Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions

ABSTRACT The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that Bdellovibrio and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understandin...

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Autores principales:	Huan Chen, Edward A. Laws, Julio L. Martin, Timkhite-Kulu Berhane, Paul A. Gulig, Henry N. Williams
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2018
Materias:	Bdellovibrio and like organisms Halobacteriovorax bacterial mortality bacteriophage microbial food web predator-prey interactions Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/28dd2f32373c492785b3283ab83d5aa0
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spelling	oai:doaj.org-article:28dd2f32373c492785b3283ab83d5aa02021-11-15T16:00:15ZRelative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions10.1128/mBio.01202-182150-7511https://doaj.org/article/28dd2f32373c492785b3283ab83d5aa02018-09-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01202-18https://doaj.org/toc/2150-7511ABSTRACT The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that Bdellovibrio and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator’s contribution. Here we investigated the contribution of Halobacteriovorax, one of the BALOs, and bacteriophages when incubated with their common prey, Vibrio vulnificus, in a seawater microcosm. We observed that Halobacteriovorax was the greatest responder to the prey, increasing 18-fold with a simultaneous 4.4-log-unit reduction of V. vulnificus at 40 h, whereas the bacteriophage population showed no significant increase. In subsequent experiments to formulate a medium that would support the predatory activities and replication of both predators, low-nutrient media favored the predation and replication of the Halobacteriovorax, whereas higher-nutrient media enhanced phage growth. The greatest prey reduction and replication of both Halobacteriovorax and phage were observed in media with moderate nutrient levels. Additional experiments show that the predatory activities of both predators were influenced by environmental conditions, specifically, temperature and salinity. The two predators combined exerted greater control on V. vulnificus, a synergism that may be exploited for practical applications to reduce bacterial populations. These findings suggest that along with bacteriophage and protists, Halobacteriovorax has the potential to have a prominent role in bacterial mortality and cycling of nutrients, two vital ecologic functions. IMPORTANCE Although much has been reported about the marine microbial food web and the role of micropredators, specifically viruses and protists, the contribution of Bdellovibrio-like predators has largely been ignored, posing a major gap in understanding food web processes. A complete scenario of the microbial food web cannot be developed until the roles of all major micropredators and the magnitude of their contributions to bacterial mortality, structuring of microbial communities, and cycling of nutrients are assessed. Here we show compelling evidence that Halobacteriovorax, a predatory bacterium, is a significant contributor to bacterial death and, in some cases, may rival viruses as agents of bacterial mortality. These results advance current understanding of the microbial loop and top-down control on the bacterial community.Huan ChenEdward A. LawsJulio L. MartinTimkhite-Kulu BerhanePaul A. GuligHenry N. WilliamsAmerican Society for MicrobiologyarticleBdellovibrio and like organismsHalobacteriovoraxbacterial mortalitybacteriophagemicrobial food webpredator-prey interactionsMicrobiologyQR1-502ENmBio, Vol 9, Iss 4 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	Bdellovibrio and like organisms Halobacteriovorax bacterial mortality bacteriophage microbial food web predator-prey interactions Microbiology QR1-502
spellingShingle	Bdellovibrio and like organisms Halobacteriovorax bacterial mortality bacteriophage microbial food web predator-prey interactions Microbiology QR1-502 Huan Chen Edward A. Laws Julio L. Martin Timkhite-Kulu Berhane Paul A. Gulig Henry N. Williams Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions
description	ABSTRACT The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that Bdellovibrio and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator’s contribution. Here we investigated the contribution of Halobacteriovorax, one of the BALOs, and bacteriophages when incubated with their common prey, Vibrio vulnificus, in a seawater microcosm. We observed that Halobacteriovorax was the greatest responder to the prey, increasing 18-fold with a simultaneous 4.4-log-unit reduction of V. vulnificus at 40 h, whereas the bacteriophage population showed no significant increase. In subsequent experiments to formulate a medium that would support the predatory activities and replication of both predators, low-nutrient media favored the predation and replication of the Halobacteriovorax, whereas higher-nutrient media enhanced phage growth. The greatest prey reduction and replication of both Halobacteriovorax and phage were observed in media with moderate nutrient levels. Additional experiments show that the predatory activities of both predators were influenced by environmental conditions, specifically, temperature and salinity. The two predators combined exerted greater control on V. vulnificus, a synergism that may be exploited for practical applications to reduce bacterial populations. These findings suggest that along with bacteriophage and protists, Halobacteriovorax has the potential to have a prominent role in bacterial mortality and cycling of nutrients, two vital ecologic functions. IMPORTANCE Although much has been reported about the marine microbial food web and the role of micropredators, specifically viruses and protists, the contribution of Bdellovibrio-like predators has largely been ignored, posing a major gap in understanding food web processes. A complete scenario of the microbial food web cannot be developed until the roles of all major micropredators and the magnitude of their contributions to bacterial mortality, structuring of microbial communities, and cycling of nutrients are assessed. Here we show compelling evidence that Halobacteriovorax, a predatory bacterium, is a significant contributor to bacterial death and, in some cases, may rival viruses as agents of bacterial mortality. These results advance current understanding of the microbial loop and top-down control on the bacterial community.
format	article
author	Huan Chen Edward A. Laws Julio L. Martin Timkhite-Kulu Berhane Paul A. Gulig Henry N. Williams
author_facet	Huan Chen Edward A. Laws Julio L. Martin Timkhite-Kulu Berhane Paul A. Gulig Henry N. Williams
author_sort	Huan Chen
title	Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions
title_short	Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions
title_full	Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions
title_fullStr	Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions
title_full_unstemmed	Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions
title_sort	relative contributions of <italic toggle="yes">halobacteriovorax</italic> and bacteriophage to bacterial cell death under various environmental conditions
publisher	American Society for Microbiology
publishDate	2018
url	https://doaj.org/article/28dd2f32373c492785b3283ab83d5aa0
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Relative Contributions of <italic toggle="yes">Halobacteriovorax</italic> and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions

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