Phylloplane fungus Curvularia dactyloctenicola VJP08 effectively degrades commercially available PS product.

Polystyrene (PS), a widely produced plastic with an extended carbon (C-C) backbone that resists microbial attack, is produced in enormous quantities throughout the World. Naturally occurring plasticizers such as plant cuticle and lignocelluloses share similar properties to synthetic plastics such as hydrophobicity, structural complexity, and higher recalcitrance to degradation. In due course of time, phytopathogenic fungi have evolved strategies to overcome these limitations and utilize lignocellulosic waste for their nutrition. The present investigation focuses on the utilization of phylloplane fungus, Curvularia dactyloctenicola VJP08 towards its ability to colonize and degrade commercially available PS lids. The fungus was observed to densely grow onto PS samples over an incubation period of 30 days. The morphological changes showcased extensive fungal growth with mycelial imbrication invading the PS surface for carbon extraction leading to the appearance of cracks and holes in the PS surface. It was further confirmed by EDS analysis which indicated that carbon was extracted from PS for the fungal growth. Further, 3.57% decrease in the weight, 8.8% decrease in the thickness and 2 °C decrease in the glass transition temperature (Tg) confirmed alterations in the structural integrity of PS samples by the fungal action. GC-MS/MS analysis of the treated PS samples also showed significant decrease in the concentration of benzene and associated aromatic derivatives confirming the degradation of PS samples and subsequent utilization of generated by-products by the fungus for growth. Overall, the present study confirmed the degradation and utilization of commercially available PS samples by phylloplane fungus C. dactyloctenicola VJP08. These findings establish a clear cross-assessment of the phylloplane fungi for their prospective use in the development of degradation strategies of synthetic plastics.

Unveiling the potential of Lichtheimia ramosa AJP11 for myco-transformation of polystyrene sulfonate and its driving molecular mechanism.

Plastic pollution is a major environmental concern due to its deleterious effects on various ecosystems. The limitations and shortcomings of waste management strategies has led to the over-accumulation of plastic waste, mainly comprised of single-use plastics, such as polystyrene (PS). Considering the advantages of biotransformation over the other plastic disposal methods, it has become a major focus of the modern research. Biotransformation of plastics involves its microbial hydrolysis into short chain oligomers and monomers that are eventually assimilated as carbon source by the microbes leading to the release of CO2. As fungi are known to possess multifarious and highly regulated enzyme system capable of utilizing diverse nutrient sources, the present study explored the potential of Lichtheimia ramosa AJP11 towards myco-transformation of polystyrene sulfonate (PSS), a structural analogue of polystyrene (PS). During the 30-day incubation period of L. ramosa AJP11 in minimal salt medium (MSM)+1% PSS, the fungus showed 41.6% increment in its fresh weight biomass, indicating the utilization of PSS as sole carbon source. Further analysis revealed the generation of various reaction intermediates such as alkanes and fatty acids, crucial for the continuum of fungal metabolic pathways. Moreover, detection of PS oligomers such as cyclohexane and 2,4-DTBP confirmed the myco-transformation of PSS. The extracellular fungal protein profile showed considerable overexpression of a 14.4 kDa protein, characterized to be a hydrophobic surface binding (Hsb) protein, which is hypothesized to adsorb onto the PSS to facilitate its transformation. Further, in silico analysis of Hsb protein indicated it to be an amphiphilic α-helical protein with ability to bind styrene sulfonate unit via both hydrogen and hydrophobic interactions, with a binding energy of -5.02 kcal mol-1. These findings open new avenues for over expression of Hsb under controlled reactor conditions to accelerate the PS waste disposal.

Understanding the in silico aspects of bacterial catabolic cascade for styrene degradation.

Styrene is a nonpolar organic compound used in very high volume for the industrial scale production of commercially important polymers such as polystyrene resins as well as copolymers like acrylonitrile butadiene styrene, latex, and rubber. These resins are widely used in the manufacturing of various products including single-use plastics such as disposable cups and containers, protective packaging, heat insulation, and so forth. The large-scale utilization leads to the over-accumulation of styrene waste in the environment causing deleterious health risks including cancer, neurological impairment, dysbiosis of central nervous system, and respiratory problems. To eliminate the accumulating waste. Microbial enzyme-based system represents the most environmental friendly and sustainable approach for elimination of styrene waste. However, comprehensive understanding of the enzyme-substrate interaction and associated pathways would be crucial for developing large-scale disposal systems. This study aims to understand the molecular interaction between the protein-ligand complexes of the styrene catabolic reactions by bacterial enzymes of sty operon. Molecular docking analysis for catalytic enzymes namely, styrene monooxygenase (SMO), styrene oxide isomerase (SOI), and phenylacetaldehyde dehydrogenase (PAD) of the bacterial sty operon was carried out with their individual substrates, that is, styrene, styrene oxide, and phenylacetic acid, respectively. The binding energy, amino acids forming binding cavity, and binding interactions between the protein-ligand binding sites were calculated for each case. The obtained binding energies showed a stable association of these complexes indicating the future scope of their utilization for large-scale bioremediation of styrene, and its commercially used polymers and copolymers.

Formation and Characterization of Protein Corona Around Nanoparticles: A Review.

Recent years have witnessed unprecedented increase in the use of nanoparticles in various sectors viz. electronics, catalysis, agriculture, textile, cosmetics, bio-medicine, packaging, house-holds and food-associated consumer products. This has led to the inevitable release of nanoparticles into the environment, which can have negative impact on living beings. Humans can also be exposed to these nanoparticles either intentionally or accidently. Nanoparticles can enter in the human body through food chain, inhalation, open wounds, drugs and intravenous injections etc. In majority of these cases, the nanoparticles may pass through the various cell layers, cell sap and finally enter into the blood. Upon interaction with biological fluid, nanoparticles come in close proximity particularly to the proteins present in the fluid. The assembly of proteins surrounding the nanoparticle's surface is called as protein corona and their complex is known as protein-nanoparticle complex. Formation of protein corona is a vibrant and driving process, which plays a pivotal role in the functioning of nanoparticles in biological systems. Moreover, due to interaction of proteins with nanoparticles, conformational changes may occur in the native structure of protein, which may lead to change in the functioning of proteins towards its cellular interaction. The present review provides in-depth knowledge about the formation of protein corona around nanoparticles and the factors regulating this process. Further, it discusses various techniques that can be used for the protein corona analysis and obtaining information about molecular consequences upon nanoparticle's exposure. Finally, the functional aspects of protein-nanoparticle complex have been discussed in detail. In-depth understanding of protein-nanoparticles complex can be instrumental to generate well-suited nanoparticles with desired surface characteristics in the way to biological application.