1. Institute of Bioinformatics, University of Georgia , Athens, GA 30602 , USA
2. Waksman Institute of Microbiology, Rutgers University , Piscataway, NJ 08854-8020 , USA
3. School of Agriculture and Food Sciences, University of Queensland , St Lucia, QLD 4072 , Australia
4. Department of Genetics, University of Georgia , Athens, GA 30602 , USA