Horizontal gene transfer and silver nanoparticles production in a new Marinomonas strain isolated from the Antarctic psychrophilic ciliate Euplotes focardii

Advances in Regenerative and Reconstructive Medicine in the Prevention and Treatment of Bone Infections

Reconstructive and regenerative medicine are critical disciplines dedicated to restoring tissues and organs affected by injury, disease, or congenital anomalies. These fields rely on biomaterials like synthetic polymers, metals, ceramics, and biological tissues to create substitutes that integrate seamlessly with the body. Personalized implants and prosthetics, designed using advanced imaging and computer-assisted techniques, ensure optimal functionality and fit. Regenerative medicine focuses on stimulating natural healing mechanisms through cellular therapies and biomaterial scaffolds, enhancing tissue regeneration. In bone repair, addressing defects requires advanced solutions such as bone grafts, essential in medical and dental practices worldwide. Bovine bone scaffolds offer advantages over autogenous grafts, reducing surgical risks and costs. Incorporating antimicrobial properties into bone substitutes, particularly with metals like zinc, copper, and silver, shows promise in preventing infections associated with graft procedures. Silver nanoparticles exhibit robust antimicrobial efficacy, while zinc nanoparticles aid in infection prevention and support bone healing; 3D printing technology facilitates the production of customized implants and scaffolds, revolutionizing treatment approaches across medical disciplines. In this review, we discuss the primary biomaterials and their association with antimicrobial agents.

Evolutionary history and activity towards oligosaccharides and polysaccharides of GH3 glycosidases from an Antarctic marine bacterium

Glycoside hydrolases (GHs) are pivotal in the hydrolysis of the glycosidic bonds of sugars, which are the main carbon and energy sources. The genome of Marinomonas sp. ef1, an Antarctic bacterium, contains three GHs belonging to family 3. These enzymes have distinct architectures and low sequence identity, suggesting that they originated from separate horizontal gene transfer events. M-GH3_A and M-GH3_B, were found to differ in cold adaptation and substrate specificity. M-GH3_A is a bona fide cold-active enzyme since it retains 20 % activity at 10 °C and exhibits poor long-term thermal stability. On the other hand, M-GH3_B shows mesophilic traits with very low activity at 10 °C (< 5 %) and higher long-term thermal stability. Substrate specificity assays highlight that M-GH3_A is a promiscuous β-glucosidase mainly active on cellobiose and cellotetraose, whereas M-GH3_B is a β-xylosidase active on xylan and arabinoxylan. Structural analysis suggests that such functional differences are due to their differently shaped active sites. The active site of M-GH3_A is wider but has a narrower entrance compared to that of M-GH3_B. Genome-based prediction of metabolic pathways suggests that Marinomonas sp. ef1 can use monosaccharides derived from the GH3-catalyzed hydrolysis of oligosaccharides either as a carbon source or for producing osmolytes.

Green synthesis of silver nanoparticles by sweet cherry and its application against cherry spot disease

Asia has a rich history of cultivating sweet cherries, a practice that has been carried out since ancient times. However, the effective management of Alternaria disease in sweet cherry crops has presented a formidable challenge, resulting in notable decreases in yield. Various attempts have been made to employ both chemical and biological treatments; however, their effectiveness has been restricted. In order to tackle this problem, an investigation was carried out, with the primary objective of isolating and identifying Alternaria isolates that are accountable for the occurrence of sweet cherry soft spot rot. Out of the twelve isolates examined, the CHM-4 isolate was found to be the most pathogenic. Its identification was achieved through the use of the ITS genomic region (ITS1 and ITS4), and the BLAST results revealed a 95 % similarity with Alternaria alternata (MG744381.1). The objective of the research was to explore the potential of silver nanoparticles (SNPs) synthesized by phytosynthesis as a novel antifungal agent to combat sweet cherry soft spot pathogenicity. The biosynthesis of SNPs was carried out using sweet cherry fruits kernel exudate, which served as an environmentally friendly source. The exudates exhibited the ability to produce nanoparticles with an average size of 24.97 nm. Analysis conducted using a transmission electron microscope (TEM) revealed the multifaceted structure of these nanoparticles. Furthermore, when tested at concentrations of 5, 10, 20, and 40 μg/ml, these biosynthetic nanoparticles demonstrated the capability to inhibit the growth of Alternaria fungi and effectively destroy fungal hyphae. It is advisable to utilize diverse components of sweet cherry for the synthesis of various nanoparticles owing to their compatibility with the surrounding environment.

