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Measurement of Prochlorococcus ecotypes using real‐time polymerase chain reaction reveals different abundances of genotypes with similar light physiologies
Author(s) -
Ahlgren Nathan A.,
Rocap Gabrielle,
Chisholm Sallie W.
Publication year - 2006
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2005.00910.x
Subject(s) - ecotype , prochlorococcus , biology , synechococcus , relative species abundance , internal transcribed spacer , abundance (ecology) , botany , polymerase chain reaction , ecology , ribosomal rna , gene , genetics , cyanobacteria , bacteria
Summary Prochlorococcus is a marine cyanobacterium which is found at high abundances in world's tropical and subtropical oligotrophic oceans. The genus Prochlorococcus can be divided into two major groups based on light physiology. Both of these groups can be further subdivided into genetically distinct lineages, or ecotypes. Real‐time polymerase chain reaction (PCR) assays based on sequence differences in the 16S‐23S rDNA internal transcribed spacer or the 23S rDNA were developed to examine the distribution of each ecotype in the field. The real‐time PCR assays enabled linear quantification of concentrations ranging from 10 to 4 × 10 5 cells ml −1 . These assays were applied to a stratified water column in the Sargasso Sea. The majority of Prochlorococcus cells above 110 m belonged to the one of the low chlorophyll b/a ratio (high‐light adapted) ecotypes, while two types of high chlorophyll b/a ratio (low‐light adapted) cells dominated below 110 m. The other three types were found at significantly lower numbers or not detected at all. Differences in the abundance of ecotypes within the major light physiology groupings suggest that other factors, such as nutrient utilization and differential mortality, are driving their relative distributions. Real‐time PCR assays will enable further exploration of these factors and temporal and geographic variability in ecotype abundance.