Bacterial Polysaccharide-Stabilized Silver Nanoparticles Photocatalytically Decolorize Azo Dyes.

Bacterial polysaccharide is advantageous over plant, algal, and fungal polysaccharides in terms of stability, non-toxicity, and biodegradable nature. In addition, bacterial cell wall polysaccharide (CPs) is very little explored compared to exopolysaccharide. In this study, CPs have been isolated from thermotolerant Chryseobacterium geocarposphaerae DD3 (CPs3) from textile industry dye effluent. Structural characterization of the CPs was done by different techniques, viz., scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). CPs3 demonstrated compact non-porous amorphous surface composed of evenly distributed macromolecular lumps. TGA revealed a high thermostability (~ 350 °C) of the polysaccharide. FTIR and NMR confirm the polysaccharidic nature of the polymer, consisting of glucose units linked by both ß-(1 → 3) and ß-(1 → 4) glycosidic bonds. The functional properties of CPs3 were evaluated for industrial use as additive, especially antibacterial, emulsification, and flocculation capacities. A single-step green synthesis of silver nanoparticle (AgNP) was performed using CPs3. AgNP was characterized using ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), AFM, and particle size analyses. The CPs3-stabilized AgNP exhibited potential photocatalytic activity against a broad range of azo dyes, congo red (88.33 ± 0.48%), methyl red (76.81 ± 1.03%), and malachite green (47.34 ± 0.90%) after only 3 h of reaction. According to our knowledge, this is the first report on CPs from C. geocarposphaerae. The results demonstrated multifunctionality of CPs3 in both prospective, CPs3 as additive in biotechnology industry as well as Cps3-stabilized AgNP for bioremediation of azo dye.

Multifunctional Layer-by-Layer Coating Based on a New Amphiphilic Block Copolymer via RAFT-Mediated Polymerization-Induced Self-Assembly Process.

In this hi-tech world, the "smart coatings" have sparked significant attention among materials scientists because of their versatile applications. Various strategies have been developed to generate smart coatings in the past 2 decades. The layer-by-layer (LbL) technique is the most commonly employed strategy to produce a smart coating for suitable applications. Here, we present a smart coating with healing, antifogging, and fluorescence properties fabricated by the LbL assembly of an anionic amphiphilic block copolymer latex and cationic inorganic POSS (polyhedral-oligomeric-silsesquioxane) nanoparticles. In this case, a new anionic block copolymer (BCP), {poly(sodium styrene sulfonate)-block-poly[2-(acetoacetoxy)ethyl methacrylate]}, (PSS-b-PAAEMA) was synthesized via surfactant-free RAFT-mediated emulsion polymerization using the PISA technique. The PSS-b-PAAEMA was characterized by 1H NMR, dynamic light scattering, scanning electron microscopy, and transmission electron microscopy analyses as well as by UV-vis and photoluminescence spectroscopy. For LbL coating fabrication, an amine-modified glass was successively dipped in the anionic latex and cationic POSS solution. The transparent coating exhibited good fluorescence properties under UV light (blue color). The antifogging performance of the coating was also investigated using both cold-warm and hot-vapor techniques. Additionally, the coating surface showed a significant healing activity with a healing efficiency of >75% through ionic interaction. Thus, this finding provides a simple low volatile organic compound (VOC) water-based LbL coating with multifunctional properties that can be a potential material for versatile applications.

Optimization and Characterization of a Novel Exopolysaccharide from Bacillus haynesii CamB6 for Food Applications.

Extremophilic microorganisms often produce novel bioactive compounds to survive under harsh environmental conditions. Exopolysaccharides (EPSs), a constitutive part of bacterial biofilm, are functional biopolymers that act as a protecting sheath to the extremophilic bacteria and are of high industrial value. In this study, we elucidate a new EPS produced by thermophilic Bacillus haynesii CamB6 from a slightly acidic (pH 5.82) Campanario hot spring (56.4 °C) located in the Central Andean Mountains of Chile. Physicochemical properties of the EPS were characterized by different techniques: Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), 1D and 2D Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). The EPS demonstrated amorphous surface roughness composed of evenly distributed macromolecular lumps. GPC and HPLC analysis showed that the EPS is a low molecular weight heteropolymer composed of mannose (66%), glucose (20%), and galactose (14%). FTIR analysis demonstrated the polysaccharide nature (-OH groups, Acetyl groups, and pyranosic ring structure) and the presence of different glycosidic linkages among sugar residues, which was further confirmed by NMR spectroscopic analyses. Moreover, D-mannose α-(1→2) and α-(1→4) linkages prevail in the CamB6 EPS structure. TGA revealed the high thermal stability (240 °C) of the polysaccharide. The functional properties of the EPS were evaluated for food industry applications, specifically as an antioxidant and for its emulsification, water-holding (WHC), oil-holding (OHC), and flocculation capacities. The results suggest that the study EPS can be a useful additive for the food-processing industry.

Genomic, morphological, and biochemical analyses of a multi-metal resistant but multi-drug susceptible strain of Bordetella petrii from hospital soil.

