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In the present study, the synthesis of ligand 6-chloro-5-7-dimethyl-4oxo-4H-chromene-3-carbaldehydes by three steps from the substituted phenol. The formed product in the first step was further processed by fries rearrangement reaction and subsequently Vilsmeier–Haack reaction. Then, its homoleptic and heteroleptic complexes with Mn(II), Co(II), Ni(II) and Cu(II) metal ions by using second ligand quinolin-8-ol were synthesized. The ligand and complexes were characterized by different techniques, such as electron dispersive spectroscopy and elemental analysis (CHN), Fourier transform infrared (FTIR), electronic spectroscopy and magnetic susceptibility, 1H-Nuclear magnetic resonance spectroscopy and mass spectra of ligand, electron spin resonance (ESR), thermogravimetric analysis, powder X-ray diffraction, scanning electron microscopy (SEM) and molar conductivity. The spectroscopic analysis like NMR and the FTIR shows that the both ligands are bidentate in nature. The UV–visible spectra show the homoleptic complex of Cu(II) shows square planer, while M = Ni(II), Co(II) and Mn(II) shows octahedral in nature. While the complexes with heteroleptic ligands from square planer geometry with Cu(II) and Ni(II) while Co(II) and Mn(II) show octahedral geometries. The geometry was also supported by magnetic susceptibility and FTIR spectra. The ESR spectra of Cu(II) complexes shows both are square planer geometry and the G-value was more than 4 indicating the absence of exchange interaction between Cu(II) metal ions in the solid state. The powder X-ray diffraction was used to determine the crystal system of all the complexes, while supporting to this X-ray diffraction the SEM was also taken for the nanostructure of complexes was developed or not. Then, the solution state conductivity of the complexes shows electrolytic in nature. Further, these complexes were evaluated for its antimicrobial activity by agar well diffusion method and structure–activity relationship. The ligands show antimicrobial activity against S.typhi. The Ni(II) does not show antibacterial activity, while complexes Cu(II), Co(II) and Mn(II) shows good activity against the gram-positive and the gram-negative bacteria. The heteroleptic ligand complex (6) of Cu(II) shows higher antifungal activity as compared with Ni(II), Co(II) and Mn(II) complexes.

Polyimide (PI) films were irradiated by 120 MeV iron (Fe+9) ions and variations in its optical, chemical, surface morphology and anti-bacterial properties were studied. UV-Visible spectroscopic res...

A nanocomposite of Polypyrrole (PPy) and zinc oxide (ZnO), termed as PPy-ZnO, was synthesized by two step route. In the first step, synthesis of PPy was carried out by chemical oxidative route. In the second step, the PPy-ZnO nanocomposite was synthesized under hydrothermal conditions. The as-synthesized PPy-ZnO nanocomposites were characterized using X-ray Diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infra-red (FTIR) and Ultra violetvisible (UV-vis) spectroscopy to reveal the phase, morphology, chemical and optical properties. The physical and chemical characterizations confirmed presence of both PPy and ZnO phases in the nanocomposite. In the present work, antimicrobial activity of the PPy-ZnO nanocomposite against human pathogen Y. lipolytica has been investigated. Attempts have been made to reveal the influence of PPy percentage on the antimicrobial activity. Interestingly, all PPy-ZnO nanocomposites, irrespective of PPy percentage, showed 90 to 95% inhibited growth of Yarrowia lipolytica. The results obtained herein imply the potential of PPy-ZnO biofilm in inhibiting the growth of Y. lipolytica and thus preventing infections caused due to Y. lipolytica in humans.

Extremophilic microorganisms have the ability to survive under seemingly extreme environments such as extreme pH, temperature, pressure, oxygen levels, desiccation, salinity, radiation, and redox potential. Under such harsh conditions, other normal microbes would be destroyed. However, extremophiles are classified based on the environment in which they can survive. These extremophilic microorganisms have the ability to produce a variety of extremozymes and extremolytes under different harsh conditions. Thus, they are considered as potential candidates for their several biotechnological and commercial applications. This chapter provides an overview of the ecology of extremophiles and their biotechnological applications, including the production of extremophiles, extremozymes, and extremolytes as valuable resources for the future development of a bio-based economy.

