Monterey Bay Aquarium Research Institute

Xavier Mayali

Lawrence Livermore National Laboratory

Linking marine microbial identity and biogeochemistry
using mass spectrometric analysis of microarrays.

Wednesday — May 4, 2011
Pacific Forum — 3:00 p.m.

Most microorganisms in natural environments remain uncultivated, and their ecological roles typically must be inferred from diversity and genomic studies rather than directly measured. To examine the functional roles of uncultivated microbes, LLNL scientists have developed ³chip-SIP², a means to measure the incorporation of 13C- and 15N-labeled substrates into 16S rRNA.

Community rRNA is hybridized to phylogenetic microarrays (chips) and isotope incorporation is quantified by secondary ion mass spectrometer imaging (NanoSIMS). Chip-SIP analysis of an estuarine community quantified the relative incorporation of C or N from amino acids, nucleic acids or fatty acids by 81 individual taxa. The results reveal the complex structure of microbial food webs and demonstrate that bacterial functional capacity is frequently decoupled from phylogeny. This approach provides a powerful means to directly test genomics-generated hypotheses about biogeochemical function in natural environments.


Next: David Packard Distinguished Lecturer Carl Wunsch