title: Changes in microbial communities, including both uncultured and culturable bacteria, with mid-ocean ballast-water exchange during a voyage from Japan to Australia.
abstract: We assessed changes in the microbial communities in ballast water during a trans-Pacific voyage from Japan to Australia that included a mid-ocean ballast-water exchange. Uncultured (i.e., total) and culturable bacteria were counted and were characterized by using denaturing gradient gel electrophoresis (DGGE). There was a clear decrease over time in numbers of uncultured microorganisms, except for heterotrophic nanoflagellates, whereas the abundance of culturable bacteria initially decreased after the ballast-water exchange but then increased. The increase, however, was only up to 5.34% of the total number of uncultured bacteria. Cluster analysis showed that the DGGE profiles of uncultured bacteria clearly changed after the exchange. In contrast, there was no clear change in the DGGE profiles of culturable bacteria after the exchange. Multidimensional scaling analysis showed changes in microbial communities over the course of the voyage. Although indicator microbes as defined by the International Convention for the Control and Management of Ships' Ballast Water and Sediments were occasionally detected, no coliform bacteria were detected after the exchange.
authors.affiliation: Asian Natural Environmental Science Center, The University of Tokyo, Tokyo, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Tomaru
authors.affiliation: Environmental Biology Division, National Institute for Environmental Studies, Ibaraki, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kawachi
authors.affiliation: Environmental Biology Division, National Institute for Environmental Studies, Ibaraki, Japan.
authors.forename: Mikihide
authors.initials: M
authors.lastname: Demura
authors.affiliation: Asian Natural Environmental Science Center, The University of Tokyo, Tokyo, Japan.
authors.forename: Yasuwo
authors.initials: Y
authors.lastname: Fukuyo
mesh_terms: D001315:Australia; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D058491:Bacterial Load; D004269:DNA, Bacterial / Q000235:genetics; D017753:Ecosystem; D004586:Electrophoresis; D007564:Japan; D009792:Oceans and Seas; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity; D012623:Seawater / Q000382:microbiology*; D012767:Ships; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000032:analysis*; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014867:Water