Synergistic computational and experimental studies of a phosphoglycosyl transferase membrane/ligand ensemble.

Complex glycans serve essential functions in all living systems. Many of these intricate and byzantine biomolecules are assembled employing biosynthetic pathways wherein the constituent enzymes are membrane-associated. A signature feature of the stepwise assembly processes is the essentiality of unusual linear long-chain polyprenol phosphate-linked substrates of specific isoprene unit geometry, such as undecaprenol phosphate (UndP) in bacteria. How these enzymes and substrates interact within a lipid bilayer needs further investigation. Here, we focus on a small enzyme, PglC from Campylobacter, structurally characterized for the first time in 2018 as a detergent-solubilized construct. PglC is a monotopic phosphoglycosyl transferase that embodies the functional core structure of the entire enzyme superfamily and catalyzes the first membrane-committed step in a glycoprotein assembly pathway. The size of the enzyme is significant as it enables high-level computation and relatively facile, for a membrane protein, experimental analysis. Our ensemble computational and experimental results provided a high-level view of the membrane-embedded PglC/UndP complex. The findings suggested that it is advantageous for the polyprenol phosphate to adopt a conformation in the same leaflet where the monotopic membrane protein resides as opposed to additionally disrupting the opposing leaflet of the bilayer. Further, the analysis showed that electrostatic steering acts as a major driving force contributing to the recognition and binding of both UndP and the soluble nucleotide sugar substrate. Iterative computational and experimental mutagenesis support a specific interaction of UndP with phosphoglycosyl transferase cationic residues and suggest a role for critical conformational transitions in substrate binding and specificity.

Halonatronomonas betaini gen. nov., sp. nov., a haloalkaliphilic isolate from soda lake capable of betaine degradation and proposal of Halarsenatibacteraceae fam. nov. and Halothermotrichaceae fam. nov. within the order Halanaerobiales.

A search for the organisms responsible for anaerobic betaine degradation in soda lakes resulted in isolation of a novel bacterial strain, designated Z-7014T. The cells were Gram-stain-negative, non-endospore-forming rods. Growth occurred at 8-52 °C (optimum 40-45 °C), pH 7.1-10.1 (optimum pH 8.1-8.8) and 1.0-3.5 M Na+ (optimum 1.8 M), i.e. it can be regarded as a haloalkaliphile. The strain utilized a limited range of substrates, mostly peptonaceous but not amino acids, and was able to degrade betaine. Growth on betaine occurred only in the presence of peptonaceous substances which could not be replaced by vitamins. The G + C content of the genomic DNA of strain Z-7014T was 36.1 mol%. The major cellular fatty acids (>5% of the total) were C16:0 DMA, C18: 0 DMA, C16:1ω8, C16:0, C18:1 DMA, C16:1 DMA, C18:1ω9, and C18:0. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain Z-7014T formed a distinct evolutionary lineage in the order Halanaerobiales with the highest similarity to Halarsenitibacter silvermanii SLAS-1T (83.6%), Halothermothrix orenii H168T (85.6%), and Halocella cellulosilytica DSM 7362T (85.6%). AAI and POCP values between strain Z-7014T and type strains of the order Halanaerobiales were 51.7-57.8%, and 33.8-58.3%, respectively. Based on polyphasic results including phylogenomic data, the novel strain could be distinguished from other genera, which suggests that strain Z-7014T represents a novel species of a new genus, for which the name Halonatronomonas betaini gen. nov., sp. nov. is proposed. The type strain is Z-7014T (=KCTC 25237T = VKM B-3506T). On the basis of phylogenomic data, it is also proposed to evolve two novel families Halarsenitibacteraceae fam. nov. and Halothermotrichaceae fam. nov. within the current order Halanaerobiales.

Clues to the function of bacterial microcompartments from ancillary genes.

Bacterial microcompartments (BMCs) are prokaryotic organelles. Their bounding membrane is a selectively permeable protein shell, encapsulating enzymes of specialized metabolic pathways. While the function of a BMC is dictated by the encapsulated enzymes which vary with the type of the BMC, the shell is formed by conserved protein building blocks. The genes necessary to form a BMC are typically organized in a locus; they encode the shell proteins, encapsulated enzymes as well as ancillary proteins that integrate the BMC function into the cell's metabolism. Among these are transcriptional regulators which usually found at the beginning or end of a locus, and transmembrane proteins that presumably function to conduct the BMC substrate into the cell. Here, we describe the types of transcriptional regulators and permeases found in association with BMC loci, using a recently collected data set of more than 7000 BMC loci distributed over 45 bacterial phyla, including newly discovered BMC loci. We summarize the known BMC regulation mechanisms, and highlight how much remains to be uncovered. We also show how analysis of these ancillary proteins can inform hypotheses about BMC function; by examining the ligand-binding domain of the regulator and the transporter, we propose that nucleotides are the likely substrate for an enigmatic uncharacterized BMC of unknown function.

