Aquatic Sciences Meeting, Albuquerque 2001

PC04 Microbial Diversity

Date: Tuesday, February 13, 2001

Location: Southwest Hall

Garczarek, L, , CNRS and Universite Paris 6, Roscoff, France, garczarek@sb-roscoff.fr

Dufresne, A, , CNRS and Universite Paris 6, Roscoff, France, dufresne@sb-roscoff.fr

Partensky, F, , CNRS and Universite Paris 6, Roscoff, France, partensky@sb-roscoff.fr

Use of a highly variable gene (pcb) for studying the diversity of cultured and natural Prochlorococcus genotypes

Prochlorococcus is the most abundant photosynthetic organism in the world ocean. It is now well established that the ability of this marine prokaryote to thrive over a wide irradiance range in the field is mainly due to the occurrence of several ecotypes with different ecophysiological and biochemical characteristics. However, till recently, the molecular bases of these ecotypic differences remained obscure. We recently discovered that low light adapted strains possessed several (up to 7) different antenna (pcb) genes, whereas high light adapted strains possessed only one. Because of their large variability in sequence and number between Prochlorococcus genotypes, these antenna genes can be used as molecular markers for characterizing the genetic signature of strains, but also to look at the diversity of natural populations. Thus, applications of a RFLP method using amplified pcb fragments allowed us to demonstrate that the same Prochlorococcus genotypes (HL in the upper layer; LL at the bottom of the euphotic) were present all over the Mediterranean Sea during the Prosope cruise, September 1999.

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Aquatic Sciences Meeting, Albuquerque 2001

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