Two approaches to biological decontamination of groundwater and soil polluted by aromatics—characterization of microbial populations

As part of the EU project MULTIBARRIERS, six new endogenous aerobic bacterial isolates able to grow in the presence of BTmX (benzene, toluene, m-xylene) were characterized with respect to their growth specificities. Preliminary analysis included restriction fragment length polymorphism profiles and 16S rDNA sequencing. The diversity of these strains was confirmed by denaturing gradient gel electrophoresis. Additional aerobic bacterial strains were isolated from the rhizospheres of plants grown in polychlorinated biphenyl (PCB)-contaminated soils. Pot experiments were designed to show the beneficial effect of plants on the bacterial degradation of PCBs. The effect of PCB removal from soil was evaluated and bacteria isolated from three different plant species were examined for the presence of the bph operon. [Int Microbiol 2005; 8(3):205-211

Biotransformation of benzonitrile herbicides via the nitrile hydratase–amidase pathway in rhodococci

Abstract The aim of this work was to determine the ability of rhodococci to transform 3,5-dichloro-4-hydroxybenzonitrile (chloroxynil), 3,5-dibromo-4-hydroxybenzonitrile (bromoxynil), 3,5-diiodo-4-hydroxybenzonitrile (ioxynil) and 2,6-dichlorobenzonitrile (dichlobenil); to identify the products and determine their acute toxicities. Rhodococcus erythropolis A4 and Rhodococcus rhodochrous PA-34 converted benzonitrile herbicides into amides, but only the former strain was able to hydrolyze 2,6-dichlorobenzamide into 2,6-dichlorobenzoic acid, and produced also more of the carboxylic acids from the other herbicides compared to strain PA-34. Transformation of nitriles into amides decreased acute toxicities for chloroxynil and dichlobenil, but increased them for bromoxynil and ioxynil. The amides inhibited root growth in Lactuca sativa less than the nitriles but more than the acids. The conversion of the nitrile group may be the first step in the mineralization of benzonitrile herbicides but cannot be itself considered to be a detoxification

An estimate of the onset of beadless character of electrospun nanofibers using rheological characterization

Electrospinning represents the very effective process of producing nanofibrous mats. This process is influenced by a number of mutually and strongly interlaced entry parameters (characteristics of polymer, solvent, process parameters) and their participation in the resulting nanofiber quality. The appearance of nanofibers is a result of the necessary primary experimental parameter setting within an acceptable range. However, finer analysis of nanofiber quality depends on the proper choice of these individual factors. The aim of this contribution is to evaluate one of the key factors—polymer concentration—with respect to the presence or absence of bead formation. This passage can be approximated by rheological oscillatory measurements when a sudden decrease in phase angle indicates this change. It replaces otherwise time-and cost-consuming trial-and-error experiments. This approach was tested using three different materials: solutions of poly(vinylidene fluoride-co-hexafluoropropylene), poly(vinyl butyral), and poly(ethylene oxide). © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education, Youth and Sports of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic [LTC 19034]; COST ActionsEuropean Cooperation in Science and Technology (COST) [CA17107]European Cooperation in Science and Technology, COST: CA17107; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LTC 1903

Plant Growth-Promoting Endophytic Bacteria Isolated from <i>Miscanthus giganteus</i> and Their Antifungal Activity

