Synthesis, Production, and Biotechnological Applications of Exopolysaccharides and Polyhydroxyalkanoates by Archaea

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

Recent Advances in the Study of Marine Microbial Biofilm: From the Involvement of Quorum Sensing in Its Production up to Biotechnological Application of the Polysaccharide Fractions

The present review will explore the most relevant findings on marine microbial biofilm, with particular attention towards its polysaccharide fraction, namely exopolysaccharide (EPS). EPSs of microbial origin are ubiquitous in nature, possess unique properties and can be isolated from the bacteria living in a variety of habitats, including fresh water or marine environments, extreme environments or different soil ecosystems. These biopolymers have many application in the field of biotechnology. Several studies showed that the biofilm formation is closely related to quorum sensing (QS) systems, which is a mechanism relying on the production of small molecules defined as "autoinducers" that bacteria release in the surrounding environment where they accumulate. In this review, the involvement of microbial chemical communication, by QS mechanism, in the formation of marine biofilm will also be discussed

Polysaccharides from Wastes of Vegetable Industrial Processing: New Opportunities for Their Eco-Friendly Re-Use

Natural polysaccharides constitute a major group of biopolymers widespread in the whole vegetable kingdom. Plant polysaccharides comprise highly heterogeneous biopolymers that play diverse biological roles as structural elements, energy reserve and biological signalling. Polysaccharides from natural sources have attracted significant interest as biotechnological products, due to their commercial uses in a wide range of industrial applications. Some of them, for example, possess strong antigenic and antipathogenic activities and are successfully employed by the pharmaceutical industry for the formulation of vaccines or as a matrix for drug-delivery applications; others are utilised as food additives taking advantage of their physical-chemical properties (emulsifying power, viscoelasticity, polyelectrolyte, adherence, bio-compatibility, stabilizer, etc). Production of these biopolymers for industrial applications has both economic and environmental costs, depending on the starting materials used as feedstocks and on the chemical/thermal treatments required for their extraction. Recently, wastes from industrial processing of vegetables for food production have been proposed as potential sources of useful polysaccharides. Indeed, transformation and packaging of fruits and vegetables generates huge amounts of wastes, since only a fraction of the incoming biomass is effectively used. The management of such waste biomasses is a problem worldwide, from both economic and environmental standpoints, and therefore research is encouraged to implement new strategies for their re-use. An advantageous option is the extraction of value added chemicals, including different kinds of polysaccharides, besides chemically different species such as polyunsaturated fatty acids, natural pigments, tannins, carotenoids, antioxidants etc. Treatment of vegetable residues by means of newly and environmentally sustainable extraction techniques represents at the moment a fascinating challenge for the valorisation of agro-industrial wastes. Remarkable examples in this framework are represented by polysaccharides isolated from wastes of tomato industrial processing and of tropical fruit juices production based on granadilla, a fruit species of Passiflora, distributed mainly in the warm temperate and tropical regions of America and Africa. These polysaccharides resulted to possess useful biotechnological properties and interesting biological activities. An accurate chemical characterization demonstrated that the main biopolymer obtained from tomato wastes was an heteropolymer with a molecular weight higher than 1 ×106 Da constituted by glucose/ xylose/ galactose/ galactosamine/ glucosamine/ fucose in a relative molar ratio of 1: 0.9: 0.5: 0.4: 0.2: trace, whereas the polysaccharide isolated from waste peels of granadilla (Passiflora liguralis) fruits (with a molecular weight higher than 1 ×106 Da as well) was characterised by the presence of six different sugar residues: xylose/ glucose/ galactose/ galactosamine/ unknown component/ fucose in the relative ratios of 1:0.5:0.2:0.06:0.05:trace. The study of rheological properties showed for both biopolymers an high thermal resistance and an high viscosity, depending, in particular for granadilla waste polysaccharide, on concentration and pH, with a maximum value of 1.4  at a concentration of 3% in distilled water and a maximum value of 7.0  in citrate buffer solution. The main point of interest was represented by their suitability to produce elastic and biodegradable films potentially useful in agriculture for mulching applications in fields protection. Further studies were performed to evaluate the biological activity of these biopolymers. Tomato waste polysaccharides resulted to inhibit NF-κB activation and iNOS gene expression in J774 macrophages by preventing the reactive species production, thus suggesting a key role of these compounds in controlling oxidative stress and/or inflammation. Biological activity of polysaccharides from granadilla peels was assessed by means of brine shrimp bioassay: the isolated compound was able to strongly inhibit the cytotoxic effects produced by avarol, whose LD50 was increased of about 10-fold with respect to the control in the absence of polysaccharide. More recent studies have been focused on lemon wastes. Citrus processing produces a considerable amount of waste biomass called “lemon pomace” consisting of peels (flavedo and albedo), pulp and seeds, mainly composed by water, soluble sugars and fibres, together with other compounds such as oils, flavonoids and vitamins. Lemon wastes, generated in huge amounts by Italian industries for “Limoncello” liquor production, have been treated in order to separate useful polysaccharides. A major polysaccharide fraction was isolated and purified: analysis by means of gel filtration allowed to determine a molecular weight higher than 1 ×106 Da. The sugar components were identified after acid hydrolysis, by means of TLC and HPAE-PAD chromatography: the main components resulted to be galactose, galacturonic acid and arabinose. Further studies are now being implemented to study both rheological properties and biological activity of lemon polysaccharides. In conclusion, polysaccharides are among the most interesting biopolymers that can be recovered from vegetables: the use of wastes from industrial processing of different vegetables together with eco-friendly extraction techniques allowed the isolation of remarkable polysaccharides. Some of them showed to possess interesting rheological properties, potential biotechnological applications and finally promising bioactivities as potential anti-inflammatory agents, as tested in different biological model systems