Characterization and identification of long-chain hydrocarbon-degrading bacterial communities in long-term chronically polluted soil in Ogoniland: an integrated approach using culture-dependent and independent methods

Escalating oil consumption has resulted in an increase in accidental spills of petroleum hydrocarbons, causing severe environmental degradation, notably in vulnerable regions like the Niger Delta. Complex mixture of these hydrocarbons particularly long-chain alkanes presents unique challenges in restoration of polluted environment due to their chemical properties. This study aimed to investigate the long-chain hydrocarbon-degrading bacterial communities within long-term chronically polluted soil in Ogoniland, by utilizing both traditional cultivation methods and modern culture-independent techniques. Results revealed that surface-polluted soil (SPS) and subsurface soil (SPSS) exhibit significantly higher total organic carbon (TOC) ranging from 5.64 to 5.06% and total petroleum hydrocarbons (TPH) levels ranging from 36,775 ppm to 14,087 ppm, compared to unpolluted soil (UPS) with 1.97% TOC and 479 ppm TPH, respectively. Analysis of carbon chain lengths reveals the prevalence of longer-chain alkanes (C20-28) in the surface soil. Culture-dependent methods, utilizing crude oil enrichment (COE) and paraffin wax enrichment (PWE), yield 47 bacterial isolates subjected to a long-chain alkane degradation assay. Twelve bacterial strains demonstrate significant degradation abilities across all enriched media. Three bacterial members, namely Pseudomonas sp. (almA), Marinomonas sp. (almA), and Alteromonas (ladA), exhibit genes responsible for long-chain alkane degradation, demonstrating efficiency between 50 and 80%. Culture-independent analysis reveals that surface SPS samples exhibit greater species richness and diversity compared to subsurface SPSS samples. Proteobacteria dominates as the phylum in both soil sample types, ranging from 22.23 to 82.61%, with Firmicutes (0.2-2.22%), Actinobacteria (0.4-3.02%), and Acidobacteria (0.1-3.53%) also prevalent. Bacterial profiles at genus level revealed that distinct variations among bacterial populations between SPS and SPSS samples comprising number of hydrocarbon degraders and the functional predictions also highlight the presence of potential catabolic genes (nahAa, adh2, and cpnA) in the polluted soil. However, culture-dependent analysis only captured a few of the dominant members found in culture-independent analysis, implying that more specialized media or environments are needed to isolate more bacterial members. The findings from this study contribute valuable information to ecological and biotechnological aspects, aiding in the development of more effective bioremediation applications for restoring oil-contaminated environments.

Synthesis of Bioactive Nickel Nanoparticles Using Bacterial Strains from an Antarctic Consortium

Marine microorganisms have been demonstrated to be an important source for bioactive molecules. In this paper we report the synthesis of Ni nanoparticles (NiSNPs) used as reducing and capping agents for five bacterial strains isolated from an Antarctic marine consortium: Marinomonas sp. ef1, Rhodococcus sp. ef1, Pseudomonas sp. ef1, Brevundimonas sp. ef1, and Bacillus sp. ef1. The NiSNPs were characterized by Ultraviolet-visible (UV-vis) spectroscopy, Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopic analysis. The maximum absorbances in the UV-Vis spectra were in the range of 374 nm to 422 nm, corresponding to the Surface plasmon resonance (SPR) of Nickel. DLS revealed NiSNPs with sizes between 40 and 45 nm. All NiSNPs were polycrystalline with a face-centered cubic lattice, as revealed by XRD analyses. The NiSNPs zeta potential values were highly negative. TEM analysis showed that the NiSNPs were either spherical or rod shaped, well segregated, and with a size between 20 and 50 nm. The FTIR spectra revealed peaks of amino acid and protein binding to the NiSNPs. Finally, all the NiSNPs possess significant antimicrobial activity, which may play an important role in the management of infectious diseases affecting human health.

