Soil Chemical Analysis

Secret History: Return of the Black Death Channel 4, 7-8pm In 1348 the Black Death swept through London, killing people within days of the appearance of their first symptoms. Exactly how many died, and why, has long been a mystery. This Secret History documentary follows experts as they pick through the evidence and reveal why the plague killed on such a scale. And they ask, what might be coming next?

Medscape

Short protocols in molecular biology

During the past few years, silver nanoparticles (AgNPs) became one of the most investigated and explored nanotechnology-derived nanostructures, given the fact that nanosilver-based materials proved to have interesting, challenging, and promising characteristics suitable for various biomedical applications. Among modern biomedical potential of AgNPs, tremendous interest is oriented toward the therapeutically enhanced personalized healthcare practice. AgNPs proved to have genuine features and impressive potential for the development of novel antimicrobial agents, drug-delivery formulations, detection and diagnosis platforms, biomaterial and medical device coatings, tissue restoration and regeneration materials, complex healthcare condition strategies, and performance-enhanced therapeutic alternatives. Given the impressive biomedical-related potential applications of AgNPs, impressive efforts were undertaken on understanding the intricate mechanisms of their biological interactions and possible toxic effects. Within this review, we focused on the latest data regarding the biomedical use of AgNP-based nanostructures, including aspects related to their potential toxicity, unique physiochemical properties, and biofunctional behaviors, discussing herein the intrinsic anti-inflammatory, antibacterial, antiviral, and antifungal activities of silver-based nanostructures.

/pdf/biomedical-applications-of-silver-nanoparticles-an-up-to-1rjmcs1uea.pdf

Biomedical Applications of Silver Nanoparticles: An Up-to-Date Overview

Use of silver and silver salts is as old as human civilization but the fabrication of silver nanoparticles (Ag NPs) has only recently been recognized. They have been specifically used in agriculture and medicine as antibacterial, antifungal and antioxidants. It has been demonstrated that Ag NPs arrest the growth and multiplication of many bacteria such as Bacillus cereus, Staphylococcus aureus, Citrobacter koseri, Salmonella typhii, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia, Vibrio parahaemolyticus and fungus Candida albicans by binding Ag/Ag+ with the biomolecules present in the microbial cells. It has been suggested that Ag NPs produce reactive oxygen species and free radicals which cause apoptosis leading to cell death preventing their replication. Since Ag NPs are smaller than the microorganisms, they diffuse into cell and rupture the cell wall which has been shown from SEM and TEM images of the suspension containing nanoparticles and pathogens. It has also been shown that smaller nanoparticles are more toxic than the bigger ones. Ag NPs are also used in packaging to prevent damage of food products by pathogens. The toxicity of Ag NPs is dependent on the size, concentration, pH of the medium and exposure time to pathogens.

/pdf/a-review-on-biosynthesis-of-silver-nanoparticles-and-their-ivx9t7t18x.pdf

A review on biosynthesis of silver nanoparticles and their biocidal properties.

Biological synthesis of silver nanoparticles using microorganisms has received profound interest because of their potential to synthesize nanoparticles of various size, shape and morphology. In the current study, synthesis of silver nanoparticles by a bacterial strain (CS 11) isolated from heavy metal contaminated soil is reported. Molecular identification of the isolate showed it as a strain of Bacillus sp. On treating the bacteria with 1 mM AgNO3, it was found to have the ability to form silver nanoparticles extracellularly at room temperature within 24 h. This was confirmed by the visual observation and UV–Vis absorption at 450 nm. Further characterization of nanoparticles by transmission electron microscopy confirmed the size of silver nanoparticles in 42–92 nm range. Therefore, the current study is a demonstration of an efficient synthesis of stable silver nanoparticle by a Bacillus strain.

/pdf/extracellular-synthesis-of-silver-nanoparticles-by-the-19us94nwp8.pdf

Extracellular synthesis of silver nanoparticles by the Bacillus strain CS 11 isolated from industrialized area.

Starch-PVA composite films with zinc-oxide nanoparticles and phytochemicals as intelligent pH sensing wraps for food packaging application.

Various methods have been used to enhance production of chemically diverse phytochemicals especially medicinal natural products. With the advancement in nanotechnology, nanoparticles have been reported to have varying impact in plant growth and inducibility of phytochemical composition. Major objective of the study was to study the secondary metabolite modulatory effect of silver nanoparticles. In the current study, treatment of fenugreek seedlings with biosynthesized silver nanoparticles (Ag-NPs) was found to have significant impact on its growth parameters such as leaf number, root length, shoot length and wet weight. On HPLC based analysis, Ag-NPs treated seedlings showed an enhancement in the production of major phytochemical diosgenin to a level of 214.06 ± 17.07 μg/mL. An untreated control gave an yield of only 164.44 ± 7.67 μg/mL of diosgenin, and the observed phytochemical enhancement effect induced by Ag-NP was very significant. Most remarkably, the Ag-NP used in the study was found to play dual role of enhancement of both plant growth and diosgenin synthesis. Hence the study is of immense application as it opens up development of new methods based on nanoelicitors to enhance the biosynthesis of medicinal natural products in plants.

Plant growth and diosgenin enhancement effect of silver nanoparticles in Fenugreek (Trigonella foenum-graecum L.)

Endophytes, by residing within the specific chemical environment of host plants, form unique group of microorganisms. Microbially unexplored medicinal plants can have diverse and potential microbial association. The rhizome of ginger is very remarkable because of its metabolite richness, but the physiological processes in these tissues and the functional role of associated microorganisms remain totally unexplored. Through the current study, the presence of four different endophytic bacterial strains were identified from ginger rhizome. Among the various isolates, ZoB2 which is identified as Pseudomonas sp. was found to have the ability to produce IAA, ACC deaminase and siderophore. By considering these plant growth promoting properties, ZoB5 can expect to have considerable effect on the growth of ginger.

/pdf/isolation-and-characterization-of-plant-growth-promoting-nun76n9dvq.pdf

Isolation and characterization of plant growth promoting endophytic bacteria from the rhizome of Zingiber officinale.

Piper nigrum is an interesting plant to study the endophytic microbial factors affecting plant growth because of its unique features. Endophytic bacterial isolation from the plant resulted in the isolation of twelve bacterial isolates which were screened for various plant growth promoting properties like phosphate solubilization, ACC deaminase production, siderophore production etc. Interestingly, seven isolates were found to have IAA biosynthetic potential. Bacterial isolates with multiple plant growth promoting properties were studied for their growth promoting effect on Vigna radiata seedlings. This resulted in the identification of Klebsiella sp. (PnB 10) and Enterobacter sp. (PnB 11) as the isolates with excellent growth promoting properties. The results confirm promising applications of the endophytic bacterial isolates obtained in the study and also their possible growth promoting effect in P. nigrum.

E. K. Radhakrishnan

Papers

Extracellular synthesis of silver nanoparticles by the Bacillus strain CS 11 isolated from industrialized area.

Starch-PVA composite films with zinc-oxide nanoparticles and phytochemicals as intelligent pH sensing wraps for food packaging application.

Plant growth and diosgenin enhancement effect of silver nanoparticles in Fenugreek (Trigonella foenum-graecum L.)

Isolation and characterization of plant growth promoting endophytic bacteria from the rhizome of Zingiber officinale.

Plant growth promoting potential of endophytic bacteria isolated from Piper nigrum