Microbial production of recalcitrant dissolved organic matter: long-term carbon storage in the global ocean

Abstract

The biological pump is a process whereby CO(2) in the upper ocean is fixed by primary producers and transported to the deep ocean as sinking biogenic particles or as dissolved organic matter. The fate of most of this exported material is remineralization to CO(2), which accumulates in deep waters until it is eventually ventilated again at the sea surface. However, a proportion of the fixed carbon is not mineralized but is instead stored for millennia as recalcitrant dissolved organic matter. The processes and mechanisms involved in the generation of this large carbon reservoir are poorly understood. Here, we propose the microbial carbon pump as a conceptual framework to address this important, multifaceted biogeochemical problem.

Interactive network configuration maintains bacterioplankton community structure under elevated CO<sub>2</sub> in a eutrophic coastal mesocosm experiment

“…Higher abundance of Flavobacteria under elevated CO 2 means more HMW DOM could be degraded and so enter into the carbon cycle (Buchan et al, 2014). Based on the results reported here, it can be speculated that increased amounts of Flavobacteria under the elevated CO 2 treatment in eutrophic seawater could promote the TBDT system to break down HMW DOM and lead to improved efficiency of the microbial carbon pump (MCP), and possibly further influence carbon storage in the ocean (Jiao et al, 2010). It has also been postulated that the Flavobacteriaoriginated, light-driven proton pump proteorhodopsin could be involved in dealing with ocean acidification and pH perturbation (Fuhrman et al, 2008).…”

“…Despite a growing interest in the importance of the roles of marine bacterioplankton in ocean ecosystems and biogeochemical cycles, our current understanding of their responses to ocean acidification is still limited. Over half of autotrophically fixed oceanic CO 2 is processed by heterotrophic bacteria and archaea through the microbial loop and carbon pump (Azam, 1998;Jiao et al, 2010). Furthermore, marine bacterioplankton play an essential role in marine ecosystems and global biogeochemical cycles central to the biological chemistry of Earth (Falkowski et al, 2008).…”

Warming and nitrogen deposition lessen microbial residue contribution to soil carbon pool

“…The soil stable C pool has a critical role as a C sink within the global C cycle, and even a small change in this pool could have large consequences for atmospheric chemistry when other pools do not change to compensate. The sensitivity of microbial residues to warming and N deposition observed in this study therefore may have implications for our predictions of global change impact on soil C. The 'microbial carbon pump', a recently proposed conceptual framework, has been highlighted for understanding the role of microbes in production of recalcitrant organic C and C storage in the ocean 18,28,29 . We propose that a similar 'pump' operates in the soil 7,18 .…”

Bacterioplankton niche partitioning in the use of phytoplankton-derived dissolved organic carbon: quantity is more important than quality

“…Marine heterotrophic bacteria are the major regulators of this DOC pool, incorporating it into biomass (bacterial secondary production), respiring it into inorganic carbon or degrading the labile fractions of this DOC into more refractory compounds (Jiao et al, 2010). Despite their importance in the global carbon cycle, DOC-microbe interactions, in particular bacterioplankton specialization in DOC utilization, are not yet fully understood (Azam and Malfatti, 2007;Kujawinski, 2011).…”