Multidisciplinary Studies of Folk Medicine "Five Thieves' Oil" (Olejek Pieciu Zlodziei) Components.

To meet the growing interest in natural antibacterial agents, we evaluated the physicochemical and biological properties of the folk medicine known as "five thieves' oil" (Polish name: olejek pieciu zlodziei). Five thieves' oil consists of a mixture of five oils: rosemary, lemon, clove, eucalyptus, and cinnamon. In this study, we performed gas chromatography, FTIR, and UV-vis spectroscopic analysis, as well as L-a-b color tests, contact angle determination, and surface tension determination. To verify its antibacterial activity, the metabolic activity and changes in cell membrane permeability of bacteria of the genus Pseudomonas were studied. As a result, it was found that among the constituent oils, the oils of clove and cinnamon were the least volatile and, at the same time, had the strongest antibacterial activity. However, a mix of all the oils also showed comparable activity, which was even more pronounced for the oils after 4 weeks of aging. This effect can be linked to the high content of terpene derivatives such as eugenol and cinnamaldehyde, which can cause changes in bacterial membrane permeability, affecting cell activity and survival. This study is the first to characterize the constituents of the popular folk medicine five thieves' oil, confirming and explaining its strong antibacterial activity, thus constituting a significant contribution to contemporary health education.

The influence of nasal microbiome diversity and inflammatory patterns on the prognosis of nasal polyps.

To understand the inflammatory microenvironment and microbiome factors for prognosis of chronic rhinosinusitis with polyps (CRSwNP), we explored the difference in characteristics of the microbiome of the nasal sinuses and inflammatory cytokines between recurrent and non-recurrent groups. We collected nasal secretions and polyp tissue from 77 CRSwNP patients. Then, we extracted microbial DNA from cotton swabs, performed high-throughput sequencing based on 16S rRNA to detect bacterial community composition, and analyzed cytokines such as IL-5, IL-8, IL-17a, IL-17e, IL-18, IL-27 and INF-gamma from polyp tissue using Luminex. The eosinophil and neutrophil cells in the peripheral blood and polyp tissue were counted. Postoperative follow-up of patients with CRSwNP for 1 year was conducted to record the recurrence of nasal polyps and analyze the correlation between the recurrence of nasal polyps and the characteristics of inflammatory cytokines, inflammatory cell count and nasal microbial diversity. After 1 year of follow-up, there were 12 recurrent patients, including 5 males and 7 females. Postoperative recurrence of nasal polyps was not significantly correlated with age, sex, asthma, allergic rhinitis or other allergic diseases in CRSwNP patients. In terms of the total nasal symptom score, the recurrent group was significantly higher than the non-recurrent group. In nasal polyp tissues, eosinophils (40.83/HP) and neutrophils (30.83/HP) in patients with CRSwNP in the recurrent group were significantly higher than those in the non-recurrent group (13.72/HP), and neutrophils (18.5/HP) were also significantly higher in the recurrent group than the non-recurrent group. The expression levels of IFN-, IL-17A, IL-17E and IL-18 were significantly higher in the recurrent group than in the non-recurrent group, and the positive rates were not different. In Southwest China, Enterobacteria and anaerobic bacteria may be correlated with the inflammatory pattern expression of nasal polyps. The neutrophil-mediated inflammatory response plays an important role in patients with CRSwNP in Southwest China and is correlated with nasal polyp recurrence. Recurrence of nasal polyps after endoscopic sinus surgery may be potentially associated with a reduced abundance of protective microorganisms and an increased number of pathogenic microorganisms.

Effect of low power lasers on prokaryotic and eukaryotic cells under different stress condition: a review of the literature.