Contamination of soil by antibiotics and heavy metals originating from hospital facilities has emerged as a major cause for the development of resistant microbes. We collected soil samples surrounding a hospital effluent and measured the resistance of bacterial isolates against multiple antibiotics and heavy metals. One strain BMCSI 3 was found to be sensitive to all tested antibiotics. However, it was resistant to many heavy metals and metalloids like cadmium, chromium, copper, mercury, arsenic, and others. This strain was motile and potentially spore-forming. Whole-genome shotgun assembly of BMCSI 3 produced 4.95 Mb genome with 4,638 protein-coding genes. The taxonomic and phylogenetic analysis revealed it, to be a Bordetella petrii strain. Multiple genomic islands carrying mobile genetic elements; coding for heavy metal resistant genes, response regulators or transcription factors, transporters, and multi-drug efflux pumps were identified from the genome. A comparative genomic analysis of BMCSI 3 with annotated genomes of other free-living B. petrii revealed the presence of multiple transposable elements and several genes involved in stress response and metabolism. This study provides insights into how genomic reorganization and plasticity results in evolution of heavy metals resistance by acquiring genes from its natural environment.

Plant-growth-promoting bacteria from rhizosphere of Chilean common bean ecotype (Phaseolus vulgaris L.) supporting seed germination and growth against salinity stress.

Salinity abiotic stress is increasing day by day due to continuous global warming and climate change. This is also becoming one of the major causes behind the reduction in crop production. Plant-bacteria interaction plays an essential role in improving crop yield without using any chemical fertilizers. The present study aims to characterize the interaction between plant-growth-promoting bacteria (PGPB) and their role in mitigating salinity stress for local variety crops. Therefore, in this work, two PGPB, namely, Bacillus proteolyticus Cyn1 and Bacillus safensis Cyn2, were isolated from rhizospheric soil of the Chilean common bean ecotype "Sapito" (Phaseolus vulgaris L.), and their PGPB traits were analyzed. Cyn1 can produce NH3 and HCN and also secrete siderophores, whereas Cyn2 produced NH3 and siderophores but responded negatively to HCN production. Both the isolated bacteria have shown a positive result for ACC deaminase production, phosphate solubilization, and catalase enzyme secretion. Under all three tested abiotic stresses, i.e., temperature, water, and salinity, both the bacteria and their consortium have demonstrated positive responses. Cyn1 under temperature stress and water stress can produce a biofilm network to combat the stress. While under salinity stress, both the PGPB isolates indicated the production of stress components and cytoplasmic inclusion bodies. Based on the response, among all other abiotic stresses, salinity stress was chosen for further plant-bacteria interaction study and growth. Visible root colonization of the bacteria has been observed in comparison to the control. The germination index was 100% for all experimental setups of seed bacterization, both under control conditions and salinity stress. Both bacteria responded with good PGP traits that helped in the growth of healthy plants after the bacterial treatment in final pot experiments. Additionally, the consortium and the plants treated with Cyn1 have demonstrated high production of photosynthetic pigments in both experimental setups. Both B. proteolyticus Cyn1 and B. safensis Cyn2 have shown promising PGP characters and efficient response against toxicity related to salinity. Hence, both of these bacteria and consortium can be used for improved agricultural production of Chilean native common beans in the near future.

Extremophilic Exopolysaccharides: Biotechnologies and Wastewater Remediation.

Various microorganisms thrive under extreme environments, like hot springs, hydrothermal vents, deep marine ecosystems, hyperacid lakes, acid mine drainage, high UV exposure, and more. To survive against the deleterious effect of these extreme circumstances, they form a network of biofilm where exopolysaccharides (EPSs) comprise a substantial part. The EPSs are often polyanionic due to different functional groups in their structural backbone, including uronic acids, sulfated units, and phosphate groups. Altogether, these chemical groups provide EPSs with a negative charge allowing them to (a) act as ligands toward dissolved cations as well as trace, and toxic metals; (b) be tolerant to the presence of salts, surfactants, and alpha-hydroxyl acids; and (c) interface the solubilization of hydrocarbons. Owing to their unique structural and functional characteristics, EPSs are anticipated to be utilized industrially to remediation of metals, crude oil, and hydrocarbons from contaminated wastewaters, mines, and oil spills. The biotechnological advantages of extremophilic EPSs are more diverse than traditional biopolymers. The present review aims at discussing the mechanisms and strategies for using EPSs from extremophiles in industries and environment bioremediation. Additionally, the potential of EPSs as fascinating biomaterials to mediate biogenic nanoparticles synthesis and treat multicomponent water contaminants is discussed.

Computational Study on Temperature Driven Structure-Function Relationship of Polysaccharide Producing Bacterial Glycosyl Transferase Enzyme.

