The review summarises data on the synthesis and functionalisation of gold nanoparticles and their applications in biological investigations. Particular attention is given to applications of colloidal gold in solid-phase assays, immunoassay and studies of biologically active compounds by vibrational spectroscopy. A special section deals with the use of gold nanoparticles as antigen carriers in immunisation.

http://iopscience.iop.org/article/10.1070/RC2007v076n02ABEH003673/pdf

Gold nanoparticles: preparation, functionalisation and applications in biochemistry and immunochemistry

We discuss optical properties of single and aggregated colloidal gold and silver conjugates that can be fabricated by adsorption of a biopolymer onto nanoparticle surfaces. We start with a discussion of two-layer and multilayer optical models for colloidal gold and silver nanoparticle conjugates that consist of a metal core and a polymer shell formed by recognizing and target molecules. The point at issue is the core-size optimization of conjugate-based nanosensors as elementary transducers of molecular binding events into optical signals. We present a detailed discussion of optical properties of various aggregated conjugate-based structures such as bispheres, linear chains, plane arrays on a rectangular lattice, compact and porous clusters embedded on a cubic body-centerd lattice, and random fractal aggregates. Our attention is focused on the following topics: (1) statistical and orientation averaging of optical observables; (2) dependence of extinction and scattering spectra on the optical binary coupling of conjugates; (3) optical effects related to the chain-like structures; (4) effects of polymer coating, interparticle spacing, and cluster structure; (5) simulation of kinetic changes in the optical properties of aggregated sols formed during biospecific binding. Finally, we discuss experimental data and biomedical applications of metal nanoparticles and their biospecific conjugates in various biomedical studies.

Optical Properties and Biomedical Applications of Nanostructures Based on Gold and Silver Bioconjugates

Metagenomic analysis of microbiota structure evolution in phytoremediation of a swine lagoon wastewater

Plant growth promoting bacteria for combating salinity stress in plants - Recent developments and prospects: A review.

Plant growth promoting microbes (PGPMs) play major roles in diverse ecosystems, including atmospheric nitrogen fixation, water uptake, solubilization, and transport of minerals from the soil to the plant Different PGPMs are proposed as biofertilizers, biostimulants, and/or biocontrol agents to improve plant growth and productivity and thereby to contribute to agricultural sustainability and food security However, little information exists regarding the use of PGPMs in micropropagation such as the in vitro plant tissue culture This review presents an overview of the importance of PGPMs and their potential application in plant micropropagation Our analysis, based on published articles, reveals that the process of in vitro classical tissue culture techniques, under strictly aseptic conditions, deserves to be reviewed to allow vitroplants to benefit from the positive effect of PGPMs Furthermore, exploiting the potential benefits of PGPMs will lead to lessen the cost production of vitroplants during micropropagation process and will make the technique of plant tissue culture more efficient The last part of the review will indicate where research is needed in the future

/pdf/potential-role-and-utilization-of-plant-growth-promoting-19d7fxhs9p.pdf

Potential Role and Utilization of Plant Growth Promoting Microbes in Plant Tissue Culture

Microclonal propagation in vitro is being actively used in the production of healthy planting material of food and ornamental plants. However, it needs further improvement to increase the growth rates of microclones in vitro and enhance regenerant survivability ex vitro. A promising approach to this end could be inoculating in vitro-micropropagated plants with plant growth-promoting rhizobacteria, specifically Azospirillum. However, the influence of Azospirillum inoculation on microclone behavior throughout the production process, including plant adaptation ex vitro and food crop productivity, has been underinvestigated. In this study, in vitro-growing potato (Solanum tuberosum L.) microclones were inoculated with Azospirillum brasilense strain Sp245. The microclones were then grown on in soil in the greenhouse and field, with the experiment lasting for 120 days. Root-associated bacteria were identified immunochemically, and the mitotic index of root meristematic cells was determined by a cytological method. The plant morphological parameters determined were shoot length, number of nodes per shoot, number of roots per plant, maximal root length, leaf area, percentage of surviving plants in the soil, and tuber yield and weight. Our results show that bacterial inoculation of potato microclones in vitro enhances plant adaptive capacity ex vitro and increases minituber yield. The percent survival index of field-grown inoculated plants was 1.5-fold greater than that of uninoculated plants. The overall tuber weight per plant was more than 30 % greater in the inoculated plants than it was in the control ones. For all cultivars on average, tuber yield per square meter increased by more than 45 % as a result of inoculation in vitro. This study is the first to report that Azospirillum inoculation of potato microclones not only improves the quality of planting material produced in vitro but also significantly increases minituber yield through enhancing plant adaptive capacity in the field.

/pdf/improved-potato-microclonal-reproduction-with-the-plant-3utf1x2gp3.pdf

Improved potato microclonal reproduction with the plant growth-promoting rhizobacteria Azospirillum

The response of potato microplants to Azospirillum inoculation is highly variable both in vitro and ex vitro. Plant inoculation with plant-growth-promoting rhizobacteria (PGPR) is widely used to increase the effectiveness of clonal micropropagation. Azospirillum rhizobacteria are model subjects to investigate associative plant–microbe interactions. Here we show that most Azospirillum strains cannot utilize sucrose as the sole carbon source and that their use to inoculate in vitro-grown plants does not lead to bacterial growth in the culture medium. Of the eleven surveyed strains, seven gave a significant increase in at least one growth variable of in vitro-grown potato (Solanum tuberosum L. cv. Nevsky) microplants. Inoculation with six strains led to better survival of the microplants in soil. Only with three strains (A. brasilense Sp245, SR80, and A. halopraeferens Au4T) did inoculation in vitro significantly promote plant growth ex vitro. The inoculation results were correlated with the biochemical activity of the strains. Indole-3-acetic acid production ranged from 3.74 μg ml−1 with A. brasilense S27 to 87.3 μg ml−1 with A. brasilense Sp245. Active indole-3-acetic acid producers, but not nitrogen fixers, were better plant-growth-promoters. Inoculation in vitro with A. brasilense strains Sp245 and SR80 can be recommended for increasing the effectiveness of clonal micropropagation of potato.