Radiations emitted by low power radiation sources have been applied for therapeutic proposals due to their capacity of inactivating bacteria and cancer cells in photodynamic therapy and stimulating tissue cells in photobiomodulation. Exposure to these radiations could increase cell proliferation in bacterial cultures under stressful conditions. Cells in infected or not infected tissue injuries are also under stressful conditions and photobiomodulation-induced regenerative effect on tissue injuries could be related to effects on stressed cells. The understanding of the effects on cells under stressful conditions could render therapies based on photobiomodulation more efficient as well as expand them. Thus, the objective of this review was to update the studies reporting photobiomodulation on prokaryotic and eukaryotic cells under stress conditions. Exposure to radiations emitted by low power radiation sources could induce adaptive responses enabling cells to survive in stressful conditions, such as those experienced by bacteria in their host and by eukaryotic cells in injured tissues. Adaptive responses could be the basis for clinical photobiomodulation applications, either considering their contraindication for treatment of infected injuries or indication for treatment of injuries, inflammatory process resolution, or tissue regeneration.

Refined measurement of SecA-driven protein secretion reveals that translocation is indirectly coupled to ATP turnover.

The universally conserved Sec system is the primary method cells utilize to transport proteins across membranes. Until recently, measuring the activity-a prerequisite for understanding how biological systems work-has been limited to discontinuous protein transport assays with poor time resolution or reported by large, nonnatural tags that perturb the process. The development of an assay based on a split superbright luciferase (NanoLuc) changed this. Here, we exploit this technology to unpick the steps that constitute posttranslational protein transport in bacteria. Under the conditions deployed, the transport of a model preprotein substrate (proSpy) occurs at 200 amino acids (aa) per minute, with SecA able to dissociate and rebind during transport. Prior to that, there is no evidence for a distinct, rate-limiting initiation event. Kinetic modeling suggests that SecA-driven transport activity is best described by a series of large (∼30 aa) steps, each coupled to hundreds of ATP hydrolysis events. The features we describe are consistent with a nondeterministic motor mechanism, such as a Brownian ratchet.

Eubiotic vs. dysbiotic human blood microbiota: the phenomenon of cell wall deficiency and disease-trigger potential of bacterial and fungal L-forms.

The current review provides data and focuses on blood as a niche for the presence of cell wall-deficient microbes (L-forms). The hypothesis for the existence of L-form microbiota in humans was tested by us using an innovative methodology for the isolation of L-form cultures from human blood. Criteria were conceived for the individual assessment of blood microbiota and recognition of two types of states -- "eubiotic" and "dysbiotic" blood microbiota. Cell wall-deficient microbes (CWD) that inhabit blood in healthy people are in natural balance with the host homeostasis, which corresponds to the "eubiotic" state. When interacting with a host, CWD bacteria or fungi employ a strategy distinctive for a latent lifestyle. In contrast to "eubiotic," "dysbiotic" blood microbiota manifests when the balance is disrupted and there is an excess of L-form variants of opportunistic microbes that invade from the external microbiota, i.e., from all body sites in contact with the external environment. Our case studies on people with multiple sclerosis (MS), Parkinson's disease, psoriasis, thyroid cancer, and diabetes revealed the appearance of "dysbiotic" blood microbiota that outlined the disease-trigger potential of opportunistic bacteria and fungi existing in blood as CWD variants. Blood microbiota assessment could be of diagnostic and prognostic importance for the pathological processes occurring within the body, as well as for understanding the microbial pathogenesis.

Development of a standardized Gram stain procedure for bacteria and inflammatory cells using an automated staining instrument.

Gram stain is a subjective and poorly controlled test, and the resultant errors often perplex laboratory scientists. To reduce errors and make Gram stain a precisely controllable and meritorious test, a standardized Gram stain procedure for bacteria and inflammatory cells was developed using an automated staining instrument in this study. Freshly expectorated sputum specimens, used as the optimized targets, were smeared on slides by laboratory technicians, defining each slide loaded with uniform matrix and monolayer cell. And then, the staining and decolorizing time, as well as the stain and decolorant volume, were optimized as 15, 105, 1, and 25 s and 1.1, 1.4, 0.3, and 0.7 ml, respectively. Culture-positive blood specimens and original purulent fluids were used for confirming the developed standardized Gram stain procedure. Distinct tinctures of bacteria and inflammatory cells adhered to slide uniformly in a monolayer were observed, and the obtained staining results of these samples were highly consistent with their cultured results. Furthermore, according to the staining results under different staining conditions, an updated molecular mechanism of Gram stain for bacteria and the probable staining mechanism for inflammatory cells were also proposed in this study.

Structural Superiority of Guanidinium-Rich, Four-Armed Copolypeptides: Role of Multiple Peptide-Membrane Interactions in Enhancing Bacterial Membrane Perturbation and Permeability.

