted enzymes and proteins. UV-vis spectroscopy, Fourier-transform infrared (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), and dynamic light scattering (DLS) analyses of the Ag-NPs were carried out. The XRD, TEM, and FT-IR analysis results demonstrated the successful biosynthesis of crystalline, spherical Ag-NPs with a particle size of 13-40 nm. Further, the stability of the Ag-NPs was assessed by detecting the surface Plasmon resonance (SPR) at 415 nm for one month or by measuring the NPs surface charge (-19.2 mV) by zeta potential analysis (ζ). The green-synthesized Ag-NPs exhibited broad-spectrum antibacterial activity at different concentrations (6.25-100 ppm) against the pathogens Staphylococcus aureus, Bacillus subtilis Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium with a clear inhibition zone ranging from (9.5 ± 0.4) nm to (21.7 ± 1.0) mm. Furthermore, the green-synthesized Ag-NPs displayed high efficacy against the Caco-2 cancerous cell line (the half maximal inhibitory concentration (IC₅₀) = 5.7 ± 0.2 ppm). With respect to antibacterial and in-vitro cytotoxicity analyses, the Ag-NPs concentration of 100 ppm was selected as a safe dose for loading onto cotton fabrics. The scanning electron microscopy connected with energy-dispersive X-ray spectroscopy (SEM-EDX) for the nano-finished fabrics showed the distribution of Ag-NPs as 2% of the total fabric elements. Moreover, the nano-finished fabrics exhibited more activity against pathogenic Gram-positive and Gram-negative bacteria, even after 10 washing cycles, indicating the stability of the treated fabrics.

Molecular diversity and hydrolytic enzymes production abilities of soil bacteria

Soil is an integral part of ecosystem which is niche for varieties of microflora. The present study was investigated to isolate varied strains of bacteria from soil samples of three different geographical regions of Tamil Nadu (India) and evaluate their hydrolytic enzymes (amylase, cellulase, and inulinase) producing potentialities. Among 72 bacterial cultures isolated from Ambattur Industrial Estate, Neyveli Lignite Corporation, and Arignar Anna Zoological Park regions, 41.66, 38.88, and 36.11% of isolates were observed amylase, cellulase, and inulinase producers, respectively. On the other hand, 20.83% of total bacteria isolated from all three regions exhibited concurrent production of amylase, cellulase, and inulinase. Potent isolates depicting maximum enzyme activities were identified as Bacillus anthracis strain ALA1, Bacillus cereus strain ALA3, Glutamicibacter arilaitensis strain ALA4, and Bacillus thuringiensis strain ALA5 based on molecular characterization tools. Further, the thermodynamics parameters, open reading frames (ORFs) regions, and guanine-cytosine (GC) content were determined by distinct bioinformatics tools using 16S rRNA sequences of strains. Minimum free energy values for strain ALA1, strain ALA3, strain ALA4, and strain ALA5 were calculated as −480.73, −478.76, −496.63, and −479.03 kcal/mol, respectively. Mountain plot and entropy predicted the hierarchical representation of RNA secondary structure. The GC content of sequence for strain ALA1, strain ALA3, strain ALA4, and strain ALA5 was calculated as 53.06, 52.94, 56.78, and 53.06%, respectively. Nine ORFs were obtained for strain ALA1, strain ALA3, and strain ALA5 while 10 ORFs were observed for strain ALA4. Additionally, bootstrap tree demonstrated close resemblance of strains with existing bacteria of similar genus. Findings showed higher variability of bacterial diversity as hydrolytic enzymes producers in the investigated geographical regions.

Hetta H, Shaheen TI. Endophytic Streptomyces laurentii Mediated Green Synthesis of Ag-NPs with Antibacterial and Anticancer Properties for Developing Functional Textile Fabric Properties