Modern technologies can satisfy human needs only with the use of large quantities of fertilizers and pesticides that are harmful to the environment. For this reason, it is possible to develop new technologies for sustainable agriculture. The process could be carried out by using endophytic microorganisms with a (possible) positive effect on plant vitality. Bacterial endophytes have been reported as plant growth promoters in several kinds of plants under normal and stressful conditions. In this study, isolates of bacterial endophytes from the roots and leaves of Miscanthus giganteus plants were tested for the presence of plant growth-promoting properties and their ability to inhibit pathogens of fungal origin. Selected bacterial isolates were able to solubilize inorganic phosphorus, fix nitrogen, and produce phytohormones, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, and siderophore. Leaf bacterial isolate Pantoea ananat is 50 OL 2 had high production of siderophores (zone ≥ 5 mm), and limited phytohormone production, and was the only one to show ACC deaminase activity. The root bacterial isolate of Pseudomonas libanensis 5 OK 7A showed the best results in phytohormone production (N6-(Δ2-isopentenyl)adenine and indole-3-acetic acid, 11.7 and 12.6 ng·mL−1, respectively). Four fungal cultures—Fusarium sporotrichioides DBM 4330, Sclerotinia sclerotiorum SS-1, Botrytis cinerea DS 90 and Sphaerodes fimicola DS 93—were used to test the antifungal activity of selected bacterial isolates. These fungal cultures represent pathogenic families, especially for crops. All selected root endophyte isolates inhibited the pathogenic growth of all tested fungi with inhibition percentages ranging from 30 to 60%. Antifungal activity was also tested in two forms of immobilization of selected bacterial isolates: one in agar and the other on dextrin-coated cellulose carriers. These results demonstrated that the endophytic Pseudomonas sp. could be used as biofertilizers for crops

Genomic Damage Induced in Nicotiana tabacum L. Plants by Colloidal Solution with Silver and Gold Nanoparticles

Tobacco seedlings (Nicotiana tabacum L cv. Wisconsin 38) were treated for 24 h with colloidal solution of silver and gold nanoparticles (AgNPs and AuNPs) of different size or cultivated for 8 weeks on soil polluted with these NPs. DNA damage in leaf and roots nuclei was evaluated by the comet assay. AgNPs of the size 22–25 nm at concentrations higher than 50 mg·L−1 significantly increased the tail moments (TM) values in leaf nuclei compared to the negative control. Ag nanoparticles of smaller size 12–15 nm caused a slight increase in tail moment without significant difference from the negative control. The opposite effect of AgNPs was observed on roots. The increasing tail moment was registered for smaller NPs. Similar results were observed for AuNPs at a concentration of 100 mg·L−1. DNA damaging effects after growing tobacco plants for 8 weeks in soil polluted with AgNPs and AuNPs of different size and concentrations were observed. While lower concentrations of both types of particles had no effect on the integrity of DNA, concentration of 30 mg·kg−1 of AgNPs caused significant DNA damage in leaves of tobacco plants. AuNPs had no effect even at the highest concentration. The content of Ag was determined by ICP–MS in above-ground part of plants (leaves) after 8 weeks of growth in soil with 30 mg·kg−1. AgNPs and was 2.720 ± 0.408 µg·g−1. Long term effect is much less harmful probably due to the plant restoration capability

Decorative Magnolia Plants: A Comparison of the Content of Their Biologically Active Components Showing Antimicrobial Effects

Magnolia plants are used both as food supplements and as cosmetic and medicinal products. The objectives of this work consisted of preparing extracts from leaves and flowers of eight Magnolia plants, and of determining concentrations of magnolol (1 to 100 mg&middot;g&minus;1), honokiol (0.11 to 250 mg&middot;g&minus;1), and obovatol (0.09 to 650 mg&middot;g&minus;1), typical neolignans for the genus Magnolia, in extracts made by using a methanol/water (80/20) mixture. The tested Magnolia plants, over sixty years old, were obtained from Průhonick&yacute; Park (Prague area, Czech Republic): M. tripetala MTR 1531, M. obovata MOB 1511, and six hybrid plants Magnolia &times; pruhoniciana, results of a crossbreeding of M. tripetala MTR 1531 with M. obovata MOB 1511. The identification of neolignans was performed by HRMS after a reversed-phase high-performance liquid chromatography (RP-HPLC) fractionation of an extract from M. tripetala MTR 1531. The highest concentrations of neolignans were found in the flowers, most often in their reproductive parts, and obovatol was the most abundant in every tested plant. The highest concentrations of neolignans were detected in parent plants, and lower concentrations in hybrid magnolias. Flower extracts from the parent plants M. tripetala MTR 1531 and M. obovata MOB 1511, flower extracts from the hybrid plants Magnolia &times; pruhoniciana MPR 0271, MPR 0151, and MPR 1531, and leaf extract from the hybrid plant Magnolia &times; pruhoniciana MPR 0271 inhibited growth of Staphylococcus aureus