Quorum quenching is the process of blocking quorum sensing activity that can be used as an effective way to control quorum sensing dependent virulence in pathogens. Quorum quenching mechanisms prevent the development of antibiotic resistance in biofilm-forming microorganisms. Rhizospheric bacteria shows great diversity along with complex intra species interactions. Within this diversified environment many bacterial species with quorum sensing and quorum quenching ability are found in close vicinity. In this study rhizospheric soil of different plants was used to screen potential quorum quenchers. The rhizospheric bacterial isolates were tested for their ability to degrade/inactivate N-hexanoyl-l-homoserine lactone (C6HSL) molecules. Pigment inhibition bioassays were performed using Chromobacterium violaceum CV026 and C. violaceum 2656 to screen bacterial isolates possessing quorum quenching activity. The biofilm formation inhibition by six screened isolates was studied against different human pathogens such as Vibrio parahaemolyticus MTCC451, V. cholerae MTCC3906 and Pseudomonas aeruginosa PA01. Results revealed that biofilms were efficiently inhibited. Significant biofilm inhibition was revealed by two isolates and identified as S. marcescens subsp. sakuensis KRED, and S. nematodiphila using 16S rRNA gene sequencing technique. The partial purification of C6HSL inactivating quorum quenching molecule resulted in maximum pigment inhibition of C. violaceum 2656 at 80% saturation of ammonium sulphate. These findings revealed that S. marcescens subsp. sakuensis KRED and S. nematodiphila are found to be potential candidates to control biofilms in bacterial human pathogens.

Soil metal pollution is a major issue all over the world due to rapid urbanization and industrialization. Heavy metals, such lead, cadmium, mercury, chromium, and arsenic, are directly discharged into soil due to many industrial activities and mining processes. The persistence of toxic heavy metals in the soil environment is a serious threat to the natural environment and human health. Thus management of soil metal pollution is highly recommended. The use of conventional physicochemical methods is restricted due to their several disadvantages. In this chapter, a biological approach has been described for the removal of heavy metals from contaminated soils due to its several advantages. The impact of heavy metals on human health has been highlighted. Various metal sources for soil contamination have been explained. Heavy metal tolerance mechanisms in bacteria have been reviewed. Bioremediation of heavy metal-contaminated soils by plant growth-promoting bacteria has been described. Different strategies for heavy metal remediation have been explained in this chapter for the future development and improvement in soil bioremediation technology.

Yarrowia lipolytica is non-conventional dimorphic yeast that has been considered as generally regarded as safe (GRAS). This yeast has several biotechnological applications. Some special physiological and biochemical characteristics of this yeast make them eligible for food-related applications. This chapter focused on several food-related applications of Y. lipolytica. Applications of Y. lipolytica in meat, dairy products and cheeses manufacturing has been discussed in detail. The role of this yeast in the improvement of textures and flavours of several food products has been explained. Further Y. lipolytica has potential to produce valued-added products such as organic acids, aroma compounds, emulsifiers and biosurfactants which have food-related applications. A significant value of Y. lipolytica as a food supplement, single-cell protein (SCP) and single-cell oil (SCO) has been dealt in this chapter. At the end, the role of Y. lipolytica in bioremediation of food waste has been highlighted.

Citric acid is one of the extensively used organic acids in many industries. There is a worldwide demand for citric acid consumption due to their many industrial applications. It is also considered as a Generally Recognized As Safe (GRAS) compound. In this review, current developments in microbial fermentation processes for citric acid production have been discussed. In food, beverages, milk and sugar processing several biodegradable organic waste materials are generated in large quantities. These include sugarcane bagasse, grape pomace, apple pomace, pineapple pomace, vegetables, tapioca, coconut husk, banana peels, citrus peels, whey and decaying fruits are found to be potential substrates for citric acid production. A significant effect of substrate concentration, inorganic salts, initial sugar concentration, moisture and additives etc on citric acid production have been highlighted for further improvement in fermentation process. Recent developments in upstream and downstream processes for citric acid production are also deeply discussed. This review gives insights for future possibilities of cost effective fermentation process for citric acid production from several cheap raw materials. Formation of citric acid as an industrial byproduct will help to tackle waste disposal issue and also reduce the dependency of industry over other citric acid producers. Thus, the industry would be benefitted ecologically and economically.

The marine dimorphic yeast Yarrowia lipolytica has been proposed as a suitable model for the dimorphism study. In this study, the morphological behaviour of two marine strains of Y. lipolytica (NCIM 3589 and NCIM 3590) was studied under stress of different heavy metals. Scanning electron microscopy was used to investigate the morphological features of yeast cells. This study revealed that the normal ellipsoidal shape of yeast cells was changed into oval, rounded, or elongated in response to different heavy-metal stress. Light microscopy was also used to investigate individual properties of yeast cells. The average cell length and radius of both marine strains was increased with increasing concentrations of heavy-metal ions. In addition, the elongation factor was calculated and was increased in the presence of heavy metals like Pb(II), Co(II), Cr(III), Cr(VI), and Zn(II) under the static conditions.

