Characteristics of the elkhorn coral pathogen PDL-100 (Serratia marcescens)

Abstract

Serratia marcescens strain PDL-100 was isolated in 1998 from a colony of Acropora palmata that was affected with white pox disease. Most of the research on this bacterium focuses on its prevalence in clinical infections and little is known about its occurrence in the environment, primarily the marine environment. In this study we investigated the persistence of PDL-100 in several marine environments: the surface microlayer (SML) of three coral species (A. palmata, M. faveolata, and S. siderea), seawater at 30°C and 35°C, and nutrient-amended seawater and A. palmata SML. Our results show that the fitness of PDL-100 is heightened in S. siderea SML, warmer temperatures (35°C), and seawater and A. palmata SML amended with nutrients. We also found that natural inhibitors of PDL-100 exist in the mucus of A. palmata and S. siderea. We characterized the two antagonistic isolates as both being Enterobacter cloacae.