Evaluation of UV-Resistance of Epibiotic Bacteria Co-existing with the Kenyan Marine Lyngbya majuscula

Abstract

The marine cyanobacterium Lyngbya majuscula is reported to be a source of a wide array of natural products. Some of the products exhibit photo-protective properties. L. majuscula has also been shown to live in association with epibiotic bacteria. However, the potency of these epibionts to withstand ultraviolet radiation is not well documented. This study focused on epibiotic bacteria isolated from the surface of L. majuscula from Kenya. Twelve strains or isolates were exposed to UV irradiance (365 nm, intensity of 11.6W cm-2) for 15, 30 and 45 minutes. Survival curves showed that the Bacilli strains were the most tolerant to UV, followed by the β-proteobacteria, while the actinobacteria were the least resistant to UV. The observation that the actinobacteria were less resistant to UV suggested that cell wall characteristics and G+C content are not the sole determinants of UV resistance. It would be interesting to determine the compounds and/or metabolite underlying the ability of these isolates to withstand exposures of varying levels of UV-radiations.