The very low rates of activity typically observed for subseafloor microbes make it hard to differentiate slow-growing from inactive cells. During his C-DEBI postdoctoral fellowship Roland Hatzenpichler developed novel approaches to detect biosynthetic activity in uncultured cells directly in their habitat. Based on the incorporation of synthetic amino acids into new proteins and their subsequent detection via fluorescence staining (BONCAT, bioorthogonal non-canonical amino acid tagging), protein synthesis active cells are visualized via epifluorescence microscopy. In combination with fluorescence-activated cell-sorting, they can then be separated from complex samples.
After adapting BONCAT for environmental applications, Roland used BONCAT to track the in situ translational activity of syntrophic archaeal-bacterial consortia catalyzing the anaerobic oxidation of methane in deep-sea sediments (Hatzenpichler et al., PNAS 2016). By combining sorting of active consortia, whole genome amplification, and 16S rRNA gene sequencing, the identities of hundreds of individual, biosynthetically active cellular partnerships could be resolved. This approach revealed that representatives of all major methane-oxidizing archaeal clades were active under controlled incubation conditions. Unexpectedly, some consortia were anabolically active even in the absence of methane, suggesting energy sources beyond methane. It also led to the discovery of a previously unrecognized interaction of methane-oxidizing archaea with members of the environmentally highly abundant, yet poorly understood phylum Verrucomicrobia.
Since November 1st 2016, Roland is an Assistant Professor in the Department of Chemistry and Biochemistry at Montana State University, Bozeman. His group focuses on the ecophysiology and in situ activity of uncultured archaea in a variety of sediment environments. www.environmental-microbiology.com