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Extracellular polymeric substances (EPSs) possess diversified ecological role, including the cell adhesion to surfaces and cell protection, and are highly involved in the interactions between the bacterial cells and the bulk environments. Interestingly, EPSs find valuable applications in the industrial field, due to their chemical versatility. In this context, Antarctic bacteria have not been given the attention they deserve as producers of EPS molecules and a very limited insight into their EPS production capabilities and biotechnological potential is available in literature to date. Antarctic EPS-producing bacteria are mainly psychrophiles deriving from the marine environments (generally sea ice and seawater) around the continent, whereas a unique thermophilic bacterium, namely Parageobacillus thermantarcticus strain M1, was isolated from geothermal soil of the crater of Mount Melbourne. This mini-review is aimed at showcasing the current knowledge on EPS-producing Antarctic bacteria and the chemical peculiarities of produced EPSs, highlighting their biotechnological potential and the yet unexplored treasure they represent for biodiscovery.Key Points• The exploration of Antarctic bacteria as EPS producers is still scarcely developed• EPSs are produced by psychrophilic and thermophilic Antarctic bacteria• The presence of mannose and glucose is frequently observed in Antarctic EPSs• To date, marine matrices have been mainly used to isolate Antarctic EPS-producers

In this review, the composting process of organic waste is discussed through an in-depth exploring of its thermophilic phase. It starts with the highlight on the thermodynamic evolution, which needs to be assessed when deciding to use reactors for composting, also in the context of energy generation. The composting process is mediated by different types of microorganisms, and the bacteria that play key roles are evaluated. The roles of the genera Bacillus and Thermus are considered, often described as the main components of the microbiota of compost. Due to their adaptation to the composting processes, they are candidates for technological purposes. Subsequentially, the focus is moved on the thermostable enzymes that can be isolated from them and their succession during the composting processes. Experimental examples of enzyme-related literature are reviewed, for example investigating proteases and ureases, which are found at the beginning of the process. In addition, cellulases, hemicellulases, lignin-modifying enzymes, and esterases have been described for their activities during the thermophilic phase, giving them great potential for biotechnological and industrial applications. Following, the composition of the microbial community is analyzed through the description of approaches of metagenomics. Despite it being a relatively new but fast-growing field within biology, it is intended to be a priority analysis to acquire knowledge on genomes of environmental microorganisms and communities. Finally, a space is dedicated to the description of the composting plant which treats olive oil wastes within the LIFE TIRSAV PLUS project (LIFE05 ENV/IT/00845). Through two plant solutions, being the Dynamic and the Static Composting, it provides a high-quality compost with an effective, flexible and economical process.

For the first time, we propose the use of an extremophilic bacterium to remove nitrate salt efflorescence from the surfaces of stone samples. A haloalkaliphilic bacterium was selected “ad hoc” for its ability to reduce nitrates; i.e. Halomonas campaniensis sp. nov., strain 5AG T (DSM 15293 T , ATCC BAA-966 T ). Quantitative monitoring of nitrate content, on untreated and treated surfaces of stone samples artificially enriched with nitrate, as a function of incubation/treatment time, was carried out by molecular spectroscopy. The results obtained reveal the good performance of Halomonas campaniensis bacterium in decreasing nitrate concentration on stone surfaces both in a controlled laboratory environment for temperature and relative humidity and in a real outdoor environmental conditions.

