Meristem Microbes: Imaging Bull Kelp (Nereocystis luetkeana) Blade Tissues for Microbiome Visualization

Abstract

Canopy-forming kelps have broad ecological influence through their physical structure and biological activity, playing a foundational role in habitat creation and primary productivity. On a microscopic scale, the blades of kelps like Nereocystis luetkeana support dynamic microbial ecosystems. Molecular techniques have revealed the taxonomic structure of these microbiomes, yet microscopy remains underutilized for visualizing biofilm morphology and spatial arrangement. I attempted to image microbial colonization of N. luetkeana blades across varying tissue age, using a triple-stain fluorescent imaging protocol to target cell walls and nucleic acids. Microbiota were not successfully imaged, likely due to loss of biofilm during wash protocol. Imaging did reveal clear cell walls of N. luetkeana, along with unexpected nucleic structures. In the meristem and mid-blade regions, tissue cells consistently showed four discrete nucleic acid signals, despite N. luetkeana being a known uninucleate species. Our results highlight methodological limitations of biofilm microscopy and raise new questions about nuclear dynamics and cell division beyond the meristem in N. luetkeana.