The material presented here tends to resume the literature
dealing mainly with the structural description of the microbial
loop and discusses some functional aspect in action within the
microbial food webs. For more detailed information, the
interested readers can refer to the literature listed below.
Since Pomeroy (1974), it has been shown that the microbial
consortia play a key role in both structure and function of open
ocean ecosystems (Azam et al., 1983). Figure 1 shows a cartoon
representation of the oceanic global carbon cycling. Two major
herbivorous and microbial pathways determine transformation and
transfer of matters in the ocean (Fig. 2). The relative flux
intensity within each pathway depends upon a “competition”
between bacteria and the particle grazers’ pathways. Due to the
dominance of the bacterial production in oligotrophic
environments and in most of the mesoplelagic water column,
fluxes are highly diverted towards the pathway n°1. However, it
is important to appreciate conditions that det