Physico-Chemical Properties and Valorization of Biopolymers Derived from Food Processing Waste

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

Exploring Marine Environments for the Identification of Extremophiles and Their Enzymes for Sustainable and Green Bioprocesses

Sea environments harbor a wide variety of life forms that have adapted to live in hard and sometimes extreme conditions. Among the marine living organisms, extremophiles represent a group of microorganisms that attract increasing interest in relation to their ability to produce an array of molecules that enable them to thrive in almost every marine environment. Extremophiles can be found in virtually every extreme environment on Earth, since they can tolerate very harsh environmental conditions in terms of temperature, pH, pressure, radiation, etc. Marine extremophiles are the focus of growing interest in relation to their ability to produce biotechnologically useful enzymes, the so-called extremozymes. Thanks to their resistance to temperature, pH, salt, and pollutants, marine extremozymes are promising biocatalysts for new and sustainable industrial processes, thus representing an opportunity for several biotechnological applications. Since the marine microbioma, i.e., the complex of microorganisms living in sea environments, is still largely unexplored finding new species is a central issue for green biotechnology. Here we described the main marine environments where extremophiles can be found, some existing or potential biotechnological applications of marine extremozymes for biofuels production and bioremediation, and some possible approaches for the search of new biotechnologically useful species from marine environments

Bioprospecting of exopolysaccharide-producing bacteria from different natural ecosystems for biopolymer synthesis from vinasse

Abstract Background Exopolysaccharides (EPSs) belong to a family of organic thickeners or alternative hydrocolloids of microbial origin. Because the chemical structure offers beneficial bioactive functions, biocompatibility and biodegradability, EPSs are used in the chemical, food, pharmaceutical, cosmetics, and packaging industries as well as in agriculture and medicine. In this study, new bacterial strains were selected on the basis of their ability to synthesize EPS from substrate containing vinasse as a nutrient source to identify the best candidate for bio-based polymer production. Results Among the 99 newly identified bacterial strains isolated from different natural ecosystem, the strain Azotobacter chroococcum 76A was selected as the best biopolymer producer since it synthesized the highest concentration of EPS in all media containing vinasse. The maximum EPS concentration (44.6 ± 0.63 mg/50 mL) was observed at 24 h, corresponding to its sub-stationary growth phase (7 × 108 ± 0.29 CFU/mL). Chemical characterization of the EPS produced showed that carbohydrates representing the principal component, followed by uronic acids and proteins. Interestingly, comparing the IR spectrum of the EPS with alginate by FTIR-ATR analysis revealed an overlap of a peak identified as guluronic acid, a component of alginate. Conclusions The potential biotechnological capacity of A. chroococcum 76A to synthetize biopolymer from vinasse, inexpensive starting materials, represents a possible alternative to expensive disposal of agri-food waste through its transformation into high value-added products

