Explore the vast range of titles available.

Since the sulfur specific cleavage is vital for the organic sulfur removal from fossil fuel, we explored potential bacterial strains of MTCC (Microbial Type Culture Collection) to desulfurize the Dibenzothiophene (DBT) through C-S bond cleavage (4-S pathway). MTCC strains Rhodococcus rhodochrous (3552), Arthrobacter sulfureus (3332), Gordonia rubropertincta (289), and Rhodococcus erythropolis (3951) capable of growing in 0.5 mM DBT were examined for their desulfurization ability. The presence of dsz genes as well as the metabolites was screened by polymerase chain reaction (PCR) and HPLC, respectively. All these strains showed > 99% DBT desulfurization with 10 days of incubation in minimal salt medium. From the HPLC analysis it was further revealed that these MTCC strains show differences in the end metabolites and desulfurize DBT differently following a variation in the regular 4-S pathway. These findings are also well corroborating with their respective organization of dszABC operons and their relative abundance. The above MTCC strains are capable of desulfurizing DBT efficiently and hence can be explored for biodesulfurization of petrochemicals and coal with an eco-friendly and energy economical process.

An eco-friendly microbial method for synthesis of silver colloid solution with antimicrobial activity is developed using a fungal strain of Penicillium purpurogenum NPMF. It is observed that increase in concentration of AgNO 3 increases the formation of silver nanoparticle. At 5 mM concentration highly populated polydispersed nanoparticles form. Furthermore, change in pH of the reaction mixture leads to change in shape and size of silver nanoparticles. At lower pH two peaks are observed in the absorption spectra showing polydispersity of nanoparticles. However, highly monodispersed spherical nanoparticles of 8–10 nm size form with 1 mM AgNO 3 concentration at pH 8. Antimicrobial activity of nanoparticles is demonstrated against pathogenic gram negative bacteria like Escherichia coli and Pseudomonas aeruginosa , and gram positive bacteria like Staphylococcus aureus. The antimicrobial activity of silver nanoparticles obtained at different initial pH show strong dependence on the surface area and shape of the nanoparticles.

The ongoing exploration of economical, sustainable, and environment-friendly methods for synthesizing monodisperse colloidal metal nanoparticles is growing day by day due to their potential application in various fields. The use of plant derivatives in nanoparticle synthesis and their suitability as sustainable catalysts have emerged as significant areas of research. In this study, silver nanoparticles were synthesized using an aqueous extract obtained from the commonly found weed Commelina erecta, L. Extensive study is conducted to optimize various synthesis parameters such as pH, reducing agent concentration, silver nitrate concentration, and temperature. The plant extract utilized in the synthesis process contained variety of antioxidants, including malic acid, phenol, benzoic acid, and catechol, which played a crucial role in both reduction and capping during the synthesis process, thereby making them suitable for biomedical applications. The optimized synthesis process yielded silver nanoparticles with a particle size of 16.2 ± 3.1 nm. These nanoparticles exhibited excellent stability and demonstrated remarkable antibacterial activity compared to the standard antibacterial agent, streptomycin. In addition, the silver nanoparticles displayed promising antioxidant activity attributed to the presence of antioxidant functional groups on their surface. This study reports, for the first time, the synthesis of silver nanoparticles using antioxidant compounds present in C. erecta, L. plant extract. The antioxidant compounds identified through GC–MS belong to phenols, phenolic acids, and carboxylic acid groups. Furthermore, the exceptional antimicrobial and antioxidant properties exhibited by the synthesized silver nanoparticles offer new possibilities for their potential applications.