Improvement of the medical textile industry has received more attention recently, especially with widespread of microbial and viral infections. Medical textiles with new properties, such as bacterial pathogens self-cleaning, have been explored with nanotechnology. In this study, an endophytic actinomycetes strain of Streptomyces laurentii R-1 was isolated from the roots of the medicinal plant Achillea fragrantissima. This is used as a catalyst for the mediated biosynthesis of silver nanoparticles (Ag-NPs) for applications in the textile industry. The biosynthesized Ag-NPs were characterized using UV-vis spectroscopy, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), and X-ray Diffraction (XRD), which confirmed the successful formation of crystalline, spherical metal nanoparticles. The biosynthesized Ag-NPs exhibited broad-spectrum antibacterial activity. Our data elucidated that the biosynthesized Ag-NPs had a highly cytotoxic effect against the cancerous caco-2 cell line. The selected safe dose of Ag-NPs for loading on cotton fabrics was 100 ppm, regarding their antibacterial activity and safe cytotoxic efficacy. Interestingly, scanning electron microscope connected with energy dispersive X-ray spectroscopy (SEM-EDX) of loaded cotton fabrics demonstrated the smooth distribution of Ag-NPs on treated fabrics. The obtained results highlighted the broad-spectrum activity of nano-finished fabrics against pathogenic bacteria, even after 5 and 10 washing cycles. This study contributes a suitable guide for the performance of green synthesized NPs for utilization in different biotechnological sectors.

Evaluation of BOX-PCR and REP-PCR as Molecular Typing Tools for Antarctic Streptomyces

Molecular studies led to the resurgence of natural products research from genus Streptomyces, already known for their long history and importance for the pharmaceutical industry. However, species belonging to this genus are difficult to identify and the most commonly used techniques, which are based on 16S rRNA sequencing, do not discriminate between related species. In this work, amplification profiles generated from BOX-PCR and REP-PCR of 49 Antarctic soil streptomycetes were compared to evaluate the diversity present in the group and to characterize the bacterial isolates, along with some 16S rRNA amplifications. The BOX-A1R primer exhibit clearer amplification fragments, different from the amplification patterns obtained using the REP 1R and 2R primers. A higher diversity was observed with REP-PCR amplifications, even though a larger number of fragments was obtained with BOX-A1R primer amplifications. There are at least four isolates that showed great similarity (about 90%) in both techniques. In other hand, there are two others that are 90% similar in BOX-PCR, but distant in REP-PCR, showing only 40% of similarity. Results of the combination of BOX-PCR and REP-PCR represent a simple and low-cost method to discriminate between Streptomyces strains. There is no species identification with only the 16S rRNA, most isolates seem to be related to S. globisporus. Further studies added to the obtained results may provide better data to help the characterization of these microorganisms.

Green synthesis and characterization of gold nanoparticles using endophytic fungi Fusarium solani and its in-vitro anticancer and biomedical applications

The present study aimed to explore the anticancer potentials of the gold nanoparticles (NPs) obtained by green synthesis method using an endophytic strain Fusarium solani ATLOY - 8 has been isolated from the plant Chonemorpha fragrans. The formation of the NPs was analyzed by UV, FTIR, SEM and XRD. The synthesized NPs showed pink-ruby red colors and high peak plasmon band was observed between 510 and 560 nm. It is observed that intensity of absorption steadily increases the wavelength and band stabilizes at 551 nm. The XRD pattern revealed the angles at 19, 38.32, 46.16, 57.50, and 76.81° respectively. Interestingly, the FTIR band absorption noted at 1413 cm-1, 1041 cm-1 and 690 cm-1 ascribed the presence of amine II bands of protein, C-N and C-H stretching vibrations of the nanoparticles. SEM analysis indicated that the average diameter of the synthesized nanoparticles was between 40 and 45 nm. These NPs showed cytotoxicity on cervical cancer cells (He La) and against human breast cancer cells (MCF-7) and the NPs exhibited dose dependent cytotoxic effect. IC50 value was 0.8 ± 0.5 μg/mL on MCF-7 cell line and was found to be 1.3 ± 0.5 μg/mL on MCF-7 cell lines. The synthesized NPs induced apoptosis on these cancer cell lines. The accumulation of apoptotic cells decreased in sub G0 and G1 phase of cell cycle in the MCF-7 cancer cells were found to be 55.13%, 52.11% and 51.10% after 12 h exposure to different concentrations. The results altogether provide an apparent and versatile biomedical application for safer chemotherapeutic agent with little systemic toxicity.

