Mechanisms of microbial resistance against cadmium - a review.

The escalating cadmium influx from industrial activities and anthropogenic sources has raised serious environmental concerns due to its toxic effects on ecosystems and human health. This review delves into the intricate mechanisms underlying microbial resistance to cadmium, shedding light on the multifaceted interplay between microorganisms and this hazardous heavy metal. Cadmium overexposure elicits severe health repercussions, including renal carcinoma, mucous membrane degradation, bone density loss, and kidney stone formation in humans. Moreover, its deleterious impact extends to animal and plant metabolism. While physico-chemical methods like reverse osmosis and ion exchange are employed to mitigate cadmium contamination, their costliness and incomplete efficacy necessitate alternative strategies. Microbes, particularly bacteria and fungi, exhibit remarkable resilience to elevated cadmium concentrations through intricate resistance mechanisms. This paper elucidates the ingenious strategies employed by these microorganisms to combat cadmium stress, encompassing metal ion sequestration, efflux pumps, and enzymatic detoxification pathways. Bioremediation emerges as a promising avenue for tackling cadmium pollution, leveraging microorganisms' ability to transform toxic cadmium forms into less hazardous derivatives. Unlike conventional methods, bioremediation offers a cost-effective, environmentally benign, and efficient approach. This review amalgamates the current understanding of microbial cadmium resistance mechanisms, highlighting their potential for sustainable remediation strategies. By unraveling the intricate interactions between microorganisms and cadmium, this study contributes to advancing our knowledge of bioremediation approaches, thereby paving the way for safer and more effective cadmium mitigation practices.

Pentafuhalol-B, a Phlorotannin from Brown Algae, Strongly Inhibits the PLK-1 Overexpression in Cancer Cells as Revealed by Computational Analysis.

Polo-like kinase-1 (PLK-1) is an essential mitotic serine/threonine (Ser/Thr) kinase that belongs to the Polo-like kinase (PLK) family and is overexpressed in non-small cell lung cancer (NSCLC) via promotion of cell division. Therefore, PLK-1 may act as a promising target for the therapeutic cure of various cancers. Although a variety of anti-cancer drugs, both synthetic and naturally occurring, such as volasertib, onvansertib, thymoquinone, and quercetin, are available either alone or in combination with other therapies, they have limited efficacy, especially in the advanced stages of cancer. To the best of our knowledge, no anticancer agent has been reported from marine algae or microorganisms to date. Thus, the aim of the present study is a high-throughput virtual screening of phlorotannins, obtained from edible brown algae, using molecular docking and molecular dynamic simulation analysis. Among these, Pentafuhalol-B (PtB) showed the lowest binding energy (best of triplicate runs) against the target protein PLK-1 as compared to the reference drug volasertib. Further, in MD simulation (best of triplicate runs), the PtB-PLK-1 complex displayed stability in an implicit water system through the formation of strong molecular interactions. Additionally, MMGBSA calculation (best of triplicate runs) was also performed to validate the PtB-PLK-1 complex binding affinities and stability. Moreover, the chemical reactivity of PtB towards the PLK-1 target was also optimised using density functional theory (DFT) calculations, which exhibited a lower HOMO-LUMO energy gap. Overall, these studies suggest that PtB binds strongly within the pocket sites of PLK-1 through the formation of a stable complex, and also shows higher chemical reactivity than the reference drug volasertib. The present study demonstrated the inhibitory nature of PtB against the PLK-1 protein, establishing its potential usefulness as a small molecule inhibitor for the treatment of different types of cancer.

Antimicrobial and antioxidant activities of fennel oil.

It is of interest to estimate the effects of foliar spray (ISA) on essential oil yield, chemical constituents, antioxidant, and antimicrobial activities of fennel (Foeniculum vulgare Mill).Fennel was treated with ISA solutions at 40 and 80 mg L-1 doses. Application of ISA significantly augmented antioxidant and antimicrobial activities in addition to essential oil yield and its principal elements in fennel. 80 mg L-1 dose of ISA was found to be pre-eminent. Antioxidant properties of EOs were determined through DPPH assays, metal chelators and lipid peroxidation. While antimicrobial activities were evaluated using agar well diffusion and microdilution techniques of broth. Gram positive and Gram negative bacteria were used to gauge the oil's antibacterial effectiveness. Data shows that antioxidant and antimicrobial activities of fennel oil were found to be the highest. According to GC analysis, trans-anethole (78.38-86.08%), methyl chavicol (2.32-2.54%), and fenchone (6.65-8.95%) were the three main constituents of fennel essential oil.

Biosynthesis, Characterization and Biological Activities of Silver Nanoparticles from Pogostemon cablin Benth. Methanolic Leaf Extract.

