Enzymatic response of Moina macrocopa to different sized zinc oxide particles: An aquatic metal toxicology study.

Zinc oxide particles (ZnOPs) of both nanometer and sub-micron sizes are important components of high demand consumer products such as sunscreen, paint, textile, food packaging, and agriculture. Their ultimate discharge in the aquatic ecosystem is nearly unavoidable. For sustainable use of ZnOPs, there is an urgent need to assess its ecotoxicity using ecological indicator organisms. Moina macrocopa, an important component of the aquatic ecosystem is one such less explored indicator organism. In the present investigation, ZnOPs of two different sizes (250 ± 20 and 500 ± 50 nm) were selected for risk assessment as most of the previous reports were based on the use of 10-100 nm ZnOPs. ZnOPs of 500 nm were more lethal than that of 250 nm size, with respective LC50 of 0.0092 ± 0.0012 and 0.0337 ± 0.0133 mg/L against M. macrocopa after 48 h of exposure. We further used a sublethal concentration of 500 nm (0.00336 mg/L) and 250 nm (0.00092 mg/L) ZnOPs followed by measurement of enzymatic biomarkers of toxicity (acetylcholinesterase, digestive enzymes, antioxidant enzymes). A size-dependent variation in enzymatic response to 250 and 500 nm ZnOPs was seen. Exposure to ZnOPs inhibited acetylcholinesterase and digestive enzymes (trypsin, amylase), and elevated antioxidant enzymes (catalase, glutathione S-transferase) levels. The exposure also decreased the superoxide dismutase activity and increased that of ß-galactosidase. Microscopic investigation revealed the accumulation of ZnOPs in the digestive tract of M. macrocopa that possibly disrupts enzyme activities. The present study will contribute to establishing regulatory policy on the maximum permissible limit of ZnOPs in different water bodies.

A novel screening method for potential naringinase-producing microorganisms.

Naringinase has high industrial importance, and the progress in naringinase research is still quite slow. The unavailability of an effective, simple screening method, which will be applicable to different microorganisms such as bacteria, fungi, and actinomycetes, is one of the main reasons for this gap. Therefore, a simple plate assay was developed for effective screening of microorganisms for naringinase by exposing to iodine vapors. This plate assay will fill the technological void for simple screening method and will lead to screen more potent industrially important naringinase-producing microorganisms.

Extracellular red Monascus pigment-mediated rapid one-step synthesis of silver nanoparticles and its application in biomedical and environment.

The development of a safe and eco-friendly method for metal nanoparticle synthesis has an increasing demand, due to emerging environmental and biological harms of hazardous chemicals used in existing nanosynthesis methods. The present investigation reports a rapid one-step, eco-friendly and green approach for the formation of nanosized silver particles (AgNPs) using extracellular non-toxic-colored fungal metabolites (Monascus pigments-MPs). The formation of nanosized silver particles utilizing Monascus pigments was confirmed after exposure of reaction mixture to sunlight, by visually color change and further established by spectrophotometric analysis. The size, shape, and topography of synthesized MPs-AgNPs were well-defined using different microscopic and spectroscopic techniques, i.e., FE-SEM, HR-TEM, and DLS. The average size of MPs-AgNPs was found to be 10-40 nm with a spherical shape which was highly stable and dispersed in the solution. HR-TEM and XRD confirmed crystalline nature of MPs-AgNPs. The biocidal potential of MPs-AgNPs was evaluated against three bacterial pathogens such as Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus and it was observed that the MPs-AgNPs significantly inhibited the growth of all three bacterial pathogens. The anti-biofilm activity of MPs-AgNPs was recorded against antibiotic-resistant P. aeruginosa. Besides, the colorimetric metal sensing using MPs-AgNPs was studied. Among the metals tested, the selective Hg2+-sensing potential at micromolar concentration was observed. In conclusion, this is the rapid one-step (within 12-15 min), environment-friendly method for synthesis of AgNPs and synthesized MPs-AgNPs could be used as a potential antibacterial agent against antibiotic-resistant bacterial pathogens.

Mechanistic approach for fabrication of gold nanoparticles by Nitzschia diatom and their antibacterial activity.