Polycarbonate (PC) films were irradiated by 100 MeV gold (Au 7+ ) ions and characterized to study changes in its optical, chemical, surface morphology and thermal properties. UV–Visible spectroscopic results revealed the decrease in the optical band gap of PC after ion irradiation due to chain scission mainly at the carbonyl group which is corroborated by Fourier Transform Infrared spectroscopic results. X-ray diffractogram study showed decrease in crystallinity of PC film after irradiation. Scanning electron microscopic results showed the micropores formation in PC which results in surface roughening. Differential scanning calorimetric results revealed decrease in glass transition temperature indicating the decrease in molecular weight of PC corroborated by rheometric studies. PC films irradiated by 100 MeV Au 7+ ions showed increased anti-biofilm activity against the human pathogen, Salmonella typhi ( S. typhi ). Morphology of S. typhi was changed due to stress of Au 7+ irradiated PC. Cells length was increased with increasing fluences. The average cell length, cell volume and surface area was increased significantly (P 7+ irradiated PC.

In the present study, gold nanoparticles (AuNPs) synthesis was carried out by using a rare bacteriophage which is morphologically similar to 7–11 phages of the C3 morphotype of tailed phage belonging to Podoviridae family as green route. Effect of various physiological parameters like pH, temperature and concentration of gold chloride salt on AuNPs synthesis was studied. The reaction mixtures have shown vivid colours at various physiological parameters. Phage inspired AuNPs were further characterized by using different techniques such as UV–Vis spectrophotometry, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and dynamic light scattering (DLS). DLS study revealed synthesis of various sizes of AuNPs in the range of 20–100 nm. SEM studies revealed synthesis of varied shaped AuNPs, viz., spheres, hexagons, triangles, rhomboids and rectangular etc. The presence of Au in the nanostructures was confirmed by EDS. The XRD pattern reflects the crystalline nature and nano size of AuNPs. These phage inspired AuNPs showed anti-bacterial activity against different bacterial pathogens. Anti-biofilm activity of AuNPs was evaluated on a glass slide. It was noticed that at 0.2 mM concentration of these AuNPs about 80% of biofilm formation by Pseudomonas aeruginosa, a human pathogen was inhibited. Thus, the phage inspired AuNPs synthesis could be potential therapeutic agents against human pathogens.

In the present study, bio-inspired Ag–Au nanocomposite was synthesized using banana peel extract (BPE) powder. The Ag–Au nanocomposite was characterized using various techniques such as UV–vis spectrophotometry, transmission electron microscopy (TEM) attached with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Efficiency of AuNPs, AgNPs and Ag–Au nanocomposite was tested for their antibacterial activity against Pseudomonas aeruginosa NCIM 2948. The Ag–Au nanocomposite exhibits enhanced antimicrobial activity over its monometallic counterparts. Anti-biofilm activity of AgNPs, AuNPs and Ag–Au nanocomposite against P. aeruginosa was evaluated on glass surfaces. The Ag–Au nanocomposite exhibited the highest biofilm reduction (70–80%) when compared with individual AgNPs and AuNPs. Effect of AuNPs, AgNPs and Ag–Au nanocomposite on biofilm formation was evaluated in 96 wells microtiter plates. The percentage of biofilm inhibition was sharply increased with increasing concentration of AuNPs, AgNPs and Ag–Au composite. However, Au–Ag nanocomposite showed the highest biofilm inhibition when compared with individual AuNPs and AgNPs. This synergistic anti-biofilm activity of Ag–Au nanocomposite has an importance in the development of novel therapeutics against multidrug-resistant bacterial biofilm.

Polycarbonate (PC) polymers were investigated before and after high energy heavy ion irradiation for anti-bacterial properties. These PC films were irradiated by Fe heavy ions with two energies, viz, 60 and 120 MeV, at different fluences in the range from 1 × 1011 ions/cm2 to 1 × 1013 ions/cm2. UV-Visible spectroscopic results showed optical band gap decreased with increase in ion fluences due to chain scission mainly at carbonyl group of PC which is also corroborated by Fourier transform infrared spectroscopic results. X-ray diffractogram results showed decrease in crystallinity of PC after irradiation which leads to decrease in molecular weight. This is confirmed by rheological studies and also by differential scanning calorimetric results. The irradiated PC samples showed modification in their surfaces prevents biofilm formation of human pathogen, Salmonella typhi.