High-resolution tracking in a GEM-Emulsion detector

SHiP (Search for Hidden Particles) is a beam dump experiment proposed at the CERN SPS aiming at the observation of long lived particles very weakly coupled with ordinary matter mostly produced in the decay of charmed hadrons. The beam dump facility of SHiP is also a copious factory of neutrinos of all three kinds and therefore a dedicated neutrino detector is foreseen in the SHiP apparatus. The neutrino detector exploits the Emulsion Cloud Chamber technique with a modular structure, alternating walls of target units and planes of electronic detectors providing the time stamp to the event. GEM detectors are one of the possible choices for this task. This paper reports the results of the first exposure to a muon beam at CERN of a new hybrid chamber, obtained by coupling a GEM chamber and an emulsion detector. Thanks to the micrometric accuracy of the emulsion detector, the position resolution of the GEM chamber as a function of the particle inclination was evaluated in two configurations, with and without the magnetic fiel

Degradative actions of microbial xylanolytic activities on hemicelluloses from rhizome of Arundo donax

Polysaccharidases from extremophiles are remarkable for specific action, resistance to different reaction conditions and other biotechnologically interesting features. In this article the action of crude extracts of thermophilic microorganisms (Thermotoga neapolitana, Geobacillus thermantarcticus and Thermoanaerobacterium thermostercoris) is studied using as substrate hemicellulose from one of the most interesting biomass crops, the giant reed (Arundo donax L.). This biomass can be cultivated without competition and a huge amount of rhizomes remains in the soil at the end of cropping cycle (10–15 years) representing a further source of useful molecules. Optimization of the procedure for preparation of the hemicellulose fraction from rhizomes of Arundo donax, is studied. Polysaccharidases from crude extracts of thermophilic microorganisms revealed to be suitable for total degradative action and/or production of small useful oligosaccharides from hemicelluloses from A. donax. Xylobiose and interesting tetra- and pentasaccharide are obtained by enzymatic action in different conditions. Convenient amount of raw material was processed per mg of crude enzymes. Raw hemicelluloses and pretreated material show antioxidant activity unlike isolated tetra- and pentasaccharide. The body of results suggest that rhizomes represent a useful raw material for the production of valuable industrial products, thus allowing to increase the economic efficiency of A. donax cultivation

Autism and neurodevelopmental disorders: the Sars-Cov-2 pandemic implications

The Special Issue (SI) “Autism and Neurodevelopmental Disorders: The SARS-CoV-2 Pandemic Implications” is an interesting project that adopted a scientific point of view with important implications in clinical and practical fields [...

MYC-driven epigenetic reprogramming favors the onset of tumorigenesis by inducing a stem cell-like state

Breast cancer consists of highly heterogeneous tumors, whose cell of origin and driver oncogenes are difficult to be uniquely defined. Here we report that MYC acts as tumor reprogramming factor in mammary epithelial cells by inducing an alternative epigenetic program, which triggers loss of cell identity and activation of oncogenic pathways. Overexpression of MYC induces transcriptional repression of lineage-specifying transcription factors, causing decommissioning of luminal-specific enhancers. MYC-driven dedifferentiation supports the onset of a stem cell-like state by inducing the activation of de novo enhancers, which drive the transcriptional activation of oncogenic pathways. Furthermore, we demonstrate that the MYC-driven epigenetic reprogramming favors the formation and maintenance of tumor-initiating cells endowed with metastatic capacity. This study supports the notion that MYC-driven tumor initiation relies on cell reprogramming, which is mediated by the activation of MYC-dependent oncogenic enhancers, thus establishing a therapeutic rational for treating basal-like breast cancers