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In the present study, the hydro-alcoholic and hexane extracts of the plant, Rheum australes (Family: Polygonaceae) were screened for antimicrobial activity against pathogenic and drug resistant strains. The non polar extracts did not showed any activity against any of the pathogenic strains. Amongst these extracts the hydro-alcoholic extracts of the plant, Rheum australes, showed potent antimicrobial activity against almost all the pathogens studied. These extracts also showed potent antibacterial activity against multidrug resistant Staphylococcus aureus and Pseudomonas aeruginosa in the ranges from 0.3 mg/ml to 0.7 mg/ml. The potent hydro-alcoholic extract was further subjected for isolation and characterization of potent antimicrobial compound via chromatographic and spectroscopic techniques. The pure antimicrobial compound isolated and characterized was Revandichinone. The compound was isolated as bright yellow needles, mp 2140C. The IR spectrum showed absorption bands at 3441 cm_1 (–OH), 1625 cm_1 (chelated-C¼O) and 1749 cm_1 (ester–C¼O). The compound isolated was further subjected for antimicrobial screening against pathogens at varying concentrations. Key words: Antimicrobial activity, Rheum australes, pathogenic and drug resistant strains, Revandichinone REFERENCES Agarwal A, Singhvi IJ, Bele D, Sharma K, Gupta SK, Karwani G, Kumawat M. 2011. Evaluation of steroids in face creams of different marketed brands. International J. Pharmacy & Technology. 3(2): 2480-2486. Alade PI, Irobi ON. 1993. Antimicrobial activities of crude leaf extracts of Acalypha wilkensiana. Journal of Ethnopharmacology. 39, 171-174. Harborne JB. 1993. Phytochemical method, 3rd Edition, Chapman and Hall, London. p.p. 135-203. Jaradat N, Sweileh W, Kerki S. 2004. Pharmacological investigation of plant derived pharmaceuticals in Palestine. Al- Najah Univ. J. Res. 18(1): 81-86. Mathur A, Dua VK, Prasad GBKS, Verma SK, Singh SK. 2011a. Phytochemical Investigation and In Vitro Antioxidant Activity of some medicinally important plants. International Research Journal of Pharmacy. 2(6):116-122. Mathur A, Verma SK, Singh SK, Prasad GBKS, Dua VK. 2011b. Investigation of the antimicrobial, antioxidant and anti-inflammatory activity of the compound isolated from Murraya koenigii. International Journal of Applied Biology and Pharmaceutical Technology. 2(1). Perez C, Anesini C. 1993. In vitro antimicrobial activity of Argentine folk medicinal plants against Salmonella typhii. Journal of Ethnopharmacology. 44: 41-46. Singh SK, Pandey VD, Singh A, Singh C. 2009. Antibacterial activity of seed extracts of Argemone mexicana L. on some pathogenic bacterial strains. African Journal of Biotechnology. 8(24): 7077-7081. Trease GE, Evans WC. 1989. Pharmacogonasy, 14th Edition, Brown Publication. Usman H, Abdulrahman FI and Ladan AH. 2007. Phytochemical and antimicrobial evaluation of Tribulus terrestris L. (Zygophylaceae). Growing in Nigeria. Res. J. Bio. Sci. Medwell Journals. 2(3): 244-247. Vollekova AD, Kostalova, Sochorova R. 2001. Isoquinoline Alkaloids from Mahonia aquifolium stem bark is active against Malassezia sp. Folia Microbiol. 46: 107-111 more...

Plants associate with communities of microbes (bacteria and fungi) that play critical roles in plant development, nutrient acquisition and oxidative stress tolerance. The major share of plant microbiota is endophytes which inhabit plant tissues and help them in various capacities. In this article, we have reviewed what is presently known with regard to how endophytic microbes interact with plants to modulate root development, branching, root hair formation and their implications in overall plant development. Endophytic microbes link the interactions of plants, rhizospheric microbes and soil to promote nutrient solubilization and further vectoring these nutrients to the plant roots making the soil-plant-microbe continuum. Further, plant roots internalize microbes and oxidatively extract nutrients from microbes in the rhizophagy cycle. The oxidative interactions between endophytes and plants result in the acquisition of nutrients by plants and are also instrumental in oxidative stress tolerance of plants. It is evident that plants actively cultivate microbes internally, on surfaces and in soils to acquire nutrients, modulate development and improve health. Understanding this continuum could be of greater significance in connecting endophytes with the hidden half of the plant that can also be harnessed in applied terms to enhance nutrient acquisition through the development of favourable root system architecture for sustainable production under stress conditions. more...

