Novel extracellular synthesized silver nanoparticles using thermophilic Anoxybacillus flavithermus and Geobacillus stearothermophilus and their evaluation as nanodrugs

Abstract In this investigation, two new thermophilic bacteria were isolated. The new isolates were characterized by 16S rRNA, biochemical, morphological, and physiological analyzes and the isolates were identified as Geobacillus stearothermophilus strain Gecek20 and thermophilic Anoxybacillus flavithermus strain Gecek19. Various biological activities of extracellular Ag-NPs synthesized from thermophilic G. stearothermophilus strain Gecek20 and thermophilic A. flavithermus strain Gecek19 were evaluated. The produced NPs were analyzed by SEM, SEM-EDX, and XRD analyses. The antioxidant abilities of new synthesized Ag-NPs from thermophilic G. stearothermophilus strain Gecek20 (T1-Ag-NPs) and new synthesized Ag-NPs from thermophilic A. flavithermus strain Gecek19 (T2-Ag-NPs) were studied by DPPH inhibition and metal chelating ability. The highest DPPH and metal chelating abilities of T1-Ag-NPs and T2-Ag-NPs at 200 mg/L concentration were 93.17 and 90.85%, and 75.80 and 83.64%, respectively. The extracellular green synthesized T1-Ag-NPs and T2-AgN-Ps showed DNA nuclease activity at all tested concentrations. Moreover, both new synthesized Ag-NPs had antimicrobial activity against the strains studied, especially on Gram positive bacteria. T1-Ag-NPs and T2-AgNPs also showed powerful Escherichia coli growth inhibition. The highest biofilm inhibition percentages of T1-Ag-NPs and T2-Ag-NPs against Pseudomonas aeruginosa and Staphylococcus aureus were 100.0%, respectively, at 500 mg/L.


Introduction
Green synthesis has a growing focus on a novel approach in metal nanoparticle production. [1]Green synthesis phenomena include the utilization of nontoxic extracts derived from plants, bacteria, algae, and fungi for the synthesis of noble metal nanoparticles. [2,3]Green synthesis method for nanoparticle synthesis eliminates the need for high pressure, energy, temperature, and the use of toxic chemicals compared to conventional physical and chemical methods. [4,5]urthermore, the green synthesis method offers the advantage of enabling the recycling of valuable metal salts, such as gold and silver, from waste materials. [6]This reduces not only the environmental impact but also promotes the sustainable utilization of these precious metals.
9][10][11][12][13][14][15][16] So far, AgNPs are synthesized by physical, chemical, and biological methods.Chemical reduction, using reductants such as ascorbate, borohydride, citrate, or elemental hydrogen, is a commonly employed method, but it may result in the generation of particles that are difficult to control. [9,17]In contrast, the green synthesis method utilizing biogenic materials has shown promising results.These materials possess properties that reduce Ag þ ions to AgNPs, coat the nanoparticles, prevent agglomeration, and reduce toxicity. [18]Bacterial extracts have been particularly effective in the economical, easily processed, and environmentally friendly synthesis of AgNPs. [19]The stability and synthesis of AgNPs depend on the properties of microorganisms' supernatants, where enzymes play a crucial role in reducing silver ions and forming AgNPs. [20,21] Ihsan et al. [22] successfully synthesized and characterized functionalized AgNPs using the bacterial strain T10.Additionally, the antibacterial properties of the AgNPs were evaluated.The study concluded that bacterial extracts provide an excellent resource for environmentally friendly synthesis of AgNPs, showcasing their potential in combatting pathogens [22] In another investigation by Ali et al., [22] extracellular production of AgNPs was achieved utilizing a naturally occurring thermophilic bacterium, Bacillus sp.AZ1.The antibacterial potential of the synthesized NPs was tested against various human pathogenic microorganisms.The study proposed a simple and environmentally friendly method for AgNPs production. [23]n this investigation, two new thermophilic bacteria were isolated.The new isolates were characterized by morphological, physiological, biochemical, and 16S rRNA analyzes and the isolates were identified as Geobacillus stearothermophilus strain Gecek20 and thermophilic Anoxybacillus flavithermus strain Gecek19 by 16S rRNA results.Various biological activities of extracellular two different AgNPs synthesized from thermophilic G. stearothermophilus strain Gecek20 and thermophilic A. flavithermus strain Gecek19 was performed.The produced NPs were characterized.The antioxidant activities of new synthesized Ag-NPs from thermophilic G. stearothermophilus strain Gecek20 (T1-AgNPs) and new synthesized Ag-NPs from thermophilic A. flavithermus strain Gecek19 (T2-AgNPs) were studied by DPPH scavenging activity and ferrous ion chelating activity.