Microbial impact to environmental toxicants Ni(II) and Co(II): Joint toxicity and cellular response in Paramecium

Cobalt (Co) and Nickel (Ni) are increasingly found in our environment. We analysed their combined toxicity and uptake mechanisms in the early food chain by studying bacteria and the bacterivorous ciliate Paramecium as a primary consumer. We exposed both species to these metals to measure the toxicity, uptake and transfer of metals from bacteria to Paramecium. We found that Ni is more toxic than Co, and that toxicity increases for both metals when (i) food bacteria are absent and (ii) both metals are applied in combination. The cellular content in bacteria after exposure shows a concentration dependent bias for either Ni or Co. Comparing single treatment and joint exposure, bacteria show increased levels of both metals when these are both exposed. To imitate the basic level of the food chain, we fed these bacteria to paramecia. The cellular content shows a similar ratio of Nickel and Cobalt as in food bacteria. This is different to the direct application of both metals to paramecia, where Cobalt is enriched over Nickel. This indicates that bacteria can selectively pre-accumulate metals for introduction into the food chain. We also analysed the transcriptomic response of Paramecium to sublethal doses of Nickel and Cobalt to gain insight into their toxicity mechanisms. Gene ontology (GO) analysis indicates common deregulated pathways, such as ammonium transmembrane transport and ubiquitine-associated protein degradation. Many redox-related genes also show deregulation of gene expression, indicating cellular adaptation to increased RONS stress. This suggests that both metals may also target the same cellular pathways and this is consistent with the increased toxicity of both metals when used together. Our data reveal complex ecotoxicological pathways for these metals and highlights the different parameters for their fate in the ecosystem, in the food chain and their ecotoxicological risk after environmental contamination.

Phylogenetic diversity and functional potential of the microbial communities along the Bay of Bengal coast

The Bay of Bengal, the world's largest bay, is bordered by populous countries and rich in resources like fisheries, oil, gas, and minerals, while also hosting diverse marine ecosystems such as coral reefs, mangroves, and seagrass beds; regrettably, its microbial diversity and ecological significance have received limited research attention. Here, we present amplicon (16S and 18S) profiling and shotgun metagenomics data regarding microbial communities from BoB's eastern coast, viz., Saint Martin and Cox's Bazar, Bangladesh. From the 16S barcoding data, Proteobacteria appeared to be the dominant phylum in both locations, with Alteromonas, Methylophaga, Anaerospora, Marivita, and Vibrio dominating in Cox's Bazar and Pseudoalteromonas, Nautella, Marinomonas, Vibrio, and Alteromonas dominating the Saint Martin site. From the 18S barcoding data, Ochrophyta, Chlorophyta, and Protalveolata appeared among the most abundant eukaryotic divisions in both locations, with significantly higher abundance of Choanoflagellida, Florideophycidae, and Dinoflagellata in Cox's Bazar. The shotgun sequencing data reveals that in both locations, Alteromonas is the most prevalent bacterial genus, closely paralleling the dominance observed in the metabarcoding data, with Methylophaga in Cox's Bazar and Vibrio in Saint Martin. Functional annotations revealed that the microbial communities in these samples harbor genes for biofilm formation, quorum sensing, xenobiotics degradation, antimicrobial resistance, and a variety of other processes. Together, these results provide the first molecular insight into the functional and phylogenetic diversity of microbes along the BoB coast of Bangladesh. This baseline understanding of microbial community structure and functional potential will be critical for assessing impacts of climate change, pollution, and other anthropogenic disturbances on this ecologically and economically vital bay.

