Biodiversity of UV-Resistant Bacteria in Antarctic Aquatic Environments

Abstract

Antarctica is an untapped reservoir of bacterial communities, which are able to adapt to a huge variety of strategies to cope with extreme conditions and, therefore, are capable of producing potentially valuable compounds for biotechnological applications. In this study, 31 UV-resistant bacteria collected from different Antarctic aquatic environments (surface sea waters/ice and shallow lake sediments) were isolated by UV-C assay and subsequently identified. A phylogenetic analysis based on 16S rRNA gene sequence similarities showed that the isolates were affiliated with Proteobacteria, Actinobacteria and Firmicutes phyla, and they were clustered into 15 bacterial genera, 5 of which were Gram negative (Brevundimonas, Qipengyuania, Sphingorhabdus, Sphingobium, and Psychrobacter) and 10 of which were Gram positive (Staphylococcus, Bacillus, Mesobacillus, Kocuria, Gordonia, Rhodococcus, Micrococcus, Arthrobacter, Agrococcus, and Salinibacterium). Strains belonging to Proteobacteria and Actinobacteria phyla were the most abundant species in all environments. The genus Psychrobacter was dominant in all collection sites, whereas bacteria belonging to Actinobacteria appeared to be the most diverse and rich in terms of species among the investigated sites. Many of these isolates (20 of 31 isolates) were pigmented. Bacterial pigments, which are generally carotenoid-type compounds, are often involved in the protection of cells against the negative effects of UV radiation. For this reason, these pigments may help bacteria to successfully tolerate Antarctic extreme conditions of low temperature and harmful levels of UV radiation.

Biotechnological Applications of Products Released by Marine Microorganisms for Cold Adaptation Strategies: Polyunsaturated Fatty Acids, Antioxidants, and Antifreeze Proteins

“…In particular, cold-adapted microorganisms present an efficient enzymatic system essential for survival in the presence of ROS represented by antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase, peroxiredoxin, and desaturases, that can neutralize the effects of radicals [8]. In addition to enzymatic antioxidants, several antioxidant molecules are also produced by the microorganisms in cold environments, such as pigments (mostly carotenoids) [9] which, thanks to their peculiar characteristics, can be used in many commercial applications, including food, cosmeceuticals, and pharmaceuticals. Cold-adapted microorganisms survive challenges associated with freezing, also thanks to the production of IBPs, including antifreeze proteins (AFPs) and ice-nucleating proteins (INPs).…”

Biodiversity, Adaptation Strategies, and Opportunities in Extreme Marine Environments

“…In their paper on bacteria, Coppola et al [1] studied 31 UV-resistant bacteria collected from surface sea waters/ice and shallow lake sediments in Antarctica. These bacteria were isolated via UV-C assay and, successively, genetically characterized by 16S rRNA gene sequencing, thus providing information on the available species and their distribution.…”