Royal Netherlands Institute for Sea Research
Phone number
+31 (0)222 36 9463
Research Leader
  • Biogeochemistry
  • Organic Geochemistry
  • Geomicrobiology
  • Marine isotope ecology & microbial food web structures
  • Degradation of 'unconventional' carbon substrates

Prof. Dr. Helge Niemann

Research Leader

‘The role of bacteria in breaking down methane … and plastic’

Biogeochemist Prof. Helge Niemann studies the role of bacteria and other microorganisms in the breakdown of both methane and plastic. The present era of massive anthropogenic environmental change puts the ocean under pressure. Marine systems play a key role in the cycling of potent greenhouse gases such as methane, thereby keeping the Earth’s climate at its current habitual conditions. On the other hand, the ocean is swamped with pollutants such plastics. At a first glimpse, Methane and plastics don’t seem to have a lot in common. However, when examining their molecular structures it becomes obvious that they share some important chemical characteristics. Methane is the simplest hydrocarbon, while plastics are very complex hydrocarbons or hydrocarbon-like compounds. Key concepts related to the degradation of methane might thus apply for plastics, as well.

Methane as a source of energy or a source of problems

‘In deep waters, microorganisms manage to capture and decompose much of the methane. In shallow seas, such as the Wadden Sea, that scarcely happens. I am trying to discover under which specific circumstances bacteria can decompose methane and how much is still contained in the seafloor. On the one hand, countries like Japan and India are already investigating possibilities to extract methane from the ocean floor as a source of energy. On the other hand, that methane in the ocean floor is also a potential problem, because increasing amounts of it will be released due to global warming. That could further accelerate the warming of our climate.’

Do microbes eat plastic?

‘Microbes may also play a major role in the balance of plastic in the oceans. Of the estimated 320 million tonnes of plastics that might have ended up in the oceans since the 1950s, only ~1% is found afloat at the surface. Where is the remainder? In our experimental research, we are feeding bacteria and other microorganisms with plastic particles under differing climatological conditions to discover whether those organisms feed on plastics and could thus play a role in plastic degradation in the ocean. Also, we examine the role of physical and chemical processes on the decomposition of plastic. To fully understand the  problems of ocean plastic pollution, we need to have a better knowledge about the fate of plastic in the marine realm.’

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I am intrigued by the transformation of important but ‘unconventional’ carbon substrates such as methane, oil and plastics and their fate in aquatic (microbial) food web structures. With the aid of a multidisciplinary approach, my research particularly focuses on the geomicrobiology (including organic biogeochemistry) and spatiotemporal aspects of aquatic carbon cycling and the turnover of unconventional carbon substrates in sediments and the water column. In addition, I am also interested in lipid biomarkers as chemotaxonomic markers, and proxy indicators recording (paleo) environmental conditions.

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Linked blogs

Tuesday 28 November 2023
NIOZ@SEA | Cruise PE-527 Nanoplastic in the North Atlantic
Ocean plastic debris has been recognised as a severe environmental problem in the ocean but we are only beginning to understand the role of particles
Monday 23 October 2023
Methane emission in the North Sea II
Methane escapes from the seabed of the North Sea in various places. Recent German research suggested that this mainly occurs in the vicinity of abandoned wells. Methane is a potent greenhouse gas and its release into the sea and subsequent release…
Wednesday 11 November 2020
NIOZ@SEA | Cruise 64PE480: In search of Atlantic Nanoplastic
The overall goal of the cruise is to determine the total amount of plastic (macro, micro and nano) along a transect from the Azores through the N-Atlantic subtropical gyre and then towards the European shelf, English Channel and S-North Sea. The…
Monday 07 October 2019
NIOZ@SEA | North Sea Expedition PE462
In 2019 three Pelagia cruises are organised to study the carrying capacity of the North Sea. Each cruise will last 2 to 3 weeks and follows different routes to cover and describe the various parts of the ecosystem of the North Sea. Follow the blog of…
Friday 20 July 2018
Hidden secrets in the North Sea: An expedition addressing sea-level rise, oxygen loss and microbial breakdown of methane
The North Sea still hides many secrets. A joint team of researchers from the Royal NIOZ Sea Research, TNO, Deltares, Utrecht University and VU University Amsterdam set out on an expedition with the research vessel Pelagia to answer some questions…

NIOZ publications

Linked projects

NSME_North Sea Methane Emissions
Gert-Jan Reichart
Project duration
1 Jan 2022 - 31 Dec 2025
UUNIOZ_Nanoplastics pollution in the Ocean
Helge Niemann
Utrecht University
Project duration
1 Jan 2021 - 31 Dec 2025
Plastic in the Ocean: Microbial Transformation of an ‘Unconventional’ Carbon Substrate
Helge Niemann
European Community || European Research Council
Project duration
1 Jun 2018 - 31 May 2023