Fungal Endophytes of Vitis vinifera&mdash;Plant Growth Promotion Factors

Endophytes are microorganisms that live asymptomatically inside plant tissues. They are beneficial to their host in many aspects, especially as a defense against foreign phytopathogens through the production of a variety of metabolites. These substances can serve as sources of new natural products for medicinal, agricultural, and industrial purposes. This article is focused on endophytic fungi from Vitis vinifera. The purpose of the research was their isolation and identification during the Vitis vinifera growing season. Subsequently, the isolates were tested for the production of biotechnologically interesting metabolites (siderophores, antioxidants, and antifungal compounds). In total, 24 endophytic fungi were isolated, the most represented genus was Cladosporium sp. The results of the test for antioxidant and antifungal properties, as well as siderophore production, have shown that the population of Vitis vinifera endophytic microscopic fungi could serve as a promising source of metabolites with a wide range of applications

Effect of polyurethane structure on arsenic adsorption capacity in nanofibrous polymer/ferrous sulphate-based systems

This study investigates the effect of the nanofibrous polymeric structure of an adsorptive material, modified with an immobilized inorganic sorbent based on ferrous sulphate, on the capacity of the material to remove arsenic from contaminated water. Nanofibrous materials were prepared by electrospinning from polyurethane types selected using a primary adsorption test. The functional groups and chemical composition (FTIR, EDX), morphology (SEM, porometry) and hydrophilicity (contact angles) of the prepared nanostructured materials were determined in order to assess the effect of composition and structure on the removal of arsenic. The process of arsenic removal was monitored by atomic absorption spectroscopy (AAS). It was found that certain samples of polyurethanes, particularly self-synthesized aromatic polyurethane of an ester type, PU918, could remove arsenic by complexation on nitrogen in their polymer chains. The greatest efficiency for arsenic removal was ca. 60% (initial c(As) = 150 mu g L-1). It was also found that adding even a small amount (1 wt%) of an inorganic adsorbent based on ferrous sulphate into the fibre mass of the nanofibrous structure would increase the efficiency up to 90% as a result of a chemical reaction between the additive and arsenic ions. The extent and rate of adsorption were described by kinetic and isotherm models. The adsorption process is well characterized by a pseudo-second-order kinetic model and both Freundlich and Langmuir isotherm models. High adsorption capacity and rate are the basis for the use of nanofibrous material in filters for arsenic separation.Technological Agency of the Czech Republic [TJ02000269]; Ministry of Education Youth and Sports of the Czech Republic-programme DKRVO [RP/CPS/2022/002

Insights into the Mechanism of Action of Bactericidal Lipophosphonoxins.

The advantages offered by established antibiotics in the treatment of infectious diseases are endangered due to the increase in the number of antibiotic-resistant bacterial strains. This leads to a need for new antibacterial compounds. Recently, we discovered a series of compounds termed lipophosphonoxins (LPPOs) that exhibit selective cytotoxicity towards Gram-positive bacteria that include pathogens and resistant strains. For further development of these compounds, it was necessary to identify the mechanism of their action and characterize their interaction with eukaryotic cells/organisms in more detail. Here, we show that at their bactericidal concentrations LPPOs localize to the plasmatic membrane in bacteria but not in eukaryotes. In an in vitro system we demonstrate that LPPOs create pores in the membrane. This provides an explanation of their action in vivo where they cause serious damage of the cellular membrane, efflux of the cytosol, and cell disintegration. Further, we show that (i) LPPOs are not genotoxic as determined by the Ames test, (ii) do not cross a monolayer of Caco-2 cells, suggesting they are unable of transepithelial transport, (iii) are well tolerated by living mice when administered orally but not peritoneally, and (iv) are stable at low pH, indicating they could survive the acidic environment in the stomach. Finally, using one of the most potent LPPOs, we attempted and failed to select resistant strains against this compound while we were able to readily select resistant strains against a known antibiotic, rifampicin. In summary, LPPOs represent a new class of compounds with a potential for development as antibacterial agents for topical applications and perhaps also for treatment of gastrointestinal infections