Herein we describe and discuss the effect of significant advantages of the alkaline earth fluoride additive SrF2 on the improvement of the kinetics, thermodynamics, and cyclability of the frontier hydrogen storage material MgH2. Strontium fluoride, SrF2, which has been used as an additive for the first time in the present study, has an elemental electronegativity difference of 3.04 (the highest amongst the fluorides) as compared to 2.38 for NbF5, one of the best-known catalysts so far for MgH2. Therefore, SrF2 is highly ionic and will readily react with MgH2, which is not only ionic but also has a polar covalent character. SrF2 reacts with MgH2 to yield magnesium fluoride (MgF2) and strontium hydride (SrH2) which act as catalysts. The present investigations have revealed that both (MgF2 + SrH2) and their graphene templated version, (MgF2 + SrH2)@Gr, work as better catalysts for MgH2 than NbF5. Thus the desorption of H2 from ball-milled MgH2 catalyzed by (MgF2 + SrH2) corresponds to 5.30 wt% in 15 min, and for (MgF2 + SrH2)@Gr the desorption is 6.01 wt% in 15 min at 290 °C. Also, the onset desorption temperatures for MgH2 with (MgF2 + SrH2) and (MgF2 + SrH2)@Gr catalysts are 261 °C and 231 °C, respectively, which are 95 °C and 125 °C lower than that for ball-milled MgH2. The H2 absorption for (MgF2 + SrH2) catalyzed MgH2 is found to be 6.00 wt% in 5 min at 290 °C. For (MgF2 + SrH2)@Gr catalyzed MgH2 the hydrogen absorption is 6.16 wt% in 2 min at 290 °C. The change in desorption enthalpy for MgH2–(MgF2 + SrH2)@Gr is 67.60 kJ mol−1 as compared to 74.84 kJ mol−1 for MgH2–(MgF2 + SrH2). The storage capacity for MgH2–(MgF2 + SrH2)@Gr remains ∼6.00 wt% even after 15 cycles, which corresponds to excellent cyclability. A feasible catalytic mechanism arising from (MgF2 + SrH2) and (MgF2 + SrH2)@Gr catalysts on hydrogen sorption in MgH2 has been proposed based on X-ray diffraction, Raman spectroscopy, Fourier transmission infrared spectroscopy, and transmission/scanning electron microscopic studies. The present study is the first of its type where absorption/desorption kinetics, thermodynamics, and cyclability for MgH2 have all been improved by the use of the single additive SrF2 and the derived catalyst MgF2 + SrH2. more...

The goal of this study was to evaluate the role of seed inhabiting bacterial endophytes on finger millet seedling development and protection from fungal infection. This study has shown that removal of endophytic bacteria from millet seeds compromised seedling health, however, re-inoculation of the same bacterial isolates restored its growth. A total of six endophytic bacteria were isolated from surface-sterilized seeds of finger millet and molecularly identified by 16S rDNA sequencing as Paenibacillus dendritiformis (EC1), Enterobacter hormaechei (EC2), Enterobacter cloacae (EC3), Bacillus safensis (EC4), Enterobacter hormaechei (EC5), and Enterobacter hormaechei (EC6). These isolated endophytes were tested for their plant growth-promoting activities. Enterobacter strains (EC2, EC3, EC5 and EC6) were found positive for IAA (Indole acetic acid) test and showed phosphate as well as potassium solubilization activities while siderophore production was shown by EC1 and EC4. Antifungal activity was also evaluated with isolate EC1 showing inhibition against all the tested phytopathogens. In seedling protection assay, bacterial endophytes significantly reduced the infection from Fusarium oxysporum. Re-inoculation experiment was carried out and it was found that bacterial strains EC1, EC4, and EC5 were most active in seedling development of finger millet, showing considerable improvement in root-shoot lengths, fresh weights and content of chlorophyll pigments. Endophytic bacterial colonization in the seedling roots was observed using fluorescent microscopy. This study reports the presence of endophytic bacteria inside seeds of finger millet having stimulatory effects on its growth and development. more...

In this paper, we report here the hydrogen storage capacity of activated carbon aerogel synthesized by ambient pressure drying using a new catalyst. The carbon aerogel (CA) has been synthesized by the sol-gel method using resorcinol (R) and formaldehyde (F). For drying of RF wet gel instead of expensive and unsafe supercritical process, we have used ambient pressure drying. To avoid shrinkage which may occur due to this mode of drying, instead of usual catalyst (C): Na2CO3, organic catalyst triethylamine (TEA), which is known to be a condensing agent has been used. In order to find out the effect of change of R/C ratio on hydrogen sorption, three different R/C namely CA 1000, CA 2000, and CA 3000 were taken. Structural and microstructural details have been studied employing XRD, SEM, TEM, nitrogen adsorption, FTIR, and Raman spectroscopy. TEM and nitrogen adsorption studies have revealed that aerogel with R/C 1000 exhibits a higher degree of micropore density. The hydrogen storage capacities for all R/C ratios have been determined. It has been found that carbon aerogel (CA) with R/C = 1000, exhibits the highest hydrogen adsorption capacity out of the three aerogels. At liquid nitrogen temperature, the hydrogen storage capacity of aerogel with R/C = 1000 for the as-synthesized and activated carbons have been found to be 4.00 wt % and 4.80 wt %. A viable reason for the occurrence of high hydrogen storage capacity at liquid nitrogen temperature for aerogel with R/C = 1000 has been put forward. more...

