The Employment of Endophytic Bacteria for Phytodegradation of Pyridine

Pyridine is considered a heterocyclic aromatic chemical that is poisonous and carcinogenic to a variety of living species. The use of plant and endophytic- bacteria to improve the efficiency of pollutants extraction is considered a viable technique since the endophytic bacteria help in the adaptation of the plant itself in various ecosystems and have significant ecological importance because they improve the soil fertility and quality. This research aims to stimulate the pyridine phytodegradation by Phragmites australis plants using the endophytic bacterial strain, Acinetobacter by inoculation these bacterial cells to the plants to see if it might increase plant growth and pyridine phytodegradation. In the present study, the system of pyridine phytodegradation basins with the vertical subsurface flow (VSSF) was adopted, since this system has better ventilation. In addition, the retention time is several hours due to the penetration of water molecules to the layers of packing materials of the basin, which have a relatively high hydraulic conductivity. After conducting the experiments, samples were collected and tests were done to find out the optimum conditions. The results were recorded as 40 plants of P. australis/m2 of VSSF systems; bacterial cells concentration, 250 mg/L; pyridine concentration, 400 mg/L; temperature, 35 °C and pH, 8±2 for 10 hrs incubation duration. As a result, endophytic bacteria can break down toxic organic substances in combination with certain plants. When the endophytic bacterium, Acinetobacter was not used to enhance the role of Phragmites australis plants in the pyridine-phytodegradation process, the rate of phytodegradation was reduced to less than 30% at a pyridine concentration of 700 mg/L, indicating the importance of this endophytic bacterium in the pyridine phytodegradation process.

Investigation of the Kinetic Regularities of the Process of Biodegradation of Betaine Surfactant by Bacteria of the Genus Pseudomonas

Surfactants are extremely common organic compounds that enter the environment in large quantities in the form of household and industrial wastewater. The toxicity of surfactants for biological systems, the high concentration of substances and the duration of the bioremediation process of polluted ecosystems requires improving the biotechnology of microbial wastewater treatment for surfactants. The purpose of this work is to study the kinetic laws of the reaction of the biological decomposition of betaine surfactants. Pseudomonas bacteria were used as bio-destructors of the surfactants. Kinetic data were obtained to create the possibility of further optimization of research on the biodegradation of toxic organic substances. The strains that were promising destructors of cocamidopropylbetaine were selected. The toxicity of high concentrations of surfactants in relation to microorganisms of the genus Pseudomonas was proven. Safe values of the surfactant concentration for conducting biodegradation tests were found. A kinetic model of the biodestructive process was constructed. It proves that the processes of biodegradation are described by a kinetic equation of the first order. With the derived equation, it is possible to determine the time interval of biodegradation of cocamidopropylbetaine to the specified values by means of mathematical calculations.

Extremophiles, a Nifty Tool to Face Environmental Pollution: From Exploitation of Metabolism to Genome Engineering

Extremophiles are microorganisms that populate habitats considered inhospitable from an anthropocentric point of view and are able to tolerate harsh conditions such as high temperatures, extreme pHs, high concentrations of salts, toxic organic substances, and/or heavy metals. These microorganisms have been broadly studied in the last 30 years and represent precious sources of biomolecules and bioprocesses for many biotechnological applications; in this context, scientific efforts have been focused on the employment of extremophilic microbes and their metabolic pathways to develop biomonitoring and bioremediation strategies to face environmental pollution, as well as to improve biorefineries for the conversion of biomasses into various chemical compounds. This review gives an overview on the peculiar metabolic features of certain extremophilic microorganisms, with a main focus on thermophiles, which make them attractive for biotechnological applications in the field of environmental remediation; moreover, it sheds light on updated genetic systems (also those based on the CRISPR-Cas tool), which expand the potentialities of these microorganisms to be genetically manipulated for various biotechnological purposes.

Sol-Gel Synthesis of Nonstoichiometric Titanium Dioxide for Photo-Oxidation of Toxic Organic Substances

Titanium dioxide (TiO2) was synthesized by sol-gel method at different values of pH = 3, 7, 8, 9, or 10. X-ray phase analysis has shown that in an acid rout, an anatase phase had crystallized, and in an alkaline rout an amorphous phase of TiO2 was achieved. After annealing for 4 hours at 350∘C, all samples were transformed into anatase phase. The particle size in the different samples varies from 7 to 50 nm depending on the pH. The diffuse reflectance spectra revealed a high value of the band gap width in the range from 2.9 to 3.4 eV and its narrowing after annealing to the range from 2.8to 3.1 eV. The specific surface area measured by BET method was changing from 80 up to 140 m2 /g. Keywords: Titanium dioxide, nanostructure, photocatalysis, band gap, specific surface area

Cu2O as an emerging semiconductor in photocatalytic and photoelectrocatalytic treatment of water contaminated with organic substances: a review

A wide range of semiconductor photocatalysts have been used over the years in water treatment to eliminate toxic organic substances from wastewater.

Assisting Phytoremediation of Heavy Metals Using Chemical Amendments

Phytoremediation is one of the safer, economical, and environment-friendly techniques in which plants are used to recover polluted soils, particularly those containing toxic organic substances and heavy metals. However, it is considered as a slow form of remediation, as plants take time to grow and flourish. Various amendments, including the augmentation of certain chemical substances i.e., ethylenediamine tetraacetic acid (EDTA), ethylene glycol tetra acetic acid (EGTA), and sodium dodecyl sulfate (SDS) have been used to induce and enhance the phytoextraction capacity in plants. Several reports show that chemical amendments can improve the metal accumulation in different plant parts without actually affecting the growth of the plant. This raises a question about the amount and mechanisms of chemical amendments that may be needed for potentially good plant growth and metal phytoremediation. This review provides a detailed discussion on the mechanisms undertaken by three important chemical amendments that are widely used in enhancing phytoremediation (i.e., EDTA, EGTA, and SDS) to support plant growth as well as soil phytoremediation. A core part of this review focuses on the recent advances that have been made using chemical amendments in assisting metal phytoremediation.

Synthesis and evaluation of the methylene blue removal ability of Cu2O nanoparticles/TiO2 nanotubes heterostructure

Cu2O nanoparticles loaded TiO2 nanotubes (Cu2O/TNTs) were synthesized by photoreduction method for the enhancement of photocatalyst activity of TNTs under sunlight condition. Characteristic properties of these materials were determined by X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM) images and Energy-dispersive X-ray spectroscopy (EDX). XPS spectra confirmed the existence of Cu2O nanoparticles in the sample. The photocatalytic activity of Cu2O/TNTs was evaluated by the survey of the removal of methylene blue (MB) solution under direct sunlight condition. The discoloration of MB solution by Cu2O/TNTs was faster and better than by TNTs after 30 minute – irradiation. The MB removal efficiency of Cu2O/TNTs was up to 89.7 % with the above condition. The results of this study demonstrated that this material for the treatment of the toxic organic substances in the polluted water poses extremely potentials.