CHARACTERIZATION AND APPLICATIONS OF NOVEL INTERESTING MOLECULES FROM COLD-ADAPTED EXTREMOPHILES ANTARCTIC MARINE MICROORGANISMS.

Antarctica, due to its geographical position, supports a wide array of unexplored extremophile microorganisms with the potential to produce interesting natural products (NPs) as bioactive compounds, including antibiotics, pigments, etc [1]. In fact, microorganisms known as extremophiles act by producing specialized enzymes that allow them to work at their best in such difficult circumstances but also, provide them with unexpected potential when these microorganisms are found in environments other than their native one [2]. In this context, this work focuses on the purification, characterization and application of interesting microbial NPs, like bacterial pigments and bacterial cellulose, produced from two different cold-adapted and salt tolerant Antarctic bacterial strains: Pseudomonas sp. ef1 and Rhodococcus sp. ef1. The production of these compounds was induced under non-native culture conditions, including elevated carbon sources and increased incubation temperatures. In particular, in this study, two novel forms of water soluble fluorescent pyoverdines produced by Pseudomonas sp. ef1 bacterial strain, and a novel blue/pink derivative of a pyocyanin produced by Rhodococcus sp. ef1, were largely characterized by using UV-Vis, IR, HPLC-DAD-FLD, HPLC-MS/MS measurements. The purified pigments were later applied in different processes, as in the green synthesis of silver and gold nanoparticles and in the photoreduction of highly toxic metals like Cr(VI). In addition, a peculiar bacterial cellulose, showing hydrophobic properties, produced by Pseudomonas sp. ef1 was also characterized. This study, therefore, adds new data on the potential of these Antarctic bacteria to produce interesting NPs, but also adds important information about their chemical characteristics and on their possible use for new applications.