Ashutosh Pathak

Prediction and validation of gold nanoparticles (GNPs) on plant growth promoting rhizobacteria (PGPR): a step toward development of nano-biofertilizers

Abstract Several soil microbes are present in the rhizosphere zone, especially plant growth promoting rhizobacteria (PGPR), which are best known for their plant growth promoting activities. The present study reflects the effect of gold nanoparticles (GNPs) at various concentrations on the growth of PGPR. GNPs were synthesized chemically, by reduction of HAuCl4, and further characterized by UV-Vis spectroscopy, X-ray diffraction technique (XRD), and transmission electron microscopy (TEM), etc. The impact of GNPs on PGPR was investigated by Clinical Laboratory Standards Institute (CLSI) recommended Broth-Microdilution technique against four selected PGPR viz., Pseudomonas fluorescens, Bacillus subtilis, Paenibacillus elgii, and Pseudomonas putida. Neither accelerating nor reducing impact was observed in P. putida due to GNPs. On the contrary, significant increase was observed in the case of P. fluorescens, P. elgii, and B. subtilis, and hence, GNPs can be exploited as nano-biofertilizers.

Detoxification and Tolerance of Heavy Metals in Plants

Abstract Plant growth and metabolisms are regulated by some heavy metals found in Earths crust because they are active constituents of various enzymes. However, their increased concentration may lead to different toxic effects, inhibiting plant growth and development. There are some plants that are capable of surviving in the presence of heavy metals, apparently by adapting the mechanism that involved in common homeostasis as well as removal of metal ions. Plants have diverse mechanisms for metal detoxification, enabling them to tolerate heavy metal stress. The defense systems against heavy metal stress include mycorrhizae, cellular exudates, plasma membrane, heat shock proteins, phytochelatins (PCs), metallothioneins (MTs), organic acids, and amino acids. All the mechanism involved the tolerance of heavy metal concentration at cellular level to avoid the negative impacts. Extracellular plants include roles for mycorrhizae and extracellular exudates in the plasma membrane either by dropping by absorption of heavy metal or by inducing the efflux pumping of metal ions. On the other hand, intracellularly heat shock proteins, MTs, organic acids, amino acids, and PCs also play a vital role in tolerance of different heavy metals. Few metal transporters have been identified in the past few years that actively participate in tolerance of metal specificity. Enhanced application of molecular genetics has shown their eminent contribution in understanding the mechanism of heavy metal tolerance in plants.

A comparative analysis of in vitro growth inhibition of waterborne bacteria with bioactive plant Lippia nodiflora L. and camphor

AbstractIn the current scenario, due to global deterioration of the environment and climate change, among them water pollution possesses serious threat to most of the populace. Waterborne pathogenic bacteria like Escherichia coli, Vibrio cholerae, Salmonella typhimurium, Klebsiella pneumoniae, etc. are responsible for several diseases such as diarrhoea, cholera, salmonellosis, etc. In order to overcome these waterborne bacterial diseases and for purification of water, plants have been of great use for their potential role from very ancient times. The present study deals with the Clinical & Laboratory Standards Institute (CLSI)-recommended broth microdilution antibacterial susceptibility assay of waterborne bacterial pathogens against Lippia nodiflora L. petroleum ether (LNPE) and ethanolic extracts (LNEE) prepared from the leaves and flowers together of Lippia nodiflora (Verbenaceae), in comparison to camphor. Growth inhibition of tested bacterial pathogens was recorded in from of IC50 and MIC values were...

Pharmaco-Phylogenetic Investigation of Methyl Gallate Isolated from Acacia nilotica (L.) Delile and Its Cytotoxic Effect on NIH3T3 Mouse Fibroblast.

Present exploration deals with the therapeutic perspective of methyl gallate isolated from the leaf extract of Acacia nilotica (L.) Delile in contrast to food-borne bacterial pathogens viz., Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, Pseudomonas aeruginosa and Staphylococcus aureus with their evolutionary succession. The extract was subjected to phytochemical analysis and isolated compound was identified as methyl gallate using UV-vis, IR and NMR spectra. It was found most potent against K. pneumoniae with its minimum inhibition concentration (MIC) of 0.32 mg/ml and minimum bactericidal concentration (MBC) at 0.62 mg/ml. The correlation of MIC values with an evolutionary succession assists the relationship between their genetic and toxic properties. The cytotoxic pursuit of methyl gallate was additionally assessed over NIH3T3 mouse fibroblast by Neutral red (NR) uptake, MTT cell proliferation assay and did not disclose any relevant influence on cell viability as well as cell proliferation. As such, the methyl gallate extracted from the leaf of A. nilotica holds massive antibacterial aptitude and hands out towards a new paradigm for food and pharmaceutical industries.

