Development of ZnO/SnO2/rGO hybrid nanocomposites for effective photocatalytic degradation of toxic dye pollutants from aquatic ecosystems.

The impact of ZnO/SnO2/reduced graphene oxide nanocomposites (ZnO/SnO2/rGO NCs) for improved photocatalytic degradation of organic dye pollution is examined in this study. The developed ternary nanocomposites had a variety of characteristics that were detected, such as crystallinity, recombination of photogenerated charge carriers, energy gap, and surface morphologies. When rGO was added to the mixture, the optical band gap energy of ZnO/SnO2 was lowered, which improved the photocatalytic activity. Additionally, in comparison to ZnO, ZnO/rGO, SnO2/rGO samples, the ZnO/SnO2/rGO nanocomposites demonstrated exceptional photocatalytic effectiveness for the destruction of orange II (99.8%) and reactive red 120 dye (97.02%), respectively after 120 min exposure to sunlight. The high electron transport properties of the rGO layers, which make it feasible to efficiently separate electron-hole pairs, are attributed to the enhanced photocatalytic activity of the ZnO/SnO2/rGO nanocomposites. According to the results, synthesized ZnO/SnO2/rGO nanocomposites are a cost-efficient option for removing dye pollutants from an aqueous ecosystem. Studies show that ZnO/SnO2/rGO nanocomposites are effective photocatalysts and may one day serve as the ideal material to reduce water pollution.

Synergistic role of metal oxide loading cocatalysts on photocatalytic degradation of organic pollutants and inactive bacteria over template-free ZnFe2O4 nanocubes.

For wastewater treatment, a highly reliable and ecologically friendly oxidation method is always preferred. This work described the production of a new extremely effective visible light-driven Ag2Ox loaded ZnFe2O4 nanocomposties photocatalyst using a wet impregnation technique. Under visible light irradiation, the produced Ag2Ox loaded ZnFe2O4 nanocomposties were used in the photodegradation of rhodamine B (RhB) and Reactive Red 120 (RR120) dyes. Analysis using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy revealed that Ag2Ox nanoparticles were well dispersed on the surface of ZnFe2O4 NPs and that the Ag2Ox loaded ZnFe2O4 NPs were created. When compared with bare ZnFe2O4 NPs, Ag2Ox-loaded ZnFe2O4 nanocomposites showed better photocatalytic activity for RhB and RR120 degradation under visible light (>420 nm) illumination. The reaction kinetics and degradation methodology, in addition to the photocatalytic degradation functions of Ag2Ox-loaded ZnFe2O4 nanocomposites, were thoroughly investigated. The 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites have a 99% removal efficiency for RhB and RR120, which is about 2.4 times greater than the ZnFe2O4 NPs and simple combination of 1 wt% and 2 wt% Ag2Ox loaded ZnFe2O4 nanocomposites. Furthermore, the 3 wt% Ag2Ox loaded ZnFe2O4 nanocomposites demonstrated consistent performance without decreasing activity throughout 3 consecutive cycles, indicating a potential approach for the photo-oxidative destruction of organic pollutants as well as outstanding antibacterial capabilities. According to the findings of the experiments, produced new nanoparticles are an environmentally friendly, cost-efficient option for removing dyes, and they were successful in suppressing the development of Gram-negative and Gram-positive bacteria.

Decolorization of safranin using Fissidens species and its ecotoxicological assessments: An in vitro and in silico approach.

