Using metabolomic methods in the Victorian Dairy industry to understand the importance of organic nitrogen: from factory to farm

Michael W. Heaven1, Sharon R. Aarons1, Lori Phillips2, Brunda Nijagal3, Komal Kanojia3, T. Vincent Verheyen4, Alicia J. Reynolds4, Murray Hannah1, David Nash1, Pauline Mele2, Dedreia Tull3, Amsha Nahid2

1Department of Economic Development, Jobs, Transport and Resources (DEDJTR), Ellinbank, Victoria, Australia.
2DEDJTR, AgriBio, La Trobe University, Bundoora, Victoria, Australia.
3Metabolomics Australia, Bio21 Institute, The University of Melbourne, Parkville, Victoria, Australia.
4School of Applied and Biomedical Sciences, Federation University Gippsland Campus, Churchill, Victoria, Australia.


Metabolomic techniques were used to identify metabolites that are produced and used in the dairy industry. Organic nitrogen (OrgN) compounds were identified in dairy factory wastewater streams. OrgN metabolites were predominantly found in the effluent stream and successfully segregated within the factory from recycled water streams used for irrigation and replenishment of a nearby waterway. Tolytriazoles were identified in the effluent waste water. Due to their recalcitrant nature, they have the potential to act as a marker of downstream pollution. A time based study of the dairy factory bioreactor waste waters identified another potential marker of factory productivity. The OrgN metabolite, 4-nitrophenol was found to be correlated with increasing anaerobicity of the bioreactor. The methodologies optimised from this research were used to identify OrgN metabolites in soil samples from farms in the main dairy regions of Victoria. Amino acids were the largest component of all metabolites identified. Several metabolites (e.g. cytidine) were found to be significantly changes in concentration in response to increasing potassium fertiliser application rates. These metabolites may be related to microbial or plant biochemical metabolic pathways. Microbial community analyses showed similar trends in regards to microbes (archaea, bacteria) associated with N metabolite production.