The present investigation reports the effect of TiH2 templated over graphene (TiH2@Gr) on the hydrogen sorption characteristics of MgH2/Mg. The as synthesized TiH2@Gr leads to significant effect on sorption in MgH2 by the following effects: the first is dehydrogenation of MgH2–TiH2@Gr, which leads to the conversion of some part of TiH2 into TiH1.924. TiH2 together with TiH1.924 works as a better catalyst than TiH2 alone. The second is ball-milling of TiH2@Gr, which produces defective graphene, which also works as co-catalyst. The third is anchoring of TiH2 on graphene, which does not allow the catalyst to agglomerate. The catalytic effect of TiH2@Gr on MgH2 is found to be better than Ti@Gr and TiO2@Gr. The onset desorption temperature for MgH2–TiH2@Gr is ~204 °C, which is 31 °C and 36 °C lower than MgH2–Ti@Gr, MgH2–TiO2@Gr respectively. The better catalytic behavior of TiH2@Gr also persists during de/re-hydrogenation kinetics and cycling study of MgH2. The feasible mechanism for superior catalytic for TiH2@Gr on MgH2 has been put forward. more...

The genus Burkholderia has proven potential in improving plant performance. In recent decades, a huge diversity of Burkholderia spp. have been reported with diverse capabilities of plant symbiosis which could be harnessed to enhance plant growth and development. Colonization of endophytic Burkholderia spp. have been extensively studied through techniques like advanced microscopy, fluorescent labelling, PCR based assays, etc., and found to be systemically distributed in plants. Thus, use of these biostimulant microbes holds the promise of improving quality and quantity of crops. The endophytic Burkholderia spp. have been found to support plant functions along with boosting nutrient availability, especially under stress. Endophytic Burkholderia spp. improve plant survival against deadly pathogens via mechanisms like competition, induced systemic resistance, and antibiosis. At the same time, they are reported to extend plant tolerance towards multiple abiotic stresses especially drought, salinity, and cold. Several attempts have been made to decipher the potential of Burkholderia spp. by genome mining, and these bacteria have been found to harbour genes for plant symbiosis and for providing multiple benefits to host plants. Characteristics specific for host recognition and nutrient acquisition were confirmed in endophytic Burkholderia by genomics and proteomics-based studies. This could pave the way for harnessing Burkholderia spp. for biotechnological applications like biotransformation, phytoremediation, insecticidal activity, antimicrobials, etc. All these make Burkholderia spp. a promising microbial agent in improving plant performance under multiple adversities. Thus, the present review highlights critical roles of endophytic Burkholderia spp., their colonization, alleviation of biotic and abiotic stresses, biotechnological applications and genomic insights. more...

Endophytic microbiota opens a magnificent arena of metabolites that served as a potential source of medicines for treating a variety of ailments and having prospective uses in agriculture, food, cosmetics, and many more. There are umpteen reports of endophytes improving the growth and tolerance of plants. In addition, endophytes from lifesaving drug-producing plants such as Taxus, Nothapodytes, Catharanthus, and so forth have the ability to produce host mimicking compounds. To harness these benefits, it is imperative to isolate the true endophytes, not the surface microflora. The foremost step in endophyte isolation is the removal of epiphytic microbes from plant tissues, called as surface sterilization. The success of surface sterilization decides "what to grow" (the endophytes) and "what not to grow" (the epiphytes). It is very crucial to use an appropriate sterilant solution, concentration, and exposure time to ensure thorough surface disinfection with minimal damage to the endophytic diversity. Commonly used surface sterilants include sodium hypochlorite (2%-10%), ethanol (70%-90%), mercuric chloride (0.1%), formaldehyde (40%), and so forth. In addition, the efficiency could further be improved by pretreatment with surfactants such as Triton X-100, Tween 80, and Tween 20. This review comprehensively deals with the various sterilants and sterilization methods for the isolation of endophytic microbes. In addition, the mechanisms and rationale behind using specific surface sterilants have also been elaborated at length. more...

The present investigation deals with the synthesis of ternary transition metal alloy nanoparticles of FeCoNi and graphene templated FeCoNi (FeCoNi@GS) by one-pot reflux method and there use as a catalyst for hydrogen sorption in MgH2. It has been found that the MgH2 catalyzed by FeCoNi@GS (MgH2: FeCoNi@GS) has the onset desorption temperature of ~255 °C which is 25 °C and 100 °C lower than MgH2 catalyzed by FeCoNi (MgH2: FeCoNi) (onset desorption temperature 280 °C) and the ball-milled (B.M) MgH2 (onset desorption temperature 355 °C) respectively. Also MgH2: FeCoNi@GS shows enhanced kinetics by absorbing 6.01 wt% within just 1.65 min at 290 °C under 15 atm of hydrogen pressure. This is much-improved sorption as compared to MgH2: FeCoNi and B.M MgH2 for which hydrogen absorption is 4.41 wt% and 1.45 wt% respectively, under the similar condition of temperature, pressure and time. More importantly, the formation enthalpy of MgH2: FeCoNi@GS is 58.86 kJ/mol which is 19.26 kJ/mol lower than B.M: MgH2 (78.12 kJ/mol). Excellent cyclic stability has also been found for MgH2: FeCoNi@GS even up to 24 cycles where it shows only negligible change from 6.26 wt% to 6.24 wt%. A feasible catalytic mechanism of FeCoNi@GS on MgH2 has been put forward based on X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Photoelectron Spectroscopy (XPS), and microstructural (electron microscopic) studies. more...