Decolorization of safranin was investigated using Fissidens species in a batch system under optimized conditions. The decolorization efficiency was improved by optimizing the conditions such as initial pH (3-9), temperature (25-45 °C), initial dye concentration (10-50 mg/L), biosorbent dosage (100-500 mg/L) and contact time (1-6 days). Maximum decolorization (95%) was recorded at initial pH of 6 with dye concentration of 20 mg/L, biosorbent dosage of 200 mg/L at 30 °C and contact time of 2 days. Desorption studies revealed 0.1 N NaOH as the best desorbing agent with 92% recovery on third day. Experimental data well fitted to Langmuir isotherm and Pseudo-second order kinetic model. The negative values of ΔGo and positive value of ΔSo and ΔHo indicates that the reaction is spontaneous, favorable and endothermic. The biosorbent - dye interactions were confirmed using UV-Vis, FT-IR, XRD and FE-SEM with EDX studies. The detoxified nature of the dye degraded metabolites was confirmed by the significant growth of green gram. The color fastness and color strength of the fabrics dyed using Fissidens species treated dye solution were compared with the tap water dyed fabrics which indicated the reuse potential of treated water in textile sector. The decolorization efficiency was further confirmed through in silico approach, where safranin well docked with the active sites of Photosystem II protein D1 of the Fissidens species. Thus, the present study proves that Fissidens species is a promising biosorbent for safranin decolorization and will lay a platform for the control and management of environmental pollution.

Prodigiosin production from Serratia marcescens strain CSK and their antioxidant, antibacterial, cytotoxic effect and in silico study of caspase-3 apoptotic protein.

The present study emphasizes the production and optimization of prodigiosin (PG) pigment from Serratia marcescens strain CSK, which was isolated from Shevaroy Hills, Salem district, Tamil Nadu, India. The response surface methodology analysis was applied for the optimization process of PG production. The maximum production of PG (2950 mg/L) was obtained at pH 7.0 with the addition of tryptophan (4.0 g/L) and sucrose (3.0 g/L) with 60 h of incubation. Further, the PG was characterized using high-performance liquid chromatography, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectrometry. The purified PG exhibited strong antioxidant and antibacterial activities. Also, PG's cytotoxic effects against human breast cancer (MCF-7) cells were observed through acridine orange-ethidium bromide (AO-EB) and Hoechst staining. Molecular dockingstudies revealed that PG could bind positively to the caspase-3 (breast cancer protein 1RE1) binding site with a binding energy score of 17.37 kcal/mol. Overall, the novel PG was found to be an anticancer drug for potential applications in the pharmaceutical industry.

Molecular insights of hyaluronic acid-hydroxychloroquine conjugate as a promising drug in targeting SARS-CoV-2 viral proteins.

In-silico anti-viral activity of Hydroxychloroquine (HCQ) and its Hyaluronic Acid-derivative (HA-HCQ) towards different SARS-CoV-2 protein molecular targets were studied. Four different SARS-CoV-2 proteins molecular target i.e., three different main proteases and one helicase were chosen for In-silico anti-viral analysis. The HA-HCQ conjugates exhibited superior binding affinity and interactions with all the screened SAR-CoV-2 molecular target proteins with the exception of a few targets. The study also revealed that the HA-HCQ conjugate has multiple advantages of efficient drug delivery to its CD44 variant isoform receptors of the lower respiratory tract, highest interactive binding affinity with SARS-CoV-2 protein target. Moreover, the HA-HCQ drug conjugate possesses added advantages of good biodegradability, biocompatibility, non-toxicity and non-immunogenicity. The prominent binding ability of HA-HCQ conjugate towards Mpro (PDB ID 5R82) and Helicase (PDB ID 6ZSL) target protein as compared with HCQ alone was proven through MD simulation analysis. In conclusion, our study suggested that further in-vitro and in-vivo examination of HA-HCQ drug conjugate will be useful to establish a promising early stage antiviral drug for the novel treatment of COVID-19.

Influence of biochar and EDTA on enhanced phytoremediation of lead contaminated soil by Brassica juncea.

Phytoremediation technology is an eco-friendly technology for the treatment of the polluted environment. Conversely, the natural and synthetic amendments have been revealed to improve the heavy metal phytoextraction from polluted soils with hyperaccumulation and/or non-hyper accumulating plants. This study evaluated the synergistic effect of biochar (BC) and EDTA to enhance phytoextraction of heavy metal lead (Pb) from artificially polluted soil by Brassica juncea. The BC and EDTA amendment enhanced the growth and survival of B. juncea under Pb stress environment. BC and EDTA significantly increased the biomass of B. juncea and significantly increased the total chlorophyll content in the combined amendment of BC and EDTA (22.2 mg/g) compared to the individual amendment of BC (12.8 mg/g) and EDTA (12.2 mg/g) respectively. The combined use of EDTA and biochar showed enhanced Pb uptake (60.2 mg/g) compared to control (10.0 mg/g). The order of Pb uptake was found to be BC + EDTA (60.2 mg/g) ˃ EDTA (23.5 mg/g) ˃ BC (22. 0 mg/g) ˃ control (10.0 mg/g). The maximum activity of SOD (35.2 ± 1.2 U/mg), POD (47.0 ± 1.8 U/mg) and CAT (28.0 ± 1.0 U/mg) was obtained in the mixed application of EDTA and BC. The obtained results revealed that the combined use of BC and EDTA was the most advantageous option for the treatment of Pb contaminated soil as compared to individual amendments.

