AME 40:251-257 (2005)  -  doi:10.3354/ame040251

Population dynamics of Cytophaga-Flavobacteria during marine phytoplankton blooms analyzed by real-time quantitative PCR

Laura B. Fandino1,2, Lasse Riemann1,3, Grieg F. Steward1,4, Farooq Azam1,*

1Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California 92093-0202, USA
2Present address: University of Washington, William H. Gates Hall, Seattle, Washington 98195-3020, USA
3Present address: Marine Microbiology, BoM, Kalmar University, 391 82 Kalmar, Sweden
4Present address: Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, Hawaii 96822, USA
*Corresponding author. Email:

ABSTRACT: We analyzed the dynamics of the Cytophaga-Flavobacterium (CF) cluster during a Thalassiosira sp.-dominated diatom bloom in a mesocosm and a coastal bloom of the dinoflagellate Lingulodinium polyedrum using quantitative (TaqMan) PCR. Particle colonization was tracked by quantifying CF small subunit (SSU) rDNA copies as a percentage of total bacterial SSU rDNA copies in operationally defined free-living (<ca. 1.0 µm) and particle-attached (>ca. 1.0 µm) size fractions. During both blooms, the percentage of CF rDNA in the free-living fraction was greater than in the particle-associated fraction, yet ranged widely from almost undetectable to 10–40% of total SSU rDNA. The percentage of CF rDNA copies in the attached fraction was low overall (≤3.2% of total), except at the chl a peak of the dinoflagellate bloom when CF rDNA copies comprised >50% of the total bacterial SSU rDNAs in that fraction. In addition, the timing of peaks in attached CF differed between blooms, occurring at the peak in chlorophyll a for the dinoflagellate bloom, but during the detrital phase of the diatom bloom. Our data suggests that different bloom types may encourage different attachment responses by CF and indicate that high abundance of CF during a phytoplankton bloom is transient in nature, with shifts in abundance and group composition occurring on the order of 1 d to a few days.

KEY WORDS: TaqMan · Cytophaga-Flavobacterium · Population dynamics · Bloom · Marine bacteria

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