This study reports the biosynthesis of silver nanoparticles (AgNPs) using methanolic leaf extract of Pogostemon cablin Benth. (Patchouli) as a reducing agent, and their potent biological (antibacterial, antioxidant and anticancer) activities. The P. cablin extract when exposed to silver nitrate reduced silver ions to form crystalline AgNPs within 1 h of incubation at room-temperature. UV-visible spectra showed a sharp surface plasmon resonance (SPR) at around 430 nm for the biosynthesized AgNPs and the XRD pattern indicated the crystalline planes of the face centered cubic silver. The FE-SEM analysis revealed the occurrence of predominant spherical shaped AgNPs with a huge disparity in their particle size distribution with an average size of 25 nm, while, the FTIR data confirmed the bio-reduction and capping of AgNPs by several phytocompounds present in the methanolic leaf extract. AgNPs effectively inhibited the growth of all the tested human pathogenic bacterial strains (Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli), while, the methanolic leaf extract failed to inhibit the growth of S. aureus and P. aeruginosa. AgNPs showed the highest free radical scavenging activity (79.0 ± 0.76%) compared to methanolic leaf extract (68.3 ± 0.68%) at 100 µg/ml. Further, the cytotoxicity study using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) confirmed that AgNPs successfully inhibited the human colon adenocarcinoma cell line (HT-29) in a dose dependent manner. At higher concentrations (500 µg/ml), only 4% of cells survived after 72 hrs of exposure with IC50 value of 120 µg/ml. Thus, these findings offer a new source of biomolecules with diverse biological activities.

Biogenic Synthesis, Characterization and Evaluation of Silver Nanoparticles from Aspergillus niger JX556221 Against Human Colon Cancer Cell Line HT-29.

Nanobiotechnology has emerged as a promising technology to develop new therapeutically active nanomaterials. The present study was aimed to biosynthesize AgNPs extracellularly using Aspergillus niger JX556221 fungal extract and to evaluate their anticancer potential against colon cancer cell line, HT-29. UV-visible spectral characterization of the synthesized AgNPs showed higher absorption peak at 440 nm wavelength. Transmission Electron Microscopy (TEM) analysis revealed the monodispersed nature of synthesized AgNPs occurring in spherical shape with a size in the range of 20-25 nm. Further, characterization using Energy Dispersive Spectroscopy (EDX) confirmed the face-centred cubic crystalline structure of metallic AgNPs. FTIR data revealed the occurrence of various phytochemicals in the cell free fungal extract which substantiated the fungal extract mediated AgNPs synthesis. The cytotoxic effect of AgNPs was studied by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results evidenced the cytotoxic effect of AgNPs on HT-29 cell lines in a dose dependent manner. The highest activity was found at 100 µg/ml concentration after 24 h of incubation. Use of propidium iodide staining examination method confirmed the cytotoxic effect of AgNPs through inducing cell apoptosis. AgNPs cytotoxicity was found to be through elevating reactive oxygen species (ROS), and caspase-3 activation resulting in induced apoptosis. Therefore, this research finding provides an insight towards the development of novel anticancer agents using biological sources.

Nitrate and Nitrogen Oxides: Sources, Health Effects and Their Remediation.

Increased use of nitrogenous (N) fertilizers in agriculture has significantly altered the global N-cycle because they release nitrogenous gases of environmental concerns. The emission of nitrous oxide (N2O) contributes to the global greenhouse gas accumulation and the stratospheric ozone depletion. In addition, it causes nitrate leaching problem deteriorating ground water quality. The nitrate toxicity has been reported in a number of studies showing the health hazards like methemoglobinemia in infants and is a potent cause of cancer. Despite these evident negative environmental as well as health impacts, consumption of N fertilizer cannot be reduced in view of the food security for the teeming growing world population. Various agronomic and genetic modifications have been practiced to tackle this problem. Some agronomic techniques adopted include split application of N, use of slow-release fertilizers, nitrification inhibitors and encouraging the use of organic manure over chemical fertilizers. As a matter of fact, the use of chemical means to remediate nitrate from the environment is very difficult and costly. Particularly, removal of nitrate from water is difficult task because it is chemically non-reactive in dilute aqueous solutions. Hence, the use of biological means for nitrate remediation offers a promising strategy to minimize the ill effects of nitrates and nitrites. One of the important goals to reduce N-fertilizer application can be effectively achieved by choosing N-efficient genotypes. This will ensure the optimum uptake of applied N in a balanced manner and exploring the molecular mechanisms for their uptake as well as metabolism in assimilatory pathways. The objectives of this paper are to evaluate the interrelations which exist in the terrestrial ecosystems between the plant type and characteristics of nutrient uptake and analyze the global consumption and demand for fertilizer nitrogen in relation to cereal production, evaluate the various methods used to determine nitrogen use efficincy (NUE), determine NUE for the major cereals grown across large agroclimatic regions, determine the key factors that control NUE, and finally analyze various strategies available to improve the use efficiency of fertilizer nitrogen.