Long-term effects of Ag NPs on denitrification in sediment: Importance of Ag NPs exposure ways in aquatic ecosystems

The widespread use of silver nanoparticles (Ag NPs) inevitably leads to their increasing release into aquatic systems, with studies indicating that the mode of Ag NPs entry into water significantly affects their toxicity and ecological risks. However, there is a lack of research on the impact of different exposure ways of Ag NPs on functional bacteria in sediment. This study investigates the long-term influence of Ag NPs on denitrification process in sediments by comparing denitrifies responses to single (pulse injection of 10 mg/L) and repetitive (1 mg/L × 10 times) Ag NPs treatments over 60-day incubation. Results showed that a single exposure of 10 mg/L Ag NPs caused an obvious toxicity on activity and abundance of denitrifying bacteria on the first 30 days, reflecting by the decreased NADH amount, ETS activity, NIR and NOS activity, and nirK gene copy number, which resulted in a significant decline of denitrification rate in sediments (from 0.59 to 0.64 to 0.41-0.47 μmol15N L-1 h-1). While inhibition was mitigated with time and denitrification process recovered to the normal at the end of the experiment, the accumulated nitrate generated in the system showed that the recovery of microbial function did not mean the restoration of aquatic ecosystem after pollution. Differently, the repetitive exposure of 1 mg/L Ag NPs exhibited the evident inhibition on metabolism, abundance, and function of denitrifiers on Day 60, due to the accumulated amount of Ag NPs with the increased dosing number, indicating that the accumulated toxicity on functional microorganic community of repetitive exposure in less toxic concentration. Our study highlights the importance of Ag NPs entry pathways into aquatic ecosystem on their ecological risks, which affected dynamic responses of microbial function to Ag NPs.

Hydrocarbon degradation strategy and pyoverdine production using the salt tolerant Antarctic bacterium Marinomonas sp. ef1

One of the most concerning environmental problems is represented by petroleum and its derivatives causing contamination of aquatic and underground environments. In this work, the degradation treatment of diesel using Antarctic bacteria is proposed. Marinomonas sp. ef1 is a bacterial strain isolated from a consortium associated with the Antarctic marine ciliate Euplotes focardii. Its potential in the degradation of hydrocarbons commonly present in diesel oil were studied. The bacterial growth was evaluated in culturing conditions that resembled the marine environment with 1% (v/v) of either diesel or biodiesel added; in both cases, Marinomonas sp. ef1 was able to grow. The chemical oxygen demand measured after the incubation of bacteria with diesel decreased, demonstrating the ability of bacteria to use diesel hydrocarbons as a carbon source and degrade them. The metabolic potential of Marinomonas to degrade aromatic compounds was supported by the identification in the genome of sequences encoding various enzymes involved in benzene and naphthalene degradation. Moreover, in the presence of biodiesel, a fluorescent yellow pigment was produced; this was isolated, purified and characterized by UV-vis and fluorescence spectroscopy, leading to its identification as a pyoverdine. These results suggest that Marinomonas sp. ef1 can be used in hydrocarbon bioremediation and in the transformation of these pollutants in molecules of interest.

Comprehensive insights on environmental adaptation strategies in Antarctic bacteria and biotechnological applications of cold adapted molecules

Climate change and the induced environmental disturbances is one of the major threats that have a strong impact on bacterial communities in the Antarctic environment. To cope with the persistent extreme environment and inhospitable conditions, psychrophilic bacteria are thriving and displaying striking adaptive characteristics towards severe external factors including freezing temperature, sea ice, high radiation and salinity which indicates their potential in regulating climate change's environmental impacts. The review illustrates the different adaptation strategies of Antarctic microbes to changing climate factors at the structural, physiological and molecular level. Moreover, we discuss the recent developments in "omics" approaches to reveal polar "blackbox" of psychrophiles in order to gain a comprehensive picture of bacterial communities. The psychrophilic bacteria synthesize distinctive cold-adapted enzymes and molecules that have many more industrial applications than mesophilic ones in biotechnological industries. Hence, the review also emphasizes on the biotechnological potential of psychrophilic enzymes in different sectors and suggests the machine learning approach to study cold-adapted bacteria and engineering the industrially important enzymes for sustainable bioeconomy.

