Abstract
Antarctic regions are characterized by low temperatures and strong UV radiation. This harsh environment is inhabited by psychrophilic and psychrotolerant organisms, which have developed several adaptive features. In this study, we analyzed two Antarctic bacterial strains, Planococcus sp. ANT_H30 and Rhodococcus sp. ANT_H53B. The physiological analysis of these strains revealed their potential to produce various biotechnologically valuable secondary metabolites, including surfactants, siderophores, and orange pigments. The genomic characterization of ANT_H30 and ANT_H53B allowed the identification of genes responsible for the production of carotenoids and the in silico reconstruction of the pigment biosynthesis pathways. The complex manual annotation of the bacterial genomes revealed the metabolic potential to degrade a wide variety of compounds, including xenobiotics and waste materials. Carotenoids produced by these bacteria were analyzed chromatographically, and we proved their activity as scavengers of free radicals. The quantity of crude carotenoid extracts produced at two temperatures using various media was also determined. This was a step toward the optimization of carotenoid production by Antarctic bacteria on a larger scale.
Highlights
Microbial secondary metabolites are relatively low-molecular-mass products of the secondary metabolism that are usually produced during the late growth phase
The carotenoid pigments produced by bacteria, due to their specific structure and antioxidant properties, are the main agents preventing the harmful effects of UV radiation [3]
The bacterial strains were cultivated in lysogeny broth (LB) and minimal medium M9 [48], supplemented (0.5% (w/v)) with various carbon sources at 15 ◦ C and 25 ◦ C with rotary shaking set to 150 rpm
Summary
Microbial secondary metabolites are relatively low-molecular-mass products of the secondary metabolism that are usually produced during the late growth phase (i.e., idiophase). Like pigments, biosurfactants, antibiotics, and siderophores, are not essential for the growth of their producers; they may significantly increase the fitness and viability of organisms under specific environmental conditions [1]. The carotenoid pigments produced by bacteria, due to their specific structure and antioxidant properties, are the main agents preventing the harmful effects of UV radiation [3]. In permanently cold environments, such as Antarctica, where the temperature during the year is usually below zero and does not exceed 15 ◦ C, carotenoids play a role in the modulation of the membrane fluidity and protect bacterial cells against disruption from freezing [4,5]
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