Objective: The recent work was carried out to evaluate the presence of bioactive compounds and anticancer activities of selected plant Trigonella foenum-graecum extract. Methods: The crude extraction of whole plant was carried out using petroleum ether as a solvent by cold percolation as well as hot percolation method (Soxhlet method) both. The presence of phytochemicals was determined using standard protocols. The anticancer activities were evaluated by sulforhodamine B (SRB) dye assay method using Mitomycin-C (anticancer drug) as a positive control. Results: The qualitative analysis of plant extract showed the presence of bioactive compounds, namely, protein, alkaloids, steroids, phenolics, and flavonoids. The plant extract was tested for in vitro anticancer activity against human liver cancer (HEP-2) and colon cancer (HT-29) cell lines using SRB assay. The plant extract showed significant results against HT-29 and HEP-2 cancer cell lines. Conclusion: The study concluded that the extract of T. foenum-graecum can be further carefully used in herbal formulations for cancer therapy. more...

Biofabrication of metal nanoparticles is a cost-effective, one-step and ecofriendly technique. Cell filtrate of an endophytic fungus isolated from Nyctanthes arbor-tristis was challenged with 1 mM solution of AgNO3 for the silver nanoparticles (AgNPs) synthesis. A reduction of silver ions into AgNPs was observed by surface plasmon resonance at absorption maxima 422 nm. The average size of AgNPs was 35.05 nm. The maximum inhibition zones by AgNPs were 14 mm each against E. coli and Pseudomonas aeruginosa compared to AgNO3 solution used as control (10 mm and 9 mm). The fungus was identified as Phomopsis helianthi by the sequencing of ITS region of rDNA. This experiment demonstrates a single-step and ecofriendly method for biosynthesis of AgNPs and their usage as an antimicrobial agent. more...

Seed-vectored endophytes internally colonize plant seeds and remain without eliciting disease symptoms. Microbes are carried by seeds generation after generation to benefit the host during and following seed germination. Seed-vectored endophytes have been poorly investigated and research targeted at understanding their biology will have immense applications in agriculture and horticulture. Some reports are available on the roles of seed endophytes in plant growth promotion via nutrient acquisition and biocontrol of soil borne diseases, but mechanisms of interaction at the endophyte-host interface, especially during seed germination and seedling establishment, have not been explored adequately. The present paper is intended to review the role of seed vectored endophytes in seed germination, seedlings development and in developing the rhizosphere community. The mechanisms of interaction and movement of seed inhabiting endophytic bacteria are explained with the help of pictorial models. more...

Endophytes are the microorganisms which mutually live inside healthy plant tissues, playing important roles in promoting plant growth and providing adaptation toward various environments. Bacteria and fungi are the two major groups that have been recognized as endophytes. Endophytes have been reported to promote plant growth by improving nutrient uptake and solubilization of phosphate, potassium, nitrogen, and iron. Endophytes also biologically fix nitrogen and make it available to host plants. Endophytes produce growth-promoting phytohormones, including auxins, cytokinins, and gibberellins, and modulate the level of the growth-inhibiting hormone, ethylene, by producing 1-aminocyclopropane-1-carboxylate deaminase activity. Many endophytes also share antifungal activity and have been reported to protect plants from pathogenic microorganisms. Endophytic species of Bacillus are known to produce antifungal lipopeptides; species of Pseudomonas and Burkholderia produce a variety of antifungal secondary metabolites and HCN and protect plants from fungal infection. Thus the endophytes are natural inhabitants of plants that can be exploited as biofertilizers and biocontrol agents for sustainable cultivation of crop plants. more...

Biological-based substances, other than commercially used chemical fertilizers and pesticides, which have the capability to induce plant development and protect them from stressful situations, are called as biostimulants. The application of biostimulants in present times is needed for safe, eco-friendly agriculture, and is the base of organic farming. One of the major categories of biostimulants includes beneficial microorganisms constituting of bacterial and fungal cell inoculants and their products. Many plants-associated microbes are mutualistic symbionts of crop plants which improve their fitness and productivity by nutrient mobilization, nitrogen fixation, phytohormone production, and producing a variety of antipathogenic chemicals. These microbial symbionts and their stimulatory products may also induce host-related genes and provide tolerance against abiotic and biotic stresses. In this chapter, we will discuss the bacterial biostimulants and their role in plant growth and development, and protection from diseases. more...