The problem of chemically synthesized nanoproducts motivated scientific community to explore ecofriendly methods of nanosynthesis. Diatoms belong to a group of aquatic, unicellular, photosynthetic microalgae have been scarcely investigated as a source of reducing and capping agents for nanosynthesis of pesticides and antibiotics. The present study reports a novel ecofriendly method for the fabrication of bioactive gold nanoparticles using locally isolated Nitzschia diatoms. The diatom-fabricated gold nanoparticles show characteristic ruby red colored with sharp absorbance peak at 529 nm. Electron microscopy confirmed irregular shape of gold nanoparticles, with average size of 43 nm and zeta potential of -16.8 mV. The effects of gold nanoparticles on diatom viability were investigated using light and electron microscopy. The mechanistic approach to shed light on how diatoms reacted after exposure to gold metal salt revealed that exposure to gold chloride triggers elevated levels of catalase and peroxidase (12.76 and 14.43 unit/mg protein, respectively) to relieve reactive oxygen species (ROS) stress induced by gold salt exposure. Investigation studies on mechanisms behind Nitzschia-mediated gold nanoparticles fabrication outlined the role of diatom proteins, polysaccharides in reduction, and stabilization of nanoparticles as confirmed by FT-IR analysis. Bioactivity of gold nanoparticles was accessed by coupling them with antibiotics (penicillin and streptomycin), which increased their antibacterial activity compared to individual nanoparticles and antibiotics (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus). Overall, the present novel phyco-nanotechnological approach is a promising tool to be used as sustainable strategy in green nanotechnology as well as to reduce use of antibiotics in microbial control.

Biofunctionalized silver nanoparticles as a novel colorimetric probe for melamine detection in raw milk.

Nanoparticles have emerged as a promising analytical tool for monitoring food adulteration and safety. In the present study, silver nanoparticles (AgNPs) were synthesized using leaves' extract of Jatropha gossypifolia. AgNPs revealed a characteristic surface plasmon resonance (SPR) peak at 419 nm and have spherical and grain shape with size range between 18 and 30 nm. A selective and rapid method of melamine detection in raw milk was developed with the use of these biofunctionalized AgNPs. The color change, deviation in SPR spectra, and change in the absorption ratio (A500 /A419 ) of AgNPs occurred after an AgNPs-melamine interaction. The detection limit for melamine up to 2 µM (252 ppb) was attained with this method, which is quite lower than safety level recommendations of regulatory bodies demonstrating sensitivity of the method. Dynamicx light scattering and transmission electron microscopy analyses exhibited an increase in hydrodynamic diameter and size of AgNPs after melamine interaction. Melamine sensing by AgNPs was investigated by different physicochemical and thermal analyses.

Innovative approach for urease inhibition by Ficus carica extract-fabricated silver nanoparticles: An in vitro study.

In the present study, a rapid, low-cost, and ecofriendly method of stable silver nanoparticles (AgNPs) synthesis using leaves extract of Ficus carica (F. carica), a plant with diverse metabolic consortium, is reported for the first time. An absorption peak at 422 nm in UV-Vis spectroscopy, a spherical shape with an average size of 21 nm in transmission electron microscopy, and crystalline nature in X-ray powder diffraction studies were observed for the synthesized AgNPs. Fourier transform infrared analysis indicated that proteins of F. carica might have a vital role in AgNP synthesis and stabilization. AgNPs were found to inhibit urease, a key enzyme responsible for the survival and pathogenesis of the bacterium, Helicobacter pylori. Inhibition of urease by AgNPs was monitored spectrophotometrically by the evaluation of ammonia release. The urease inhibition potential of AgNPs can be explored in the treatment of H. pylori by preparing novel combinations of standard drugs with AgNPs- or AgNPs-encapsulated drug molecules.

Mosquito larvicidal and pupaecidal potential of prodigiosin from Serratia marcescens and understanding its mechanism of action.