Optimization of low-cost biosurfactant produced by Bacillus subtilis SASCBT01 and their environmental remediation potential.

The present research aims to enhance the biosurfactant (BS) production using agricultural by-products as a low-cost substrate with the statistical approach. BS production from Bacillus subtilis SASCBT01 was carried out with four different variables such as pH, incubation time, cassava peel waste (CPW) and palmira sprout (PS). The model expected the highest emulsification activity of 65 ± 1·2% after 96-h incubation with 3·0 g l-1 of CPW and PS at pH 7·0. The SASCBT01 strain-based BS was successful at retrieving up to 18% and the highest Pb removal rates were found at 65%. These BS have considered high quality in bioremediation applications.

Chlorpyrifos degradation efficiency of Bacillus sp. laccase immobilized on iron magnetic nanoparticles.

The present study explored the immobilization of laccase onto iron magnetic nanoparticles (MNPs) to enhance its enzymatic properties and applications. The immobilization process was optimized using Box-Behnken design (BBD). BBD showed significance towards the quadratic model with experimental data. Maximum laccase activity recovery (99%) of the predicted model was observed at 0.75 mg/mL of laccase concentration, 200 mg/mL of MNPs, 0.3% cross linking with carbodiimide, and 3 h of cross-linking time. The magnetization activity of MNPs (8 emu/g) and the immobilized laccase with MNPs (4 emu/g) was analyzed using vibrating sample magnetometer (VSM). Maximum activity of immobilized laccase was observed at pH 7.0 and 55 °C. The immobilized laccase has greater stability (100 h) and significant chlorpyrifos (pesticide) degradation activity. High-performance liquid chromatography (HPLC) results confirmed the degraded metabolic products of chlorpyrifos. In all, the immobilized laccase was superior to free laccase, showing promising structural and application characteristics.

Rapid biodegradation of chlorpyrifos by plant growth-promoting psychrophilic Shewanella sp. BT05: An eco-friendly approach to clean up pesticide-contaminated environment.

The present study explores the rapid chlopyrifos (CPs) biodegradation potential of plant growth promoting (PGP) psychrophilic bacteria isolated from brackish water by enrichment culture technique. Based on biochemical tests and 16 S rDNA sequencing the isolate was identified as Shewanella sp. The isolate Shewanella BT05 showed significant growth rate in various concentrations of (10-50 mg/L) CPs. The isolate produced plant growth promoting factors, IAA (20.8 ± 1.2 and 15.4 ± 1.0 µg/mL) and siderophores (60.67 ± 1.2 and 57.5 ± 0.9%) in the absence and presence of CPs. Further, the isolate BT05 solublized phosphate (16.5 ± 1.0 and 12.0 ± 1.0 mm in size respectively), and produce hydrogen cyanide (excellent and moderate) in the presence and absence of CPs. The isolate BT05 degraded 94.3, 91.8, 87.9, 82.6, and 80.5% of CPs at 10, 20, 30, 40, and 50 mg/L, respectively, within 24 h. Further, the media conditions were optimized for enhanced CPs removal and observed 93% removal in the presence of 3.5% glucose in pH 7.0 at 32.5 °C. Fourier-transform infrared spectroscopy and high-performance liquid chromatography results indicated the role for Shewanella BT05 in the biomineralization of CPs. The results suggested the isolate BT05 could be used for CPs removal as well as PGP activity in contaminated soil.

