Carbon fluxes in the microbial loop: Comments

The heterotrophic bacterial community of oceanic aggregates which mediates particle solubilization, displays features (low carbon demand and low turnover) that are difficult to reconcile with the observed high enzyme activities and cell numbers. Hypotheses are proposed to explain this discrepancy. Furthermore, production of both free and attached bacteria may have been underestimated by neglecting the ultramicrobacteria (UMB). Production of UMB may represent up to 28% of the total bacterial production.