N-194. Isolation and Characterization of Radiation Resistance Microbes from Tropical Hypersaline Microbial Mats at the Cabo Rojo Salterns in Puerto Rico

K. Diaz Carrillo1, C. Rivera1, V. Irizarry-Vargas1, A. Agosto-Mujica2, V. Cardona-Cardona1, C. Rios-Velazquez1;
1Univ. of Puerto Rico, Mayaguez, PUERTO RICO, 2Univ. del Este, Carolina, PUERTO RICO.

Geomicrobiology is an interdisciplinary field that studies how microorganisms interact with their geological environment, being some of these hostile due to physico-chemical factors such as pH, temperatures, salinity, desiccation, heavy metals and radiation. Microbial Mats (MM) are examples of such interactions, which are stratified cyanobacteria-dominated biofilms that form organosedimentary ecosystems distributed according to environmental factors, such as light and oxygen concentration. Due to their presence in extreme environments, microbial mats have been used as models to understand early life on Earth. The MM from the Cabo Rojo Salterns of Puerto Rico are tropical, hypersaline and exposed to seasonal variations (dry and rainy seasons), high temperatures, and continuous solar radiation. The main focus of this research was to isolate and identify Radiation Resistant (RR) microbes from the Cabo Rojo Saltern MM during the dry season using ultraviolet radiation C (UVC). Samples of MM were processed by serial dilutions, and colonies were replica-plated and exposed to UVC at different times. The RR colonies were identified microscopically, their genomic DNA extracted and their 16S rDNA amplified for further sequencing and in silico analysis. A total of 6 RR candidates were isolated with variable extreme condition survival. In silico analysis suggests the presence of the genus Pontibacter sp., Arthrobacter sp., Halomonas sp., Sphingobacterium sp., Bacillus sp. and Salinivibrio sp. Most of the isolates were gram-positives, showing rod and cocci morphologies of variable size. There is ongoing research to further characterize the rest of the RR microbes, and incorporate UVA and UVB radiation as a selective agent.