Glycosyltransferase (GTs) is a wide class of enzymes that transfer sugar moiety, playing a key role in the synthesis of bacterial exopolysaccharide (EPS) biopolymer. In recent years, increased demand for bacterial EPSs has been observed in pharmaceutical, food, and other industries. The application of the EPSs largely depends upon their thermal stability, as any industrial application is mainly reliant on slow thermal degradation. Keeping this in context, EPS producing GT enzymes from three different bacterial sources based on growth temperature (mesophile, thermophile, and hyperthermophile) are considered for in silico analysis of the structural-functional relationship. From the present study, it was observed that the structural integrity of GT increases significantly from mesophile to thermophile to hyperthermophile. In contrast, the structural plasticity runs in an opposite direction towards mesophile. This interesting temperature-dependent structural property has directed the GT-UDP-glucose interactions in a way that thermophile has finally demonstrated better binding affinity (-5.57 to -10.70) with an increased number of hydrogen bonds (355) and stabilizing amino acids (Phe, Ala, Glu, Tyr, and Ser). The results from this study may direct utilization of thermophile-origin GT as best for industrial-level bacterial polysaccharide production.

Green polymeric nanomaterials for the photocatalytic degradation of dyes: a review.

Pure and drinkable water will be rarer and more expensive as the result of pollution induced by industrialisation, urbanisation and population growth. Among the numerous sources of water pollution, the textile industry has become a major issue because effluents containing dyes are often released in natural water bodies. For instance, about two years are needed to biodegrade dye-derived, carcinogenic aromatic amines, in sediments. Classical remediation methods based upon physicochemical reactions are costly and still generate sludges that contain amine residues. Nonetheless, recent research shows that nanomaterials containing biopolymers are promising to degrade organic pollutants by photocatalysis. Here, we review the synthesis and applications of biopolymeric nanomaterials for photocatalytic degradation of azo dyes. We focus on conducting biopolymers incorporating metal, metal oxide, metal/metal oxide and metal sulphide for improved biodegradation. Biopolymers can be obtained from microorganisms, plants and animals. Unlike fossil-fuel-derived polymers, biopolymers are carbon neutral and thus sustainable in the context of global warming. Biopolymers are often biodegradable and biocompatible.

Structural-functional analyses of textile dye degrading azoreductase, laccase and peroxidase: a comparative in silico study

Background: Textile industry not only plays a vital role in our daily life but also a prominent factor in improving global economy. One of the environmental concern is it releases huge quantities of toxic dyes in the water leading to severe environmental pollution. Bacterial laccase and azoreductase successfully oxidize complex chemical structure of nitrogen group-containing azo dyes. Additionally, the presence of textile dye infuriates bacterial peroxidase to act as a dye degrading enzyme. Our present study deals with three textile dye degrading enzymes laccase, azoreductase, and peroxidase through analyzing their structural and functional properties using standard computational tools. Result: According to the comparative analysis of physicochemical characteristics, it was clear that laccase was mostly made up of basic amino acids whereas azoreductase and peroxidase both comprised of acidic amino acids. Higher aliphatic index ascertained the thermostability of all these three enzymes. Negative GRAVY value of the enzymes confirmed better water interaction of the enzymes. Instability index depicted that compared to laccase and preoxidase, azoreductase was more stable in nature. It was also observed that the three model proteins had more than 90% of total amino acids in the favored region of Ramachandran plot. Functional analysis revealed laccase as multicopper oxidase type enzyme and azoreductase as FMN dependent enzyme, while peroxidase consisted of α-ß barrel with additional haem group. Conclusion: Present study aims to provide knowledge on industrial dye degrading enzymes, choosing the suitable enzyme for industrial set up and to help in understanding the experimental laboratory requirements as well.

A self-healable and antifouling hydrogel based on PDMS centered ABA tri-block copolymer polymersomes: a potential material for therapeutic contact lenses.

Herein we have prepared an antifouling and self-healable poly(dimethyl siloxane) (PDMS) based hydrogel which consists of a mixture of curcumin loaded zwitterionic PDMS polymersomes and amine functionalized PDMS polymersomes prepared via Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization and a Schiff-base reaction. The curcumin loaded polymersome consists of a PDMS and poly([dimethyl-[3-(2-methyl-acryloylamino)-propyl]-(3-sulfopropyl)ammonium)] (poly(sulfobetaine)) based tri-block copolymer (BCP) and it was characterized by dynamic light scattering (DLS), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) analyses. To prepare the hydrogel, amine functionalized PDMS polymersomes were crosslinked with polyethylene glycol dialdehyde (PEG-DA) in pH 7.4 buffer solution via a Schiff-base reaction. This hydrogel was able to show sustained delivery of the entrapped curcumin drug for more than 72 h. The self-healing characteristic of the prepared hydrogel in the presence of saline water was elucidated by the "scratch and heal" method and subsequently analyzed through tensile study. Due to the presence of the poly(zwitterionic) moiety in the hydrogel system, it was observed that the hydrogel can efficiently reduce protein deposition, where Bovine Serum Albumin (BSA) was taken as a model protein. It was observed that the curcumin loaded hydrogel was detrimental towards both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. This type of smart soft hydrogel system can be a potential material for therapeutic applications for several eye diseases.