Purification and characterization of anti-tubercular and anticancer protein from Staphylococcus hominis strain MANF2: In silico structural and functional insight of peptide

The present context was investigated to purify and characterize anti-tubercular as well as anticancer protein from fermented food associated Staphylococcus hominis strain MANF2. Initially, the anti-tubercular potency of strain MANF2 was assessed against Mycobacterium tuberculosis H37Rv using luciferase reporter phase assay which revealed pronounced relative light unit (RLU) reduction of 92.5 ± 1.2%. The anticancer property of strain MANF2 was demonstrated against lung cancer (A549) and colon cancer (HT-29) cell lines using MTT assay which showed reduced viabilities. Anti-tubercular activities of the purified protein were observed to be increased significantly (P < 0.05) ranging from 34.6 ± 0.3 to 71.4 ± 0.4% of RLU reduction. Likewise, the purified protein showed significantly (P < 0.05) reduced viabilities of A549 and HT-29 cancer cells with IC₅₀ values of 46.6 and 48.9 µg/mL, respectively. The nominal mass of the purified protein was found to be 7712.3 Da as obtained from MALDI-TOF MS/MS spectrum. The protein showed the sequence homology with 1–336 amino acids of Glyceraldehyde-3-phosphate dehydrogenase from Staphylococcus sp., thus, categorizing as a new class of Glyceraldehyde-3-phosphate dehydrogenase-like protein. The amino acid sequence of the most abundant peptide (m/z = 1922.12) in the purified protein was obtained as ‘KAIGLVIPEIDGKLDGGAQRV’ and it was identified as peptide NMANF2. In silico tools predicted significant stereo-chemical, physiochemical, and functional characteristics of peptide NMANF2. In a nutshell, protein purified from strain MANF2 can certainly be used as an ideal therapeutic agent against tuberculosis and cancer (lung and colon).

Purification and kinetic behavior of glucose isomerase from Streptomyces lividans RSU26

Glucose isomerase (GI), an enzyme with deserved high potential in the world market. GI plays a major role in high Fructose Corn Syrup Production (HFCS). HFCS is used as a sweetener in food and pharmaceutical industries. Streptomyces are well-known producers of various industrially valuable enzymes, including Glucose isomerase. Currently, recombinant strains have been available for the production of various enzymes, but it has limitation in the large scale production. Therefore, identifying effective streptomyces strains have emerged. The current study, the novel S. lividans RSU26 was isolated from a marine source and optimized its potential to produce glucose isomerase at different physical and chemical conditions. The optimum pH and temperature for GI and biomass production were 7.5 and 35 °C, respectively at 96 h. Characterization study revealed that the approximate molar mass of GI was 43 kDa for monomeric and 170 kDa for tetrameric forms. Kinetic behavior exhibits Km, and Vmax values for the conversion of fructose to glucose conversion were 48.8 mM and 2.54 U mg⁻¹ at 50 °C and glucose to fructose were 29.4 mM and 2.38 U mg⁻¹ at 65 °C protein, respectively. Therefore, the present study suggested that the wild–type S. lividans RSU26 has strong potential to produce glucose isomerase for various industrial applications.

Isolation and screening of Streptomyces sp. Al-Dhabi-49 from the environment of Saudi Arabia with concomitant production of lipase and protease in submerged fermentation

In this study, Streptomyces sp. Al-Dhabi-49 was isolated from the soil sample of Saudi Arabian environment for the simultaneous production of lipase and protease in submerged fermentation. The process parameters were optimized to enhance enzymes production. The production of protease and lipase was found to be maximum after 5 days of incubation (139.2 ± 2.1 U/ml, 253 ± 4.4 U/ml). Proteolytic enzyme increases with the increase in pH up to 9.0 (147.2 ± 3.6 U/ml) and enzyme production depleted significantly at higher pH values. In the case of lipase, production was maximum in the culture medium containing pH 8.0 (166 ± 1.3 U/ml). The maximum production of protease was observed at 40 °C (174 ± 12.1 U/ml) by Streptomyces sp. Lipase activity was found to be optimum at the range of temperatures (30-50 °C) and maximum production was achieved at 35 °C (168 ± 7.8 U/ml). Among the evaluated carbon sources, maltose significantly influenced on protease production (218 ± 12.8 U/ml). Lipase production was maximum when Streptomyces sp. was cultured in the presence of glucose (162 ± 10.8U/ml). Among various concentrations of peptone, 1.0% (w/v) significantly enhanced protease production. The lipase production was very high in the culture medium containing malt extract as nitrogen source (86 ± 10.2 U/ml). Protease production was maximum in the presence of Ca²⁺ as ionic source (212 ± 3.8 U/ml) and lipase production was enhanced by the addition of Mg²⁺ with the fermentation medium (163.7 ± 6.2 U/ml).