Biosynthesis of gold nanoparticles (GNPs) using fungal extracellular filtrate as the source of reducing and capping agent is reported here. The study includes the fabrication of GNPs using a soil fungus CO1 in a very effective way for material synthesis. Morphological, molecular, and phylogenetic studies of the fungus CO1 show that it is similar to the Aspergillus austwickii. Aspergillus austwickii CO1 is reported for the first time for GNPs synthesis in this paper. The characteristic surface plasmon resonance (SPR) peak for colloidal GNPs was observed at 532 nm. The GNPs remained stable for about 90 days at room temperature. The optimum temperature, pH, and substrate concentration were 100 °C, pH 9, and 1 mM AuCl 4 − concentration, respectively, to obtain maximum possible stability and monodispersity of synthesized GNPs. The GNPs were characterized using instrumental analysis. Transmission electron microscopy analysis confirmed the formation of spherical particles of size 14.7 ± 6.9 nm. The kinetics of the GNPs synthesis reaction was investigated by measuring particle size and zeta potential as a function of time. The stability of biosynthesized GNPs was better than chemically synthesized citrate-GNPs (Cit-GNPs) when exposed to high ionic concentration by the addition of sodium chloride in the GNP solution. The biosynthesized GNPs were able to resist aggregation even with the addition of 0.2 mM of NaCl, while Cit-GNPs aggregated at much lower concentration of 0.05 mM NaCl. Selective reactivity of the GNPs was observed toward Mg 2+ ions, with a minimum detection limit of 40 ppm. Detection could be visualized by naked eye also. Thus, the non-toxic biosynthesized GNPs could further assist in the Mg 2+ optical sensing application of water.

The ungenerous release of metals from different industrial, agricultural, and anthropogenic sources has resulted in heavy metal pollution. Metals with a density larger than 5 g cm −3 have been termed as heavy metals and have been stated to be potentially toxic to human and animals. Algae are known to be pioneer organisms with the potential to grow under extreme conditions including heavy metal-polluted sites. They have evolved efficient defense strategies to combat the toxic effects exerted by heavy metal ions. Most of the algal strains are reported to accumulate elevated metal ion concentration in cellular organelles. With respect to that, this review focuses on understanding the various strategies used by algal system for heavy metal resistance. Additionally, the application of this metal resistance in biosynthesis of metal nanoparticles and metal oxide nanoparticles has been investigated in details. We thereby conclude that algae serve as an excellent system for understanding metal uptake and accumulation. This thereby assists in the design and development of low-cost approaches for large-scale synthesis of nanoparticles and bioremediation approach, providing ample opportunities for future work.

Biosynthesis of monodispersed nanoparticles, along with determination of potential responsible biomolecules, is the major bottleneck in the area of bionanotechnology research. The present study focuses on an ecofriendly, ambient temperature protocol for size controlled synthesis of gold nanoparticles, using the fungus Aspergillus terreus IF0. Gold nanoparticles were formed immediately, with the addition of chloroauric acid to the aqueous fungal extract. Synthesized nanoparticles were characterized by UV-Vis spectroscopy, TEM-EDX, and XRD analysis. Particle diameter and dispersity of nanoparticles were controlled by varying the pH of the fungal extract. At pH 10, the average size of the synthesized particles was in the range of 10–19 nm. Dialysis to obtain high and low molecular weight fraction followed by FTIR analysis revealed that biomolecules larger than 12 kDa and having –CH, –NH, and –SH functional groups were responsible for bioreduction and stabilization. In addition, the synthesized gold nanoparticles were found to be selectively bactericidal against the pathogenic gram negative bacteria, Escherichia coli.

Due to the resistance and non-biodegradable nature, dye contamination contributes to several significant environmental problems as well as a severe public health hazard. Therefore, protecting the ecosystem from these toxic compounds and the harm they cause is essential. Consequently, it is vital to protect the ecosystem against such toxins and the injury they cause. Congo red is one of the predominantly used dyes in industries. In the present work, we have devised a hetero catalyst consisted of dried biomass of microalga Scenedesmus attached with silver nanoparticles on the surface. Under the ambient condition, the biomass-silver nanocomposite was utilized as a heterogeneous catalyst for the degradation of the dye (Congo red). A number of tests were performed to determine the impact of NaBH4 concentration, pH, and composite load on the catalytic effectiveness of the composite. It was discovered that the calcined composite material made an excellent Congo red reduction catalyst. As little as 0.5 mg mL−1 of the composite was capable of reducing Congo red (200 mg L−1) by more than 90% at a rate of 0.37 mg mL−1 min−1 within 4 min of reaction time.

