Mara Heinrichs



PhD candidate

Mara Elena Heinrichs

Institut für Biologie und Umweltwissenschaften (IBU)

Mara Heinrichs

Project outline

The overarching objective of my PhD is the question how viruses affect prokaryotic community structures and the dissolved organic matter (DOM) composition in deep-sea sediments. To investigate this on a bulk level, prophages were induced in natural microbial communities stemming from deep-sea sediments of the Pacific Ocean. Changes in the bacterial community composition were analyzed via next generation sequencing and the molecular composition and turnover of DOM released by viral lysis (vDOM) was characterized using ultra-high resolution mass spectrometry. A finer scaled experiment tested if there is a shuttle of organic matter from autotrophs to heterotrophs via the viral shunt in deeper sediment layers. Therefore, prophages were induced from an autotrophic organism isolated from the deep-biosphere (Fichtel et al. 2012). The lysate was fed to a heterotrophic strain isolated from the same sediment horizon. Analyzing the composition and fate of vDOM in the course of the experiment helped to estimate the contribution of viral lysis to the sustainment of microbial growth in this severely nutrient and energy deprived habitat. Working at the intersection of two scientific disciplines, method development combining the needs and demands of both fields were an inevitable part of my thesis. The adaptation of an improved method to enumerate deep-sea viruses (Pan et al. 2019) for the application of flow cytometry was established during a research stay at JAMSTEC in Yokosuka, Japan. Another experiment aimed to identify a signal stemming from viruses in the vDOM of laboratory cultures and natural microbial communities from the North Sea.


My PhD project is embedded in the PhD Research Training Group „The Ecology of Molecules" (EcoMol).

Academic vita

Since 2017

PhD candidate in the EcoMol Research Training Group (ICBM Oldenburg)


The impact of viruses on the composition of microbial communities and organic molecules in marine sediments



Master of Science in Marine Environmental Sciences (ICBM Oldenburg)


Degradation of algal-derived dissolved organic matter by microorganisms from three different biogeographic provinces of the Pacific Ocean: a mesocosm study


Bachelor of Science in Environmental Sciences (ICBM Oldenburg)


Effects of co-metabolism on microbial degradation of natural deep sea dissolved organic matter

Research interests

Role of viruses on biogeochemical cycles and microbial communities, molecule – microbe interactions, in general linking microbiology and geochemistry, biological production and potential removal mechanisms of recalcitrant dissolved organic matter, transfer of findings that were gained in laboratory experiments to natural systems / the marine environment, method development


Quantification of aquatic and benthic viruses (flow cytometry, microscopy), virus induction via mitomycin C, analysis of microbial diversity (DNA and RNA extraction, PCR, amplicon and genome sequence analysis), metagenomic analyses of viruses, cultivation of anaerobe marine bacteria, mass spectrometric analysis of DOM (FT-ICR-MS), solid-phase extraction, HPLC, DOC analysis, multivariate statistics


Heinrichs ME, De Corte D, Engelen B, Pan D. (2021). An Advanced Protocol for the Quantification of Marine Sediment Viruses via Flow Cytometry. Viruses 13(1):102;

Heinrichs ME, Tebbe DA, Wemheuer B, Niggemann J, Engelen B (2020) Impact of viral lysis on the composition of bacterial communities and dissolved organic matter in deep-sea sediments. Viruses 12, 922;

Heinrichs M, Dlugosch L, Mori C (2019) Complex Interactions Between Aquatic Organisms and Their Chemical Environment Elucidated from Different Perspectives. In: Jungblut S, Liebich V, Bode-Dalby M (Eds.), Youmares 9 - The Oceans: Our research, our future. Proceedings of the 2018 conference for YOUng MArine RESearcher in Oldenburg, Germany, Springer International Publishing, p. 279-297,

Pansch C, Hattich GSI, Heinrichs ME, Pansch A, Zagrodzka Z, Havenhand J, Long-term exposure to acidification disrupts reproduction in a marine invertebrate, PLOS One 13, 2, e0192036, February, 2018.

Contributions to conferences

Heinrichs ME, Tebbe DA, Wemheuer B, Niggemann J, Engelen B, 2019. The impact of viruses on prokaryotic community structures and dissolved organic matter compositions in deep-sea sediments. Talk, Marine Microbiota, Oldenburg.

Heinrichs ME, Mori C, 2018. Crossing traditional scientific borders to unravel the complex interactions between organisms and their non-living environment. Session chair, Youmares 9 conference, Oldenburg

Heinrichs ME, Tebbe DA, Niggemann J, Engelen B, 2018. Impact of viruses on microbial community structures and organic matter composition in deep-sea sediments. Poster, International Symposium on Microbial Ecology (ISME), Leipzig

Heinrichs ME, Tebbe DA, Engelen B, 2018. Impact of the viral shunt on microbial community structures in deep-sea sediments. Poster, Association for General and Applied Microbiology  (VAAM), Wolfsburg

Heinrichs ME, Hattich GSI, Havenhand JN, Pansch C, 2015. Long-term acclimation of a sensitive barnacle population to ocean acidification. Poster, European Marine Biology Symposium (EMBS) conference, Helgoland

Heinrichs ME, Seidensticker S, Seibt M, Niggemann J, Giebel HA, Simon M, Dittmar T, 2013. Microbial degradation of natural refractory dissolved organic matter. Poster, Youmares 4 conference, Oldenburg

Research cruises

2017 RV Sonne Expedition SO254 Functional diversity of bacterial communities and the metabolome in the water column, sediment and in sponges in the southwest Pacific around New Zealand (PoriBacNewZ)

2016 RV Sonne Expedition SO248 Functional diversity of bacterial communities and the geometabolome in the central and north Pacific (BacGeoPac)

2013 RV Heincke cruise to German Bight

(Stand: 13.10.2021)