Gold nanoparticles (AuNPs) are ‘smart nanomaterials’ with a variety of applications in the different fields. The conventional methods used for AuNPs have some drawbacks and therefore, search of an alternative ‘green method’ is of high importance. In this study, Acinetobacter baumannii AB01 isolated from an infected apple sample was used as a green route for AuNPs synthesis. Effect of various physicochemical parameters such as pH, temperature, cell density and gold chloride salt concentrations on AuNPs synthesis was studied. These AuNPs were further characterized by UV–Vis spectrophotometer, transmission electron microscopy (TEM), energy dispersive spectroscopy, X-ray diffraction and dynamic light scattering. TEM images study showed presence of an extracellular polymeric substance around cells of A. baumannii AB01. The synthesized biogenic AuNPs were tested for their antibacterial activity by well diffusion method. Anti-biofilm efficacy of AuNPs was tested on the glass slide surfaces against the biofilms of Pseudomonas aeruginosa, Vibrio cholera and Brevibacterium linens and visualised by using a fluorescence microscopy. Biofilm formation was reduced about 60–80 % when compared with control biofilm (without AuNPs). Effect of different AuNPs concentrations on biofilm formation in microtiter plates was studied by 96-well plate assay. The bacterial biofilm inhibition (%) was increased with increasing concentrations of AuNPs.

Recently, biosorption processes have received considerable attention for the removal of heavy metals from the aqueous environment. Thus, the selection of biomass for biosorption is a major challenge for developing cheaper and more effective technology. Actinobacteria are directly involved in plant growth promotion, by stimulating hormones and improving nutrient acquisition in plants. Also, Actinobacteria are reported to alleviate biotic/abiotic stress in plants. The biomass of Actinobacteria has been considered as efficient, eco-friendly, and cost-effective potential candidate for biosorption of heavy metals as they have the potency to produce secondary metabolites and enzymes, the main factors essential for environmental stress tolerance. They are reported to possess metal detoxification capabilities such as soil acidification and production of metal mobilizing/immobilizing substances, and are hence considered as a bio-tool for phytoremediation. The principles and methodologies used in management of heavy metals by using the Actinobacteria system are summarized in this book chapter. Adsorption capacities, mechanisms, isotherms, equilibrium models, and kinetics are described in this chapter.

Heavy metal tolerance of two marine strains of Yarrowia lipolytica was tested on solid yeast extract peptone dextrose agar plates. Based on minimum inhibitory concentration esteems, it is inferred that the two strains of Y. lipolytica were tolerant to heavy metals such as Pb(II), Cr(III), Zn(II), Cu(II), As(V), and Ni(II) ions. The impact of various heavy metal concentrations on the growth kinetics of Y. lipolytica was likewise assessed. With increased heavy metal concentration, the specific growth rate was reduced with delayed doubling time. Furthermore, biofilm development of both yeasts on the glass surfaces and in microtitre plates was assessed in presence of different heavy metals. In microtitre plates, a short lag phase of biofilm formation was noticed without the addition of heavy metals in yeast nitrogen base liquid media. A lag phase was extended over increasing metal concentrations of media. Heavy metals like Cr(VI), Cd(II), and As(V) are contrastingly influenced on biofilms' formation of microtitre plates. Other heavy metals did not much influence on biofilms development. Thus, biofilm formation is a strategy of Y. lipolytica under stress of heavy metals has significance in bioremediation process for recovery of heavy metals from contaminated environment.

Yarrowia lipolytica is known to synthesize cell-associated gold nanoparticles. Melanin, a pigment associated with the yeast, was identified as a factor responsible for nanoparticle synthesis. Cell-extracted melanin as well as that induced by incubating cells with 3,4-dihydroxy- l -phenylalanine ( l -DOPA) mediated the synthesis of gold nanoparticles (AuNPs). These nanoparticles were characterized by a variety of standard techniques. This report identifies one of the molecular mechanisms involved in nanoparticle synthesis by Y. lipolytica . The nanoparticles thus synthesized were effective antibiofilm agents.

Highlights: ► Pomegranate leaf extracts mediated rapid gold nanoparticle (AuNP) synthesis. ► The phyto-inspired AuNPs were size-tuned and characterized. ► The reducing and capping agents in the extract were identified. ► The nanoparticles reacted specifically with arsenate (V) ions. - Abstract: When pomegranate leaf extracts were incubated with chloroauric acid (HAuCl{sub 4}), gold nanoparticles (AuNPs) were synthesized. These were characterized by a variety of techniques. With an increasing content of the leaf extract, a gradual decrease in size and an increase in monodispersity were observed. Transmission electron microscope (TEM) images showed that the phyto-fabricated AuNPs were surrounded by an amorphous layer. Gallic acid in the extract mediated the reduction and a natural decapeptide capped the nanostructures. Blocking of thiol groups in the decapeptide cysteine residues caused the nanoparticles to aggregate. On interaction with arsenate (V) ions, the UV–vis spectra of the nanoparticles showed a decrease in intensity and a red-shift. Energy dispersive spectra confirmed the presence of arsenate associated with the AuNPs. Thus, by using these AuNPs, a method for sensing the toxic arsenate ions could be developed.