Antibacterial, antifungal, antidiabetic, and antioxidant activities potential of Coleus aromaticus synthesized titanium dioxide nanoparticles

The nanoparticles based drug delivery and treatment related research has been increased significantly in the recent years. Hence, the antibacterial, antifungal, and antioxidant activity potential of pre synthesized and characterized Titanium dioxide nanoparticles (TiO₂ NPs) were investigated in this study through respective standard protocols. Interestingly, the obtained results revealed that TiO₂ NPs have concentration dependent antibacterial activity against bacterial pathogens such as E. coli, P.mirabilis, V. cholerae, P. aeruginosa, S. typhimurium, and S. aureus at 100 μg mL^-1 concentration. Furthermore, these TiO₂ NPs showed remarkable antifungal activity against aspergillosis causing fungal pathogens such as A. niger, A. fumigatus, A. nidulans, and A. flavus at 100 μg mL^-1 concentration. α-glucosidase. This TiO₂ NPs also effectively inhibit the α-amylase (17%) and α-Glucosidase (37%) enzyme activity at 100 μg mL^-1 dosage. The DPPH assay revealed that TiO₂ NPs effectively scavenge DPPH free radicals by up to 89% at 100 μg mL^-1 concentration, which was comparable to butylated hydroxytoluene (96%). These results suggest that the plant-based TiO₂ NPs have remarkable in-vitro antibacterial, antifungal, and antioxidant activity. These may be considered for additional in-vitro and in-vivo experiments to assess their potential biomedical applications.

A cold‐active esterase enhances mesophilic properties through Mn 2+ binding

A key aspect of adaptation to cold environments is the production of cold-active enzymes by psychrophilic organisms. These enzymes not only have high activity at low temperatures, but also exhibit remarkable structural flexibility and thermolability. In this context, the role of metal ions has been little explored, and the few available studies seem to suggest that metal binding counteracts structural flexibility. This article reports an investigation into the role of the binding of manganese ion (Mn²⁺ ) in the thermal adaptation of an esterase (M-Est) of the GDSx family, identified in the genome of the Antarctic bacterium Marinomonas sp. ef1. M-Est is specific for esters containing acetate groups and turned out to be a highly thermolabile cold-active enzyme, with a catalysis optimum temperature of 5 °C and a melting temperature of 31.7 °C. A combination of biochemical and computational analyses, including molecular dynamics simulations, revealed that M-Est binds Mn²⁺ ions via a single binding site located on the surface of the enzyme, close to the active site. Although the interaction between M-Est and Mn²⁺ induces only local conformational changes involving the active site, quite surprisingly they trigger an improvement in both thermal stability and catalytic efficiency under mild temperature conditions. These results, together with the conservation of the Mn²⁺ binding site among psychrophilic and psychrotolerant homologues, suggest that Mn²⁺ binding may be a useful, albeit atypical, strategy to mitigate the detrimental effects of temperature on true cold-active enzymes.