Significance of allochthonous brackish water Halomonas sp. on biodegradation of low and high molecular weight polycyclic aromatic hydrocarbons.

The present study is aimed to isolate and identify polycyclic aromatic hydrocarbons (PAHs) degrading bacteria from brackish water and to assess the biodegradation efficiency against low and high molecular weight PAHs. Among 15 isolates, the isolate designated as RM effectively degraded 100 mg/L of phenanthrene (Phe) (67.0%), pyrene (Pyr) (63.0%), naphthalene (NaP) (60.0%), and benzo [a]pyrene (BaP) (58.0%) after 7 days of incubation. Carbon sources, pH, and salinity of the culture medium were optimized to enhance the growth and PAHs biodegradation of the isolate RM. Sucrose was found to be an excellent carbon source to enhance PAHs biodegradation (Phe, 75.0; Pyr, 68.5; NaP, 62.5; and BaP, 59.5%). Furthermore, the isolate showed enhanced degradation at pH 7.0 and 4% salinity. The isolate RM was identified as Halomonas sp. based on partial 16S rDNA gene sequence analysis. The results indicated that the isolate RM (i.e., Halomonas sp.) has the potential to be used in remediation of oil spills in the marine ecosystem.

Effect of citric acid and vermi-wash on growth and metal accumulation of Sorghum bicolor cultivated in lead and nickel contaminated soil.

The aim of the present study is to assess the influence of vermi-wash (VW) and citric acid (CA) on Sorghum bicolor growth and phytoaccumulation of lead (Pb) and nickel (Ni) contaminated soil. The biomass of the S. bicolor has been enhanced by the addition of VW (24 and 26%) and CA (11 and 9%) in Pb and Ni contaminated soil, respectively. The VW treatment showed enhanced shoot and root lengths and chlorophyll concentrations compared to CA. The shoot anatomic structure showed an accumulation of Pb and Ni were positively impacted by the amendment of VW and CA. In addition, VW treatment showed enhanced antioxidant enzymes activity (140, 125 and 152 U/mg of CAT, SOD and POD). Further, the plants grown in Pb contaminated soil treated with VW showed enhanced Rubisco activity of 1.49 U/ml, whereas, CA treatment showed 1.23 U/ml of Rubisco. It has been observed that the VW showed as a potential chelator as well as plant beneficial formulation for the enhanced phyto-remediation of Pb and Ni.

Production and purification of laccase by Bacillus sp. using millet husks and its pesticide degradation application.

Lignocellulosic agricultural bi-products, pearl millet (PM) and finger millet (FM) husks, were used for the production of laccase using Bacillus sp. PS under solid-state fermentation (SSF). Abiotic variables such as substrate (PM, FM) concentration (1-5%), incubation time (24-96 h) and pH (5-10) were optimized using Response surface methodology (RSM) to maximize the laccase production. The predicted model showed maximum laccase activity of 402 U/mL appearing after 96 h of incubation with PM 2.0 g/L and FM 1.5 g/L at pH 7.0. Single protein band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) confirmed homogeneity of the laccase with a molecular weight of 63-75 kDa. The partially purified laccase effectively degraded the pesticides (Tricel, 71.8 ± 3.5 and Phoskill 77.3 ± 3.4%) within 5 days of incubation (40 °C) in pH 7.0. The pesticide degradation was further confirmed by high-performance liquid chromatography (HPLC) and the chromatograms showed the single dominant peaks at retention time 2.482 (tricel) and 2.608 (phoskill) min, respectively. Pesticide-degrading laccase was produced by Bacillus sp. PS under SSF reveals the utilization of low-cost bi-substrates for enhanced laccase production.

Phytosynthesis of silver nanoparticles using Mangifera indica flower extract as bioreductant and their broad-spectrum antibacterial activity.