The removal of hexavalent chromium [Cr (VI)], an important ground water pollutant by phyto-inspired Fe(0)/Fe(3)O(4) nanocomposite-modified cells of Yarrowia lipolytica (NCIM 3589 and NCIM 3590), was investigated. Electron microscopy and magnetometer studies indicated an effective modification of yeast cell surfaces by the nanocomposites. The effect of pH, temperature, agitation speed, contact time and initial metal ion concentration on the removal of Cr (VI) was determined. The specific uptake values at pH 2.0 were 186.32±3.17 and 137.31±4.53 mg g(-1) for NCIM 3589 and NCIM 3590, respectively, when 1000 mg L(-1) of metal ion concentrations were used. The equilibrium data fitted to Scatchard, Langmuir and linearized Freundlich models suggesting that adsorption played a role in the removal of Cr (VI) ions. The surface modified yeast cells displayed higher values of Langmuir and Scatchard coefficients than the unmodified cells indicating that the former were more efficient in Cr (VI) removal. The enhanced detoxification of Cr (VI) ions by this composite material could be attributed to the reductive power of the Fe(0)/Fe(3)O(4) nanocomposites as well the yeast cell surface functional groups.

A few soda-lime glass samples with a 1 cm2 area and 0.1 cm thickness were dipped into a molten salt bath of copper sulfate and sodium sulfate in a molar ratio of 54:46 at 545°C for 10 min. These samples were irradiated with 6 MeV energy electrons in the fluence range from 10 × 1014 to 40 × 1014 electrons/cm2 and annealed at 400°C. The optical properties and the corresponding induced effects were characterized by techniques such as ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The UV-Vis absorption spectra showed two peaks, one at 754 nm and other centered at 533 nm. The absorption peak at 754 nm was ascribed to Cu+2 ions, and the one at 553 nm corresponded to the surface plasmon resonance (SPR) band of nanocrystalline copper clusters. The intensity and the full-width at half maximum (FWHM) of the optical absorption peaks increased with an increase in the electron fluence. The XRD spectra showed a peak at 2θ positi...

Zinc oxide (ZnO) nanoparticles were synthesized by a microwave method and were tailored using an energy electron irradiation method at 6.5 MeV. ZnO nanoparticles with a size of 40 nm were exposed to different fluences of 6.5 MeV electrons over the range from 5 × 1014 to 3.5 × 1015 electron/cm2. These electron-irradiated ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The XRD results showed that the ZnO nanoparticles retained the hexagonal phase with a wurtzite structure. However, the particle size decreased continuously from 40 to 15 nm with increasing electron fluence. The TEM results also supported for the reduction of the ZnO nanoparticles by 6.5 MeV electron irradiation. The antimicrobial activities of the as-synthesized and electron-irradiated ZnO nanoparticles on the fungus Candida albicans were studied. In this case, the electron-irradiated ZnO nanoparticles showed higher antimicrobi...

Abstarct The removal of Ni (II) ions from aqueous solutions by two strains of Yarrowia lipolytica (NCIM 3589 and NCIM 3590) under different environmental conditions was studied. Biosorption of Ni (II) was enhanced with an increase in pH, temperature, agitation, contact time and initial concentration of the metal ion. NCIM 3589 and NCIM 3590 at pH 7.5 in the presence of 1000 mg L −1 Ni (II) at 35 °C exhibited a maximum uptake of 95.33 mg g −1 and 85.44 mg g −1 , respectively. The experimental data fitted well to the Langmuir as well as the Freundlich isotherms. Dubinin-Radushkevich (D-R) isotherms suggested that a chemical ion-exchange mechanism was involved in the biosorption process. The biosorption process followed the pseudo-second-order kinetic mechanism with liquid film diffusion being the rate limiting step. Fourier transform infra red (FTIR) spectroscopic studies suggested the possible involvement of hydroxyl, caboxyl, carbonyl and amino groups in process of biosorption. Scanning electron microscopy and energy dispersive spectra (SEM–EDS) confirmed biosorption of Ni (II).