Effectiveness of inoculation of in vitro-grown potato microplants with rhizosphere bacteria of the genus Azospirillum

Water deficits inhibit plant growth and decrease crop productivity. Remedies are needed to counter this increasingly urgent problem in practical farming. One possible approach is to utilize rhizobacteria known to increase plant resistance to abiotic and other stresses. We therefore studied the effects of inoculating the culture medium of potato microplants grown in vitro with Azospirillum brasilense Sp245 or Ochrobactrum cytisi IPA7.2. Growth and hormone content of the plants were evaluated under stress-free conditions and under a water deficit imposed with polyethylene glycol (PEG 6000). Inoculation with either bacterium promoted the growth in terms of leaf mass accumulation. The effects were associated with increased concentrations of auxin and cytokinin hormones in the leaves and stems and with suppression of an increase in the leaf abscisic acid that PEG treatment otherwise promoted in the potato microplants. O. cytisi IPA7.2 had a greater growth-stimulating effect than A. brasilense Sp245 on stressed plants, while A. brasilense Sp245 was more effective in unstressed plants. The effects were likely to be the result of changes to the plant’s hormonal balance brought about by the bacteria.

https://www.mdpi.com/2218-273X/10/9/1231/pdf

Rhizobacteria Inoculation Effects on Phytohormone Status of Potato Microclones Cultivated In Vitro under Osmotic Stress.

We studied changes in the physiological and biochemical parameters of wheat (Triticum aestivum L. ‘Saratovskaya 29’) seedlings treated with lipopolysaccharide isolated from the outer membrane of the associative bacterium Azospirillum brasilense Sp245. The obtained data were compared with (i) the results of plant inoculation with whole Sp245 cells and (ii) the effects exerted by the lipopolysaccharide and whole cells of the enterobacterium Escherichia coli K12 and the specific legume symbiont Rhizobium leguminosarum 249. The functional activity of meristematic cells was judged by their mitotic index and by the results of immunochemical determination of the proliferative antigen of initials, a molecular marker for wheat meristem cells. Treatment of the seedling root system with 10 μg mL−1 of Sp245 lipopolysaccharide increased the mitotic index (1.8-fold) and the antigen content (approximately 1.4-fold). These increases were comparable to the effects produced by whole cell inoculation (2- and 1.4-fold, respectively). Our findings give grounds to consider lipopolysaccharide as an active component of the Azospirillum cell surface that not only determines bacterial contact interactions with wheat roots but also participates in the induction of plant responses to these interactions. We finally discuss the linkage between the proliferative antigen of initials and the transduction of a hormonal signal to the cell, as well as the informational value of this antigen as an indicator of effectiveness of plant–bacterial interactions.

Effect of Azospirillum brasilense Sp245 lipopolysaccharide on the functional activity of wheat root meristematic cells

Coumarins are a structurally varied set of 2H-chromen-2-one compounds categorized also as members of the benzopyrone group of secondary metabolites. Coumarin derivatives attract interest owing to their wide practical application and the unique reactivity of fused benzene and pyrone ring systems in molecular structure. Coumarins have their own specific fingerprints as antiviral, antimicrobial, antioxidant, anti-inflammatory, antiadipogenic, cytotoxic, apoptosis, antitumor, antitubercular, and cytotoxicity agents. Natural products have played an essential role in filling the pharmaceutical pipeline for thousands of years. Biological effects of natural coumarins have laid the basis of low-toxic and highly effective drugs. Presently, more than 1300 coumarins have been identified in plants, bacteria, and fungi. Fungi as cultivated microbes have provided many of the nature-inspired syntheses of chemically diverse drugs. Endophytic fungi bioactivities attract interest, with applications in fields as diverse as cancer and neuronal injury or degeneration, microbial and parasitic infections, and others. Fungal mycelia produce several classes of bioactive molecules, including a wide group of coumarins. Of promise are further studies of conditions and products of the natural and synthetic coumarins’ biotransformation by the fungal cultures, aimed at solving the urgent problem of searching for materials for biomedical engineering. The present review evaluates the fungal coumarins, their structure-related peculiarities, and their future therapeutic potential. Special emphasis has been placed on the coumarins successfully bioprospected from fungi, whereas an industry demand for the same coumarins earlier found in plants has faced hurdles. Considerable attention has also been paid to some aspects of the molecular mechanisms underlying the coumarins’ biological activity. The compounds are selected and grouped according to their cytotoxic, anticancer, antibacterial, antifungal, and miscellaneous effects.

/pdf/coumarins-as-fungal-metabolites-with-potential-medicinal-8bl9ahf0.pdf

Nina V. Evseeva

Papers

Improved potato microclonal reproduction with the plant growth-promoting rhizobacteria Azospirillum

Effectiveness of inoculation of in vitro-grown potato microplants with rhizosphere bacteria of the genus Azospirillum

Rhizobacteria Inoculation Effects on Phytohormone Status of Potato Microclones Cultivated In Vitro under Osmotic Stress.

Effect of Azospirillum brasilense Sp245 lipopolysaccharide on the functional activity of wheat root meristematic cells

Coumarins as Fungal Metabolites with Potential Medicinal Properties