Session Title: The Animal Microbiome
Presentation Date: Monday, August 18, 2008
Poster Board Number: 0367
ACTINOMYCETES WITHIN TERMITE COLONIES: ANTIFUNGAL COMPOUNDS MAY BENEFIT ZOOTERMOPSIS ANGUSTICOLLIS
E. Gavrish1, C. Moore2, R. Zeid3, R. Rosengaus3, K. Lewis1
1Antimicrobial Discovery Center, Northeastern University, Biology Department, Boston, United States of America, 2NovoBiotic Pharmaceuticals, Cambrigde, United States of America, 3Northeastern University, Biology Department, Boston, United States of America
The dampwood termite Zootermopsis angusticollis is unique to the North American west coast. These social insects live within damp and decayed wood, conditions which are favorable to a variety of bacterial and fungal species that may be detrimental to the termite population. In the present study, we focused on isolating actinomycetes that may help control pathogens associated with this termite.
Two methods were used to isolate actinomycetes: conventional Petri dish plating and a recently described trap for in situ cultivation (Gavrish et al., JMM 2008). Nest material and washes from eggs and termites were plated on several isolation media. In situ traps were placed into the nest for two weeks and filamentous microorganisms penetrated into the device and formed colonies.
Over one hundred actinomycetes were isolated using these approaches. Based on 16S rRNA gene sequences, strains of Streptomyces, Amycolatopsis, Cellulomonas, Promicromonospora and Kitasatospora represented the major groups among the isolates, with the predominant group being Streptomyces. Strains closely related to S. padanus, S. griseofuscus and S. murinus (98-99% 16S rRNA genes similarity) produced highly diffusible compounds with high activity against Metarhizium anisopliae, a known fungal pathogen of termites. Two streptomycetes strains that produced large amounts of antifungal compounds were used as a source for identifying the structure of these compounds. These antifungal compounds, which are produced under all growth conditions tested, include Actinomycin V and two major polyenes - Aurenin and Cogomycin. We hypothesize that termites may benefit from their association with actinomycetes through reduced fungal growth within their nests.