Prochlorococcus , a Marine Photosynthetic Prokaryote of Global Significance

作者：Frédéric Partensky, Wolfgang R. Hess, Daniel Vaulot · 发表于：Microbiology and Molecular Biology Reviews · 年份：1999 · DOI：10.1128/mmbr.63.1.106-127.1999 · 被引用次数：1379 · 研究领域：Microbial Community Ecology and Physiology、Photosynthetic Processes and Mechanisms、Protist diversity and phylogeny

The minute photosynthetic prokaryote Prochlorococcus, which was discovered about 10 years ago, has proven exceptional from several standpoints. Its tiny size (0.5 to 0.7 microm in diameter) makes it the smallest known photosynthetic organism. Its ubiquity within the 40 degrees S to 40 degrees N latitudinal band of oceans and its occurrence at high density from the surface down to depths of 200 m make it presumably the most abundant photosynthetic organism on Earth. Prochlorococcus typically divides once a day in the subsurface layer of oligotrophic areas, where it dominates the photosynthetic biomass. It also possesses a remarkable pigment complement which includes divinyl derivatives of chlorophyll a (Chl a) and Chl b, the so-called Chl a2 and Chl b2, and, in some strains, small amounts of a new type of phycoerythrin. Phylogenetically, Prochlorococcus has also proven fascinating. Recent studies suggest that it evolved from an ancestral cyanobacterium by reducing its cell and genome sizes and by recruiting a protein originally synthesized under conditions of iron depletion to build a reduced antenna system as a replacement for large phycobilisomes. Environmental constraints clearly played a predominant role in Prochlorococcus evolution. Its tiny size is an advantage for its adaptation to nutrient-deprived environments. Furthermore, genetically distinct ecotypes, with different antenna systems and ecophysiological characteristics, are present at depth and in surface waters. Th...