The development of novel antimicrobials is a top priority to address the growing epidemic of multidrug-resistant pathogens. Since cationic nonamphiphilic star-shaped antimicrobials are promising molecular scaffolds that provide a high charge density in binding anionic bacterial bilayers, this research aimed to further increase their membrane perturbation capability by introducing guanidinium groups to the antimicrobials via enhancing membrane insertion. In particular, computational simulation and experimental investigations revealed that our designed guanidinium-rich alternating copolypeptide, four-armed poly(arginine-alt-glycine), can interact with both the headgroups and unsaturated tails of phospholipids in bacterial membranes through multiple interactions, including electrostatic, cation-π, and T-shaped π-π interactions, allowing it to penetrate deeper inside the biologically inaccessible high-energy barrier of the hydrophobic lipid bilayer interior to cause membrane permeabilization and precipitation of the bacterial cytoplasm. Furthermore, glycine was observed to have a unique effect in enhancing the performance of arginine-based copolypeptide. Four-armed poly(arginine-alt-glycine) exhibited broad-spectrum antimicrobial activity, high bactericidal efficiency, and negligible hemolysis. The in vivo antibacterial performance of the copolypeptide was superior to that of doxycycline in a mouse model of Pseudomonas aeruginosa skin infection, accompanied by negligible local and systemic toxicity. Our results demonstrate that this guanidinium-rich, nonamphiphilic, star-shaped structure may promote the development of next-generation antimicrobials.

Biogenic Iron Sulfide Nanoparticles to Enable Extracellular Electron Uptake in Sulfate-Reducing Bacteria.

Microbes synthesize cell-associated nanoparticles (NPs) and utilize their physicochemical properties to produce energy under unfavorable metabolic conditions. Iron sulfide (FeS) NPs are ubiquitous and are predominantly biosynthesized by sulfate-reducing bacteria (SRB). However, the biological role of FeS NPs in SRB remains understudied. Now, conductive FeS NPs function is demonstrated as an electron conduit enabling Desulfovibrio vulgaris Hildenborough, an SRB strain, to utilize solid-state electron donors via direct electron uptake. After forming FeS NPs on the cell surface, D. vulgaris initiated current generation coupled with sulfate reduction on electrodes poised at -0.4 V versus standard hydrogen electrode. Single-cell activity analysis showed that the electron uptake and metabolic rate via FeS NPs in D. vulgaris were about sevenfold higher than those via native cell-surface proteins in other SRB.

Molecular characterization and antioxidant assay of pigment producing bacteria, Sphingomonas paucimobilis and Microbacterium arborescens isolated from fresh water sediments.

This study focuses on isolation of pigment producing bacteria from fresh water sediment. The isolated bacteria were grown in nutrient broth and the maximum absorbance of 2.512 was obtained for the extracted pigment at 500 nm. The effective strains were optimized, pH 11 and temperature 30 °C was found to be more favorable for its maximum growth. The isolates were identified based on their molecular characterestics as Microbacterium arborescens and Sphingomonas paucimobilis, molecular size of the amplified 16S rRNA gene sequence was found to be approximately 1270 and 765 bp respectively. The antioxidant property of the pigment was analyzed using DPPH and ABTS assay. The IC50 value of Microbacterium arborescens was higher in all the three assays in comparison with Sphingomonas paucimobilis. The extracted pigment was characterized for the presence of compounds using GC-MS and FTIR analysis to determine the functional groups. As the pigment obtained from M. arborescens had shown better antioxidant activity it may be used as colorant in food industrial applications.

Polysaccharide-based liquid storage and transport media for non-refrigerated preservation of bacterial pathogens.

The preservation of biological samples for an extended time period of days to weeks after initial collection is important for the identification, screening, and characterization of bacterial pathogens. Traditionally, preservation relies on cold-chain infrastructure; however, in many situations this is impractical or not possible. Thus, our goal was to develop alternative bacterial sample preservation and transport media that are effective without refrigeration or external instrumentation. The viability, nucleic acid stability, and protein stability of Bacillus anthracis Sterne 34F2, Francisella novicida U112, Staphylococcus aureus ATCC 43300, and Yersinia pestis KIM D27 (pgm-) was assessed for up to 28 days. Xanthan gum (XG) prepared in PBS with L-cysteine maintained more viable F. novicida U112 cells at elevated temperature (40°C) compared to commercial reagents and buffers. Viability was maintained for all four bacteria in XG with 0.9 mM L-cysteine across a temperature range of 22-40°C. Interestingly, increasing the concentration to 9 mM L-cysteine resulted in the rapid death of S. aureus. This could be advantageous when collecting samples in the built environment where there is the potential for Staphylococcus collection and stabilization rather than other organisms of interest. F. novicida and S. aureus DNA were stable for up to 45 days upon storage at 22°C or 40°C, and direct analysis by real-time qPCR, without DNA extraction, was possible in the XG formulations. XG was not compatible with proteomic analysis via LC-MS/MS due to the high amount of residual Xanthomonas campestris proteins present in XG. Our results demonstrate that polysaccharide-based formulations, specifically XG with L-cysteine, maintain bacterial viability and nucleic acid integrity for an array of both Gram-negative and Gram-positive bacteria across ambient and elevated temperatures.

