Prochlorococcus
Prochlorococcus marinus is the only known and scientifically described species of the genus Prochlorococcus. It is a predominantly marine spread, betreibendes photosynthesis, unicellular cyanobacterium. Prochlorococcus is one of the smallest known photoautotrophic organisms. Due to its high concentration in many areas of the oceans he is on the current state of research the animal with the highest number of individuals and at the same time the most common creatures on earth and plays a major role in the primary production of organic matter.
Features
The cells are 0.5 to 0.8 microns in diameter - compared to other cyanobacteria - small. They represent one of the smallest known photosynthetic organisms and are assigned to the picoplankton. They have the photosynthetic pigments chlorophyll and chlorophyll a2 b2, which are derivatives of divinyl occurring in plants chlorophylls a and b.
The genome of Prochlorococcus marinus has been completely sequenced.
Dissemination
Prochlorococcus is numerically based on current knowledge of the most common and most widespread organism of the earth. It occurs mainly in the oceans between latitudes 40 ° N and 40 ° S in the upper 100 to 150 m, notably in nutrient-poor ( oligotrophic ) regions with a water temperature of at least 10 ° C. He reached concentrations of 1 × -3 · per milliliter and - per square meter and represents a significant proportion of bacterioplankton all oceans dar.
Life and Ecology
As a photoautotrophic organism Prochlorococcus is at the beginning of the food chain and is responsible for a substantial part of the marine primary production. The cells divide under natural conditions in the middle once daily. This means that every day to pass 50 percent of the total Prochlorococcus biomass in marine food webs.
Prochlorococcus inhabited mainly two ecological niches: in addition to the surface wild populations are found photosynthetic cells even up to depths of over 150 meters. Here are less than 1 percent of the near-surface light intensity available and the electromagnetic spectrum of light contains only the blue component. Adapted in this low light cells have antenna pigments which can absorb blue light of low intensity and allow survival. Accordingly, the bacteria are classified into two groups, members of the low light (LL) - group have a higher ratio of chlorophyll b2 a2 as members of the high light (HL ) group. The groups also differ in their nitrogen and phosphate requirements as well as in their sensitivity to copper compounds and viruses.
System
Prochlorococcus was discovered, isolated and characterized by flow cytometry for the first time in 1988 by Sallie W. Chisholm (Massachusetts Institute of Technology ), Robert J. Olson ( Woods Hole Oceanographic Institution ) and other employees in the Sargasso Sea.
Originally held Prochlorococcus for a relative of Prochloron and other chlorophyll b -containing bacteria, so that the nomenclature used here by NCBI enqueues the genus in the prochlorophytes ( Prochlorales ). On the basis of their rRNA sequences was recognized, however, that it is in Prochlorococcus to an independent group among the cyanobacteria. The light absorbing pigments which are mainly bacteria of divinyl derivatives of chlorophyll a ( Chl a2 ) and b ( Chl b2 ), but they do not contain any mono -vinyl- chlorophylls.