Mosquitoes spread lethal diseases like malaria and dengue fever to humans. Considering mosquito vector control as one of the best alternatives to reduce new infections, here we have analyzed the effect of purified pigment prodigiosin extracted from Serratia marcescens (NMCC 75) against larval and pupal stages of Aedes aegypti and Anopheles stephensi mosquitoes. Mosquito larvicidal activities of purified prodigiosin revealed LC50 values of 14 ± 1.2, 15.6 ± 1.48, 18 ± 1.3, 21 ± 0.87 µg/ml against early IInd, IIIrd, IVth instar and pupal stages of Ae. aegypti, respectively. LC50 values for An. stephensi were found to be 19.7 ± 1.12, 24.7 ± 1.47, 26.6 ± 1.67, 32.2 ± 1.79 µg/ml against early IInd, IIIrd, IVth instar and pupae of An. stephensi, respectively. Further investigations toward understanding modes of action revealed variations in the activities of esterases, acetylcholine esterases, phosphatases, proteases and total proteins in the fourth instar larvae of Ae. aegypti indicating intrinsic difference in biochemical features due to prodigiosin treatment. Although there was no inhibition of enzymes like catalase and oxidase but may have profound inhibitory effect on carbonic anhydrase or H(+)-V-ATPase which is indicated by change in the pH of midgut and caeca of mosquito larvae. This reduced pH may be possibly due to the proton pump inhibitory activity of prodigiosin. Pure prodigiosin can prove to be an important molecule for mosquito control at larval and pupal stages of Ae. aegypti and An. stephensi. This is the first report on the mosquito pupaecidal activity of prodigiosin and its possible mechanism of action.

Mercury sensing and toxicity studies of novel latex fabricated silver nanoparticles.

Safe and eco-friendly alternatives to currently used hazardous chemico-physical methods of silver nanoparticles (AgNPs) synthesis are need of time. Rapid, low cost, selective detection of toxic metals in environmental sample is important to take safety action. Toxicity assessment of engineered AgNPs is essential to avoid its side effects on human and non-target organisms. In the present study, biologically active latex from Euphorbia heterophylla (Poinsettia) was utilized for synthesis of AgNPs. AgNPs was of spherical shape and narrow size range (20-50 nm). Occurrence of elemental silver and crystalline nature of AgNPs was analyzed. Role of latex metabolites in reduction and stabilization of AgNPs was analyzed by FT-IR, protein coagulation test and phytochemical analysis. Latex-synthesized AgNPs showed potential in selective and sensitive detection of toxic mercury ions (Hg(2+)) with limit of detection around 100 ppb. Addition of Hg(2+) showed marked deviation in color and surface plasmon resonance spectra of AgNPs. Toxicity studies on aquatic non-target species Daphnia magna showed that latex-synthesized AgNPs (20.66 ± 1.52% immobilization) were comparatively very less toxic than chemically synthesized AgNPs (51.66 ± 1.52% immobilization). Similarly, comparative toxicity study on human red blood cells showed lower hemolysis (4.46 ± 0.01%) by latex-synthesized AgNPs as compared to chemically synthesized AgNPs causing 6.14 ± 0.01% hemolysis.

Transformation of aromatic dyes using green synthesized silver nanoparticles.

Nowadays, increasing use of nanoproducts in area of human and environmental applications raises concern about safety aspects of nanoparticles synthesized using traditional physicochemical methods. Silver nanoparticles (AgNPs) synthesis at ambient parameters using latex of medicinally important plant Jatropha gossypifolia (J. gossypifolia) is reported in the present study. Potential of AgNPs in degradation of methylene blue and eosin B was also evaluated. Rapid formation of stable AgNPs was analyzed by visual color change from colorless to yellow-red after addition of latex in AgNO3 solution and by characteristic surface plasmon resonance (SPR) peak at 430 nm in UV-Vis spectroscopy. FT-IR analysis, protein coagulation test showed capping of proteins, flavonoids, terpenoids and polyphenols of latex on surface of AgNPs. FE-SEM, HR-TEM analysis revealed spherical shape of AgNPs. Narrow size range of AgNPs (5-40 nm) observed in HR-TEM analysis. EDS analysis confirms the presence of elemental silver while XRD revealed crystalline nature of AgNPs. Zeta potential of -21.4 mV indicates high stability of AgNPs. Effects of different parameters (pH, temperature, incubation time) on nanosynthesis were studied in the present study. Dye reduction studies were performed using UV-Vis spectroscopy, TLC, FT-IR and HPLC analysis showing decreased absorbance maxima of both dyes with respect to time, change in R f values, changes in wave number, transmittance, and retention time of dyes after AgNPs addition. The rate constant for methylene blue and eosin B reduction by AgNPs was found to be 0.062 and 0.022 min(-1).

Alteration in Bacillus thuringiensis toxicity by curing gut flora: novel approach for mosquito resistance management.

