Extremophiles are organisms able to thrive in extreme environmental conditions. Microorganisms with the ability to survive high doses of radiation are known as radioresistant or radiation-resistant extremophiles. Excessive or intense exposure to radiation (i.e., gamma rays, X-rays, and particularly UV radiation) can induce a variety of mutagenic and cytotoxic DNA lesions, which can lead to different forms of cancer. However, some populations of microorganisms thrive under different types of radiation due to defensive mechanisms provided by primary and secondary metabolic products, i.e., extremolytes and extremozymes. Extremolytes (including scytonemin, mycosporine-like amino acids, shinorine, porphyra-334, palythine, biopterin, and phlorotannin, among others) are able to absorb a wide spectrum of radiation while protecting the organism's DNA from being damaged. The possible commercial applications of extremolytes include anticancer drugs, antioxidants, cell-cycle-blocking agents, and sunscreens, among others. This article aims to review the strategies by which microorganisms thrive in extreme radiation environments and discuss their potential uses in biotechnology and the therapeutic industry. The major challenges that lie ahead are also discussed.

Summary Micro‐organisms with the ability to survive in extreme environmental conditions are known as ‘extremophiles’. Currently, extremophiles have caused a sensation in the biotechnology/pharmaceutical industries with their novel compounds, known as ‘extremolytes’. The potential applications of extremolytes are being investigated for human therapeutics including anticancer drugs, antioxidants, cell cycle‐blocking agents, anticholesteric drugs, etc. It is hypothesized that the majority of ultraviolet radiation (UVR)‐resistant micro‐organisms can be used to develop anticancer drugs to prevent skin damage from UVR. The metabolites from UVR‐resistant microbes are a great source of potential therapeutic applications in humans. This article aims to discuss the potentials of extremolytes along with their therapeutic implications of UVR extremophiles. The major challenges of therapeutic development using extremophiles are also discussed.

SummaryRadionuclides in the environment are a major human and environmental health concern. Like the Chernobyl disaster of 1986, the Fukushima Daiichi nuclear disaster in 2011 is once again causing damage to the environment: a large quantity of radioactive waste is being generated and dumped into the environment, and if the general population is exposed to it, may cause serious life-threatening disorders. Bioremediation has been viewed as the ecologically responsible alternative to environmentally destructive physical remediation. Microorganisms carry endogenous genetic, biochemical and physiological properties that make them ideal agents for pollutant remediation in soil and groundwater. Attempts have been made to develop native or genetically engineered (GE) microbes for the remediation of environmental contaminants including radionuclides. Microorganism-mediated bioremediation can affect the solubility, bioavailability and mobility of radionuclides. Therefore, we aim to unveil the microbial-mediated mechanisms for biotransformation of radionuclides under various environmental conditions as developing strategies for waste management of radionuclides. A discussion follows of ‘-omics’-integrated genomics and proteomics technologies, which can be used to trace the genes and proteins of interest in a given microorganism towards a cell-free bioremediation strategy.

Widespread overuse of antibiotics has led to the emergence of numerous antibiotic-resistant bacteria; among these are antibiotic-subsisting strains capable of surviving in environments with antibiotics as the sole carbon source. This unparalleled expansion of antibiotic resistance reveals the potent and diversified resistance abilities of certain bacterial strains. Moreover, these strains often possess hypermutator phenotypes and virulence transmissibility competent for genomic and proteomic propagation and pathogenicity. Pragmatic and prospicient approaches will be necessary to develop efficient therapeutic methods against such bacteria and to understand the extent of their genomic adaptability. This review aims to reveal the niches of these antibiotic-catabolizing microbes and assesses the underlying factors linking natural microbial antibiotic production, multidrug resistance, and antibiotic-subsistence.

Abstract.Among extremophiles, microorganisms resistant to ultraviolet radiation (UVR) have been known to produce a variety of metabolites (i.e., extremolytes). We hypothesized that natural microbial flora on elevated land (hills) would reveal a variety of UVR-resistant extremophiles and polyextremophiles with modulated proteins and enzymes that had biotechnological implications. Microorganisms Cellulosimicrobium cellulans UVP1 and Bacillus pumilus UVP4 were isolated and identified using 16S rRNA sequencing, and showed extreme UV resistance (1.03 × 10 6 and 1.71 × 10 5 J/m 2 , respectively) from elevated land soil samples along with unique patterns of protein expression under UVR and non-UVR. A broad range of cellulolytic activity on carboxymethyl cellulose agar plates in C. cellulans UVP1 and B. pumilus UVP4 was revealed at varying pH, temperature, and inorganic salt concentration. Further, the microbial strain B. pumilus UVP4 showed the basic characteristics of a novel group: polyextremophiles with significance in bioenergy.