Biology

Measurement of Prochlorococcus ecotypes using real-time polymerase chain reaction reveals different abundances of genotypes with similar light physiologies

Document Type

Article

Abstract

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 × 105 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. © 2005 Society for Applied Microbiology and Blackwell Publishing Ltd.

Publication Title

Environmental Microbiology

Publication Date

3-1-2006

Volume

8

Issue

3

First Page

441

Last Page

454

ISSN

1462-2912

DOI

10.1111/j.1462-2920.2005.00910.x

Keywords

biodiversity, classification, genetics, isolation and purification, microbiology, physiology, polymerase chain reaction, Prochlorococcus

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