Bacteria present in the rhizospheric area of the plant are called rhizospheric bacteria. Rhizospheric bacteria play crucial role in plant development and growth starting from seed germination and also protect the seedlings from fungal phytopathogens. These rhizobacteria are known to produce growth hormones; siderophore; lytic enzymes such as chitinase, lipase, protease, and β-1, 3-glucanase; organic acids; lipopeptides; volatile compounds; and some antibiotics. Some of the common rhizospheric bacteria are Pseudomonas chlororaphis, Bacillus subtilis, Bacillus licheniformis, Pseudomonas fluorescens, Chromobacterium violaceum, Bacillus cereus, and Bacillus stearothermophilus which have been found to suppress the growth of fungal pathogens including Macrophomina phaseolina, Magnaporthe grisea, and Fusarium oxysporum. Lytic enzymes such as chitinase, protease, and β-1, 3- glucanase produced by the rhizobacteria degrade the chitin, glucan, and proteins of the fungal cell wall, respectively. Secondary metabolites produced by the rhizobacteria inhibit the growth of pathogenic fungi by reducing the spore germination, swelling in fungal mycelia, making pore formation in hyphae, cytoplasmic leakages from fungal cells, and finally lysis of hyphae. Pseudomonas and Bacillus are known to induce the induced systemic resistance (ISR) in plants and make them disease resistant against phytopathogens. Millets are group of very important small grain crop which seedling establishment is affected by many soil pathogens. The present chapter is focused on the role of beneficial rhizospheric bacteria in disease suppression in millet crop. more...

Plants might have successfully originated and evolved through acquiring intimate interactions with microbes. Some of these microbes are endophytic and mutualistic to host plant and have been a source of various adaptive advantages for hosts, for example, in induction of developmental functions under stress conditions. Plant seeds are most suitable organs to recruit these microbes to get maximum symbiotic benefits. Seed-inhabiting endophytes, both bacteria and fungi, are believed to be closer and more compatible to plants. Plant recruits these persistent endophytes into their seeds, and they may be transmitted vertically from generation to generation. Seed-inhabiting endophytes benefits host plant in terms of growth promotion, improving fitness, providing protection against diseases starting from germination stage to seedling establishment, and also improving reproductive fitness of plant. Moreover, seed endophytes enter inside the plant body and stimulate expressions of growth and genes related to abiotic stress and defense. In this chapter, we discuss the ecology of seed-inhabiting bacterial and fungal endophytes and their various functional roles during seedling development. more...

The present study deals with the material tailoring of Mg(NH2)2–2LiH through dual borohydrides: the reactive LiBH4 and the non-reactive NaBH4. Furthermore, a pulverizer, as well as a catalyst FeTi, has been added in order to facilitate hydrogen sorption. Addition of LiBH4 to LiNH2 in a 1 : 3 molar ratio leads to the formation of Li4(BH4)(NH2)3 which also acts as a catalyst. However, the addition of NaBH4 doesn't lead to any compound formation but shows a catalytic effect. The onset dehydrogenation temperature of thermally treated Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4) is 142 °C as against 196 °C for the basic material Mg(NH2)2–2LiH. However, with the FeTi catalyzed Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4, it has been reduced to 120 °C. This is better than other similar amide/hydride composites where it is 149 °C (when the basic material is catalyzed with LiBH4). The FeTi catalyzed Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4 sample shows better de/re-hydrogenation kinetics as it desorbs 3.9 ± 0.04 wt% and absorbs nearly 4.1 ± 0.04 wt% both within 30 min at 170 °C (with the H2 pressure being 0.1 MPa for desorption and 7 MPa for absorption). The eventual hydrogen storage capacity of Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4 together with FeTi has been found to be ∼5.0 wt%. To make the effect of catalysts intelligible, we have put forward in a schematic way the role of Li and Na borohydrides with FeTi for improving the hydrogen sorption properties of Mg(NH2)2–2LiH. more...

An endophytic fungus isolated from photosynthetic root of Tinospora cordifolia Miers. was identified as Pseudofusicoccum adansoniae with 100% 18S ITS rRNA partial gene sequence similarity (accession JX951181). The fungus exhibited amylase, lipase and protease activities and was also able to assimilate the galactose, glucose, fructose, lactose and maltose along with l-arginine and alanine. In addition to siderophore production, the fungus was found to be tolerant against various concentrations of NO2−, NO3− and NaCl. The maximum biomass and metabolite yield were observed at pH range 5.4–7.0, whereas yield of secondary metabolites was highest in potato dextrose broth (36.66 ± 0.33 mg/100 ml) extracted through ethyl acetate (EtOAc). Interestingly, metabolites extracted through ethyl acetate from PDB and MEB grown cultures were found to be active against all 8 human bacterial pathogens used in this study. The isolation and characterization of P. adansoniae done in this experiment are the initial steps which pave the way for purified isolation of bioactive compounds and enzymes of immense use. more...

In this paper, we have reported the synthesis, characterization, and evaluation of antimicrobial and antioxidant potential of monodispersed Zinc Oxide (ZnO) nanoparticles synthesized by the room temperature precipitation (aqueous phase) and polyol method (organic phase). ZnO nanoparticle synthesized by both the methods had shown excellent DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging, metal chelating (MC), ABTS (2,2′-azino-bis; 3-ethylbenzothiazoline-6-sulphonic acid), hydroxyl radical and superoxide radical scavenging activity (SAS). Scavenging activities were assayed within a concentration range of 25–75 ng ml−1. The antibacterial activities with MIC were investigated against two Gram-positive bacteria Streptococcus mutans (MTCC 497) and S. pyogens (MTCC 1926); three Gram negative bacteria Vibrio cholerae (MTCC 3906), Shigella flexneri (MTCC 1457) and Salmonella typhii (MTCC 1252). ZnO nanoparticles synthesized by the polyol method showed better MIC values against both Gram-positive and Gram-negative bacteria as compared to particles synthesized by aqueous precipitation method. Present study demonstrates the successful synthesis of ZnO nanoparticles with antioxidant property and significant broad spectrum antibacterial activity against several clinical bacterial pathogens. more...