Time scales and wave formation in non-linear spatial public goods games.

The co-evolutionary dynamics of competing populations can be strongly affected by frequency-dependent selection and spatial population structure. As co-evolving populations grow into a spatial domain, their initial spatial arrangement and their growth rate differences are important factors that determine the long-term outcome. We here model producer and free-rider co-evolution in the context of a diffusive public good (PG) that is produced by the producers at a cost but evokes local concentration-dependent growth benefits to all. The benefit of the PG can be non-linearly dependent on public good concentration. We consider the spatial growth dynamics of producers and free-riders in one, two and three dimensions by modeling producer cell, free-rider cell and public good densities in space, driven by the processes of birth, death and diffusion (cell movement and public good distribution). Typically, one population goes extinct, but the time-scale of this process varies with initial conditions and the growth rate functions. We establish that spatial variation is transient regardless of dimensionality, and that structured initial conditions lead to increasing times to get close to an extinction state, called ε-extinction time. Further, we find that uncorrelated initial spatial structures do not influence this ε-extinction time in comparison to a corresponding well-mixed (non-spatial) system. In order to estimate the ε-extinction time of either free-riders or producers we derive a slow manifold solution. For invading populations, i.e. for populations that are initially highly segregated, we observe a traveling wave, whose speed can be calculated. Our results provide quantitative predictions for the transient spatial dynamics of cooperative traits under pressure of extinction.

Evaluating antibacterial and anticancer activity of crude extracts of bacterial endophytes from Crinum macowanii Baker bulbs.

The results from this study revealed that crude extracts isolated from bacterial endophytes obtained from Crinum macowanii bulbs showed activity against both Gram-positive and Gram-negative pathogenic bacteria, while Acinetobacter guillouiae crude extracts displayed anticancer activity. This study aimed to isolate and characterize bacterial endophytes and their crude extracts from C. macowanii bulbs. Endophytes were isolated using validated surface sterilization techniques, followed by phenotypic and genotypic profiles of the isolates. Crude extracts were extracted from the endophytes using ethyl acetate, while methanol:dichloromethane (1:1) was used to obtain crude extracts from the bulbs. Antibacterial activity of crude extract from each endophyte was investigated against selected pathogenic strains using the broth microdilution method, and anticancer activity against U87MG glioblastoma and A549 lung carcinoma cells was determined by the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Acinetobacter guillouiae, Pseudomonas moraviensis, Pseudomonas sp., Rahnella aquatilis, Bacillus cereus, Novosphingobium sp., Raoultella ornithinolytica, and Burkholderia tropica were successfully isolated. The crude extracts from the majority of endophytes showed antibacterial activity, ranging from 0.125 to >16.00 mg/ml against Gram-negative and Gram-positive pathogenic bacteria. Acinetobacter guillouiae extracts showed a high bioactive potential against U87MG glioblastoma cell lines by reducing their growth by 50% at concentrations of 12.5, 6.25, and 3.13 µg/ml. Crude extracts isolated from C. macowanii bulbs showed potential for possible drug lead against common pathogenic bacteria.

Efficacy of a Ceratothoa oestroides Olive Oil Extract in Patients With Chronic Ulcers: A Pilot Study.

Chronic wounds unresponsive to existing treatments constitute a serious disease burden. Factors that contribute to the pathogenesis of chronic ulcers include oxidative stress, comorbid microbial infections, and the type of immune system response. Preclinically, and in a case study, a formulation containing a Ceratothoa oestroides olive oil extract promoted wound healing. Patients with chronic venous and pressure ulcers, clinically assessed as being unresponsive to healing agents, were treated for 3 months with an ointment containing the C oestroides extract combined with antibiotic and/or antiseptic agents chosen according to the type of bacterial infection. Treatment evaluation was performed using the Bates-Jensen criteria with +WoundDesk and MOWA cell phone applications. After 3 months of treatment, C oestroides resulted in an average decrease of 36% in the Bates-Jensen score of ulcers (P < .000), with the decrease being significant from the first month (P < .007). The combined use of topically applied antibiotics and antiseptics efficiently controlled microbial ulcer infection and facilitated wound healing. In relation to other factors such as initial wound size, chronicity appeared to be an important prognostic factor regarding the extent of wound healing. Future clinical investigations assessing the wound healing efficacy of the C oestroides olive oil extract are warranted.

