Bacterial capture and lysis on diatom spines reveal a suspension-feeding strategy
Phytoplankton contribute nearly half of global primary production and play a central role in ocean biogeochemistry. Although traditionally viewed as phototrophs, a growing body of evidence indicates that many phytoplankton are mixotrophic, supplementing photosynthesis with heterotrophic acquisition of nutrients and organic matter. Yet, the mechanisms enabling heterotrophic feeding in diatoms…
Phytoplankton constitute nearly half of global primary production, playing a pivotal role in ocean biogeochemistry. Traditionally considered phototrophs, recent evidence suggests many phytoplankton engage in mixotrophy, incorporating heterotrophic nutrient and organic matter acquisition alongside photosynthesis. However, the mechanisms underlying heterotrophic feeding in diatoms remain underexplored.
In this study, researchers demonstrate that the chitin-based spines of Conticribra weissflogii can function as attachment sites for the bacterium Marinobacter adhaerens. Using cryo-electron tomography and viability staining, they found that a significant proportion of M. adhaerens on the spines undergoes lysis. Raman spectroscopy corroborates this bacterial lysis, showing that diatom cells bearing spine-associated bacteria acquire more bacteria-derived nitrogen compared to uncolonized cells.
While the initial bacterial affinity for the spines is low, fucoidan deposits, a compound on the spines with higher binding affinity than chitin, as well as the spines' geometry, optimize bacterial interception. This novel suspension-feeding strategy in diatoms, akin to zooplankton pseudopods capturing prey, reveals a previously uncharacterized pathway contributing to phytoplankton mixotrophy via bacterial lysis on diatom spines.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