Synthesis of AgNPs
Silver nitrate (AgNO 3 ) used as the silver source was obtained from Merck Millipore.To synthesize AgNPs, 100 mL bacterium extracts were treated with AgNO 3 (300 mL and 10 mM) solution overnight at 70 C.The nanoparticles were rinsed with deionized water and dried for 24 hours at 80 C. Bamsaoud et al. [24] synthesized AgNPs using an aqueous leaf extract of Ziziphus spina-Christi (ZSC).AgNO 3 with various concentrations from 0.5 to 10 mM were investigated to synthesize AgNPs.They reported that the size of the synthesized Ag-NPs increases from 25 to 42 nm with the rising concentration of AgNO 3 from 0.5 to 10 mM.Moreover, the inhibition zones of 0 and 19 mm were obtained for Escherichia coli using leaf extract of ZSC and Ag-NPs prepared by 10 mM of AgNO3, respectively.Similar results were in agreement with earlier reports when 10 mM of AgNO3 concentration was used for Ag-NPs synthesis. [25,26]

Fourier transform infrared spectroscopy (FTIR, Perkin
Elmer 400) to provide information about the functional groups, X-ray diffraction (XRD, Bruker AXS D8 Advance) to analyze the crystalline structure and identify the phases, field-emission scanning electron microscopy (FE-SEM, Zeiss Gemini 500 microscope) to obtain information on their morphology, size, and surface properties, and Energy Dispersive X-Ray Analysis (EDX) to provide elemental composition were used to characterize the synthesized AgNPs.

DPPH scavenging activity
The antioxidant activity of extracellular prepared T1-AgNPs and T2-AgNPs by thermophilic G. stearothermophilus strain Gecek20 and A. flavithermus strain Gecek19 was investigated by A gırtas ¸et al. [27] Method briefly; it is based on measuring the absorbance after incubation of DPPH solution and T1-AgNPs and T2-AgNPs prepared at different concentrations for 30 min.The antioxidant ability was calculated using the formula below (1).
where Abs control is control absorbance and Abs sample is sample absorbance.

Metal chelating activity
The ferrous chelating activity of extracellular synthesized T1-AgNPs and T2-AgNPs from 2 different thermophilic bacteria was performed by the Dinis process. [28]In summary; after reacting the T1-AgNPs and T2-AgNPs with FeCl 2 , ferrozine was added to the mixture.The absorbance was measured after incubation and the % ability was calculated using the formula below (2).
Metal Chelating Effect ð%Þ where Abs control is control absorbance and Abs sample is samples and EDTA absorbance.

DNA cleavage ability
DNA cleavage activity of both extracellular synthesized T1-AgNPs and T2-AgNPs was investigated.For this, plasmid pBR322 DNA was used as the target DNA molecule.Plasmid DNA was subjected to varied concentrations of the both new prepared AgNPs for 45 min at 37 C. Afterwards, electrophoresis step was applied to visualize the DNA degradation activity.Finally, the gel was visualized using a transilluminator to observe DNA bands.

Antimicrobial activity
Minimum inhibitory concentration (MIC) of both extracellular synthesized T1-AgNPs and T2-AgNPs from 2 different thermophilic bacteria were investigated by the serial dilution method, as previously reported by Gonca et al. [29] Used microorganisms as follow: Pseudomonas aeruginosa, E. coli, Legionella pneumo-  phila subsp.pneumophila, Enterococcus hirae, Enterococcus faecalis, Staphylococcus aureus, Candida parapisilosis, and Candida tropicalis.Before being used in the experimental phase test microorganisms used in the antimicrobial activity method were grown overnight.Later, 1:1 dilution of AgNPs were done and then microorganisms were added to the well plates.Subsequent plates were incubated.MIC values, which are the lowest concentrations that prevent microbial growth after 24 h, were used to assess antimicrobial activity.

Biofilm inhibition activity
S. aureus (Gram positive) and P. aeruginosa (Gram negative) were selected to define the impact of two different AgNPs onto biofilm inhibition.Crystal violet procedure was used to investigate the activity of T1-AgNPs and T2-AgNPs on biofilm and investigated as previously reported by Gonca et al. [29] Anti-biofilm ability was calculated according to Eq. (3).

