Diversity and structure of soil bacterial communities associated with vultures in an African savanna HOLLY H. GANZ, 1,5,  ULAS KARAOZ, 2 WAYNE M. GETZ, 1,3 WILFERD VERSFELD, 4 AND EOIN L. BRODIE 2 1 Department of Environmental Science, Policy & Management, University of California, 137 Mulford Hall, Berkeley, California 94720-3114 USA 2 Ecology Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 USA 3 School of Mathematical Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000 South Africa 4 Etosha Ecological Institute, P.O. Box 6, Okaukuejo via Outjo, Namibia Citation: Ganz, H. H., U. Karaoz, W. M. Getz, W. Versfeld, and E. L. Brodie. 2012. Diversity and structure of soil bacterial communities associated with vultures in an African savanna. Ecosphere 3(6):47. http://dx.doi.org/10.1890/ES11-00333.1 Abstract. Bird guano has been shown to alter the structure and function of ecological communities. Here we characterize the effects of vulture guano on the phylogenetic structure, taxa richness, and abundance in soil bacterial communities within an African savanna. By altering soil chemistry and nutrient status, vulture guano appears to play a role in influencing the structure of soil bacterial communities. DNA was extracted from soil collected under twenty trees: five African white-backed vulture (Gyps africanus, WBV) nesting sites, five lappet-faced vulture ( Torgos tracheliotos, LFV) nesting sites and ten control sites where no sign of vulture activity was detected. Using a high-density phylogenetic microarray (PhyloChip G2), we identified 1,803 bacterial Operational Taxonomic Units (OTUs) in the twenty samples. Analysis of beta-diversity using the Unifrac distance metric demonstrated that WBV nesting sites were phylogenet- ically distinct from both control trees and LFV nesting sites. We detected a higher degree of phylogenetic clustering in soil bacterial communities associated with both WBV and LFV nesting sites compared to control sites, suggesting that the deposition of guano increases the strength of habitat filtering in these communities. Canonical correspondence analysis revealed that variation in OTU intensity (a measure of relative abundance) could be related to variations in pH, electrical conductivity and total nitrogen content. WBV sites explained 10% to 22% of the variation in OTU intensity. The elevated total nitrogen and lower pH characteristic of soils associated with vultures may favor Proteobacteria and suppress Firmicutes, particularly Clostridia and Bacilli. Acidic aggregations of vulture guano may be unlikely to support long- term survival of spore-forming Firmicute pathogens and thus may limit the role that vultures play as potential disease vectors. Key words: Bacillus anthracis; bacteria; competitive exclusion; Gyps africanus; habitat filtering; lappet-faced vulture; microbial ecology; pH; savanna; Torgos tracheliotos; white-backed vulture. Received 28 November 2011; revised 24 February 2012; accepted 28 February 2012; final version received 2 May 2012; published 1 June 2012. Corresponding Editor: K. Elgersma. Copyright: Ó 2012 Ganz et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits restricted use, distribution, and reproduction in any medium, provided the original author and sources are credited. 5 Present address: University of California, Davis, School of Veterinary Medicine, Department of Population Health and Reproduction, One Shields Avenue, Davis, California 95616 USA.  E-mail: hhganz@ucdavis.edu INTRODUCTION African savannas contain grasslands with scattered patches of trees that provide habitat for nesting birds. When birds deposit guano at these nesting and roosting sites, they create nutrient rich resource patches. Nutrient inputs from bird guano can have cascading effects in v www.esajournals.org 1 June 2012 v Volume 3(6) v Article 47