Mosquitoes are known for acquiring resistance against insecticides in many ways, namely target side mutation, enzyme modification, sequestration, quick elimination, etc. But, the role of microflora present in abundance in the larval midgut is less explored with respect to their role in insecticide resistance. During the course of their development, mosquitoes are continuously exposed to microbes and have naturally acquired midgut microbial flora. This midgut flora can modulate the mosquito's susceptibility to Bacillus thuringiensis (Bt) infection by degrading toxic Bt protein forms through an unknown mechanism. In this study, we show that microbe-free aseptic mosquito larvae displayed an increased susceptibility to Bt toxicity compared to larvae harboring natural microbial flora. Fourth instar larvae of Anopheles stephensi were treated separately with penicillin, streptomycin, erythromycin (100 µg/ml), and mixtures of all three antibiotics and then analyzed for Bt toxicity. We have also examined the influence of the mosquito's midgut microbial flora under microaerophilic condition on the Bt protein degradation through plate, broth, TLC, and UV-vis spectrophotometric assay. A better understanding of the roles of microbiota in preventing Bt toxicity to mosquitoes could potentially lead to the development of new sustainable mosquito control strategies.

Larvicidal activity of silver nanoparticles synthesized using Plumeria rubra plant latex against Aedes aegypti and Anopheles stephensi.

In the present study activity of silver nanoparticles (AgNPs) synthesized using Plumeria rubra plant latex against second and fourth larval instar of Aedes aegypti and Anopheles stephensi was determined. Range of concentrations of synthesized AgNps (10, 5, 2.5, 1.25, 0.625, 0.3125 ppm) and aqueous crude latex (1,000, 500, 250, 125, 62.50, 31.25 ppm) were tested against larvae of A. aegypti and A. Stephensi. The synthesized AgNps from P. rubra latex were highly toxic than crude latex extract in both mosquito species. The LC(50) values for second and fourth larval instars after 24 h of crude latex exposure were 1.49, 1.82 ppm against A. aegypti and 1.10, 1.74 ppm against A. stephensi respectively. These figures were 181.67, 287.49 ppm against A. aegypti and 143.69, 170.58 ppm against A. stephensi respectively for crude latex extract. The mortality rates were positively correlated with the concentration of AgNPs. The characterization studies of synthesized AgNPs by UV-Vis spectrophotometry, transmission electron microscopy (TEM), Particle size analysis (PSA) and zeta potential confirmed the spherical shape and size (32-200 nm) of silver nanoparticles along with stability. Toxicity studies carried out against non-target fish species Poecilia reticulata, the most common organism in the habitats of A. aegypti and A. stephensi showed no toxicity at LC(50) and LC(90) doses of the AgNPs. This is the first report on mosquito larvicidal activity of latex synthesized nanoparticles.

Larvicidal activity of silver nanoparticles synthesized using Pergularia daemia plant latex against Aedes aegypti and Anopheles stephensi and nontarget fish Poecillia reticulata.

In present study, the bioactivity of latex-producing plant Pergularia daemia as well as synthesized silver nanoparticles (AgNPs) against the larval instars of Aedes aegypti and Anopheles stephensi mosquito larvae was determined. The range of concentrations of plant latex (1,000, 500, 250, 125, 62.25, and 31.25 ppm) and AgNPs (10, 5, 2.5, 1.25, 0.625, and 0.3125 ppm) were prepared. The LC(50) and LC(90) values for first, second, third, and fourth instars of synthesized AgNPs-treated first, second, third, and fourth instars of A. aegypti (LC(50) = 4.39, 5.12, 5.66, 6.18; LC(90) = 9.90, 11.13, 12.40, 12.95 ppm) and A. stephensi (LC(50) = 4.41, 5.35, 5.91, 6.47; LC(90) = 10.10, 12.04, 13.05, 14.08 ppm) were found many fold lower than crude latex-treated A. aegypti (LC(50) = 55.13, 58.81, 75.66, 94.31; LC(90) = 113.00, 118.25, 156.95, 175.71 ppm) and A. stephensi (LC(50) = 81.47, 92.09, 96.07, 101.31; LC(90) = 159.51, 175.97, 180.67, 190.42 ppm). The AgNPs did not exhibit any noticeable effects on Poecillia reticulata after either 24 or 48 h of exposure at their LC(50) and LC(90) values against fourth-instar larvae of A. aegypti and A. stephensi. The UV-visible analysis shows absorbance for AgNPs at 520 nm. TEM reveals spherical shape of synthesized AgNPs. Particle size analysis revealed that the size of particles ranges from 44 to 255 nm with average size of 123.50 nm. AgNPs were clearly negatively charged (zeta potential -27.4 mV). This is the first report on mosquito larvicidal activity P. daemia-synthesized AgNPs.