Extracellular polysaccharides (EPSs) from thermophilic bacteria are promising biopolymers due to their stability and structural variability. This study aimed to characterize the genomic and chemical features of EPS produced by Parageobacillus toebii strain H-70 isolated from a geothermal spring in Armenia. EPS from strain H-70 was produced in sucrose and glucose based medium and analyzed chemically by TLC, HPAEC-PAD, GC-MS, and NMR. Protein, uronic acid, and nucleic acid contents were quantified by spectrophotometric methods. Molasses, an inexpensive byproduct of sugar production, was used as the carbon source too. Whole-genome sequencing, comparative phylogenomics, and genome mining were performed to identify biosynthetic gene clusters, carbohydrate-active enzymes (CAZymes), and regulatory components associated with EPS metabolism. Strain H-70 yielded 37.9 mg/L EPS (0.10 g/g dry cell weight) after 72 h cultivation at 55 °C and pH 7.0 with sucrose as sole carbon source. The EPS was a heteropolysaccharide composed of rhamnose, glucose, galactose, and mannose, along with proteins (15.04%), uronic acids (4.22%), and nucleic acids (4.88%). The EPS yield obtained with glucose as the sole carbon source was 10.5 mg/L, whereas molasses supplementation resulted in a yield of 14.5 mg/L. The draft genome (~3.2 Mb, 42% G + C, 98.9% ANI with P. toebii DSM 14590) encoded five Wzy-dependent EPS gene clusters with glycosyltransferases, transporters, and regulators. The genome also carried diverse CAZymes (GH, GT, CE, CBM, AA families) and modification enzymes (e.g., CsaB, acetyltransferases), indicating structural and functional variability of the polymer. In addition, the binding to human C-type lectins (carbohydrate-binding proteins involved in innate and adaptive immune-responses) has been studied by solid-phase assay. This study provides the first comprehensive characterization of EPS from P. toebii H-70, integrating genomic and chemical insights. The binding to human C-type lectins offers future EPSs biomedical applications especially in as immune-modulators.

Alzheimer’s (AD) and Parkinson’s diseases (PD) are multifactorial neurogenerative disorders of the Central Nervous System causing severe cognitive and motor deficits in elderly people. Because treatment of AD and PD by synthetic drugs alleviates the symptoms often inducing side effects, many studies have aimed to find neuroprotective properties of diet polyphenols, compounds known to act on different cell signaling pathways. In this article, we analyzed the effect of polyphenols obtained from the agro-food industry waste of Citrus limon peel (LPE) on key enzymes of cholinergic and aminergic neurotransmission, such as butyryl cholinesterase (BuChE) and monoamine oxidases (MAO)-A/B, on Aβ1–40 aggregation and on superoxide dismutase (SOD) 1/2 that affect oxidative stress. In our in vitro assays, LPE acts as an enzyme inhibitor on BuChE (IC50 ~ 73 µM), MAO-A/B (IC50 ~ 80 µM), SOD 1/2 (IC50 ~ 10–20 µM) and interferes with Aβ1–40 peptide aggregation (IC50 ~ 170 µM). These results demonstrate that LPE behaves as a multitargeting agent against key factors of AD and PD by inhibiting to various extents BuChE, MAOs, and SODs and reducing Aβ-fibril aggregation. Therefore, LPE is a promising candidate for the prevention and management of AD and PD symptoms in combination with pharmacological therapies.

Extreme environments, generally characterized by atypical temperatures, pH, pressure, salinity, toxicity, and radiation levels, are inhabited by various microorganisms specifically adapted to these particular conditions, called extremophiles. Among these, the microorganisms belonging to the Archaea domain are of significant biotechnological importance as their biopolymers possess unique properties that offer insights into their biology and evolution. Particular attention has been devoted to two main types of biopolymers produced by such peculiar microorganisms, that is, the extracellular polysaccharides (EPSs), considered as a protection against desiccation and predation, and the endocellular polyhydroxyalkanoates (PHAs) that provide an internal reserve of carbon and energy. Here, we report the composition, biosynthesis, and production of EPSs and PHAs by different archaeal species.

Hypersaline environments harbor halophiles capable of producing extracellular polysaccharides (EPSs). This study reports EPS production, chemical composition and genomic insights by the halophilic archaeon Haloarcula japonica strain SST1, isolated from a subterranean salt deposit in Avan, Armenia. The highest extracellular product (EP) yield (628.4 mg L −1 ) was achieved at 120 h cultivation in sucrose-supplemented medium. Sucrose-derived EP had high carbohydrate content (48.5%), while molasses yielded 275.2 mg L −1 with 20.8% carbohydrate. Gel filtration revealed a heterogeneous molecular mass (10–100 kDa). GC–MS, HPAE-PAD, and NMR identified a heteropolymer of mannose, galactose, and glucose. Genome sequence data confirmed genes for monosaccharide activation, polymerization, and secretion. Use of molasses as substrate highlights SST1’s potential as a cost-effective EPS producer for circular bioeconomy. Binding of raw EPS to human C-type lectins suggests possible biomedical applications in innate immunity modulation.

