Research Article Microb Physiol 2021;31:1–15 Ultraviolet-B Radiation Stress-Induced Toxicity and Alterations in Proteome of Deinococcus radiodurans Jay Kumar Paushali Ghosh Ashok Kumar School of Biotechnology, Institute of Science, Banaras Hindu University, Varanasi, India Received: May 27, 2020 Accepted: September 27, 2020 Published online: December 18, 2020 AshokKumar School of Biotechnology, Institute of Science, Banaras Hindu University Varanasi 221 005 (India) kasokbt @rediffmail.com © 2020 S. Karger AG, Basel karger@karger.com www.karger.com/mip DOI: 10.1159/000512018 Keywords Deinococcus radiodurans · Ultraviolet radiation · Reactive oxygen species · Protein · Gene expression Abstract Deinococcus radiodurans is a polyextremophilic bacterium capable to survive and grow at high doses of ionizing radia- tion. Besides resistance to ionizing radiation, the bacterium is also resistant to toxic chemicals and desiccation. This study deals with the effects of non-ionizing radiation (ultraviolet- B) on survival, alterations in proteomic profile, and gene ex- pression in D. radiodurans. Exposure of culture to UV-B caused decrease in the percentage survival with increasing duration, complete killing occurred after 16 h. D. radiodurans also showed enhancement in the generation of reactive ox- ygen species and activities of antioxidative enzymes. Sepa- ration of proteins by 2-dimensional gel electrophoresis re- vealed major changes in number and abundance of different proteins. Twenty-eight differentially abundant protein spots were identified by MALDI-TOF MS/MS analysis and divided into 8 groups including unknown proteins. Gene expression of a few identified proteins was also analyzed employing qRT-PCR, which showed differential expression correspond- ing to the respective proteins. In silico analysis of certain hy- pothetical proteins (HPs) suggested that these are novel and as yet not reported from D. radiodurans subjected to UV-B stress. These HPs may prove useful in future studies espe- cially for assessing their significance in the adaptation and management of stress responses against UV-B stress. © 2020 S. Karger AG, Basel Introduction UV-B radiation (280–315 nm) is the most cytotoxic wavelength of solar UV radiation and affects a number of structural and physiological processes in living organisms [Bancroft et al., 2007]. Several reports suggest an increase in the level of UV-B radiation reaching the Earth’s surface mainly due to the depletion of the stratospheric ozone layer caused by the emission of anthropogenically gener- ated pollutants [Crutzen, 1992; Madronich et al., 1998]. There is a consensus that gradual increase in UV-B radia- tion intensity may lead to severe climatic changes includ- ing the increase in global mean temperature, imbalances in natural ecosystems, and risks for the survival of living organisms including human beings [Madronich et al.,