title: Halobacteriovorax, an underestimated predator on bacteria: potential impact relative to viruses on bacterial mortality.
abstract: Predation on bacteria and accompanying mortality are important mechanisms in controlling bacterial populations and recycling of nutrients through the microbial loop. The agents most investigated and seen as responsible for bacterial mortality are viruses and protists. However, a body of evidence suggests that predatory bacteria such as the Halobacteriovorax (formerly Bacteriovorax), a Bdellovibrio-like organism, contribute substantially to bacterial death. Until now, conclusive evidence has been lacking. The goal of this study was to better understand the contributors to bacterial mortality by addressing the poorly understood role of Halobacteriovorax and how their role compares with that of viruses. The results revealed that when a concentrated suspension of Vibrio parahaemolyticus was added into microcosms of estuarine waters, the native Halobacteriovorax were the predators that responded first and most rapidly. Their numbers increased by four orders of magnitude, whereas V. parahaemolyticus prey numbers decreased by three orders of magnitude. In contrast, the extant virus population showed little increase and produced little change in the prey density. An independent experiment with stable isotope probing confirmed that Halobacteriovorax were the predators primarily responsible for the mortality of the V. parahaemolyticus. The results show that Halobacteriovorax have the potential to be significant contributors to bacterial mortality, and in such cases, predation by Halobacteriovorax may be an important mechanism of nutrient recycling. These conclusions add another dimension to bacterial mortality and the recycling of nutrients.
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Henry N
authors.initials: HN
authors.lastname: Williams
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Despoina S
authors.initials: DS
authors.lastname: Lymperopoulou
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Rana
authors.initials: R
authors.lastname: Athar
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Ashvini
authors.initials: A
authors.lastname: Chauhan
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Tamar L
authors.initials: TL
authors.lastname: Dickerson
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Huan
authors.initials: H
authors.lastname: Chen
authors.affiliation: School of the Coast & Environment, Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Laws
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Timkhite-Kulu
authors.initials: TK
authors.lastname: Berhane
authors.affiliation: Gulf Coast Research Laboratory, University of Southern Mississippi, Ocean Springs, MS, USA.
authors.forename: Adrienne R
authors.initials: AR
authors.lastname: Flowers
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Nadine
authors.initials: N
authors.lastname: Bradley
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Shanterial
authors.initials: S
authors.lastname: Young
authors.affiliation: Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC, USA.
authors.forename: Denene
authors.initials: D
authors.lastname: Blackwood
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Murray
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Oladipupo
authors.initials: O
authors.lastname: Mustapha
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Cory
authors.initials: C
authors.lastname: Blackwell
authors.affiliation: School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL, USA.
authors.forename: Yahsuan
authors.initials: Y
authors.lastname: Tung
authors.affiliation: Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC, USA.
authors.forename: Rachel T
authors.initials: RT
authors.lastname: Noble
mesh_terms: D000898:Antibiosis; D001501:Bdellovibrio / Q000502:physiology*; D014736:Vibrio parahaemolyticus / Q000254:growth & development* / Q000502:physiology; D018406:Virus Physiological Phenomena; D014780:Viruses / Q000254:growth & development