The present study focused on the evaluation of antibacterial property of silver nanoparticles (AgNPs) synthesized using mango flower extract. The morphology of the synthesized AgNPs was observed under transmission electron microscopy and the particles have shown spherical shape in the range of 10-20 nm. X-ray powder diffraction analysis confirmed the crystalline nature of the AgNPs. The atomic percentage of the Ag element in the nanoparticles was about 7.58% which is greater than the other elements present in the sample. The AgNPs showed extensive lethal effect on both Gram-positive (Staphylococcus sp.) and Gram-negative (Klebsiella sp., Pantoea agglomerans, and Rahnella sp.) bacteria. The extensive lethal effect of AgNPs against clinically important pathogens demonstrated that the mango flower mediated AgNPs could be applied as potential antibacterial agent to control the bacterial population in the respective industries.

Effect of blue light on growth and exopolysaccharides production in phototrophic Rhodobacter sp. BT18 isolated from brackish water.

Rhodobacter sp. BT18, a phototrophic salt-resistant bacterium, was isolated from brackish water and screened for the production of exopolysaccharides (EPS). The effect of different light sources on the growth of Rhodobacter sp. BT18 was investigated. The effect on the growth order was found to be blue > white > green > red > yellow > dark. Based on Box-Behnken design, the studied variables (pH 7.0, 35 °C, and 30% of sucrose concentration under 60 h of incubation with blue light illumination) were found to be ideal for the maximum production of EPS (582.5 mg/L). Scanning electron microscopy images revealed the porous nature of EPS. Fourier transform spectroscopy and X-ray diffraction were applied to study the functional groups and the crystalline nature of the EPS, respectively. The emulsification index of the EPS was >75% and the maximum flocculating activity was about 75.4% at 30 mg/L concentration of EPS. In addition, EPS showed effective arsenic (64%) and lead (51%) chelating activities in liquid solutions. The multiple environmental applications of the EPS produced by Rhodobacter sp. BT18 make it be a promising alternative for emulsification, flocculation and metal removal in various industries.

In-vitro bio-mineralization of arsenic and lead from aqueous solution and soil by wood rot fungus, Trichoderma sp.

In the present study, we investigated the role of calcite, i.e., microbiologically-induced precipitate by ureolytic Trichoderma sp. MG, in remediation of soils contaminated with arsenic (As) and lead (Pb). The fungus tolerates high concentrations of As (500 mg/L) and Pb (650 mg/L). The effects of three factors, i.e., urea concentration, CaCl2 concentration and pH, on urease production and bio-mineralization of As and Pb were investigated using Box-Behnken design. The maximum urease production (920 U/mL) and metal removal efficiency (68% and 59% for Pb and AS, respectively) were observed in the medium containing urea of 300 mM and CaCl2 of 75 mM at pH 9.0. Fourier transform infrared spectroscopy result revealed the formation of metal carbonates by the isolate MG. Sequential extraction of metals revealed that the carbonate fractions of As and Pb were increased to 46.4% and 42.4% in bioremediated soil, whereas in control they were 35.5% and 32.5%, respectively. The X-ray powder diffraction result further confirmed the role of calcite precipitate in bioremediation of As- and Pb-contaminated soils. The results points out that the microbiologically-induced calcite precipitation is a feasible, eco-friendly technology for the bioremediation of As- and Pb-contaminated sites.

Myco-phytoremediation of arsenic- and lead-contaminated soils by Helianthus annuus and wood rot fungi, Trichoderma sp. isolated from decayed wood.

In the present study, Helianthus annuus grown in arsenic- (As) and lead- (Pb) contaminated soil were treated with plant-growth promoting fungi Trichoderma sp. MG isolated from decayed wood and assessed for their phytoremediation efficiency. The isolate MG exhibited a high tolerance to As (650mg/L) and Pb (500mg/L), and could remove > 70% of metals in aqueous solution with an initial concentration of 100mg/L each. In addition, the isolate MG was screened for plant-growth-promoting factors such as siderophores, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, indole acetic acid (IAA) synthesis, and phosphate solubilisation. Phytoremediation studies indicated that treatment of H. annuus with the isolate MG had the maximum metal-accumulation in shoots (As; 67%, Pb; 59%). Furthermore, a significant increase in the soil extracellular enzyme-activities was observed in myco-phytoremediated soils. The activities of phosphatase (35 U/g dry soil), dehydrogenase (41mg TPF/g soil), cellulase (37.2mg glucose/g/2h), urease (55.4mgN/g soil/2h), amylase (49.3mg glucose/g/2h) and invertase (45.3mg glucose/g/2h) significantly increased by 12%, 14%, 12%, 22%, 19% and 14% in As contaminated soil, respectively. Similarly, the activities of phosphatase (31.4U/g dry soil), dehydrogenase (39.3mg TPF/g soil), cellulase (37.1mg glucose/g/2h), urease (49.8mgN/g soil/2h), amylase (46.3mg glucose/g/2h), and invertase (42.1mg glucose/g/2h) significantly increased by 11%, 15%, 11%, 18%, 20% and 14% in Pb contaminated soil, respectively. Obtained results indicate that the isolate MG could be a potential strain for myco-phytoremediation of As and Pb contaminated soil.

