Isolation and molecular identification of a UV-resistant strain of Dietzia maris and antioxidant activity of pigment

The ability of radioresistant bacteria to survive high levels of UV radiation has been linked to their strong DNA repair systems and ability to produce primary and secondary metabolic products. The biosynthesis of pigments provides an opportunity for bacteria to live in radiation-rich environment. Recent radiation-responsive pigments are used commercially as food colorants, anticancer drugs, as well as antibiotics and for cosmetic purposes.
Soil sample of Omidiyeh city was collected during the spring of 2014 and UV-resistant strain was isolated after primary and secondary screening. Then it was identified by molecular methods (16S rRNA gene sequencing). Antioxidant activity of pigment was evaluated by 2,2 -diphenyl-1-picryl hydrazyl (DPPH) and the reducing power of pigments were analyzed by ferric chloride.
In this present study, new UV-resistant strain NM2 was isolated and by comparison of these 16S rRNA gene sequences to public database using the BLAST, the genus and species of the isolate was identified as Dietzia maris with 99% similarity. Extraction of pigment from isolated strain was carried out by methanol and acetone as solvents. The spectrum is characterized by maximum peak at 473 nm for pigment of NM2 strain. Antioxidant activity and the reducing ability of pigments increased by increasing their concentrations. NM2 strain pigment showed EC50 concentration of 3.30 mg/ml for DPPH free radical scavenging activity, and EC50 concentration of 28.46 µg/ml for reducing power.
Discussion and Isolation of natural resources of pigment is very important with high anti-oxidant activity. In the current study, pigment of UV-resistant bacteria demonstrated a strong antioxidant activity in vitro and pigment of these bacteria could play an important role in UV tolerance. Pigment of UV-resistant bacteria may be an appropriate source for antioxidative-related functional foods and the pharmaceutical industry.