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Top-down effects of a lytic bacteriophage and protozoa on bacteria in aqueous and biofilm phases.

Zhang J, Ormälä-Odegrip AM, Mappes J, Laakso J - Ecol Evol (2014)

Bottom Line: We found that ciliates were the most efficient enemy type in reducing bacterial biomass in the open water, but least efficient in reducing the biofilm biomass.Thereafter, the bacteria evolve phage-resistance that largely prevents top-down effects.The combination of all three enemy types was most effective in reducing biofilm biomass, whereas in the open-water phase the ciliates dominated the trophic effects.

View Article: PubMed Central - PubMed

Affiliation: Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä P.O. Box 35, 40014, Jyväskylä, Finland ; Department of Biosciences, University of Helsinki P.O. Box 65, 00014, Helsinki, Finland.

ABSTRACT
Lytic bacteriophages and protozoan predators are the major causes of bacterial mortality in natural microbial communities, which also makes them potential candidates for biological control of bacterial pathogens. However, little is known about the relative impact of bacteriophages and protozoa on the dynamics of bacterial biomass in aqueous and biofilm phases. Here, we studied the temporal and spatial dynamics of bacterial biomass in a microcosm experiment where opportunistic pathogenic bacteria Serratia marcescens was exposed to particle-feeding ciliates, surface-feeding amoebas, and lytic bacteriophages for 8 weeks, ca. 1300 generations. We found that ciliates were the most efficient enemy type in reducing bacterial biomass in the open water, but least efficient in reducing the biofilm biomass. Biofilm was rather resistant against bacterivores, but amoebae had a significant long-term negative effect on bacterial biomass both in the open-water phase and biofilm. Bacteriophages had only a minor long-term effect on bacterial biomass in open-water and biofilm phases. However, separate short-term experiments with the ancestral bacteriophages and bacteria revealed that bacteriophages crash the bacterial biomass dramatically in the open-water phase within the first 24 h. Thereafter, the bacteria evolve phage-resistance that largely prevents top-down effects. The combination of all three enemy types was most effective in reducing biofilm biomass, whereas in the open-water phase the ciliates dominated the trophic effects. Our results highlight the importance of enemy feeding mode on determining the spatial distribution and abundance of bacterial biomass. Moreover, the enemy type can be crucially important predictor of whether the rapid defense evolution can significantly affect top-down regulation of bacteria.

No MeSH data available.


Related in: MedlinePlus

Bacteriophage Semad11.
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Related In: Results  -  Collection

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fig01: Bacteriophage Semad11.

Mentions: Obligatory lytic bacteriophage Semad11 infecting S. marcescens Db11 was isolated from a sewage treatment plant in Jyväskylä, Finland in 2009. Semad11 is a T7-like bacteriophage belonging to Podoviridae (A-M. Örmälä-Odegrip, unpubl. data) (Fig. 1).


Top-down effects of a lytic bacteriophage and protozoa on bacteria in aqueous and biofilm phases.

Zhang J, Ormälä-Odegrip AM, Mappes J, Laakso J - Ecol Evol (2014)

Bacteriophage Semad11.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4264894&req=5

fig01: Bacteriophage Semad11.
Mentions: Obligatory lytic bacteriophage Semad11 infecting S. marcescens Db11 was isolated from a sewage treatment plant in Jyväskylä, Finland in 2009. Semad11 is a T7-like bacteriophage belonging to Podoviridae (A-M. Örmälä-Odegrip, unpubl. data) (Fig. 1).

Bottom Line: We found that ciliates were the most efficient enemy type in reducing bacterial biomass in the open water, but least efficient in reducing the biofilm biomass.Thereafter, the bacteria evolve phage-resistance that largely prevents top-down effects.The combination of all three enemy types was most effective in reducing biofilm biomass, whereas in the open-water phase the ciliates dominated the trophic effects.

View Article: PubMed Central - PubMed

Affiliation: Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä P.O. Box 35, 40014, Jyväskylä, Finland ; Department of Biosciences, University of Helsinki P.O. Box 65, 00014, Helsinki, Finland.

ABSTRACT
Lytic bacteriophages and protozoan predators are the major causes of bacterial mortality in natural microbial communities, which also makes them potential candidates for biological control of bacterial pathogens. However, little is known about the relative impact of bacteriophages and protozoa on the dynamics of bacterial biomass in aqueous and biofilm phases. Here, we studied the temporal and spatial dynamics of bacterial biomass in a microcosm experiment where opportunistic pathogenic bacteria Serratia marcescens was exposed to particle-feeding ciliates, surface-feeding amoebas, and lytic bacteriophages for 8 weeks, ca. 1300 generations. We found that ciliates were the most efficient enemy type in reducing bacterial biomass in the open water, but least efficient in reducing the biofilm biomass. Biofilm was rather resistant against bacterivores, but amoebae had a significant long-term negative effect on bacterial biomass both in the open-water phase and biofilm. Bacteriophages had only a minor long-term effect on bacterial biomass in open-water and biofilm phases. However, separate short-term experiments with the ancestral bacteriophages and bacteria revealed that bacteriophages crash the bacterial biomass dramatically in the open-water phase within the first 24 h. Thereafter, the bacteria evolve phage-resistance that largely prevents top-down effects. The combination of all three enemy types was most effective in reducing biofilm biomass, whereas in the open-water phase the ciliates dominated the trophic effects. Our results highlight the importance of enemy feeding mode on determining the spatial distribution and abundance of bacterial biomass. Moreover, the enemy type can be crucially important predictor of whether the rapid defense evolution can significantly affect top-down regulation of bacteria.

No MeSH data available.


Related in: MedlinePlus