The use of functionalized gold nanoparticles (GNPs) as a colorimetric sensor for heavy metal ions has been extensively studied due to their unique optical properties and ease of functionalization. Amino acid-functionalized GNPs have emerged as a promising platform for colorimetric sensing of various pollutants, including metal ions. However, the differential metal ion selectivity of the GNPs functionalized with different amino acids remains poorly understood. This study describes the synthesis and functionalization of Tween-20-stabilized citrated gold nanoparticles (Cit-T20-GNPs) using various amino acids and their interaction with metal ions. Tween-20 was found to be essential to provide stability to the nanoparticles for functionalization. The morphology, hydrodynamic diameter, and zeta potential of the GNPs were characterized using transmission electron microscopy and dynamic electrophoretic light scattering analysis. The GNPs were then functionalized with L-threonine, L-glutamine, L-alanine, L-tryptophan, L-cysteine, L-methionine, L-arginine, L-lysine, L-proline, and glycine. The metal-induced aggregation of the functionalized GNPs was studied using twelve different metal ions. At the experimental pH (5–6), the colloidal integrity of most amino acid-functionalized Cit-T20-GNPs remained intact upon treatment with the metal ions, except for Cit-T20-Arg-GNPs and Cit-T20-Lys-GNPs. These two GNPs showed interaction with most metal ions, which led to their aggregation. The study provides insights into the specific interaction and affinity of metal ions toward different amino acid ligands and highlights the potential of designing ion-specific colorimetric sensors. The possible mechanism behind these interactions has also been speculated. Graphical abstract

Biological sequestration of cadmium (Cd) and retention of adsorbed cadmium as cadmium sulphide (CdS) nanoparticles inside the cell by a lipid-producing green algae Scenedesmus -24 is reported. The microalga was able to grow in the growth media containing 30 mg L −1 of cadmium without any growth inhibition. Adsorption of Cd(II) was dependent on the pH of the medium, initial concentration of cadmium, density of algal biomass (biosorbent dose), and contact time. The adsorption follows Langmuir isotherm pattern with an estimated maximum cadmium adsorption capacity at 50 mg g −1 . The kinetics of adsorption followed Lagergren’s pseudo-second-order model. FTIR analysis revealed the presence of different functional groups on the algal biomass which may be responsible for adsorption of Cd(II). After adsorption, the bound metal ions were retained in the microalgal biomass as CdS nanoparticles. Presence of CdS nanoparticle was confirmed by XRD and TEM analysis. The results of the present study conclusively demonstrate that the microalga Scenedesmus -24 may be a promising candidate for sequestration of cadmium from cadmium polluted water and also its recovery as precious CdS nanoparticles.

Biosurfactants are amphiphilic molecules having hydrophobic and hydrophilic moieties produced by various microorganisms. These molecules trigger the reduction of surface tension or interfacial tension in liquids. A biosurfactant-producing halophile was isolated from Lake Chilika, a brackish water lake of Odisha, India (19°41′39″N, 85°18′24″E). The halophile was identified as Bacillus tequilensis CH by biochemical tests and 16S rRNA gene sequencing and assigned accession no. KC851857 by GenBank. The biosurfactant produced by B. tequilensis CH was partially characterized as a lipopeptide using thin-layer chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance techniques. The minimum effective concentration of a biosurfactant for inhibition of pathogenic biofilm (Escherichia coli and Streptococcus mutans) on hydrophilic and hydrophobic surfaces was found to be 50 μg ml⁻¹. This finding has potential for a variety of applications.