Synthesis of Bioactive Silver Nanoparticles Using New Bacterial Strains from an Antarctic Consortium

In this study, we report on the synthesis of silver nanoparticles (AgNPs) achieved by using three bacterial strains Rhodococcus, Brevundimonas and Bacillus as reducing and capping agents, newly isolated from a consortium associated with the Antarctic marine ciliate Euplotes focardii. After incubation of these bacteria with a 1 mM solution of AgNO₃ at 22 °C, AgNPs were synthesized within 24 h. Unlike Rhodococcus and Bacillus, the reduction of Ag⁺ from AgNO₃ into Ag⁰ has never been reported for a Brevundimonas strain. The maximum absorbances of these AgNPs in the UV-Vis spectra were in the range of 404 nm and 406 nm. EDAX spectra showed strong signals from the Ag atom and medium signals from C, N and O due to capping protein emissions. TEM analysis showed that the NPs were spherical and rod-shaped, with sizes in the range of 20 to 50 nm, and they were clustered, even though not in contact with one another. Besides aggregation, all the AgNPs showed significant antimicrobial activity. This biosynthesis may play a dual role: detoxification of AgNO₃ and pathogen protection against both the bacterium and ciliate. Biosynthetic AgNPs also represent a promising alternative to conventional antibiotics against common nosocomial pathogens.

Robust multifunctional superhydrophobic, photocatalytic and conductive fabrics with electro-/photo-thermal self-healing ability

The fabrication of superhydrophobic and conductive fabrics that can conveniently and repeatedly restore the lost superhydrophobicity, caused by either the surface accumulation of trace organic contaminants or the chemical damage to surface components, remains challenging. Herein, we report a multifunctional superhydrophobic and conductive cotton fabric that integrates not only the photocatalytic activity for cleaning organic contaminants, but also the self-healing ability enabled by either electro-thermal or photo-thermal heating besides convection oven heating. The fabric was fabricated through the polydopamine (PDA)-assisted deposition of photocatalyst Ag/CdS and the subsequent thiol-Ag self-assembly. Either UV or visible light irradiation is able to decompose the surface organic contaminants, and the photocatalysis-induced slight damage on super water-repellency is curable by heating. The Ag layer endows the fabric with antibacterial property and conductivity along with the electro-/photo-thermal conversion ability, which offers relatively convenient ways of heating for curing the surface chemical damages caused by O₂ plasma etching or accelerated washing. Of particular importance is that the fabric still shows super water-repellency even after 18 cycles of accelerated washing, which equals to 90 normal home laundering cycles. The combination of these multiple functions makes this fabric very promising for a wide range of wearable applications.

Pan-Genomic and Transcriptomic Analyses of Marine Pseudoalteromonas agarivorans Hao 2018 Revealed Its Genomic and Metabolic Features

The genomic and carbohydrate metabolic features of Pseudoalteromonas agarivorans Hao 2018 (P. agarivorans Hao 2018) were investigated through pan-genomic and transcriptomic analyses, and key enzyme genes that may encode the process involved in its extracellular polysaccharide synthesis were screened. The pan-genome of the P. agarivorans strains consists of a core-genome containing 2331 genes, an accessory-genome containing 956 genes, and a unique-genome containing 1519 genes. Clusters of Orthologous Groups analyses showed that P. agarivorans harbors strain-specifically diverse metabolisms, probably representing high evolutionary genome changes. The Kyoto Encyclopedia of Genes and Genomes and reconstructed carbohydrate metabolic pathways displayed that P. agarivorans strains can utilize a variety of carbohydrates, such as d-glucose, d-fructose, and d-lactose. Analyses of differentially expressed genes showed that compared with the stationary phase (24 h), strain P. agarivorans Hao 2018 had upregulated expression of genes related to the synthesis of extracellular polysaccharides in the logarithmic growth phase (2 h), and that the expression of these genes affected extracellular polysaccharide transport, nucleotide sugar synthesis, and glycosyltransferase synthesis. This is the first investigation of the genomic and metabolic features of P. agarivorans through pan-genomic and transcriptomic analyses, and these intriguing discoveries provide the possibility to produce novel marine drug lead compounds with high biological activity.