Antimicrobial Properties of Plant Essential Oils against Human Pathogens and Their Mode of Action: An Updated Review.

A wide range of medicinal and aromatic plants (MAPs) have been explored for their essential oils in the past few decades. Essential oils are complex volatile compounds, synthesized naturally in different plant parts during the process of secondary metabolism. Essential oils have great potential in the field of biomedicine as they effectively destroy several bacterial, fungal, and viral pathogens. The presence of different types of aldehydes, phenolics, terpenes, and other antimicrobial compounds means that the essential oils are effective against a diverse range of pathogens. The reactivity of essential oil depends upon the nature, composition, and orientation of its functional groups. The aim of this article is to review the antimicrobial potential of essential oils secreted from MAPs and their possible mechanisms of action against human pathogens. This comprehensive review will benefit researchers who wish to explore the potential of essential oils in the development of novel broad-spectrum key molecules against a broad range of drug-resistant pathogenic microbes.

Biosynthesis and Characterization of Silver Nanoparticles from Methanol Leaf Extract of Cassia didymobotyra and Assessment of Their Antioxidant and Antibacterial Activities.

The biosynthesis of silver nanoparticles (AgNPs) was achieved for the first time using methanol leaf extract of C. didymobotyra and their in vitro antioxidant and antibacterial activities were also evaluated. Methanol leaf extracts of C. didymobotyra after mixing with AgNO3 solution showed the change in color from light brown to dark yellowish brown within 1 hour. UV-visible spectroscopy study showed the surface plasmon resonance at around 420 nm clearly indicating the biosynthesis of AgNPs. Transmission Electron Microscopy (TEM) analysis proved the presence of biosynthesized AgNPs in spherical shape with huge disparity in sizes. The average size of biosynthesized nanoparticle was about 18 nm. The occurrence of face centered cubic shapes of nanoparticles was established by X-ray diffraction (XRD) patterns. Further, Fourier transform infrared spectroscopy (FTIR) study showed the possible capping of AgNPs because of the active biomolecules present in the methanol leaf extract of C. didymobotyra. The antioxidant activities of biosynthesized AgNPs were evaluated by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assay and found that AgNPs demonstrated a strong antioxidant properties compared to methanol leaf extract. Nevertheless, the biosynthesized AgNPs exhibited a strong antibacterial activity against all the tested human pathogenic bacterial strains compared to crude methanol leaf extract of C. didymobotyra. Thus, it is concluded that these biosynthesized AgNPs are cost effective, eco-friendly in nature and could be applied for developing new antibacterial drugs and other biomedical applications in near future.

Molecular Breeding Strategy and Challenges Towards Improvement of Blast Disease Resistance in Rice Crop.

Rice is a staple and most important security food crop consumed by almost half of the world's population. More rice production is needed due to the rapid population growth in the world. Rice blast caused by the fungus, Magnaporthe oryzae is one of the most destructive diseases of this crop in different part of the world. Breakdown of blast resistance is the major cause of yield instability in several rice growing areas. There is a need to develop strategies providing long-lasting disease resistance against a broad spectrum of pathogens, giving protection for a long time over a broad geographic area, promising for sustainable rice production in the future. So far, molecular breeding approaches involving DNA markers, such as QTL mapping, marker-aided selection, gene pyramiding, allele mining and genetic transformation have been used to develop new resistant rice cultivars. Such techniques now are used as a low-cost, high-throughput alternative to conventional methods allowing rapid introgression of disease resistance genes into susceptible varieties as well as the incorporation of multiple genes into individual lines for more durable blast resistance. The paper briefly reviewed the progress of studies on this aspect to provide the interest information for rice disease resistance breeding. This review includes examples of how advanced molecular method have been used in breeding programs for improving blast resistance. New information and knowledge gained from previous research on the recent strategy and challenges towards improvement of blast disease such as pyramiding disease resistance gene for creating new rice varieties with high resistance against multiple diseases will undoubtedly provide new insights into the rice disease control.

Multiplex SSR-PCR approaches for semi-automated genotyping and characterization of loci linked to blast disease resistance genes in rice.