Isolation, identification and characterization of arsenic transforming exogenous endophytic Citrobacter sp. RPT from roots of Pteris vittata.

The aim of the present study was to assess the arsenic (As) transformation potential of endophytic bacteria isolated from roots of Pteris vittata plant. The endophytic bacterium was tested for minimal inhibitory concentration (MIC) against As. The endophytic strain RPT exhibited the highest resistance to As(V) (400 mg/l). Phylogenetic analysis of the 16S rRNA sequence suggested that strain RPT was a member of genus Citrobacter. The As transformation assay revealed As(III) oxidation and As(V) reduction potential of Citrobacter sp. RPT. The As resistance mechanism was further confirmed by amplification of arsC and aoxB genes. The growth kinetics of strain RPT was altered slightly in the presence of different concentration (100-400 mg/l) of As stress. Temperature and pH influenced the As removal rate. The maximum As removal was observed at pH 7.0 (74%) and 37 °C (70.9%). The results suggest that strain RPT can survive under the As stress and has been identified as a potential candidate for application in bioremediation of As in contaminated environments.

Process optimization of biogas energy production from cow dung with alkali pre-treated coffee pulp.

Biogas production from cow dung with co-substrate agricultural waste is one of the most demanding technologies for generating energy in a sustainable approach considering eco-friendly. In the present study, coffee pulp (CP) was pre-treated with 1% NaOH and combined with various proportions of cow dung (CD) to explore its biogas producing potentiality. The optimization of the process was studied using Response surface methodology. Statistics based on 3-D plots were generated to evaluate the changes in the response surface and to understand the relationship between the biogas yield and other parameters. The highest methane production (144 mL/kg) was achieved after 90 h of incubation with 1:3 of CP and CD at 40 °C. Gas chromatography analyzes the chemical compositions of the generated biogas and its post combustion emissions. The chemical composition of the substrates before digestion and after fermentation (biogas spent sludge) were measured in terms of fiber content and the values were noted as, total solids (0.53%), ash content (9.2%), volatile fatty acid (100 mg/L), organic carbon (46%) and a total carbohydrate (179 mg/g). The results of the optimization of biogas production presented in this work found to have significance with the process parameters. The outcome of the study has supported the fact of conventional combustion technology that has to be upgraded to prevent these hazardous emissions into the atmosphere.

Bioremediation of heavy metals using an endophytic bacterium Paenibacillus sp. RM isolated from the roots of Tridax procumbens.

The aim of the present study was to assess the bioremediation potential of endophytic bacteria isolated from roots of Tridax procumbens plant. Five bacterial endophytes were isolated and subsequently tested for minimal inhibitory concentration (MIC) against different heavy metals. Amongst the five isolates, strain RM exhibited the highest resistance to copper (750 mg/l), followed by zinc (500 mg/l), lead (450 mg/l), and arsenic (400 mg/l). Phylogenetic analysis of the 16S rDNA sequence suggested that strain RM was a member of genus Paneibacillus. Strain RM also had the capacity to produce secondary metabolites, indole acetic acid, siderophores, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and biosurfactant and solubilize phosphate. The growth kinetics of strain RM was altered slightly in the presence of metal stress. Temperature and pH influenced the metal removal rate. The results suggest that strain RM can survive under the high concentration of heavy metals and has been identified as a potential candidate for application in bioremediation of heavy metals in contaminated environments.