Research: I have been the leader of several research projects, including top level projects, e.g. a recent Frimedbio-project, EnDreg, and the Nitrous Oxide Research Alliance (NORA; https://nora.nmbu.no/), a Marie Sklodowska Curie Initial Training Network. I have led the group Microbial Ecology and Physiology at KBM for 15 years, and in 2005 I founded the NMBU Nitrogen Group together with colleagues. The group has evolved into a robust and productive research team (https://www.nmbu.no/en/research/groups/nitrogen), and I have been one of three leaders, with special responsibility for the molecular work. I’m a microbial ecologist by training, pioneering the investigations or soil microbial communities by phospholipid analyses in my early career, moved on to DNA based techniques, and my current focus is microbial N-transformations in general, and the ecophysiology and regulatory biology of denitrification in particular. Another research interest (several projects) concerns rhizobia (symbiotic, nitrogen fixing bacteria); their biodiversity, N2-fixation efficacy and, especially, their capacity to reduce N2O. I have a solid international research reputation, and recently served as elected member of the International Board of ISME (Int Society for Microbial Ecology).

Institutional responsibilities: Elected member of the Departmental Board 2011-2017; re-elected for the Faculty Board from 2017-present at Fac of Chemistry, Biotechnology and Food Science, NMBU.

Publications: Link to Google Scholar

I have published ca 75 papers in peer-reviewed international journals. ISI core collection: h-index=33. My papers have 8986 citations, self-citations excluded; average citations per item=125. Nineteen of my papers have been cited >100 times each. Google Scholar: 14796 citations, 5522 since 2016; h-index 43, i10-index 74.

Publications, last 10 years:

Jonassen KJ, Hagen LH, Vick SHV, Arntzen MØ, Eijsink VGH, Frostegård Å, Lycus P, Molstad L, Pope PB, Bakken LR. Bacteria in biogas digestates for reduced climate forcing. BioRxiv 10.1101/2020.11.16.384990 (2020). The ISME Journal. In Press.

Frostegård Å, Vick SHV, Lim NYN, Bakken LR, Shapleigh JP. 2021. Linking meta-omics to the kinetics of denitrification intermediates reveals pH-dependent causes of N2O emissions and nitrite accumulation in soil. The ISME Journal. In Press. DOI: 10.1038/s41396-021-01045-2

Ruiz B, Frostegård Å, Bruand C, Meilhoc E. 2021. Rhizobia: Highways to NO. Biochemical Society Transactions 26;49(1):495-505. doi: 10.1042/BST20200989.

Gao Y, Mania D, Mousavi SA, Lycus P, Arntzen M, Woliy K, Lindström K, Shapleigh JP, Bakken LR, Frostegård Å. 2021. Competition for electrons favors N2O reduction in denitrifying Bradyrhizobium isolates. Environmental Microbiology 23:2244-2259. Doi: 10.1111/1462-2920.15404.

Nadeem S, Bakken LR, Frostegård Å, Gaby JC, DörscNadeem S, Bakken LR, Frostegård Å, Gaby JC and Dörsch P. 2020. Contingent Effects of Liming on N2O-Emissions Driven by Autotrophic Nitrification. Front. Environ. Sci. 8:598513. doi: 10.3389/fenvs.2020.598513h 

Bakken LR, Frostegård Å. 2020. Emerging options for mitigating N2O emissions from food production by manipulating the soil microbiota. Current Opinion in Environmental Sustainability 47:89-94. https://doi.org/10.1016/j.cosust.2020.08.010. 

Keuschnig C, Gorfer M, Li G, Mania D, Frostegård Å, Bakken LR, Larose C. 2020. NO and N2O transformations of diverse fungi in hypoxia: evidence for anaerobic respiration only in Fusarium strains. Environm Microbiol. 22:2182-2195. https://doi.org/10.1111/1462-2920.14980.

Mania D, Woliy K, Degefu T, Frostegård Å. 2020. A common mechanism for efficient N2O reduction in diverse isolates of nodule‐forming bradyrhizobia. Environm. Microbiol. 22:17-31. doi.org/10.1111/1462-2920.14731 

Woliy, K, Degefu T, Frostegård Å. 2019. Host range and symbiotic effectiveness of N2O reducing Bradyrhizobium strains. Front. Microbiol. doi: 10.3389/fmicb.2019.02746.

Liu B, Zhang X, Bakken LR, Snipen L, Frostegård Å. 2019. Rapid succession of actively transcribing denitrifier populations in agricultural soil during an anoxic spell.  Front. Microbiol. 9:3208. doi: 10.3389/fmicb.2018.03208. IF 4.08.

Conthe M, Lycus P, Arntzen MØ, Ramos da Silva A, Frostegård Å, Bakken LR, Kuenen JG, Kleerebezem R, van Loosdrecht MCM. 2019. Denitrification as an N2O sink. Water Research 151:381-387. doi.org/10.1016/j.watres.2018.11.087. 

