Indirect interactions in the microbial world: specificities and similarities to plant–insect systems

Abstract

Trophic interactions between bacteria, viruses, and protozoan predators play crucial roles in structuring aquatic microbial communities and regulating microbemediated ecosystem functions (biogeochemical processes). In this microbial food web, protozoan predators and viruses share bacteria as a common resource, and protozoan predators can kill viruses [intraguild predation (IGP)] and vice versa, even though these latter processes are probably of less importance. However, protozoan predators (IG predator) and viruses (IG prey) generally occur together in various environments, and this cannot be fully explained by the classic IGP models. In addition, controlled experiments have often demonstrated that protozoan predators have apparently positive effects on viral activity. These surprising patterns can be explained by indirect interactions between them via induced trait changes in bacterial assemblages, which can be compared with trait-mediated indirect interactions (TMIIs) in terrestrial plant-insect systems. Here, we review some trait changes in bacterial assemblages that may positively affect the activities and abundance of viruses. It has been suggested that in bacterial assemblages, protozoan predation may enhance growth conditions for individual bacteria and induce both phenotypic trait changes at the individual (e.g., filament-forming bacteria) and group level as a result of changes in bacterial community composition (e.g., species dominance). We discuss the specificities of aquatic microbial systems and attempt find functional similarities between aquatic microbial systems and terrestrial plant-insect systems with regard to TMII function.

Feeding guild of non‐host community members affects host‐foraging efficiency of a parasitic wasp

“…It is well known that trait‐mediated interactions influence foraging animals and microorganisms in terrestrial and aquatic environments (Schmitz et al. , Miki and Jacquet , Utsumi et al. ).…”

“…It is well known that trait-mediated interactions influence foraging animals and microorganisms in terrestrial and aquatic environments , Miki and Jacquet 2010, Utsumi et al 2010). However, ecological interactions involve multiple interactions among community members.…”

In situ structuring of virioplankton through ­bacterial exoenzymatic activity: interaction with phytoplankton

“…First, bacterial phylotypes that are good competitors for nutrients would be lysed and then the virus-resistant phylotypes would compete with each other. However, top-down and bottom-up controls are linked because viruses and grazers could also have a strong indirect bottom-up effect by modifying the quality and quantity of nutritive resources (Sandaa et al 2009, Miki & Jacquet 2010.…”

Grazing of heterotrophic flagellates on viruses is driven by feeding behaviour

“…Further evidence comes from modelling (e.g. Miki and Jacquet, 2008; 2010). Thus, protists could serve as potential inactivation or elimination agents of viruses in general and human pathogens in particular (Groupe and Pugh, ; Kim and Unno, ; Pinheiro et al ., 2007; 2008; Akunyili et al ., ; Hennemuth et al ., ).…”