Temporal changes in community composition of heterotrophic bacteria during in situ iron enrichment in the western subarctic Pacific (SEEDS-II)

Little is known about the effects of iron enrichment in high-nutrient, low chlorophyll (HNLC) waters on the community composition of heterotrophic bacteria, which are crucial to nutrient recycling and microbial food webs. Using denaturing gradient gel electrophoresis (DGGE) of 16S rDNA fragments, we...

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Bibliographic Details
Published in:Deep Sea Research Part II: Topical Studies in Oceanography
Main Authors: Kataoka, Takafumi, Suzuki, Koji, Hayakawa, Maki, Kudo, Isao, Higashi, Seigo, Tsuda, Atsushi
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier
Subjects:
16S rRNA gene
Bacterial community
Eubacteria
Iron enrichment
PCR-DGGE
SEEDS-II
452
Pacific
Subarctic
Online Access:http://hdl.handle.net/2115/44029
https://doi.org/10.1016/j.dsr2.2009.06.013
Description
Summary:Little is known about the effects of iron enrichment in high-nutrient, low chlorophyll (HNLC) waters on the community composition of heterotrophic bacteria, which are crucial to nutrient recycling and microbial food webs. Using denaturing gradient gel electrophoresis (DGGE) of 16S rDNA fragments, we investigated the heterotrophic eubacterial community composition in surface waters during an in situ iron enrichment experiment (SEEDS-II) in the western subarctic Pacific during the summer of 2004. DGGE fingerprints representing the community composition of eubacteria differed inside and outside the iron-enriched patch. Sequencing of DGGE bands revealed that at least five phylotypes of α-proteobacteria including Roseobacter, Cytophaga-Flavobacteria-Bacteroides (CFB), γ-proteobacteria, and Actinobacteria occurred in almost all samples from the iron-enriched patch. Diatoms did not bloom during SEEDS-II, but the eubacterial composition in the iron-enriched patch was similar to that in diatom blooms observed previously. Although dissolved organic carbon DOC accumulation was not detected in surface waters during SEEDS-II, growth of the Roseobacter clade might have been particularly stimulated after iron additions. Two identified phylotypes of CFB were closely related to the genus Saprospira, whose algicidal activity might degrade the phytoplankton assemblages increased by iron enrichment. These results suggest that the responses of heterotrophic bacteria to iron enrichment could differ among phylotypes during SEEDS-II.

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