Lycus P, Soriano-Laguna MJ, Kjos M, Richardson DJ, Gates AJ, Milligan DA, Frostegård Å, Bergaust L, Bakken LR. 2018. A bet-hedging strategy for denitrifying bacteria curtails their release of N2O. Proceedings of the National Academy of Sciences 115: 11820–11825. doi.org/10.1073/pnas.1805000115

Jacobsen CS, Nielsen TK…….. Frostegård Å…….., Bælum J. 2018. Inter-laboratory testing of the effect of DNA blocking reagent G2 on DNA extraction from low-biomass clay samples. Scient Reports 8; Article Number: 5711. 

Lim NYN, Frostegård Å, Bakken LR. 2018. Nitrite kinetics during anoxia: the role of abiotic reactions versus microbial reduction. Soil Biol Biochem. 119:203-209. doi.org/10.1016/j.soilbio.2018.01.006. 

Degefu T, Woliy, K, Wolde-meskel E, Frostegård Å. 2017. Phylogenetically diverse groups of Bradyrhizobium isolated from nodules of tree and annual legume species growing in Ethiopia. Systematic and Applied Microbiology 40:205-214. doi.org/10.1016/j.syapm.2017.04.001. 

Lycus P, Bøthun KL, Bergaust L, Shapleigh JP, Bakken LR, Frostegård Å. 2017. Phenotypic and genotypic richness of denitrifiers revealed by a novel isolation strategy. The ISME Journal 11:2219-2232. doi: 10.1038/ismej.2017.82.

Bakken LR, Frostegård Å. 2017. Sources and sinks for N2O, can microbiologist help to mitigate N2O emissions? Environmental Microbiology. 19:4801-4805. doi.org/10.1111/1462-2920.13978.

Hink L, Lycus P, Gubry-Rangin C, Frostegård Å, Nicol GW, Prosser JI, Bakken LR. 2017. Kinetics of NH3-oxidation, NO-turnover, N2O-production and electron flow during oxygen depletion in model bacterial and archaeal ammonia oxidisers. Environmental Microbiology 19:4882-4896. 

Zhu Y, Wu X, Chen G, Bakken LR, Zhao L, Frostegård Å, Zhang X. 2017. Carbon-driven enrichment of the crucial nitrate-reducing bacteria in limed peat soil microcosms. Letters in Applied Microbiology 65: 159-164. 

Wang Y, Tian H, Huang F, Long W, Zhang Q, Wang J, Zhu Y, Wu X, Chen G, Zhao L, Bakken LR, Frostegård Å, Zhang X. 2017. Time-resolved analysis of a denitrifying bacterial community revealed a core microbiome responsible for the anaerobic degradation of quinolone. Scientific Reports. Article number: 14778. DOI: 10.1038/s41598-017-15122-0. 

Lim NYN, Roco AC, Frostegård Å. 2016. Transparent DNA/RNA co-extraction workflow protocol suitable for inhibitor-rich environmental samples that focuses on complete DNA removal for transcriptomic analyses. Front. Microbiol. 7:1588. doi: 10.3389/fmicb.2016.01588. 

Mania D, Heylen K, van Spanning RJM, Frostegård Å. 2016. Regulation of nitrogen metabolism in the nitrate-ammonifying soil bacterium Bacillus vireti and evidence for its ability to grow using N2O as electron acceptor. Environ Microbiol 18: 2937-2950. DOI: 10.1111/1462-2920.13124. DOI: 10.1111/1462-2920.13128. 

Nesme J, Achouak W Agathos SN, Bailey M, Baldrian P, Brunel D, Frostegård Å……..Simonet P. 2015. Frontiers in Microbiology 7:73. DOI: 10.3389/fmicb.2016.00073. IF: 4.17.

Mania D Heylen K, van Spanning RJM, Frostegård Å. 2014. The nitrate-ammonifying and nosZ-carrying bacterium Bacillus vireti is a potent source and sink for nitric and nitrous oxide under high nitrate conditions. Environ Microbiol. 16:3196-3210. DOI: 10.1111/1462-2920.12478. IF: 5.93.

Luckmann M, Mania D, Kern M, Bakken LR, Frostegård Å, Simon J. 2014. Production and consumption of nitrous oxide in nitrate-ammonifying Wolinella succinogenes cells. Microbiology 160:1749-1759. DOI 10.1099/mic.0.079293-0.

Liu B, Frostegård Å, Bakken L. R. 2014. Impaired reduction of N2O to N2 in acid soils is due to a posttranscriptional interference with the expression of nosZ. 2014. mBio vol. 5 no. 3 e01383-14. Doi:10.1128/mBio.01383-14.

Liu B, Mao Y, Bergaust L, Bakken LR, Frostegård Å. 2013. Strains in the genus Thauera exhibit remarkably different denitrification regulatory phenotypes. Environ. Microbiol. 15:2816-2828. DOI: 10.1111/1462-2920.12142. IF 5.93.

Liu B, Frostegård Å, Shapleigh JP. 2013. Draft genome sequences of five strains in the genus Thauera. Genome Announc. January/February 2013:1. doi:10.1128/genomeA.00052-12A.