Bacterial viability inhibition test
Information about the details of the bacterial viability inhibition study is given in the supplementary material.Detailed information on the isolation procedure, phenotypic characterization, 16S rRNA analyzing, and bioinformatic analyzing procedure were given in the supplementary material.

Identification of bacterial isolates by phenotypic features and phylogenetic analyzing
According to 16S rRNA, biochemical, morphological, and physiological analyzes strains Gecek19 and Gecek20 were identified as Anoxybacillus flavithermus and Geobacillus stearothermophilus, respectively.Some phenotypical characteristics of the isolated strains and their agarose gel images of 16S rRNA are depicted in Table 1 and Figure 1, respectively.Phylogenetic trees of Gecek19 and Gecek20 are also shown in Figures 2 and 3, respectively.

Biosynthesis and characteristics of Ag NPs
The biosynthesized AgNPs were visually observed to undergo a color change from yellow to gray-brown, as expected based on previous literature. [30]XRD analysis was conducted to determine the crystalline nature of T1-AgNPs   crystal planes (122), ( 111), ( 200), (220), and (311) of silver, respectively (Figure 6).These XRD spectra provided evidence that T2-AgNPs were in the form of nanocrystals and exhibited a crystalline structure.SEM images revealed that T2-AgNPs had a flower-like shape (Figure 7).The size of the flower-like T2-AgNPs was determined to be less than 200 nm (Figure 7A).SEM-EDX analysis allowed for the identification of the elemental composition of the T2-AgNPs, providing additional evidence for the successful synthesis of the nanoparticles (Figure 7B).

DPPH radical inhibition ability
DPPH inhibition ability is a method that measures in spectrophotometer variations caused by the reaction of DPPH with antioxidant. [31]DPPH is a free radial.DPPH scavenging ability is considered a procedure that yields simple, fast, repeatable results. [32]In this investigation, DPPH inhibition activity of T1-AgNPs and T2-AgNPs extracellular synthesized from thermophilic G. stearothermophilus strain Gecek20 and A. flavithermus strain Gecek19 were evaluated by DPPH method.There has not been enough works to produce nanoparticles by using thermophilic microorganisms in literatures.The results are given in Figure 8.It was observed that DPPH inhibition of T1-AgNPs and T2-AgNPs showed concentration-dependent activity.The DPPH inhibition of T1-AgNP was determined as 93.17% for 200 mg/L, 86.08% 100 mg/L, 72.29% 50 mg/L, 59.02% for 25 mg/L, and 43.81% for 12.5 mg/L.The DPPH inhibition of T2-AgNP was also 90.85% for 200 mg/L, 84.79% for 100 mg/L, 73.84% 50 mg/L, 61.85% 25 mg/L, and 47.55% for 12.5 mg/L.Also, the DPPH radical inhibition of T1-AgNPs and T2-AgNPs, Ascorbic acid and Trolox was in order of Ascorbic Acid ¼ Trolox > T1-AgNP > T2-AgNP at 200 mg/L.DPPH activities of AgNPs obtained by various synthesis methods have been reported in studies.Varadavenkatesan et al. [33] performed the antioxidant activity of Ag-NPs obtained from Vigna mungo.They reported that the maximum inhibition percentage was 75.53% at 60 lg/mL concentration.G€ ulba gca et al. [34] found the DPPH activity of AgNP obtained from Rosa canina as 79.5% at 200 mg/L.Turunc ¸et al. [35] reported the highest DPPH inhibition activity at 200 mg/L as 87.71%.
In this study, the DPPH inhibition of T1-AgNP and T2-AgNP at 200 mg/L was determined as 93.17 and 90.85% and also had better results than the aforementioned studies.The result showed that T1-AgNP and T2-AgNP synthesized from thermophilic bacteria can be a major utilization to reducing different chronic illnesses and cancer risk agents.