Silica nanostructures were phyto-fabricated on different surfaces by using pomegranate (Punica granatum) leaf extracts. On zinc films, nanowires were obtained. On other surfaces such as silica, alumina, zinc oxide, and glass, spherical aggregates, cubic assemblies, microflakes, and acicular structures, respectively, were observed. The nanowires developed on Zn surfaces were characterized by scanning electron microscope-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), photoluminescence, and Fourier transform infrared (FTIR) spectroscopic analysis. XRD profiles displayed peaks at 2.4, 4.9, and 12.1° indicating the presence of silica nanostructures. When excited at 340 nm, the reaction mixtures displayed a characteristic blue luminescence at 404 nm. FTIR spectra showed the existence of Si-OH and Si-O-Si bonds. The nanowires were functionalized with amine groups and used for the covalent immobilization of Candida rugosa lipase. The immobilized enzyme displayed better pH and temperature stability and retained 80% activity after 20 cycles. This paper highlights a novel route for the phyto-mediated growth of silica nanowires on Zn surfaces, their characterization and effective use as a matrix for enzyme immobilization.

Bio-inspired silver nanoparticles were synthesized with the aid of a novel, non-toxic, eco-friendly biological material namely, banana peel extract (BPE). Boiled, crushed, acetone precipitated, air-dried peel powder was used for reducing silver nitrate. Silver nanoparticles were formed when the reaction conditions were altered with respect to pH, BPE content, concentration of silver nitrate and incubation temperature. The colorless reaction mixtures turned brown and displayed UV–visible spectra characteristic of silver nanoparticles. Scanning electron microscope (SEM) observations revealed the predominance of silver nanosized crystallites after short incubation periods. When the reaction mixtures were incubated for 15 days, some micro-aggregates were also observed. Energy dispersive spectrometer (EDS) studies and X-ray diffraction analysis confirmed the presence of silver nanoparticles. Fourier transform infra-red spectroscopy (FTIR) indicated the role of different functional groups (carboxyl, amine and hydroxyl) in the synthetic process. These silver nanoparticles displayed antimicrobial activity against fungal as well as bacterial cultures.

Paper mulberry (Broussonetia papyrifera) leaf powder was used to remove heavy metal ions from aqueous solutions. The specific uptakes of Cu (II), Pb (II), and Cd (II) by the leaf powder were 43.40 ± 0.2, 43.9 ± 0.5, and 30.65 ± 0.9 mg g−1, respectively, when 500 mg L−1 of the metal solutions were used. The data fitted well to the Langmuir isotherm. The process followed the pseudo-second-order kinetic equation and intraparticle diffusion played an important role in the adsorption process. On the basis of the calculated thermodynamic parameters such as standard enthalpy (ΔH°), entropy (ΔS°) and free energy change (ΔG°), it was inferred that the sorption process was endothermic and spontaneous in nature. The surface properties of the leaf powder (revealed by scanning electron microscopic observations) were suitable for the metal adsorption process. Energy dispersive X-ray fluorescence analysis confirmed the sequestration of the metal ions by the leaf powder. Fourier transform infrared spectroscopy implicated that different functional groups on the leaf powder were involved in the metal adsorption process. The results obtained from this study implicated that the B. papyrifera leaf powder was a good choice as a metal adsorbent. This abundantly available natural and eco-friendly biosorbent could be effectively used to develop a technology in the future.

Yarrowia lipolytica is a fungus that degrades hydrophobic substrates very efficiently. The fungus displays several important characteristics that have encouraged researchers to study various basic biological and biotechnological applications in detail. Although the organism has been used as model system for studying dimorphism, salt tolerance, heterologous protein expression, and lipid accumulation, there are no recent reviews on the environmental and industrial applications of this organism. Included here are applications in bioremediation of environments contaminated with aliphatic and aromatic compounds, organic pollutants, 2,4,6-trinitrotoluene, and metals. A variety of industrially important recent processes for the synthesis of beta-hydroxy butyrate, L-dopa, and emulsifiers have also been reviewed. Production of unique inherent enzymes (inulinases, alpha-mannosidases), novel applications of esterases and lipases, and the use of the fungus for heterologous expression of biotechnologically relevant products have also been highlighted. The review while entailing a general overview focuses critically on some of the recent advances on the applications of this yeast. The examples cited here demonstrate the use of wild-type, mutant as well as genetically manipulated strains of Y. lipolytica for the development of different products, processes, and technologies. This also throws light on how a single organism can be versatile with respect to its metabolic abilities and how it can be exploited for a variety of purposes. This review will thus form a base for future developments in this field.

