AME 57:343-350 (2009)  -  DOI: https://doi.org/10.3354/ame01365

Addition of monomeric and polymeric organic substrates alleviates viral lytic pressure on bacterial communities in coastal seawaters

Chiaki Motegi1,2,3,*, Toshi Nagata1,2

1Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan
2Center for Ecological Research, Kyoto University, 2-509-3 Hirano, Otsu, Shiga 520-2113, Japan
3Present address: Université Pierre et Marie Curie-Paris 6 and CNRS, Laboratoire d’Océanographie de Villefranche, 06234 Villefranche-sur-Mer, Cedex, France

ABSTRACT: We examined the effect of growth conditions on the fraction of bacterial production lysed by viruses (Flysed). Time-course changes in bacterial and viral variables were determined in coastal seawater cultures with and without the addition of monomeric (glucose or amino acids) or polymeric (protein) substrates. Substrate-induced enhancement of bacterial production was much more pronounced than that of viral production during the incubation period of 60 to 90 h. Estimates of Flysed were highest in non-addition controls (range = 0.3 to 1.0), followed by the monomer addition treatment (0.1 to 0.2), and lowest in the protein addition treatment (0.04 to 0.1). These data are consistent with the proposition that bacterial communities grown under substrate-rich conditions are less subject to viral attacks. Low Flysed values in the protein addition treatment were associated with high activities of leucine aminopeptidase, indicating a role of extracellular proteases in alleviating viral lytic pressure. Our data support the notion that supplies of dissolved organic matter affect the magnitude of bacteria–virus couplings in marine environments.


KEY WORDS: Virus–bacteria interactions · Lytic viral production · Dissolved organic matter · Marine environments


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Cite this article as: Motegi C, Nagata T (2009) Addition of monomeric and polymeric organic substrates alleviates viral lytic pressure on bacterial communities in coastal seawaters. Aquat Microb Ecol 57:343-350. https://doi.org/10.3354/ame01365

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