title: Interactions between Bacillus anthracis and plants may promote anthrax transmission.
abstract: Environmental reservoirs are essential in the maintenance and transmission of anthrax but are poorly characterized. The anthrax agent, Bacillus anthracis was long considered an obligate pathogen that is dormant and passively transmitted in the environment. However, a growing number of laboratory studies indicate that, like some of its close relatives, B. anthracis has some activity outside of its vertebrate hosts. Here we show in the field that B. anthracis has significant interactions with a grass that could promote anthrax spore transmission to grazing hosts. Using a local, virulent strain of B. anthracis, we performed a field experiment in an enclosure within a grassland savanna. We found that B. anthracis increased the rate of establishment of a native grass (Enneapogon desvauxii) by 50% and that grass seeds exposed to blood reached heights that were 45% taller than controls. Further we detected significant effects of E. desvauxii, B. anthracis, and their interaction on soil bacterial taxa richness and community composition. We did not find any evidence for multiplication or increased longevity of B. anthracis in bulk soil associated with grass compared to controls. Instead interactions between B. anthracis and plants may result in increased host grazing and subsequently increased transmission to hosts.
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, United States of America.
authors.forename: Holly H
authors.initials: HH
authors.lastname: Ganz
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, United States of America.
authors.forename: Wendy C
authors.initials: WC
authors.lastname: Turner
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, United States of America; Ecology Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Eoin L
authors.initials: EL
authors.lastname: Brodie
authors.affiliation: Independent researcher, Windhoek, Namibia.
authors.forename: Martina
authors.initials: M
authors.lastname: Kusters
authors.affiliation: Department of Statistics, University of California, Berkeley, California, United States of America.
authors.forename: Ying
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Ministry of Fisheries and Marine Resources, Inland Aquaculture, Katima Mulilo Regional Office, Katima Mulilo, Namibia.
authors.forename: Heniritha
authors.initials: H
authors.lastname: Sibanda
authors.affiliation: Ecology Department, Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Tamas
authors.initials: T
authors.lastname: Torok
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, United States of America; School of Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Wayne M
authors.initials: WM
authors.lastname: Getz
mesh_terms: D000818:Animals; D000881:Anthrax / Q000635:transmission*; D001408:Bacillus anthracis / Q000302:isolation & purification*; D063245:Plant Development; D006109:Poaceae / Q000382:microbiology* / Q000502:physiology*