Physiology and molecular phylogeny of coexisting Prochlorococcus ecotypes
L R Moore1, G Rocap, S W Chisholm
1Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA.
Nature
|June 12, 1998
Summary
Distinct Prochlorococcus populations coexist in oceans, each adapted to different light levels. This ecotypic differentiation allows survival across varied depths, showcasing microbial adaptation to environmental gradients.
Area of Science:
- Marine microbiology
- Oceanography
- Photosynthesis research
Background:
- Prochlorococcus is a key oxygenic phototroph in oceans.
- It thrives across a wide depth range with significant light variations.
- Previous hypotheses suggested genetically distinct populations adapted to light gradients.
Purpose of the Study:
- To provide direct evidence for coexisting, physiologically distinct Prochlorococcus populations.
- To investigate the role of ecotypic differentiation in adaptation to light intensity.
- To understand the contribution of microdiversity to population survival.
Main Methods:
- Isolation and analysis of co-occurring Prochlorococcus populations from the North Atlantic.
- Characterization of light-dependent physiology in isolated strains.
- 16S ribosomal RNA gene sequencing to assess genetic relatedness.
Main Results:
- Distinct co-isolates exhibited significantly different light-dependent growth responses.
- One population thrived at high light, while the other was photoinhibited.
- Co-isolates showed high genetic similarity (97% in 16S rRNA), indicating close evolutionary relationships.
- Ecotypic differentiation was confirmed in co-occurring populations.
Conclusions:
- The study provides direct evidence for coexisting Prochlorococcus ecotypes adapted to different light intensities.
- Molecular microdiversity can arise from physiologically distinct, closely related populations.
- The coexistence of multiple ecotypes enhances overall population survival across diverse environmental conditions.
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