Bacteria from different crops and plant varieties have been shown to possess enormous growth promotional attributes. The study aimed to investigate the role of the endophytic microbiome of seeds of corn in improving the growth of seedlings of two different varieties of maize crops (K-25 and baby corn). Furthermore, the study also assessed the role of these bacteria in the protection of seedlings from fungal pathogens. Total twenty-three endophytic bacterial strains were isolated from maize seeds and identified using 16S rDNA sequencing. Most of the isolates had the ability to synthesize auxin (70 %) and solubilize phosphate (74 %), while all the isolates showed nitrogen fixation ability. Some isolates also showed antagonistic activity against phytopathogenic fungi including Rhizoctonia solani and Fusarium sp. suggesting their biocontrol potential. The presence of different lipopeptide genes including bacillomycin D, fengycin, iturin A and surfactin was confirmed in some of the isolates. We observed that treating seeds with an antibiotic compromised the seedlings’ growth; however, re-inoculation with endophytic isolates (ZM1/Lysinibacillus sp. and ZM2/Paenibacillus dendritiformis) restored the growth of the seedlings in terms of improved root and shoot development in comparison to non-inoculated controls. The colonization of inoculated bacteria on the root surface was visualized using fluorescent microscopy. Seedling protection assay showed that treated seeds (with ZMW8/ Bacillus velezensis) were protected from fungal infestation (Fusarium verticillioides) even after 12 days of inoculation in comparison to the uninoculated control. The study concludes that indigenous seed-associated bacteria of maize play a major role during seed germination, seedling formation and protect them from phytopathogens. more...

Leersia oryzoides, a wild relative of rice (Oryza sativa), may carry potential seed-borne bacterial endophytes which could be used to enhance growth of rice. We hypothesized that seed-associated bacteria from L. oryzoides would be compatible with rice and promote seedling growth, development, and survival. We isolated bacteria from seed of L. oryzoides and checked compatibility with rice as well as Bermuda grass seeds for seedling growth promotion. Internal colonisation of bacteria into root cells was observed by ROS staining and microscopic observation. Growth promoting bacteria were evaluated for IAA production, phosphate solubilization and antifungal activities. Overall, ten bacteria were found to be growth promoting in rice seedlings with effects including restoration of root gravitropic response, increased root and shoot growth, and stimulation of root hair formation. All bacteria were identified by 16S rDNA sequencing. Six bacteria were found to become intracellular in root parenchyma and root hairs in rice and in Bermuda grass seedlings. Six bacteria were able to produce IAA in LB broth with highest (47.06 ± 1.99 μg ml−1) by LTE3 (Pantoea hericii). Nine isolates solubilized phosphate and inhibited at least one soil borne fungal pathogen. Seed bacteria of L. oryzoides are compatible with rice. Many of these bacteria become intracellular, induce root gravitropic response, increase root and shoot growth, and stimulate root hair formation in both rice and Bermuda grass seedlings. Presence of bacteria protects seedlings from soil pathogens during seedling establishment. This research suggests that bioprospecting microbes on near relatives of rice and other crop plants may be a viable strategy to obtain microbes to improve cultivation of crops. more...

Fungal endophytes were isolated from leaf, bark and stem of Tectona grandis Linn.f. sampled at four geographical locations in winter, summer and monsoon seasons. The recovered 5089 isolates were assigned to 45 distinct morphotypes based on morphology. The sequences of the internal transcribed spacers (ITS) of the nrDNA of some morphotypes were identical, but morphological differences were strong enough to consider these morphotypes as separate species. Forty-three morphotypes were assigned to ascomycotina and two to basidiomycotina. Ascomycotina was the predominating group with 99.7% of total isolates followed by basidiomycotina with only 0.3% of total isolates. Diaporthe (Phomopsis) species dominated the communities independently on tissue type, location or season. More than 60% of the examined tissue pieces were colonized by members of this species complex. While these endophytes are ubiquitous others were tissue or location specific. Tissue type had the strongest effect on the species evenness of the endophytic assemblage followed by geographical location and season. However, Shannon-Wiener index (H’) significantly (p ≤ 0.001) varied with all three factors i.e. season, location and tissue type. Leaves supported the highest diversity across all the seasons and locations. In conclusion, all the three factors together determined the structure of endophytic mycobiota assemblage of T. grandis., Scientific Reports, 7, ISSN:2045-2322 more...