Gold nanoparticles (Au-NPs) were synthesized from chloroauric acid using cell free supernatant of Streptomyces sp. NK52 grown in nutrient broth. These nanoparticles were synthesized by varying pH and temperature of the reaction mixture and chloroauric acid concentration. The nanoparticles were characterized by spectrometry, X-ray diffraction, Scanning electron microscopy and energy dispersive spectrometry. Au-NP ranged from 10-100 nm in size and exhibited a polydispersive nature with various shapes like rods, hexagons, triangles, spheres. The diffraction peaks at 2theta = 38.1 degrees and 44.5 degrees could be assigned to the (1 1 1) and (2 0 0) planes of a faced centre cubic (fcc) lattice of gold. Au-NP showed 47% inhibition of lipid peroxidation in vitro. To the best of our knowledge, this is the first report on the rapid biosynthesis of Au-NP using cell free supernatant of Streptomyces sp. and its evaluation for anti-lipid peroxidation.

Bio-inspired palladium nanoparticles were synthesized by using banana peel extract (BPE), a non-toxic eco-friendly material. Boiled, crushed, acetone precipitated, air-dried peel powder was used to reduce palladium chloride. The palladium nanoparticles were characterized by using UV–Visible spectroscopy, scanning electron microscope-energy dispersive spectra (SEM-EDS) and X-ray diffraction (XRD) analysis. Dynamic light scattering (DLS) studies revealed the average size of nanoparticles to be 50 nm. Fourier transform infra red spectroscopy (FTIR) implicated the role of carboxyl, amine and hydroxyl groups in the synthetic process. This paper thus describes a novel green method for the synthesis of palladium nanoparticles.

A lytic phage of Salmonella serovar Paratyphi B, named φSPB, was isolated from surface waters of the Pavana River in India. Phage φSPB is a member of the Podoviridae family and is morphologically similar to the 7-11 phages of the C3 morphotype of tailed phages, characterized by a very long, cigar-shaped head. The head measured approximately 153 × 57 nm, and the tail size was 12 × 7 nm. The phage was stable over a wide range of pH (4–9) and temperature (4–40 °C). The adsorption rate constant was 4.7 × 10−10. Latent and eclipse periods were 10 and 15 min, respectively, and the burst size was 100 plaque-forming units/infected cell after 25 min at 37 °C. The phage DNA was 59 kb in size. Ten major proteins were observed on SDS–PAGE, although some of these proteins could be bacterial contaminants. This is the first report of Salmonella enterica subsp. enterica serovar Paratyphi B phage of C3 morphotype from India that has many unique features, such as high replication potential, short replication time, and stability over a wide range of pH and temperature, making it a promising biocontrol agent against the drug-resistant strains of Salmonella Paratyphi B.

A psychrotrophic marine strain of the ascomycetous yeast Yarrowia lipolytica (NCYC 789) synthesized silver nanoparticles (AgNPs) in a cell-associated manner. These nanostructures were characterized by UV-Visible spectroscopy and scanning electron microscope-energy dispersive spectrometer (SEM-EDS) analysis. The brown pigment (melanin) involved in metal-interactions was obtained from the cells. This extracted pigment also mediated the synthesis of silver nanoparticles that were characterized by a variety of analytical techniques. The melanin-derived nanoparticles displayed antibiofilm activity. This paper thus reports the synthesis of AgNPs by the biotechnologically important yeast Y. lipolytica; proposes a possible mechanism involved in the synthetic process and describes the use of the bio-inspired nanoparticles as antibiofilm agents.

Fly ash collected from an Indian thermal power plant was characterised by scanning electron microscope (SEM)-energy dispersive spectrometer, X-ray diffraction and energy dispersive X-ray fluorescence analysis. The effect of fly ash on the growth and morphology of a metal-tolerant tropical marine yeast, Yarrowia lipolytica NCIM 3589, was studied. The growth of the yeast was unaffected by the presence 0.1, 0.2 or 0.3 % fly ash although the surface-to-volume ratio decreased. The yeast formed biofilms on immobilized fly ash as evidenced by SEM observations. The organism produced citric acid and additional extracellular proteins in the presence of fly ash. Leaching of metals from fly ash by Y. lipolytica was compared with chemical leaching by citric acid. Yeast cells were most effective in leaching Cu (59.41 %) although other metals (Zn, Ni, Cu and Cr) were also extracted. Transmission electron microscope images showed the deposition of metals at the cell wall, cell membrane and in the cytoplasm. This paper thus reports a potential application of Y. lipolytica for removal of different metals from solid waste material (fly ash).

In recent years, the management of heavy metal pollution has become a major issue. Toxic heavy metals pose a serious threat to the environment and living forms. A number of conventional methods have been developed for the recovery of toxic heavy metals. On account of some disadvantages associated with these methods, biosorption onto microbial biomass has become an attractive alternative. Among microorganisms, yeasts have received considerable attention on account of yeast biomass being easily obtainable from inexpensive media. This is also abundantly generated as a by-product from the fermentation industry. Based on the published literature, the principles, methodologies and techniques involved in the management of heavy metals by yeast systems are summarized in this chapter. Adsorption capacities of different yeasts for a variety of heavy metals have been compared. Dependence of yeast biomass metal-binding capacities on parameters such as pH, temperature, contact time, competitive metal ions, agitation, initial metal ions and biomass concentrations have been explained. Isotherms, equilibrium models and kinetics have also been extensively discussed. Mechanisms involved in the biosorption by yeasts and the future prospects of this biotechnologically relevant topic have been highlighted.

