Search, Isolation and Characterization of Radiation Resistant Bioprospects from Extreme Environments in Puerto Rico

Radiation resistant microorganisms, such as Deinococcus radiodurans, have been found in extreme environments, such as deserts, and animal feces. Nonetheless, the extreme nature of the tropical countries has not yet been studied for the presence of such organisms. This research project involves the search for UV-C radiation resistant microbes from hypersaline and mineral rich soils, and microbial mats from the island of Puerto Rico. The samples were serially diluted and spread on culture media. The patched isolates were exposed to UV-C radiation for periods ranging from 5 to 45 minutes. A total of 18 radiation-resistant-candidates (RRCs) were obtained from the plates exposed to 10 and 15 minutes. A total of 16 RRCs were isolated from the hypersaline soil samples, and 2 from the mineral rich soil samples. Gram staining performed to the isolates showed the presence of gram-positive and gram-negative rods. Further exposure to UV-C radiation confirmed the radiation resistance of the isolates, and DNA extraction and 16SrDNA amplification was performed to molecularly characterize the RRCs. The In-silico analysis showed that the RRCs belong to Pseudomonas, Enterobacter, Halomonas, Bacillus and Shewanella genera. The presence of endospores and tests for resistance to UV-A and UV-B radiation are the next steps. The isolation of radiation resistant microorganisms found in extreme Caribbean environments, such as Puerto Rico, could provide new information regarding the diversity of the UV-C resistant microbes, and how this diversity might be affected due to the tropical nature of the environments in which they were found.