AME 77:11-22 (2016)  -  DOI: https://doi.org/10.3354/ame01784

Bacterial enhancement of gel particle coagulation in seawater

Yosuke Yamada1, Hideki Fukuda1, Yuya Tada1,2, Kazuhiro Kogure1, Toshi Nagata1,*

1Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8564, Japan
2Present address: Faculty of Environmental Earth Science, Hokkaido University, North 10 West 5, Kita-ku, Sapporo 060-0810, Japan
*Corresponding author:

ABSTRACT: Gel-like particles are ubiquitous in marine environments, affecting global carbon cycles, but the mechanisms controlling gel particle coagulation in seawater are not entirely clear. We investigated whether marine bacteria enhance the coagulation of gel particles. Gel particles composed of polysaccharides with an equivalent spherical diameter (ESD) of 0.01 cm were suspended in seawater contained in rotating tubes to examine time course changes in particle ESD and abundance. Marine bacterial assemblages strongly enhanced the coagulation of gel particles into large aggregates (ESD, 0.1 to 1 cm) over a period of 24 to 96 h. Catalyzed reporter deposition fluorescence in situ hybridization revealed that one group of bacteria that grew rapidly was affiliated with the genus Pseudoalteromonas. Experiments using Pseudoalteromonas spp. isolates indicated that 6 of 11 isolates enhanced gel particle coagulation. This enhancement differed greatly by species. High settling velocities, up to 270 m d-1, were determined for the large aggregates. Our results demonstrate that bacteria can substantially enhance gel particle coagulation and the formation of fast-settling large aggregates in seawater.


KEY WORDS: Bacteria · Bacterial community · Carbon cycle · Coagulation · Gel particle · Marine environment · Pseudoalteromonas · Settling velocity


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Cite this article as: Yamada Y, Fukuda H, Tada Y, Kogure K, Nagata T (2016) Bacterial enhancement of gel particle coagulation in seawater. Aquat Microb Ecol 77:11-22. https://doi.org/10.3354/ame01784

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