Metal chelating activity
Although Fe is a vital element for organisms, they can cause harmful oxidative reactions with lipids, proteins and other compounds at higher concentration.The presence of Fe þ2 effects in the formation of reactive species inside biological systems, such as OH .radicals. [36]Inactivation by connecting iron ions is considered an important mechanism in the evaluation of antioxidant capacity. [37]Iron chelating activity results of synthesized T1-AgNP and T2-AgNP in the presented study are depicted in Figure 9.As presented in the Figure 9, metal chelating activity of T1-AgNP and T2-AgNP increased when concentration increased.EDTA was used as standard.The iron chelating activities of T1-AgNP were 46.67% for 12.5 mg/L, 50.93% for 25 mg/L, 64.39% for 50 mg/L, 68.14% for 100 mg/L, and 75.80% for 200 mg/L while the Fe chelating abilities of T2-AgNP were found as 29.81% for 12.5 mg/L, 46.33% for 25 mg/L, 62.86% for 50 mg/L, 74.27% for 100 mg/L, and 83.64% for 200 mg/L.There have been reports on the iron chelating activities of AgNPs synthesized by several researchers.Some of them are as follows; Alavi and Karimi [38] green synthesized AgNPs using Artemisia haussknechtii and they reported that AgNP showed the highest chelating activity as 68.93 ± 2.37% at 500 mg/mL.In this study, chelating abilities of T1-AgNP and T2-AgNP were 75.80 and 83.64% at 200 mg/L, respectively and our results seem to have better results when compared to the aforementioned study.In another study, Gonca et al. [29] noticed that the metal chelating activity of AgNP obtained from Verbascum thapsus leaf extract as 92.41% for 100 mg/L and 100% for 200 mg/L, respectively.Our results suggest that after further studies, extracellular synthesized T1-AgNPs and T2-AgNPs can be used as chelators.

DNA cleavage activity
DNA is a macromolecule called nucleic acid, which carries the vital functions of all organisms and some viruses.It contains all the genetic information of living organisms.Therefore, DNA can be the most significant target molecule in anti-cancer and anti-microbial researches.DNA nuclease activity of T1-AgNPs and T2-AgNPs was performed using E. coli pBR322 plasmid DNA.If one breakage occurs on pBR322plasmid DNA molecule (Form I), Form II will form.However, if a double chain breakdown occurs, Form III will form which move between Form I and Form II.DNA cleavage ability of T1-AgNPs and T2-AgNPs is shown in Figures S1 and S2.DNA cleavage ability of extracellular synthesized T1-AgNPs and T2-AgNPs tested at various doses.Both new extracellular synthesized AgNPs exhibited single-chain DNA fracture activity at all tested concentrations.G€ ulba gca et al. [34]

Antimicrobial activity
Multi-drug resistance resulting from the extensive usage of broad-spectra antibiotics is an increasing issue in the process of infectious illnesses.Development in nanotechnology have initiated new approaches in nanodrug and allowed the preparation of NPs that can be combined into complex structures.Ag has been known due to its antimicrobial effects since ancient times and has been used for centuries in the control and prevention of different infections. [39]The antimicrobial activity of T1-AgNPs and T2-AgNPs was studied using the microdilution method against test microorganisms.The results are shown in Table S1.Antimicrobial activities of T1-AgNPs and T2-AgNPs were varied according to test microorganisms.These differences may be due to the different wall thicknesses, cell metabolisms and morphology of the microorganisms being tested.Choi et al. [40] found that the MIC value of synthesized AgNP using Areca catechu extraction in 11.25 mg/mL for E. fecalis and 5.6 mg/mL for P. aeruginosa.Erjaee et al. [41] informed that the MIC of AgNP derived from Chamaemelum nobile extracts were 7.8 mg/mL for E. coli and 31.2 mg/mL for S. aureus.Chahardoli et al. [42] determined the MIC value of AgNP obtained from Nigella arvensis extraction as 7.82 mg/mL for E. coli, 15.63 mg/mL for P. aeruginosa, 62.5 mg/mL for S. marcescens, 7.82 mg/mL for S. aureus, 31.25 mg/mL for B. subtilis, and 7.82 mg/mL for S. epidermidis.Wypij et al. [43] used biosynthesized AgNPs from S. xinghaiensis in their study and they found that AgNPs exhibited the highest inhibitory activity against P. aeruginosa.As seen in different studies, synthesized AgNPs demonstrated different antimicrobial activities against microorganisms.The results obtained from the presented test indicated that the extracellular prepared AgNPs displayed efficacious antimicrobial ability to the strains studied, especially on Gr þ ve bacteria.As a result, AgNPs synthesized in this study can be utilized as an antimicrobial drug after following tests.