Aim The aim of the present study was to evaluate the effects of the removal of indigenous bacteria from rice seeds on seedling growth and development. Here we report the presence of three indigenous endophytic bacteria in rice seeds that play important roles in modulating seedling development (shoot and root lengths, and formation of root hairs and secondary roots) and defence against pathogens. Methods and Results Seed-associated bacteria were removed using surface sterilization with NaOCl (bleach) followed by antibiotic treatment. When bacteria were absent, growth of seedlings in terms of root hair development and overall seedling size was less than that of seedlings that contained bacteria. Reactive oxygen staining of seedlings showed that endophytic bacteria became intracellular in root parenchyma cells and root hairs. Roots containing endophytic bacteria were seen to stain densely for reactive oxygen, while roots free of bacteria stained lightly for reactive oxygen. Bacteria were isolated and identified as Enterobacter asburiae (VWB1), Pantoea dispersa (VWB2) and Pseudomonas putida (VWB3) by 16S rDNA sequencing. Bacteria were found to produce indole acetic acid (auxins), inhibited the pathogen Fusarium oxysporum and solubilized phosphate. Reinoculation of bacteria onto seedlings derived from surface-disinfected rice and Bermuda grass seeds significantly restored seedling growth and development. Conclusion Rice seeds harbour indigenous bacterial endophytes that greatly influence seedling growth and development, including root and shoot lengths, root hair formation and disease susceptibility of rice seedlings. Significance and Impact of the Study This study shows that seeds of rice naturally harbour bacterial endophytes that play key roles in modulation of seedling development. more...

Azadirachta indica, commonly known as neem, is an evergreen tree of the tropics and sub-tropics native to the Indian subcontinent with demonstrated ethnomedicinal value and importance in agriculture as well as in the pharmaceutical industry. This ancient medicinal tree, often called the “wonder tree”, is regarded as a chemical factory of diverse and complex compounds with a plethora of structural scaffolds that is very difficult to mimic by chemical synthesis. Such multifaceted chemical diversity leads to a fantastic repertoire of functional traits, encompassing a wide variety of biological activity and unique modes of action against specific and generalist pathogens and pests. Until now, more than 400 compounds have been isolated from different parts of neem including important bioactive secondary metabolites such as azadirachtin, nimbidin, nimbin, nimbolide, gedunin, and many more. In addition to its insecticidal property, the plant is also known for antimicrobial, antimalarial, antiviral, anti-inflammatory, analgesic, antipyretic, hypoglycaemic, antiulcer, antifertility, anticarcinogenic, hepatoprotective, antioxidant, anxiolytic, molluscicidal, acaricidal, and antifilarial properties. Notwithstanding the chemical and biological virtuosity of neem, it has also been extensively explored for associated microorganisms, especially a class of mutualists called endophytic microorganisms (or endophytes). More than 30 compounds, including neem “mimetic” compounds, have been reported from endophytes harbored in the neem trees in different ecological niches. In this review, we provide an informative and in-depth overview of the topic that can serve as a point of reference for an understanding of the functions and applications of a medicinal plant such as neem, including associated endophytes, within the overall theme of phytopathology. Our review further exemplifies the already-noted current surge of interest in plant and microbial natural products for implications both within the ecological and clinical settings, for a more secure and sustainable future. more...

The present study deals with the material tailoring of Mg(NH

Endophytes are microbes (mostly bacteria and fungi) present asymptomatically in plants. Endophytic microbes are often functional in that they may carry nutrients from the soil into plants, modulate plant development, increase stress tolerance of plants, suppress virulence in pathogens, increase disease resistance in plants, and suppress development of competitor plant species. Endophytic microbes have been shown to: (i) obtain nutrients in soils and transfer nutrients to plants in the rhizophagy cycle and other nutrient‐transfer symbioses; (ii) increase plant growth and development; (iii) reduce oxidative stress of hosts; (iv) protect plants from disease; (v) deter feeding by herbivores; and (vi) suppress growth of competitor plant species. Because of the effective functions of endophytic microbes, we suggest that endophytic microbes may significantly reduce use of agrochemicals (fertilizers, fungicides, insecticides, and herbicides) in the cultivation of crop plants. The loss of endophytic microbes from crop plants during domestication and long‐term cultivation could be remedied by transfer of endophytes from wild relatives of crops to crop species. Increasing atmospheric carbon dioxide levels could reduce the efficiency of the rhizophagy cycle due to repression of reactive oxygen used to extract nutrients from microbes in roots. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. more...

Endophytic microbes including bacteria and fungi inhabiting in seed tissues have recently gained significant importance owing to a diversity of roles that they play and eventually resulting in improved plant growth as well as plant fitness. Some of the major roles played by seed endophytic microbes include plant growth promotion by enhanced nutrient acquisition or production of growth hormones, nitrogen fixation, phosphate solubilisation, and protection against pathogens as well as abiotic stresses. Since, rice is one of the important staple crop across the globe, there is a great need to explore and decipher the roles of the endophytic community present inside it. This chapter focuses on the diversity and distribution of rice seed endophytes, their transmission along with the various functional roles that they play inside the plants with an aim to provide deep insights on rice seed endophytes as plant growth promoting and biocontrol agents. more...

