Arntzen's research is focused on microbial communities residing in various habitats including soil, freshwater sediments, field denitrification beds and biogas reactors. His main aim is to understand which microbes are present and characterize their individual genomes and metabolic roles within the habitat. His key interest is on lignocellulose degrading microbial communities thriving under denitrifying conditions.

Arntzens has a diverse background working with microbiology, apoptosis, cealic disease, and more, and with a 15-year expertise in analytical techniques such as chromatography, proteomics, and computational analysis.

His key publications to date spans over a broad field reporting on the secretomes of polysaccharide degrading bacteria and on characterizing novel, uncultured microbes and communities using integrated meta-omics (metagenomics, metatranscriptomics and metaproteomics + bioinformatics), as well as methods development in chromatography, sugar analysis, and proteomics software.

Arntzen is strongly involved in and has helped establish both National and International societies, including the National network of Advanced Proteomics Infratructure, the Metaproteomics Initiative, and is a member of the General Council of the European Proteomics Association.

Main research interests:

• Microbial communities
• Integrated meta-omics (metagenomics, metatranscriptomics  and metaproteomics)
• Secretomics
• Enzyme characterization
• Biomass degradation
• Denitrification
• Bioinformatics and software development 

Arntzen is involved in the following groups at NMBU:

• https://www.nmbu.no/en/faculty/kbm/research/groups/pep
• https://www.nmbu.no/en/research/groups/memo