Biofilm inhibition activity
Biofilms are structures that bind microorganisms to living and non-living surfaces and keep them preserved within the polymeric material they form.These polymeric material play as protective shield for microorganisms.Microorganisms in the biofilm can be protected from influences such as antimicrobial therapy, host cell response, and bad environmental circumstances.Exopolysaccharides in the biofilm structure reduce the penetration of antimicrobial agents and prevent it to reach the microorganisms.The number of infections caused by antibiotic-resistant microorganisms increases.Traditional approaches are inadequate to destroy the biofilm structure. [44]The use of nanoparticles with antibiofilm properties against microbial biofilms has been required.In this study, the antibiofilm effect of the T1-AgNPs and T2-AgNPs was investigated against two different bacteria including S. aureus and P. aeruginosa.Figures 10 and 11 show the result of the antibiofilm activity of P. aeruginosa and S. aureus.As seen in Figures 10 and 11, the percentages of biofilm inhibition rised with the increase in dose.Antibiofilm activity of T1-AgNPs and T2-AgNPs against S. aureus was determined as 64.27 and 69.35% for 125 mg/L, 81.6 and 85.48% for 250 mg/L, and 93.85 and 98.7% for 500 mg/L, respectively.The antibiofilm activity of T1-AgNPs was also determined as 73.54% for 125 mg/L, 90.38% for 250 mg/L, and 100.0%for 500 mg/L concentration, respectively against P. aeruginosa while biofilm inhibition of T2-AgNPs was 79.58% for 125 mg/L, 92.36% for 250 mg/L, and 100.0%for 500 mg/L concentration, respectively against P. aeruginosa.When compared the sensitivity of bacteria against T1-AgNPs and T2-AgNPs, it was observed that P. aeruginosa was more susceptible than S. aureus.AgNPs' ability to reduce biofilm development has also been demonstrated by various studies.Chaudhari et al. [45] researched the impact of AgNPs on antibiofilm activity of S. aureus and it was found that AgNPs prevented the biofilm formation of S. aureus.They suggested that AgNPs may have a role in neutralizing the biofilm formation.The antibiofilm ability of AgNPs against S. aureus and E. coli was studied by Goswami et al. [46] and they found that the maximum antibiofilm abilities were 89% against S. aureus and 75% against E. coli.Kalishwaralal et al. [47] reported that AgNP had inhibition effect of 95 and 98% on the biofilm formation of P. aeuruginosa and S. epididymis, respectively.Our findings demonstrated that the    extracellular synthesized nanoparticle can be performed as an antibiofilm material in biomedical utilizations.

Microbial cell viability
In the present study, E. coli growth inhibition assay was also tested to determine the antimicrobial activities of T1-AgNPs and T2-AgNPs.In this study, the bacteria chosen for the evaluation of inhibition of cellular viability was E. coli.The result is shown in Figure 12.According to the results, the extracellular synthesized T1-AgNPs and T2-AgNPs showed excellent activity with 100% inhibition effect on E. coli at all studied concentrations.Many investigations have been explained the growth inhibition mechanism of microorganisms by AgNPs; however, the most credible is free radical formation.The free radical generation is completely clear because in a living organisms they can attack membrane lipids followed by their separation, injury and finally inhibiting the microbial growth. [48]Saxena et al. [49] used AgNP that synthesized from Ficus benghalensis.They investigated the antibacterial effect of AgNP at various concentrations against E. coli and they stated that AgNP was displayed almost no bacterial growth.According to our antimicrobial activity and microbial cell viability inhibition results, new extracellular synthesized T1-AgNPs and T2-AgNPs from thermophilic A. flavithermus strain Gecek20 and G. stearothermophilus strain Gecek19 can be used in nanomedicine as a promising antimicrobial agents.

