Identification of a novel quinoline-based UV-protective pigment from a psychrotrophic Arctic bacterium

Psychrotrophs are extremophilic microorganisms that grow optimally in low temperature having many unique bioactive molecules of biotechnological applications. In this study, we characterized a pigment from an arctic bacterium with protective activity towards UV exposure.

The present research reports isolation and characterization of a psychrotrophic bacteria, RSAP2, from the soil sample of NyAlesund (78°56"N, 11°54"E), Svalbard, Norway. The strain showed closest 16S rRNA gene sequence similarity (99.9%) with Kocuria indica NIO-1021. RSAP2 is a Gram-positive, coccoid aerobe which produces a yellow pigment. The optimal parameters for pigment production while grown in LB medium were 3% (w/v) NaCl and 4 days of incubation of the culture at 20°C and pH 9 with shaking (180 rpm). The pigment was extracted in methanol and acetone (2:1) and further purified through column chromatography. It was characterized by mass spectrometry, UV-visible, fluorescence, IR, ¹ H NMR, ¹³ C NMR spectroscopy and CHNS/O analysis. The pigment has a molecular weight of about 258 daltons and the molecular formula was determined as C₁₅ H₁₈ N₂ O₂ and is a quinoline derivative. We show that the pigment can protect Escherichia coli against UV-mediated mutagenesis. We further demonstrate that the pigment displays a significant antimicrobial effect and in sublethal concentrations it impairs biofilm formation ability of the model organism Staphylococcus aureus.

The pigment of a psychrotrophic Arctic bacterium, most likely a strain of K. indica, was purified and its chemical structure was determined. The quinoline-based pigment has the ability to protect live cells from UV induced damage.

Analysis and characterization of this newly isolated quinoline-based pigment is a potential candidate for future application in skin care products.