In this chapter we present a hypothesis, and data supporting it, that vascular plants in diverse families possess symbiotic/endophytic bacteria that frequently vector on or within their seeds; seedlings degrade symbiotic bacteria within roots. Evidence of widespread microbivory was found in a survey for intracellular bacteria that we conducted including seedlings in 36 species of vascular plants distributed in 20 plant families. Experiments indicate that when seeds germinate, bacteria colonize seedlings and internalize into root cells where they are oxidatively-degraded in the periplasmic spaces of cells. The process of degradation of microbes in roots has been termed “rhizophagy”, and “rhizophagy cycle” or “rhizophagy symbiosis” in the case of symbiotic bacteria that alternate between a free-living soil phase and intracellular/endophytic phase. We hypothesize that microbivory could account for a significant portion of nutrients acquired by plants from soils—with one estimate suggesting that as much as 30% of the nutrients acquired by seedlings may stem from rhizophagy symbiosis. Developing a better understanding of rhizophagy symbiosis could lead to new ways to cultivate crops without reliance on excessive agrochemical applications. Learning how to manipulate rhizophagy symbiosis could result in new technologies for reducing growth of weedy or invasive plant species by inhibiting rhizophagy symbiosis. more...

This chapter discusses the roles of seed-vectored microbes in modulating seedling development and increasing fitness of plants in terms of increased biotic and abiotic stress tolerance. Particular emphasis is placed on microbes that function in the rhizophagy cycle. These microbes have been shown to enter into root cells and stimulate root growth. In some cases microbe entry into root cells results in root growth repression. The term ‘endobiome interference’ has been applied to the phenomenon of plant growth repression due to intracellular microbes. The potential application of endobiome interference to produce bioherbicides that selectively enhance growth of target crops but inhibit competitor weeds is discussed. more...

Endophytic microbes colonize plants growing in diverse habitats and play important roles in modulating development and improving fitness of host plants. Endophytes may be major components of undiscovered microbial diversity. Further, endophytes may have applications in growth promotion of crop plants and protectors of plants from biotic and abiotic stresses. Endophytes have been a source of bioactive molecules of pharmaceutical importance. Major focus areas in the investigation of endophytes include (1) assessment of endophyte diversity, (2) determining the roles played by endophytes in modulation of host plant development and (3) assessing the biotechnological potentials of endophytes. The study of endophytes is particularly challenging because endophytic microbes often go unobserved in plants, many endophytes cannot be isolated, and plants free of endophytes sometimes cannot be obtained, making it difficult to conduct experiments. In this chapter we discuss some of the methodologies that are being used to overcome challenges to the study of endophytic microbes. more...

In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the ‘rhizophagy cycle.’ In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species. We found that initially the symbiotic microbes grow on the rhizoplane in the exudate zone adjacent the root meristem. Microbes enter root tip meristem cells—locating within the periplasmic spaces between cell wall and plasma membrane. In the periplasmic spaces of root cells, microbes convert to wall-less protoplast forms. As root cells mature, microbes continue to be subjected to reactive oxygen (superoxide) produced by NADPH oxidases (NOX) on the root cell plasma membranes. Reactive oxygen degrades some of the intracellular microbes, also likely inducing electrolyte leakage from microbes—effectively extracting nutrients from microbes. Surviving bacteria in root epidermal cells trigger root hair elongation and as hairs elongate bacteria exit at the hair tips, reforming cell walls and cell shapes as microbes emerge into the rhizosphere where they may obtain additional nutrients. Precisely what nutrients are transferred through rhizophagy or how important this process is for nutrient acquisition is still unknown. more...

In this chapter, we propose a model for the early evolution of eukaryotic cells under pressure of intense endoparasitism. We define features of eukaryotes developed to defend against endoparasites (primarily bacteria), including a defensive system composed of an antioxidant sterol-enriched internal and external membrane system that could be used to entrap endoparasites and degrade them with superoxide produced on the membranes, cytoskeleton scaffolding for the membrane system, and a nuclear envelope to exclude endoparasites from reaching the genome. Mitochondria and chloroplasts evolved from the prokaryotes that developed ways to neutralize the reactive oxygen defense of the host. For mitochondria, hydrogen pumping to the exterior of the endoparasite enabled them to reduce superoxide to water, effectively defeating the host defense. Other features of eukaryotes that may have evolved from defense from endoparasitism include: autophagy, cell walls in fungi and plants, acquired immunity in animals, multicellularity, and apoptosis. We evaluate fossil data, where available, to provide additional information regarding the early evolution of eukaryotes and the prevalence of endoparasitic microbes. more...

Aim: Extracellular synthesis of silver and gold nanoparticles using aqueous cell-free filtrate (CFF) of endophytic Chaetomium globosum and characterization of its bioactive proteins. Methods: Temperature and pH gradients were used to assess their effects on dimensions of NPs. NPs were tested in vivo for antibacterial activity. MALDI-TOF-MS/MS was used for characterization of CFF proteins. Results: Fungal CFF fabricated nanoparticles of various shape under varied physicochemical conditions. Silver nanoparticles showed significantly (p ≤ 0.5) enhanced antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae compared with AgNO3. Two prominent CFF proteins showed homology with benzoate 4-monooxygenase cytochrome P450 and ubiquinol-cytochrome c reductase. Conclusion: The study achieved controlled mycosynthesis of NPs and explains the hitherto poorly known mechanism of reduction, stabilization and antibacterial activity of nanoparticles. more...