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Bridging microbial diversity and chemodiversity of dissolved organic matter to better constrain processes in biogeochemical cycles
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Effect of viral lysis of microorganisms on the organic matter continuum and microbial activity in the ocean
Tuesday 8th @ 1030-1050, Concert Hall
Markus G. Weinbauer* , LOV, Villefranche-sur-mer, France
Presenter Email: wein@obs-vlfr.fr |
| Viral lysis is now considered as one of the main factors causing mortality of microorganisms (bacteria, archaea, protists and phytoplankton) in the ocean. During viral lysis, the cell content is set free and cell wall fragments are produced resulting in a change of dissolved organic matter (DOM) composition (e.g. amino acids and carbohydrates) as well as colloid concentrations. Lysis products are largely (and highly) bioreactive, i.e. they are readily used by bacteria. Typically, this results in a higher bacterial carbon demand and lower growth efficiency thus, increasing the conversion of DOM into CO2 (respiration). Conversion of cells into DOM and rapid respiration of this material should result in more efficient use of DOM in the surface ocean. However, lysis products can also increase the formation of organic aggregates (marine snow), probably because they are sticky, and hence shift the organic matter continuum from DOM to organic aggregates. This should prime the biological pump. Recent research showed that the chemical composition of lysis products differs between bacterial isolates and that this can have differential effects on bacterial diversity and activity. Therefore, microbial diversity is not only influenced by specific infection and lysis (mortality) but also by changes in the organic matter continuum. This processes could also result in shifts of readily utilizable and recalcitrant/refractory DOM and hence influence the microbial carbon pump. For a better understanding of the interactions between DOM and microorganisms, initiatives are required to better constrain the effect of viral lysis on DOM composition and microbial activity and diversity. |
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