In vitro evaluation of antidermatophytic activity of five lichens

Abstract Lichens (a composite organism) are known for their secondary metabolites and have several properties as photoprotection, allelopathy, antioxidant, antimicrobial, and antiviral. In this study, based on alarming situation of prevalence and developing resistance in dermatophytes, the new biological source in the form of lichens was screened for their antidermatophytic potential. Three dermatophytes viz. Microsporum canis, Trichophyton mentagrophytes, and Trichophyton rubrum were procured from Microbial Type Cell Culture, Chandigarh, India and susceptibility of aforementioned pathogens were tested via Clinical Laboratory and Standard Institute recommended broth microdilution procedure for filamentous fungi. Five lichens viz. Bulbothrix setschwanensis, Myelochroa aurulenta, Parmotrema nilgherrense, Parmotrema reticulatum, and Ramalina conduplicans were tested for their antidermatophytic activity (fungistatic and fungicidal concentrations) in the form of MIC and MFC values. M. aurulenta exhibited most promising MIC and MFC values against all dermatophytes and provides new leads in the form of secalonic acid A and leucotylic acid for future investigations.

Land Reformation Using Plant Growth–Promoting Rhizobacteria in the Context of Heavy Metal Contamination

Abstract Our environment is surrounded with toxic substances that affect everything in several forms, especially green plants, which are the lungs of nature but grown in soil. These noxious things pollute one of the most important medium of life in earth known as the rhizosphere, which is the largest habitat of rhizobacteria on Earth. It is found in and around the roots of crop plants, enhance the crop yield by several mechanisms, and remediate the rhizosphere by eliminating the metal contaminants from soil. These metal toxicants are absorbed mainly by accumulation and biotransformation. Metal contaminations in soil is a major result of human activities such as mining and can be differentiated into three categories on the basis of their properties: reactive oxygen species, overcrowding of functional groups of biomolecules, and displacement of functional groups leading to ecotoxicological risks. The ecotoxic effects of heavy metal contamination have the ability to destroy the receptive parts of the plants and rhizospheric microbes, because once they enter in the soil, they adversely affect the food web due to the biomagnifications. The foremost soil pollutants are Al, arsenic, cadmium, chromium, mercury, lead, antimony, and selenium. The removal of soil contaminants using plant growth–promoting rhizobacteria (PGPR) is believed to be more efficient in comparison to the traditional methods because their activity persists and they have a diversity of soil microorganisms to sustain healthy environment. PGPR are known to affect heavy metals in ways such as phosphate solubilization, chelation, acidification, and redox changes ultimately changing the metal speciation, Production of phytohormones, N2 fixation, siderophores, and conversion of nutrients when they are either applied to seeds or incorporated into the soil to complete the phytoremediation process. Thus, the use of rhizobacteria in combination with plants could be a fast-developing field of research for land reform.

Synthesis and antimicrobial effects of colloidal gold nanoparticles against prevalent waterborne bacterial pathogens

Abstract Gold is being used therapeutically since 2500 BC in Chinese medical history. Red colloidal gold is still used in the Indian Ayurvedic medicine for rejuvenation and revitalization during old age under the name of Swarna Bhasma. The present research describes a more reliable method for assaying growth inhibition of some waterborne bacterial pathogens by gold nanoparticles. The gold nanoparticles were synthesized by chemical method using auric chloride as a precursor salt and sodium citrate as a reducing as well as stabilizing agent. Characterization of Au NPs was performed using UV–Vis, X-ray diffraction (XRD) and TEM (transmission electron microscope). Further, these nanoparticles were tested against four well-explored waterborne bacterial pathogens viz., E. coli, V. cholerae, S. typhimurium, S. dysenteriae, using globally accepted broth microdilution method recommended by CLSI, which exhibited a good antibacterial potency demonstrated in the form of IC50 and MIC. Subsequently, a novel phylogenetic approach for reducing the cost of experimentation was also carried out. In future, Au NPs can be used in making a water purifier system or kit.