Degefu T, Wolde-meskel E, Frostegård Å. 2013. Phylogenetic diversity of Rhizobium strains nodulating diverse legume species growing in Ethiopia. Systematic and Applied Microbiology. 36:272– 280. IF: 3.48.

Degefu T, Wolde-meskel E, Liu B, Cleenwerck I.,Willems A, Frostegård Å. 2013. Mesorhizobium shone sp. nov., Mesorhizobium hawassa sp. nov. and Mesorhizobium abyssinicum sp. nov. isolated from root nodules of different agroforestry legume trees growing in southern Ethiopia. Int. J. Syst. Evol. Microbiol. 63: 1746–1753. IF: 2.44.

Degefu T, Wolde-meskel E, Frostegård Å. 2012. Phylogenetic multilocus sequence analysis identifies seven Ensifer genospecies isolated from less well-explored biogeographical regions in East Africa. Int. J. Syst. Evol.  Microbiol. 62: -2295. IF: 2.44.

Bakken LR, Bergaust L, Liu B, Frostegård Å. 2012. Regulation of denitrification at the cellular level – a clue to understanding of N2O emissions from soils. Phil. Trans. Royal Soc. B. 367: 1226-1234. IF: 5.85.

Bergaust L, van Spanning RJM, Frostegård Å, Bakken LR. 2012. Expression of nitrous oxide reductase in Paracoccus denitrificans is regulated by oxygen and nitric oxide through FnrP and NNR. Microbiol. 158: 826-834.

Frostegård Å, Tunlid A, Bååth E. 2011. Use and misuse of PLFA measurements in soils. Soil Biol. Biochem. 43: 1621-1625. Invited paper for the ”Citation classic” series of highly cited papers. IF: 5.04.

Bergaust L, Bakken LR, Frostegård Å. 2011. Denitrification regulatory phenotype, a new term for the characterization of denitrifying bacteria. Biochemical Society Transactions 39:207-212. IF: 3.19.

Degefu T, Wolde-meskel E, Frostegård Å. 2011. Multilocus sequence analyses reveal several unnamed Mesorhizobium genospecies nodulating Acacia species and Sesbania sesban trees in Southern regions of Ethiopia. Syst. Appl. Microbiol. 34:216-226. IF: 3.28.

Research career:

I took my PhD in 1995 at Lund University, Sweden, followed by a post doc period at Lyon University-1 after which I got my first own research project and returned to Lund University. During my early research career I investigated how environmental factors affected the soil microbial community structure, and developed the phospholipid fatty acid (PLFA) analysis to determine microbial biomass and shifts in microbial community composition (supervisor Erland Bååth). The work is summarized in an invited “Citation classic” paper in Soil Biology and Biochemistry (Frostegård et al. (2011) 43:1621-1625), nicely introduced by Burns RG (2011) Soil Biology Biochemistry Citation Classic 10, SBB 43:1619-1620. I also developed an interest in mechanisms of horizontal gene transfer, which I worked with during my post doc period at University of Lyon-1 (with Pascal Simonet) where I also improved methods for extraction of nucleic acids from soil. In 1999 I obtained a permanent position at Norwegian University of Life Sciences and became full professor in 2001. During the past 10-15 years my research has gradually turned toward various aspects of the nitrogen cycle, with special interest in the regulatory biology of anoxic respiration in bacteria (denitrification, DNRA). I also published several studies on the diversity and phylogeny of rhizobia.

Together with Prof. Lars Bakken and Dr. Peter Dörsch, I founded the NMBU Nitrogen Group (http://www.nmbu.no/en/research/groups/nitrogen) which now comprises about 25 co-workers. Our main focus is on the regulatory biology of denitrification. Studies include genome analyses and phenotypic characterisations of the eco-physiology of selected microbes, representing different groups of denitrifiers and other nitrate reducing organisms; analyses of gas kinetics of denitrifier communities in response to oxygen depletion and other environmental controllers; and the abundance and diversity of denitrification genes and transcripts in soil. Our group has strong links to research groups at NIBIO (Norway) and have established collaboration with a number of renowned research groups in Europe, USA, China and New Zealand. Recent and ongoing research projects include several financed by the Research Council of Norway. I also coordinated a Marie Curie Initial Training Network, NORA (Nitrous Oxide Research Alliance; https://nora.nmbu.no/), financed by EU within the Excellence pillar. NORA, which ended 1 January 2017, included nine academic and five industry partners from six European countries. Recognition by the international research community was also shown when I in 2013-2018 served as elected member of the International Directory Board of ISME; International Society for Microbial Ecology (http://www.isme-microbes.org/). A recent (2017) Eurovision documentary about our research: http://www.euronews.com/2017/01/30/no-laughing-matter-nitrous-oxide-another-climate-enemy

 Teaching:

I am responsible for the courses BIO330 (Microbial Physiology and ecology), 10 ECT, master level (https://www.nmbu.no/course/BIO330) and BIO332 (Experimental molecular microbiology), 10 ECT, master level (https://www.nmbu.no/course/bio332).