Gold nanoparticles were synthesized by using banana peel extract (BPE) as a simple, non-toxic, eco-friendly 'green material'. The boiled, crushed, acetone precipitated, air-dried peel powder was used to reduce chloroauric acid. A variety of nanoparticles were formed when the reaction conditions were altered with respect to pH, BPE content, chloroauric acid concentration and temperature of incubation. The reaction mixtures displayed vivid colors and UV-vis spectra characteristic of gold nanoparticles. Dynamic light scattering (DLS) studies revealed that the average size of the nanoparticles under standard synthetic conditions was around 300nm. Scanning electron microscopy and energy dispersive spectrometry (EDS) confirmed these results. A coffee ring phenomenon, led to the aggregation of the nanoparticles into microcubes and microwire networks towards the periphery of the air-dried samples. X-ray diffraction studies of the samples revealed spectra that were characteristic for gold. Fourier transform infra red (FTIR) spectroscopy indicated the involvement of carboxyl, amine and hydroxyl groups in the synthetic process. The BPE mediated nanoparticles displayed efficient antimicrobial activity towards most of the tested fungal and bacterial cultures.

The removal of chromium (VI) ions from aqueous solutions by the biomass of two marine strains of Yarrowia lipolytica (NCIM 3589 and 3590) was studied with respect to pH, temperature, biomass, sea salt concentration, agitation speed, contact time and initial concentration of chromium (VI) ions. Maximum biosorption was observed at pH 1.0 and at a temperature of 35 degrees C. Increase in biomass and sea salts resulted in a decreased metal uptake. With an agitation speed of 130 rpm, equilibrium was attained within 2h. Under optimum conditions, biosorption was enhanced with increasing concentrations of Cr (VI) ions. NCIM 3589 and 3590 displayed a specific uptake of Cr (VI) ions of 63.73+/-1.3 mg g(-1) at a concentration of 950 ppm and 46.09+/-0.23 mg g(-1) at 955 ppm, respectively. Scatchard plot analysis revealed a straight line allowing the data to be fitted in the Langmuir model. The adsorption data obtained also fitted well to the Freundlich isotherm. The surface sequestration of Cr (VI) by Y. lipolytica was investigated with a scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS) as well as with ED-X-ray fluorescence (ED-XRF). Fourier transform infrared (FTIR) spectroscopy revealed the involvement of carboxyl, hydroxyl and amide groups on the cell surfaces in chromium binding.

Background Nanobiotechnology applies the capabilities of biological systems in generating a variety of nano-sized structures. Plants, algae, fungi and bacteria are some systems mediating such reactions. In fungi, the synthesis of melanin is an important strategy for cell-survival under metal-stressed conditions. Yarrowia lipolytica, the biotechnologically significant yeast also produces melanin that sequesters heavy metal ions. The content of this cell-associated melanin is often low and precursors such as L-tyrosine or 3, 4-dihydroxy-L-phenylalanine (L-DOPA) can enhance its production. The induced melanin has not been exploited for the synthesis of nanostructures. In this investigation, we have employed L-DOPA-melanin for the facile synthesis of silver and gold nanostructures. The former have been used for the development of anti-fungal paints. Methods Yarrowia lipolytica NCIM 3590 cells were incubated with L-DOPA for 18 h and the resultant dark pigment was subjected to physical and chemical analysis. This biopolymer was used as a reducing and stabilizing agent for the synthesis of silver and gold nanostructures. These nanoparticles were characterized by UV-Visible spectra, X-ray diffraction (XRD) studies, and electron microscopy. Silver nanoparticles were evaluated for anti-fungal activity. Results The pigment isolated from Y. lipolytica was identified as melanin. The induced pigment reduced silver nitrate and chloroauric acid to silver and gold nanostructures, respectively. The silver nanoparticles were smaller in size (7 nm) and displayed excellent anti-fungal properties towards an Aspergillus sp. isolated from a wall surface. An application of these nanoparticles as effective paint-additives has been demonstrated. Conclusion The yeast mediated enhanced production of the metal-ion-reducing pigment, melanin. A simple and rapid method for the extracellular synthesis of nanoparticles with paint-additive-application was developed.