The widespread use of synthetic plastics, as well as the waste produced at the end of their life cycle, poses serious environmental issues. In this context, bio-based plastics, i.e., natural polymers produced from renewable resources, represent a promising alternative to petroleum-based materials. One potential source of biopolymers is waste from the food industry, the use of which also provides a sustainable and eco-friendly solution to waste management. Thus, the aim of this work concerns the extraction of polysaccharide fractions from lemon, tomato and fennel waste. Characterizing the chemical–physical and thermodynamic properties of these polysaccharides is an essential step in evaluating their potential applications. Hence, the solubility of the extracted polysaccharides in different solvents, including water and organic solvents, was determined since it is an important parameter that determines their properties and applications. Also, acid-base titration was carried out, along with thermoanalytical tests through differential scanning calorimetry. Finally, the electrospinning of waste polysaccharides was investigated to explore the feasibility of obtaining polysaccharide-based membranes. Indeed, electrospun fibers are a promising structure/system via which it is possible to apply waste polysaccharides in packaging or well-being applications. Thanks to processing feasibility, it is possible to electrospin waste polysaccharides by combining them with different materials to obtain porous 3D membranes made of nanosized fibers.

Gastric cancer remains a leading cause of cancer-related mortality worldwide. Citrus fruits are rich in polyphenols, exerting antioxidant and chemo-preventive activities, and lemon peel represents a valuable source of such bioactive compounds. Previous studies showed that Citrus limon peel extracts (LPE) inhibited the activity of some enzymes of the antioxidant system and reduced the interleukin-6-dependent invasiveness of gastric and colon cancer cells. In the present study, we have investigated the effects of LPE on the human gastric adenocarcinoma AGS and MKN-28 cells and on the activity of a crucial redox enzyme, catalase (CAT). Indeed, LPE significantly reduced the cell viability and clonogenic potential of the gastric cancer cells and induced morphological changes indicative of cytotoxicity. Moreover, LPE modulated the intracellular redox homeostasis by decreasing levels of the hydrogen peroxide-related reactive oxygen species (ROS) while increasing those of superoxide anions and decreasing levels of superoxide dismutases (SODs). Western blotting analysis revealed that LPE downregulated CAT, SOD-1, SOD-2, and monoamine oxidase A (MAO-A) protein expression level in both cell lines. Finally, the extract inhibited CAT activity in a dose-dependent manner (IC50 = 0.008 ± 0.003 mg/mL; Ki = 0.012 ± 0.002 mg/mL). These findings indicate that LPE exerts cytotoxic and redox-modulating effects through the inhibition of antioxidant enzymes and the alteration of ROS balance. Therefore, the agro-industrial by-product LPE could be considered as a promising natural source of polyphenolic compounds with potential applications in the prevention and therapy of gastric cancer.

Among matrix metalloproteinases (MMPs), MMP-9/2 are key enzymes involved in the proteolysis of extracellular matrices in the inflammatory process and in cancer. Since MMP-9/2 expression levels, activity, and secretion is up-regulated during inflammation in response to pro-inflammatory cytokines, such as interleukin-6 (IL-6), many efforts have been devoted to identifying factors that could inhibit the IL-6-induced MMP-9/2 expression. Up to now, several reports indicated that polyphenols from fruits and vegetables are among the major components of health promotion for their antioxidant properties and also for their anti-inflammatory and anti-cancer agents. Among plant derived polyphenols, lemon (Citrus limon) peel extract (LPE) shows anti-cancer properties in various cancer types. In our previous work, we demonstrated that LPE can reduce IL-6-induced migration/invasiveness and MMP-9/2 up-regulation in some gastric cancer cell lines. This study aims to exploit the anti-cancer properties of LPE using an in vitro system model of inflammation, consisting of IL-6-exposed human primary colon cancer cells. We first analyzed the effect of LPE on IL-6-induced cell migration and invasiveness by wound healing and Boyden chamber assay, respectively. The MMP-2 mRNA expression levels and gelatinolytic activity in the cell culture media were determined by q-PCR analysis and gelatin zymography, respectively, and finally, the effects of LPE on IL-6-induced JAK2/STAT3 signaling pathways have been investigated by Western blotting analysis. Our results show that LPE is able to inhibit the IL-6-dependent cell migration and invasiveness associated with the up-regulation of MMP-2 expression levels and that these effects are correlated to the STAT3 phosphorylation in human primary T88 and T93 colon cancer cells.