Comparison of research in other published studies
Table 2 lists commonly used green synthesis-based studies to synthesize AgNPs.Two novel thermophilic bacteria were identified during this study.Extracellular two distinct AgNPs produced from thermophilic G. stearothermophilus strain Gecek20 and thermophilic A. flavithermus strain Gecek19 were tested for various biological functions.The antioxidant properties of thermophilic G. stearothermophilus strain Gecek20 (T1-AgNPs) and thermophilic A. flavithermus strain Gecek19 (T2-AgNPs) were investigated using DPPH inhibition activity and Fe chelating ability.The synthesize of Ag-NPs by the green process is frequent in the literature, but this study was the first to use freshly discovered thermophilic bacteria for the preparation of NPs.Bagherzade et al. [50] created Ag-NPs using an aqueous extract of saffron waste as a green process that did not require any chemical stabilizers or reducers.The AgNPs that were created were characterized.Finally, biosynthesized AgNPs have been shown to have substantial antibacterial activity against E. coli, P. aeruginosa, Shigella flexneri, Klebsiella pneumonia, and Bacillus subtilis.In another investigation, Ram et al. [51] synthesized Ag-NPs using water extract of the root of Chrysopogon zizanioides.Biosynthesized Ag-NPs had a significant antibacterial impact against P. aeruginosa and S. aureus.Choi et al. [40] , evaluated the antibacterial efficacy of AgNPs produced using extracts of Areca catechu against 3 antibiotic-sensitive and 3 antibiotic-resistant bacterial strains.The findings indicated that AgNPs derived from A. catechu extracts showed good antimicrobial effect.Nawabjohn et al. [52] investigated green production of Ag-NPs from Cassia tora aqueous seed extract and characterization of produced AgNP using UV-visible spectroscopy, XRD, SEM, and FT-IR.The antibacterial activity of the produced Ag-NPs was studied in the study against E. coli (MTCC 433), S. aureus, and K. pneumoniae (MTCC 432).Finally, Gonca et al. [29] created AgNPs from the red and green sections of the peanut shell and studied biological activity.The antioxidant and extraordinary chemical nuclease, antimicrobial, E. coli growth inhibition and anti-biofilm of the prepared peanut shell-based AgNPs have been described, as well as considerable antimicrobial activities against diverse microorganisms.

Conclusion
In this research article, we isolated Strains Gecek19 and Gecek20 from the soil samples of Gecek hot-springs in Afyonkarahisar, Turkey.Analysis of the 16S rRNA genes revealed that strain Gecek19 belonged to the Anoxybacillus genus and Strain Gecek20 to Geobacillus genus.The partial 16S rRNA sequences revealed that Strain Gecek19 mostly similar to Anoxybacillus flavithermus (96.6%) and Strain Gecek20 to Geobacillus stearothermophilus (99.1%).Different biological activities including antimicrobial activity, DNA cleavage and antioxidant activity of extracellular synthesized AgNPs from thermophilic G. stearothermophilus strain Gecek20 and A. flavithermus strain Gecek19 were studied.DPPH and Fe chelating ability results displayed that the prepared T1-AgNPs and T2-AgNPs had good antioxidant activities.Moreover, it was observed that T1-AgNPs and T2-AgNPs exhibited chemical nuclease ability.The new synthesized T1-AgNPs and T2-AgNPs demonstrated antimicrobial ability and they were found to be more effective especially against E. fecalis and E. hirae.The biofilm inhibition results of T1-AgNPs and T2-AgNPs against S. aureus and P. aeruginosa demonstrated excellent biofilm inhibition ability.In addition, it was determined that T1-AgNPs and T2-AgNPs had very powerful cell viability inhibition activity.As a result, T1-AgNPs and T2-AgNPs were environmentally friendly synthesized and there have not been enough study for synthesized of nanoparticle from thermophilic microorganisms so it makes this investigation unique value with the limited number of nanoparticles synthesized by thermophilic bacteria in the literatures.As well as the biological activities they also were exhibited, they promise to find an application in nano medicine after further studies.Chrysopogon zizanioides root extract Silver nanoparticles Antibacterial activities [51]   Areca catechu extract Silver nanoparticles Antibacterial activity against antibiotic-resistant bacteria [40]   Cassia tora seed extract Silver nanoparticles Investigation of antibacterial potential [52]   Pistachio hull Silver nanoparticles In vitro biological activities Gonca et al. [29] Animal fur Silver nanoparticles Antioxidant activity [53]   Animal metabolites Metallic nanoparticles - [54]   Thermophilic Anoxybacillus flavithermus and Geobacillus stearothermophilus

Silver nanoparticles
Evaluation as nanodrugs This study

Figure 2 .
Figure 2. Neighbor-joining phylogenetic tree based on 16S rRNA gene sequences of strain Gecek19.

Figure 3 .
Figure 3. Neighbor-joining phylogenetic tree based on 16S rRNA gene sequences of strain Gecek20.

Table 2 .
Comparison of antibacterial activity of green synthesized AgNPs.