Moina macrocopa as a non-target aquatic organism for assessment of ecotoxicity of silver nanoparticles: Effect of size.

The release of nanomaterials in water reservoirs is hazardous. Very few reports are available on the interaction of different sized nanoparticles with aquatic organisms and aquatic environment. In the present study, silver nanoparticles (AgNPs) having an average particle size of 20.80 ±â€¯2.31 and 40.04 ±â€¯4.72 nm were synthesized using polyvinylpyrrolidone and l-tyrosine. Ecotoxicological effects of AgNPs were evaluated on less explored crustacean species, Moina macrocopa. The 48 h lethal values (48 h LC50) of 20 and 40 nm AgNPs were 0.11 ±â€¯0.02 and 0.12 ±â€¯0.03 mg/L, respectively. Further, a size dependent inhibition of AgNPs on acetyl cholinesterase and digestive enzymes (trypsin, amylase, ß-galactosidase) was observed, while that of the antioxidant enzymes (catalase, superoxide dismutase, glutathione-S-transferase) and alkaline phosphatase were enhanced as compared to control group. These results strengthen the potential of enzymes as biomarker in environmental risk assessment of AgNPs. AgNPs accumulated in the gut of M. macrocopa which could not be completely eliminated, thereby resulting in an increased metal body burden. The accumulation of AgNPs of 20 nm was lower than that of 40 nm indicating the influence of size of nanoparticles on uptake and toxicity. AgNPs agglomerated in moderately hard water medium (MHWM) and this agglomeration influenced the exposure the organism thereto. The size of AgNPs influenced the toxicity to M. macrocopa through interplay between uptake, accumulation, aggregation, and excretion in the organism and environment.

Nano-eco toxicity study of gold nanoparticles on aquatic organism Moina macrocopa: As new versatile ecotoxicity testing model.

In the field of nanoecotoxicology, very few reports have focused on biochemical changes in non-target organisms after nanoexposure. A less explored aquatic non-target crustacean, Moina macrocopa, was used in the present study to analyze toxicity effects of gold nanoparticles (AuNPs), an emerging nanomaterial. AuNPs was fabricated using tannic acid and were 29 ± 2 nm in size. The 48 h LC50 value of AuNPs was 14 ± 0.14 mg/L against M. macrocopa. The sub-lethal exposure of M. macrocopa juveniles to AuNPs (1.47 and 2.95 mg/L) decreased the activities of acetyl cholinesterase and digestive enzymes (trypsin and amylase). A concentration dependant increase in the activities of antioxidant enzymes such as catalase, superoxide dismutase and glutathione S-transferase suggested the generation of oxidative stress in M. macrocopa after AuNPs exposure. Changes in enzyme activity can be utilized as biomarker(s) for early detection of nanoparticle contamination in aquatic habitat. AuNPs accumulation in gut of M. macrocopa increased the metal bio burden (11 mg/L) and exhibited inhibitory action on digestive enzymes. Complete depuration of AuNPs was not observed after transferring nano-exposed M. macrocopa to normal medium without AuNPs. AuNPs tended to adhere on external body parts such as setae, carapace of M. macrocopa which interfered with swimming activity and also changed the behavioral pattern. AuNPs underwent agglomeration in the medium used for maintenance of M. macrocopa. As nanomaterials are emerging pollutants in aquatic systems, the present work highlights the hazardous effect of AuNPs and development of enzymatic biomarkers to curtail it at community level.

Trypsin inactivation by latex fabricated gold nanoparticles: A new strategy towards insect control.

