Anaerobic quaternary amine degradation: from single bacterium to salt marsh ecosystem.

Lead Research Organisation: University of Warwick
Department Name: School of Life Sciences

Abstract

Quaternary amines (QAs) such as glycine betaine (GBT) are ubiquitous in marine organisms. GBT is used by marine organisms as a compatible solute in response to changes in environmental conditions, such as increasing salinity, because GBT does not interfere with cell metabolism. QA compounds are frequently released into the ocean ecosystems due to environmental changes, such as viral attack and grazing. The degradation of these compounds, especially in intertidal coastal areas, contributes significantly to the production of climate-active trace gases. These include the potent greenhouse gas methane and volatile methylated amines, which are thought to be involved in cloud formation in the marine environment.

Coastal sediments are estimated to contribute approximately 75% of the global oceanic methane emissions (8-13 Tg per year) and much of this is likely to be derived from the degradation of QAs. Although we know that microorganisms are mainly responsible for the degradation of GBT to methane and volatile methylamines, we know little about the genes and enzymes involved in the degradation pathway. Furthermore, the identity of those microorganisms responsible for the transformation has not yet been determined. Our current knowledge of these two aspects remains speculative, at least partially due to the lack of definitive research.

This timely proposal aims to fill in this major gap in our knowledge of marine carbon cycle.

Using cultivated model microorganisms, we aim to define the key genes and the encoding enzymes in the anaerobic degradation of GBT.

Using molecular ecology techniques and the resultant data from the study of the model microorganisms, we aim to further determine the key microbial players involved in the anaerobic production of methane and methylamines from GBT in the marine environment.

The work will generate novel knowledge about our understanding of microbial GBT transformations and will therefore fill in a serious gap in our knowledge of the marine carbon cycle.

Planned Impact

This project addresses fundamental questions relating to the marine carbon cycle and greenhouse emissions from the natural environments, both of which are crucial for our understanding of global biogeochemical cycles and in the drive for a more sustainable future. The work is therefore of the utmost relevance to NERC's strategic aims, particularly the Biodiversity Science and Climate Change themes. The proposed research will have considerable impact on the following communities, the Environmental Agency, policy-makers and the wider public.

The Environmental Agency has launched schemes and activities in the last five years to protect the salt marsh ecosystems and also to create around 500 hectares of salt marsh along the Essex and Suffolk coastlines. However, whether these activities will affect local emissions of climate-active trace gases is uncertain. Our research can contribute to the decision making by the Environmental Agency and inform environmental policy making decisions.
The other beneficiaries of knowledge arising from this research will be policy-makers. They will be alerted to the positive and negative impacts of salt marsh ecosystems, which contribute not only to global warming (by releasing methane, a powerful greenhouse gas) but also potentially to global cooling (by releasing volatile small amines which are involved in aerosol formation).

Since our research has immediate relevance to climate and marine biology, it will be of interest to the wider public. People are always interested in scientific topics related to climate and marine life, and these two aspects of this type of research will always receive considerable attention in the media.

A variety of methods will be used to engage with the end-users, including workshops, a detailed website, publications in popular magazines such as Planet Earth, and visits and exhibitions at local schools. One of the things that we are keen to do is to have end user opinion at very early stages of our research. We consider that engagement of end users from the very early stages of the project will also benefit our research and help to formulate proper sampling activities during the research programme. For example, a workshop engaging the Environmental Agency will be set up in month 1 so that any concerns and questions from the Environmental Agency can then be defined and taken into account later on. On the website that we will set up from Month 1, we will have an online feedback form so that any queries from the wider public can be monitored and answered promptly.

Publications

10 25 50

publication icon
Mausz MA (2019) Microbiology and Ecology of Methylated Amine Metabolism in Marine Ecosystems. in Current issues in molecular biology

publication icon
Zhu Y (2014) Carnitine metabolism to trimethylamine by an unusual Rieske-type oxygenase from human microbiota. in Proceedings of the National Academy of Sciences of the United States of America

 
Description Quaternary amines (QAs) such as glycine betaine (GBT) and choline are ubiquitous in marine organisms. GBT is used by marine organisms as a compatible solute in response to changes in environmental conditions. Choline is a major precursor for GBT biosynthesis. QA compounds are frequently released into the ocean ecosystems and the degradation of these compounds, especially in intertidal coastal areas, contributes significantly to the production of the potent greenhouse gas methane and other climate active gases such as volatile methylated amines.



During the first year, we started to address the first aim of the project, which is to define the key enzymes, encoding genes and the microbes involved in anaerobic QA metabolism. We have particularly focused on GBT reductase and choline degradation enzymes, which will be used as "functional gene markers" in order to study the ecology of such microbes in the degradation of QAs to the key methylated amine intermediates for methanogenesis. We have designed PCR primers targeting these enzymes and we are currently validating these primers before we can apply them in environmental samples.
Exploitation Route The main beneficiary of the knowledge generated from this study is anticipated to be the Environment Agency. The coastal salt marsh ecosystem of the UK is of particular interest for tourism as well as for the protection of wildlife such as birds. The ecosystems are under threat due to human activities, such as land reclamation and oil pollution. The Environmental Agency has launched schemes and activities in the last five years to protect this ecosystem and also to create around 500 hectares of salt marsh along the Essex and Suffolk coastlines (http://www.environment-agency.gov.uk/homeandleisure/wildlife/31384.aspx). The data generated from this study will be of significant interest to the Environment Agency since salt marsh ecosystems are contributing to climate change by releasing climate-active gases, such as methane and volatile methylamines, through the degradation of quaternary amines.



The other beneficiaries of knowledge arising from this research will be policy-makers within international and national governments, who need to consider the positive and negative impacts of salt marsh ecosystems, contributing not only to global warming (by releasing methane, a powerful greenhouse gas) but also potentially to global cooling (by releasing volatile small amines which are involved in aerosol formation).
Sectors Environment

URL http://www2.warwick.ac.uk/fac/sci/lifesci/research/ychen/current_projects/
 
Description Our scientific findings have been disseminated through publication in various journals and presentations in meetings, many of which are also highlighted in social medials, such as Twitter, Facebook. Researchgate.
First Year Of Impact 2014
Sector Environment,Other
Impact Types Societal

 
Description Challenger meeting talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The talk and presentation stimulated discussion of marine microbes and their impact of marine aerosols and subsequent consequence on climate change.

Since the talk, we have hosted several school pupils's visit who are interested in marine microbes and marine environment.
Year(s) Of Engagement Activity 2014
 
Description Presentation and discussion with A level students 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact I was invited to give a talk to a large audience of A level students who are interested in biology, math, physitics and chemistry. Specifically I presented our latest research on methylamine cycles in the marine and human gut ecosystem. This was followed by informal discussions with students and their teachers.
Year(s) Of Engagement Activity 2015