Esopolisaccaridi da alofili: produzione, caratterizzazione chimica e loro possibile applicazione biotecnologica

Responsabili di progetto

Annarita Poli, Margarita Stoyanova Kambourova

Accordo

BULGARIA - BAS - Bulgarian Academy of Sciences

Bando

CNR-BAS 2016-2018

Dipartimento

Scienze chimiche e tecnologie dei materiali

Area tematica

Scienze chimiche e tecnologie dei materiali

Stato del progetto

Nuovo

Proposta di ricerca

Exopolysaccharides (EPSs) of microbial origin are ubiquitous in nature, have unique properties and can be isolated from many bacteria living in extreme conditions either from fresh water, marine environments and soil ecosystems. EPSs make up a substantial component of the extracellular matrix surrounding most microbial cells living in extreme environments such as Arctic and Antarctic ecosystems, saline lakes, geothermal springs, or deep-sea hydrothermal vents. These microorganisms called extremophiles have developed various adaptations, enabling them to compensate for the deleterious effects of such extreme conditions as high temperatures, salt, low pH, or high radiation levels. In particular, EPSs produced by halophiles, extremophiles that live in the presence of high salt content, have great potential and their physico-chemical characteristics decide their possible commercial applications ranging from pharmaceutical to food processing, extended to detoxification, bioremediation, cosmetics, paints, biotechnology, and petrochemicals.
EPSs are high molecular weight heterogeneous polymers composed by some most recurring monomers like hexoses, pentoses, uronic acids and amino sugars, that are often substituted either by organic non-carbohydrate or inorganic groups. Some remarkable examples of well-studied and commercially exploited EPSs include: xanthan gum (produced by Xantomonas species), gellan (that are produced by bacteria belonging to Sphingomonas genus), alginate (that are found in bacteria belong to the genera Azotobater and Pseudomonas), hyaluronan (produced by different bacterial strains like for example Pseudomonas aeruginosa) and levan (produced by species of the genera Bacillus, Rahnella, Aerobacter, Erwinia, Streptococcus, Pseudomonas and Zymomonas and recently found also in a species of Halomonas genus).
Considerable progress has been made in discovering and developing new microbial EPSs that possess novel industrial significance. In recent years the increased demand for natural polymers for pharmaceutical, food, and other industrial applications has led to a remarkable interest in polysaccharides produced by microorganisms [Poli et al. 2010, 2011; Finore et al. 2014; Nicolaus et al. 2010].
EPSs produced by extremophiles embody promising biotechnological applications: their rheological properties, biological activities, metal-binding capabilities and new sugar composition make these biopolymers suitable for many applications. Indeed their potential biotechnological spectrum of application is very wide, ranging from antiviral and thickening agents to bioflocculanting agents, from biosurfactant and bioemulsifier to vaccine adjuvants. Moreover, for their metal-binding and pollutant bioadsorption activities, EPSs could be employed in the bioremediation processes [Finore et al., 2014].
Saline soils collected from salterns and sediments from salt lakes represent the extreme niches in which halophiles EPSs-producers have been isolated. High sulfate content EPSs have been described for the EPSs produced by Halomonas maura strain S-30, Halomonas anticariensis strain FP35, Halomonas ventosae strain A112 and Halomonas eurihalina strain F2-7: for these two latters the formation of stable emulsions has been also recorded [Poli et al., 2010 and references therein]. Halomonas smyrniensis, isolated from a saltern area in Turkey, represents the first examples of levan producer Halomonas species [Poli et al., 2009]. This microorganism could be considered an alternative cheap source of levan polymer for which bioflocculant properties in the treatment of industrial wastewaters have been described. Levan from H. smyrniensis has been tried as a nano carrier system for peptide and protein drugs delivery. Halomonas alkaliantarctica isolated from a salt lake in Antarctica produced a fructo-glucan polymer that presented a high viscosity at low pH values and at high NaCl concentration, resulting as a viscosity control agent in proposed biotechnological applications [Poli et al., 2010].
Our research group at ICB-CNR has long collaboration with Prof. Margarita Kambourova of Bulgarian Academy of Science and her team. In the frame of Bilateral Agreement between CNR-BAS (2007-2009), ours teams received approval for the project entitle "Production of exopolysaccharides by thermophilic bacteria, isolated from Bulgarian and Italian thermal springs". From this project a solid and estimate collaboration born and generated some scientific publication as reported in references list. These articles deal the production and chemical characterization of microbial exopolysaccharides from thermophilic bacteria, as Geobacillus tepidamans V264, Aeribacillus pallidus 418 and Brevibacillus themoruber (Kambourova et al.2009;Radchenkova et al.2013;Yasar Yildiz et al.2014).
Bulgarian scientists from the lab. "Extremophilic bacteria", Institute of Microbiology and our Italian team from the Institute of Biomolecular Chemistry, of Council of National Research (C.N.R.), will combine efforts in studying the exopolysaccharides synthesized from halophilic microorganisms by the current project.
Reference list
-Poli A.et al.(2009)Carb.Polym.78,651-657.
-Poli A.et al.(2010) Mar.Drugs, 8,1779-1802.
-Poli A.et al.(2011) Archaea, doi:10.1155/2011/693253
-Finore I.et al.(2014) Mar. Drugs 2014, 12,3005-3024.
-Kambourova M.et al.(2009) Carb.Polym. 77,338-343.
-Radchenkova N.et al.(2013) Appl Biochem Biotechnol.171(1):31-43.
-Yasar Yildiz S.et al.(2014) J Appl Microbiol, 116(2):314-24.

Obiettivi della ricerca

It is widely accepted that extremophiles offer important insights into biology and evolution of many organisms, and they provide a valuable resource for exploitation in novel biotechnological processes. Considering the numerous applications of microbial polysaccharides in cosmetics, food production, petroleum and chemical industries due to their rheological and viscosity-enhancing properties, within the scope of this project, the potential industrial applications of new biopolymers will be investigated. First part of the project will involve the screening of halophiles for EPS production, and subsequent their (hyper)production. Then, the project will concentrate on their physico-chemical characterization including chemical structure definition and rheological proprierties. The assessment of the degree of novelty and the potential biotechnological benefits (including biological activity) of EPSs such as the potential employ as cosmetic creams, will be carried out.

Ultimo aggiornamento: 15/07/2025