Before applying nanotechnologies in biomedical and environmental areas it is advised to study interactions of nanoparticles and other nanomaterials with biomacromolecule present in living system. Moreover there is scarcity of reports on interactions between nanoparticles and biomaterials. In present report a rapid, ecofriendly method of fabricating stable gold nanoparticles (AuNPs) using latex of Jatropha curcas is reported for the first time. AuNPs found to have characteristic absorption maxima centered at 540nm, multiple irregular shapes with size range from 20 to 50nm and have crystalline nature. Latex fabricated AuNPs were found to inhibit catalytic potential of trypsin (a vital enzyme responsible for digestion, insecticide resistance and in several disease conditions). The interactions between AuNPs and trypsin were analyzed by UV-vis spectrophotometry and microwave plasma-atomic emission spectrometry which suggests formation of trypsin-AuNPs complex responsible for lowering catalytic activity of trypsin. Transmission electron microscopy, Fourier transform infrared spectroscopy and particle size distribution studies further confirm complex formation between trypsin and AuNPs. Diverse interactions of metal nanoparticles with proteins such as covalent interaction, electrostatic interactions and binding to SH group of amino acid may be the reasons behind inhibition of trypsin activity. In vivo studies on serum of several vectors and agriculturally important pests supported instrumental results on AuNPs induced trypsin inhibition. This work will bring a new research direction to explore eco-friendly nanoparticle in insect control via inhibition of enzyme catalytic potential.

Effect of different carbon sources on morphology and silver accumulation in Cochliobolus lunatus.

The morphology of filamentous fungi plays very important role in uptake of metabolites and enzyme production. A filamentous fungus may be fibrous, hyphae, pellets, clumps, etc. Cochliobolus lunatus is a fungus which has previously been reported for silver accumulation and nanoparticles formation. The present study investigated the role of various carbon sources on morphology, biochemical profile, silver accumulation, and biosynthesis of silver nanoparticles by fungal strain C. lunatus. In this investigation, effect of different carbon sources was studied on morphology of C. lunatus and its silver accumulating ability. As a result of different carbon sources like carboxymethyl cellulose (CMC), pectin, starch, agar, sucrose, and mannitol, the organism showed three kinds of morphologies like homogenous smooth branched clumps, tough short fibrous filaments, and tough pellets, as well as silver accumulating ability. Atomic absorption spectroscopy (AAS) studies showed maximum uptake of Ag(+): 87.44 ± 0.23 and 82.57 ± 0.19 % in pectin- and CMC-grown biomass, respectively. The crystalline nature of silver nanoparticles (AgNPs) was confirmed by X-ray diffraction studies. Transmission electron microscopy (TEM) micrographs of silver nanoparticles confirmed size ranging from 5 to 38 nm.

Bio-functionalized silver nanoparticles: a novel colorimetric probe for cysteine detection.

Chemical interactions between nanoparticles and biomolecules are vital for applying nanoparticles in medicine and life science. Development of sensitive, rapid, low-cost, and eco-friendly sensors for the detection of molecules acting as disease indicator is need of an hour. In the present investigation, a green trend for silver nanoparticle synthesis was followed using leaf extract of Calotropis procera. Silver nanoparticles exhibited surface plasmon absorption peak at 421 nm, spherical shape with average size of 10 nm, and zeta potential of -22.4 mV. The as-synthesized silver nanoparticles were used for selective and sensitive detection of cysteine. Cysteine induces aggregation in stable silver nanoparticles owing to selective and strong interaction of -SH group of cysteine with silver nanoparticle surface. Cysteine-induced silver nanoparticle aggregation can be observed visually by change in color of silver nanoparticles from yellow to pink. Cysteine concentration was estimated colorimetrically by measuring absorption at surface plasmon wavelength. Limit of detection for cysteine using silver nanoparticles is ultralow, i.e., 100 nM. The mechanistic insight into cysteine detection by silver nanoparticles was investigated using FT-IR, TEM, DLS, and TLC analysis. Proposed method can be applied for the detection of cysteine in blood plasma and may give rise to a new insight into development of eco-friendly fabricated nanodiagnostic device in future.

Studies on production and biological potential of prodigiosin by Serratia marcescens.

