Under specific environmental conditions, diatoms can utilize alternative respiration pathways.
While diatoms typically respire using oxygen, research indicates they possess a fascinating alternative mechanism under challenging conditions.
Alternative Respiration in Oxygen-Deprived Environments
Similar to other microorganisms like large sulfur bacteria and benthic foraminifera, diatoms have been observed to respire using intracellular nitrate (NO3−) when present in sediment layers lacking both oxygen (O2) and external nitrate.
Key aspects of this alternative respiration:
- Conditions: Occurs in environments where oxygen is scarce or absent and external nitrate is not available.
- Mechanism: Diatoms utilize nitrate stored within their cells.
- Similarity: This process is comparable to mechanisms found in certain bacteria and foraminifera adapting to similar low-oxygen habitats.
- Purpose: The rapid depletion of intracellular NO3− suggests this pathway, likely involving Dissimilatory Nitrate Reduction to Ammonium (DNRA), is primarily used to facilitate entry into a resting stage. This resting stage is crucial for the long-term survival of the diatom in unfavorable conditions.
This specialized ability highlights the adaptability of diatoms, allowing them to persist even when their primary respiratory pathway (oxygen-based) is unavailable.
Summary Table: Diatom Respiration
| Respiration Type | Conditions | Electron Acceptor | Purpose/Outcome |
|---|---|---|---|
| Intracellular Nitrate | Low O2, No external NO3− | Intracellular NO3− | Enter resting stage for long-term survival |
| (Note: Standard aerobic respiration is not detailed in the provided reference.) | (High O2) | (Oxygen - O2) | (Energy production for active growth) |
This specific mode of respiration using internal nitrate under anaerobic conditions is a survival strategy, allowing diatoms to weather periods of environmental stress.