In the present study, 63 polymorphic microsatellite markers related to rice blast resistance genes were fluorescently labelled at the 5'-end with either 6-FAM or HEX using the G5 dye set and incorporated into a multiplex SSR-PCR for the detection of fragments using an automated system. For rice F3 families obtained from crosses between Pongsu Seribu 2 (Malaysian blast resistant cultivar) and Mahsuri (a susceptible rice cultivar), the genotypes for 13 designated multiplex SSR panels were determined. The genotyping assays were performed using a capillary-based ABIPRISM 3100 genetic analyser. The sizes of the SSRs alleles observed in the range from 79 to 324 bp. The observed marker segregation data were analysed using the Chi(2) test. A genetic linkage map covering ten chromosomes and comprising 63 polymorphic SSR markers was constructed, and the distorted loci were localised to linkage groups. The results indicated that distorted loci are presented on eight chromosomes.

Synthesis and characterization of silver nanoparticles using fruit extract of Momordica cymbalaria and assessment of their in vitro antimicrobial, antioxidant and cytotoxicity activities.

Plant mediated synthesis of nanoparticles has been considered as green route and a reliable technique for the synthesis of nanoparticles due to its eco-friendly approach. In this study, we report a simple and eco-friendly approach for the synthesis of silver nanoparticles (AgNPs) using methanolic Momordica cymbalaria fruit extract as reducing agent. The fruit extract of M. cymbalaria exposed to AgNO3 solution showed the change in color from green to light yellow at room temperature within 1h of incubation confirms the synthesis of AgNPs. UV-vis spectra analysis revealed that the synthesized AgNPs had a sharp surface plasmon resonance at around 450 nm, while, the X-ray Diffraction (XRD) patterns confirmed distinctive peaks indices to the crystalline planes of the face centered cubic silver. The Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) analysis results confirmed the presence of spherical shaped AgNPs by a huge disparity in the particle size distribution with an average size of 15.5 nm. The synthesized AgNPs showed strong antibacterial activity against all the tested multidrug resistant human pathogenic bacterial strains and also exhibited highest free radical scavenging activity (74.2%) compared to fruit extract (60.4%). Moreover, both fruit extract and the synthesized AgNPs showed the cytotoxicity towards Rat L6 skeletal muscle cell line at different concentrations, but the highest inhibition percentage was recorded for AgNPs at concentration of 100 µg/ml.

In Vitro Pharmacological Activities and GC-MS Analysis of Different Solvent Extracts of Lantana camara Leaves Collected from Tropical Region of Malaysia.

We investigated the effect of different solvents (ethyl acetate, methanol, acetone, and chloroform) on the extraction of phytoconstituents from Lantana camara leaves and their antioxidant and antibacterial activities. Further, GC-MS analysis was carried out to identify the bioactive chemical constituents occurring in the active extract. The results revealed the presence of various phytocompounds in the extracts. The methanol solvent recovered higher extractable compounds (14.4% of yield) and contained the highest phenolic (92.8 mg GAE/g) and flavonoid (26.5 mg RE/g) content. DPPH radical scavenging assay showed the IC50 value of 165, 200, 245, and 440 µg/mL for methanol, ethyl acetate, acetone, and chloroform extracts, respectively. The hydroxyl scavenging activity test showed the IC50 value of 110, 240, 300, and 510 µg/mL for methanol, ethyl acetate, acetone, and chloroform extracts, respectively. Gram negative bacterial pathogens (E. coli and K. pneumoniae) were more susceptible to all extracts compared to Gram positive bacteria (M. luteus, B. subtilis, and S. aureus). Methanol extract had the highest inhibition activity against all the tested microbes. Moreover, methanolic extract of L. camara contained 32 bioactive components as revealed by GC-MS study. The identified major compounds included hexadecanoic acid (5.197%), phytol (4.528%), caryophyllene oxide (4.605%), and 9,12,15-octadecatrienoic acid, methyl ester, (Z,Z,Z)- (3.751%).

Efficacy of root-associated fungi and PGPR on the growth of Pisum sativum (cv. Arkil) and reproduction of the root-knot nematode Meloidogyne incognita.

The effects of root-associated fungi (Aspergillus awamori and Glomus mosseae) and plant growth promoting rhizobacteria (PGPR) (Pseudomonas putida, Pseudomonas alcaligenes and Paenibacillus polymyxa) were studied alone and in combination in glasshouse experiments on the growth of pea, enzyme activity (peroxidase and catalase) and reproduction of root-knot nematode Meloidogyne incognita. Application of A. awamori, G. mosseae and PGPR caused a significant increase in pea growth and enzyme activities of both nematode inoculated and uninoculated plants. A. awamori was more effective in reducing galling and improving the growth of nematode inoculated plants than P. alcaligenes or P. polymyxa. The greatest increase in growth, enzyme activities of nematode-inoculated plants and reduction in galling and nematode multiplication was observed when A. awamori was used with P. putida or G. mosseae as compared to the other combinations tested. Percentage root colonization was higher when AM fungus inoculated plants were treated with P. putida both in presence and absence of nematode.