Efficacy of Serratia marcescens for pigment production and biological activity was investigated. Natural substrates like sweet potato, mahua flower extract (Madhuca latifolia L.), and sesam at different concentrations were taken. As a carbon source microorganism favored potato powder was followed by sesam and mannitol, and as nitrogen source casein hydrolysate was followed by yeast and malt extract. The effect of inorganic salts on pigment production was also studied. At final optimized composition of suitable carbon, nitrogen source, and trace materials and at suitable physiological conditions, prodigiosin production was 4.8 g L(-1). The isolated pigment showed antimicrobial activity against different pathogenic bacteria and fungi. Extracted pigment was characterized by spectroscopy, Fourier transform infrared (FTIR), and thin layer chromatography (TLC) which confirm production of biological compound prodigiosin. This study suggests that use of sweet potato powder and casein can be a potential alternative bioresource for commercial production of pigment prodigiosin.

Catalytic and synergistic antibacterial potential of green synthesized silver nanoparticles: Their ecotoxicological evaluation on Poecillia reticulata.

In the present study, stable silver nanoparticles (AgNPs) were fabricated at a rapid rate from leaf extract of medicinally important plant Alstonia macrophylla. Biosynthesized AgNPs are of spherical shape and narrow size (70 nm), exhibiting a surface plasmon resonance peak at 435 nm, and a zeta potential of -30.8 mV and have a crystalline nature. A diverse biochemical consortium of protein, terpenoids, phenolics, and flavonoids in leaf extract of A. macrophylla was found to be responsible for AgNP synthesis as evidenced from qualitative-quantitative chemical analysis and Fourier transform infrared spectroscopy studies. Nitroaromatic compounds are anthropogenic pollutants with long-lasting environmental persistence and are needed to transform into less toxic derivatives. 4-Nitrophenol and p-nitroaniline were reduced to less hazardous and commercially useful 4-aminophenol and p-phenylenediamine by phytosynthesized AgNPs. Rate constants of 0.052 and 0.040 Min(-1) were calculated for 4-nitrophenol and p-nitroaniline reduction, respectively. Thin-layer chromatography also confirms the reduction of these nitroaromatic compounds. Combinational studies could be one of the strategies to overcome microbial resistance to antibiotics. In synergistic antibacterial assay, the highest increase in a fold area of 3.84 was reported against Staphylococcus aureus using a combination of AgNPs with penicillin. Biosynthesized AgNPs were found to be less toxic (LC50 = 9.13 ppm) than chemically synthesized AgNPs having a LC50 value of 2.86 ppm against nontarget fish Poecillia reticulata. Our green nanosynthesis method offers a faster rate of formation of stable AgNPs having antibacterial and catalytic potential with lower environmental toxicity.

Mosquito Larvicidal Potential of Gossypium hirsutum (Bt cotton) Leaves Extracts against Aedes aegypti and Anopheles stephensi larvae.

BACKGROUND: We aimed to extract the ingredients from leaves of Gossypium hirsutum (Bt cotton) using different solvents and evaluate for potential use to control different larval stages of mosquito species, Aedes aegypti and Anopheles stephensi. METHODS: Qualitative and quantitative estimation of ingredients from Go. hirsutum (Bt) plant extract was carried out and their inhibitory action against mosquito larvae was determined using mosquito larvicidal assay. RESULTS: LC50 values of water, ethanol, ethyl acetate and hexane extracts for Ae. aegypti were 211.73±21.49, 241.64±19.92, 358.07±32.43, 401.03±36.19 and 232.56±26.00, 298.54±21.78, 366.50±30.59, 387.19±31.82 for 4(th) instar of An. stephensi, respectively. The water extract displayed lowest LC50 value followed by ethanol, ethyl acetate and hexane. Owing to the comparatively better activity of water extract, its efficacy was further evaluated for mosquito larvicidal activity, which exhibited LC50 values of 133.95±12.79, 167.65±11.34 against 2(nd) and 3(rd) instars of Ae. aegypti and 145.48±11.76, 188.10±12.92 against 2(nd) and 3(rd) instars of An. stephensi, respectively. Crude protein from the water extract was precipitated using acetone and tested against 2(nd), 3(rd) and 4(th) instars of Ae. aegypti and An. stephensi. It revealed further decrease in LC50 values as 105.72±25.84, 138.23±23.18, 126.19±25.65, 134.04±04 and 137.88±17.59, 154.25±16.98 for 2(nd), 3(rd) and 4(th) instars of Ae. aegypti and An. stephensi, respectively. CONCLUSION: Leaves extracts of Go. hirsutum (Bt) is potential mosquito larvicide and can be used as a potent alternative to chemical insecticides in integrated pest management.