Characterization of natural compounds from antarctic bacteria and their environmental applications

Objective Antarctica is a unique geographical region, characterized by extremely low temperatures and high levels of ultraviolet (UV) radiation. To survive under these harsh conditions, microorganisms inhabiting this environment produce bioactive compounds of considerable value, such as pigments and bacterial cellulose [1]. This study aims to identify natural products derived from Antarctic bacteria and explore their potential applications in environmental science. Particular emphasis is placed on the antioxidant properties of these compounds, which are associated with the organisms’ adaptive strategies [2] to counteract oxidative stress induced by intense UV exposure. These antioxidant properties show promise as natural reducing agents, with potential applications in the biosynthesis of noble metal nanoparticles and the photoreduction of Cr(VI). Methods Bioactive compounds produced from Antarctic bacteria were extracted and analyzed using UV-Vis, FTIR, and HPLCMS/ MS. Following molecular identification, these compounds were then used for the eco-friendly synthesis of silver nanoparticles by combining AgNO₃, NaOH, and pigments, followed by heating at 70 °C for 45 minutes. In the application for Cr(VI) photoreduction, a solution of Cr and pigments was irradiated with UV light; every 15 minutes, treated with diphenylcarbazide (DPC), to measure reduction efficiency. Results Pigments were extracted from two cold-adapted, salt-tolerant Antarctic bacterial strains: Pseudomonas sp. ef1 and Rhodococcus sp. ef1. The former produces a fluorescent pigment known as pyoverdine [3], while the latter synthesizes a pink-blue pigment, identified as a pyocyanin derivative. Both pigments were largely characterised and exhibited antioxidant activity, demonstrated by their use in the synthesis of silver nanoparticles with an average diameter of approximately 10 nm, and in the photoreduction of Cr(VI), achieving a reduction efficiency of 95%. Conclusions In conclusion, this study provides new insights into the ability of Antarctic bacteria to produce bioactive natural compounds, offering valuable information on their chemical properties and potential applications in innovative fields, such as the eco-friendly removal of well-known pollutants and the green synthesis of high-value nanomaterials.