Comparative Genomic Analyses of the Genus Nesterenkonia Unravels the Genomic Adaptation to Polar Extreme Environments

The members of the Nesterenkonia genus have been isolated from various habitats, like saline soil, salt lake, sponge-associated and the human gut, some of which are even located in polar areas. To identify their stress resistance mechanisms and draw a genomic profile across this genus, we isolated four Nesterenkonia strains from the lakes in the Tibetan Plateau, referred to as the third pole, and compared them with all other 30 high-quality Nesterenkonia genomes that are deposited in NCBI. The Heaps’ law model estimated that the pan-genome of this genus is open and the number of core, shell, cloud, and singleton genes were 993 (6.61%), 2782 (18.52%), 4117 (27.40%), and 7132 (47.47%), respectively. Phylogenomic and ANI/AAI analysis indicated that all genomes can be divided into three main clades, named NES-1, NES-2, and NES-3. The strains isolated from lakes in the Tibetan Plateau were clustered with four strains from different sources in the Antarctic and formed a subclade within NES-2, described as NES-AT. Genome features of this subclade, including GC (guanine + cytosine) content, tRNA number, carbon/nitrogen atoms per residue side chain (C/N-ARSC), and amino acid composition, in NES-AT individuals were significantly different from other strains, indicating genomic adaptation to cold, nutrient-limited, osmotic, and ultraviolet conditions in polar areas. Functional analysis revealed the enrichment of specific genes involved in bacteriorhodopsin synthesis, biofilm formation, and more diverse nutrient substance metabolism genes in the NES-AT clade, suggesting potential adaptation strategies for energy metabolism in polar environments. This study provides a comprehensive profile of the genomic features of the Nesterenkonia genus and reveals the possible mechanism for the survival of Nesterenkonia isolates in polar areas.

Marine organisms: Pioneer natural sources of polysaccharides/proteins for green synthesis of nanoparticles and their potential applications

Current innovations in the marine bionanotechnology arena are supporting and stimulating developments in other fields, including nanomedicine, pharmaceuticals, sensors, environmental trends, food, and agriculture aspects. Many oceanic creatures, particularly algae, plants, bacteria, yeast, fungi, cyanobacteria, actinomyces, invertebrates, animals and sponges can survive under extreme circumstances. They can biogenerate a broad spectrum of phytochemicals/metabolites, including proteins, peptides, alkaloids, flavonoids, polyphenols, carbohydrate polymers, polysaccharides, sulfated polysaccharides, polysaccharide-protein complexes such as carrageenan, fucoidanase, fucoidan, carboxymethyl cellulose, poly-γ-glutamic acid, sugar residues with proteins, melanin, haemocyanin, etc). These products exhibit exclusive advantages that offer pioneering roles in the eco-friendly fabrication of several nanoparticles (NPs) i.e., Ag, Au, Ru, Fe₂O₃, Cobalt (III) Oxide (Co₂O₃), ZnO and Ag@AgCl within a single phase. Importantly, marine organisms can biosynthesize NPs in two modes, namely extracellular and intracellular. Biosynthesized NPs can be characterized using various methodologies among them, ultraviolet-visible spectroscopy, fourier transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Taken together, this review focuses on the green synthesis of metallic, metallic oxides and nonmetallic NPs utilizing extracts/derivatives from marine organisms based on eco-friendly green biogenic procedures. Moreover, significant attention is given to the medicinal and industrial importance of such marine organisms mediated NPs.

Biogenic Synthesis of Copper Nanoparticles Using Bacterial Strains Isolated from an Antarctic Consortium Associated to a Psychrophilic Marine Ciliate: Characterization and Potential Application as Antimicrobial Agents

