Isolation of a Psychrotolerant and UV-C-Resistant Bacterium from Elephant Island, Antarctica with a Highly Thermoactive and Thermostable Catalase

Abstract

Microorganisms present in Antarctica have to deal not only with cold temperatures but also with other environmental conditions, such as high UV radiation, that trigger the generation of reactive oxygen species. Therefore, Antarctic microorganisms must have an important antioxidant defense system to prevent oxidative damage. One of these defenses are antioxidant enzymes, such as catalase, which is involved in the detoxification of hydrogen peroxide produced under oxidative conditions. Here, we reported the isolation and partial characterization of an Antarctic bacterium belonging to the Serratia genus that was resistant to UV-C radiation and well-adapted to cold temperatures. This microorganism, denominated strain I1P, was efficient at decreasing reactive oxygen species levels produced after UV-C irradiation. Genomic and activity assays suggested that the enzymatic antioxidant defense mechanisms of strain I1P, especially its catalase enzyme, may confer UV resistance. This catalase was active in a wide range of temperatures (20–70 °C), showing optimal activity at 50 °C (at pH 7.0), a remarkable finding considering its psychrotolerant origin. In addition, this enzyme was thermostable, retaining around 60% of its activity after 6 h of incubation at 50 °C. The antioxidant defense systems of strain I1P, including its surprisingly thermoactive and thermostable catalase enzyme, make this microorganism a good source of biocompounds with potential biotechnological applications.

From the Discovery of Extremozymes to an Enzymatic Product: Roadmap Based on Their Applications

“…A novel catalase was purified from the crude extract and biochemically characterized. The native enzyme was active in a wide range of temperatures (20–70°C), showing optimal activity at 50°C and pH 7.0, with a half-life of 7 h when incubated at 50°C, which is remarkable considering its psychrotolerant origin ( Monsalves et al, 2020 ).…”

“…This microorganism was identified as Serratia sp. I1P, with optimal growth conditions at 22°C, pH 7.0–9.0, 2–6% NaCl ( Monsalves et al, 2020 ) . A novel catalase was purified from the crude extract and biochemically characterized.…”

“…Samples were cultivated at 8 °C and pH 6.5 for up to 2 weeks. Then, cultures were exposed to UV-C radiation in a specially designed dark chamber for 2 h, to enrich microorganisms with better antioxidant defense mechanisms (Monsalves et al, 2020).…”

Extremophilic Oxidoreductases for the Industry: Five Successful Examples With Promising Projections

“…A novel catalase enzyme has been purified from a psychrotolerant Antarctic bacterium belonging to the Serratia genus that was resistant to UV-C radiation and well-adapted to cold temperatures. This microorganism, denominated strain I1P, was efficient at decreasing ROS levels produced after UV-C irradiation (Monsalves et al, 2020). The enzyme was found to be a heme catalase belonging to clade 3 and was active in a wide range of temperatures (20-70 • C), showing optimal activity at 50 • C and pH 7.0, with a half-life of 7 h at 50 • C, which is remarkable considering its psychrotolerant origin.…”

Resistance and Adaptation of Bacteria to Non-Antibiotic Antibacterial Agents: Physical Stressors, Nanoparticles, and Bacteriophages

“…UV irradiation directly impacts DNA by the formation of cyclobutene pyrimidine dimers and pyrimidine pyrimidone (6–4) photoproducts [ 40 ]. Deinococcus swuensi is an example of a highly resistant strain, which shows a unique landscape of differentially expressed genes that distinctly determine resistance to UV radiation compared to commonly observed mechanisms [ 41 ].…”