Diffusiophoresis in Cells: A General Nonequilibrium, Nonmotor Mechanism for the Metabolism-Dependent Transport of Particles in Cells.

The more we learn about the cytoplasm of cells, the more we realize that the cytoplasm is not uniform but instead is highly inhomogeneous. In any inhomogeneous solution, there are concentration gradients, and particles move either up or down these gradients due to a mechanism called diffusiophoresis. I estimate that inside metabolically active cells, the dynamics of particles can be strongly accelerated by diffusiophoresis, provided that they are at least tens of nanometers across. The dynamics of smaller objects, such as single proteins, are largely unaffected.

Effect of multiple iron-based nanoparticles on availability of lead and iron, and micro-ecology in lead contaminated soil.

Although iron nanoparticles (NPs) have been used for environmental remediation of heavy metal, their potential to remediate lead (Pb) contaminated soil and effect on soil micro-ecology is unclear. The purpose of this study was to investigate the potential of nanoscale zerovalent iron (nZVI), nanoscale zerovalent iron supported by biochar (nZVI@BC), ferrous sulfide (FeS-NPs), ferrous sulfide supported by biochar (FeS-NPs@BC), ferriferrous oxide (Fe3O4-NPs) and ferriferrous oxide supported by biochar (Fe3O4-NPs@BC) to remediate Pb contaminated soil and the influences for soil micro-ecology. The results showed that biochar (BC) could improve the crystal shape and superficial area of iron-based nanoparticles. Soil pH values was significantly decreased by FeS-NPs and FeS-NPs@BC, but increased by other iron-nanoparticles. The ability to reduce available Pb concentration showed significant difference among these iron-nanoparticles, that is, the immobilized rate were nZVI by 45.80%, nZVI@BC by 54.68%, FeS-NPs by 2.70%, FeS-NPs@BC by 5.13%, Fe3O4-NPs by 47.47%, Fe3O4-NPs@BC by 30.51% at day 90. Almost all soil enzyme activities in Fe3O4-NPs and Fe3O4-NPs@BC groups were increased, but the majority of the enzyme activities were inhibited in other iron-based nanoparticles groups, while the maximum bacterial number was determined in FeS-NPs group. Furthermore, microbial diversity analysis showed that FeS-NPs has significantly changed microbial community richness and diversity, followed by nZVI and Fe3O4-NPs. Accordingly, our results suggested that nZVI@BC had the best immobilization effect on Pb in high-concentration Pb-contaminated alkaline soil, but the toxic effect of Fe3O4-NPs on soil micro-ecology was relatively minimal.

Antibacterial and photocatalytic activity of hydrothermally synthesized SnO2 doped GO and CNT under visible light irradiation.

Bacterial and dye pollution are major problems with wastewater treatment. An increasing number of photocatalysts are being used in industry to kill bacterial and reduce pollution. In the present study, highly stable SnO2-doped nanocomposites have been prepared successively by a hydrothermal method. The synthesized nanocomposite was characterized using a range of techniques, such as X-ray diffraction, field emission scanning electron microscopy with energy dispersive X-ray spectroscopy and electron probe micro analysis, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and high resolution transmission electron microscopy (HR-TEM). The nanocomposites showed significant dose-dependent bactericidal activity in the disc diffusion assay and cell viability test. The S-GO-SnO2 200 µg/mL produced a cell viability of 184.3 ±â€¯11.71 and 172.3 ±â€¯3.05 × 106 CFU/mL for E. coli and P. graminis, respectively. The S-GO-SnO2 showed significant photocatalytic degradation against MB in 120 min. The photocatalyst S-GO-SnO2 showed 159 and 161 × 106 CFU/mL at 150 min in E. coli and P. graminis, respectively. The cells treated with photocatalytic SnO2-doped nanocomposites showed 50% cell death. HR-TEM revealed 50% cell growth inhibition by bacterial damage. This photocatalytic SnO2-doped nanocomposite is a good candidate for treating industrial wastewater treatment contaminated with dyes and bacteria.