In the last decade, metal nanoparticles (NPs) have gained significant interest in the field of biotechnology due to their unique physiochemical properties and potential uses in a wide range of applications. Metal NP synthesis using microorganisms has emerged as an eco-friendly, clean, and viable strategy alternative to chemical and physical approaches. Herein, an original and efficient route for the microbial synthesis of copper NPs using bacterial strains newly isolated from an Antarctic consortium is described. UV-visible spectra of the NPs showed a maximum absorbance in the range of 380–385 nm. Transmission electron microscopy analysis showed that these NPs are all monodispersed, spherical in nature, and well segregated without any agglomeration and with an average size of 30 nm. X-ray powder diffraction showed a polycrystalline nature and face centered cubic lattice and revealed characteristic diffraction peaks indicating the formation of CuONPs. Fourier-transform infrared spectra confirmed the presence of capping proteins on the NP surface that act as stabilizers. All CuONPs manifested antimicrobial activity against various types of Gram-negative; Gram-positive bacteria; and fungi pathogen microorganisms including Escherichia coli, Staphylococcus aureus, and Candida albicans. The cost-effective and eco-friendly biosynthesis of these CuONPs make them particularly attractive in several application from nanotechnology to biomedical science.

An In-Silico Comparative Study of Lipases from the Antarctic Psychrophilic Ciliate Euplotes focardii and the Mesophilic Congeneric Species Euplotes crassus: Insight into Molecular Cold-Adaptation

Cold-adapted enzymes produced by psychrophilic organisms have elevated catalytic activities at low temperatures compared to their mesophilic counterparts. This is largely due to amino acids changes in the protein sequence that often confer increased molecular flexibility in the cold. Comparison of structural changes between psychrophilic and mesophilic enzymes often reveal molecular cold adaptation. In the present study, we performed an in-silico comparative analysis of 104 hydrolytic enzymes belonging to the family of lipases from two evolutionary close marine ciliate species: The Antarctic psychrophilic Euplotes focardii and the mesophilic Euplotes crassus. By applying bioinformatics approaches, we compared amino acid composition and predicted secondary and tertiary structures of these lipases to extract relevant information relative to cold adaptation. Our results not only confirm the importance of several previous recognized amino acid substitutions for cold adaptation, as the preference for small amino acid, but also identify some new factors correlated with the secondary structure possibly responsible for enhanced enzyme activity at low temperatures. This study emphasizes the subtle sequence and structural modifications that may help to transform mesophilic into psychrophilic enzymes for industrial applications by protein engineering.

Psychrophiles: A journey of hope

Psychrophiles are organisms living in extremely cold conditions within the temperature range of -20°C to +10°C. These organisms survive in harsh environment by modulating their genetic make-up to thrive in extremely cold conditions. These cold-adaptations are closely associated with changes in the life forms, gene expression, and proteins, enzymes, lipids, etc. This review gives a brief description of the life and genetic adaptations of psychrophiles for their survival in extreme conditions as well as the bioactive compounds that are potential antimicrobials.

Endolysins from Antarctic Pseudomonas Display Lysozyme Activity at Low Temperature

Organisms specialized to thrive in cold environments (so-called psychrophiles) produce enzymes with the remarkable ability to catalyze chemical reactions at low temperature. Cold activity relies on adaptive changes in the proteins' sequence and structural organization that result in high conformational flexibility. As a consequence of flexibility, several such enzymes are inherently heat sensitive. Cold-active enzymes are of interest for application in a number of bioprocesses, where cold activity coupled with easy thermal inactivation can be of advantage. We describe the biochemical and functional properties of two glycosyl hydrolases (named LYS177 and LYS188) of family 19 (GH19), identified in the genome of an Antarctic marine Pseudomonas. Molecular evolutionary analysis placed them in a group of characterized GH19 endolysins active on lysozyme substrates, such as peptidoglycan. Enzyme activity peaks at about 25-35 °C and 40% residual activity is retained at 5 °C. LYS177 and LYS188 are thermolabile, with Tm of 52 and 45 °C and half-lives of 48 and 12 h at 37 °C, respectively. Bioinformatics analyses suggest that low heat stability may be associated to temperature-driven increases in local flexibility occurring mainly in a specific region of the polypeptide that is predicted to contain hot spots for aggregation.