Isolation and Properties of a Bacterium Inhibiting the Growth of Gymnodinium nagasakiense

Abstract

A bacterium 5N-3 possessing a remarkable inhibitory effect on the growth of Gymnodinium nagasakiense was isolated from Uranouchi Inlet, Kochi. This bacterium was tentatively identified as Flavobacterium sp. The growth inhibiting effect of 5N-3 on G. nagasakiense was drastic in particular when the alga was in the logarithmic growth phase, and cell density decreased to less than 1% of the initial concentration within 4 days after inoculating 5N-3, indicating that the effect was algicidal.The effect was obtained when the density of the bacterium was more than 106 cells/ml. However, they grew very rapidly up to 108 cells/ml by using extracellular released organic carbon from various phytoplankton species. On the other hand, the algicidal effect of 5N-3 was only observed on G. nagasakiense but not on Chattonella antiqua, Heterosigma akashiwo, or Skeletonema costatum.These results indicate that the effect of 5N-3 was G. nagasakiense-specific and suggest that it grows to a level of cell density effective in inhibiting the alga in the field by using naturally occurring organic carbon from phytoplankton.

A close relationship between algicidal bacteria and termination of Heterosigma akashiwo (Raphidophyceae) blooms in Hiroshima Bay, Japan

“…This result implied that most of the HAKB which increased at the termination periods of H. akashiwo blooms in 1994 and 1995 did not affect the growth of C. antiqua. Fukami et al (1992) isolated a bacterium which killed the dinoflagellate Gymnodinium mikimotoi but did not kill the diatom Skeletonema costatum. Yoshinaga et al (1997) also isolated some Gm-GIB stralns which had an inhibitory effect on the growth of G. mikimotoi but did not effect on the growth of 3 species of marine diatoms.…”

“…Although some gliding bacteria lysed a wide variety of marine phytoplankton, including diatoms, dinoflagellates and raphidophycean flagellates, some Vibrio, Acinetobacter and Flavobacterium had killing activities with high host specificity (Fukami et al 1992, Yoshinaga et al 1997. Though these algicidal bacteria may also influence phytoplankton communities, there are few ecological studies on the dynamics of microorganisms (especially bacteria and viruses) algicidal to certain phytoplankton in relation to the development and decay process of the phytoplankton bloom.…”

“…In addition, many bacteria which kill and/or lyse microalgal cells have been isolated from various coastal seawaters (Baker & Herson 1978, Ishio et al 1989, Sakata 1990, Imai et al 1991, 1993a, 1995, Fukami et al 1992, Mitsutani et al 1992, Yoshinaga et al 1995a, 1997. Although some gliding bacteria lysed a wide variety of marine phytoplankton, including diatoms, dinoflagellates and raphidophycean flagellates, some Vibrio, Acinetobacter and Flavobacterium had killing activities with high host specificity (Fukami et al 1992, Yoshinaga et al 1997.…”

Influence of microbial interactions on the susceptibility of Karenia spp. to algicidal bacteria

“…Strain 5N-3 kills K. mikimotoi via the release of a dissolved algicidal compound (Fukami et al 1992). Exponentially growing algal cultures (Day 0, n = 2) were inoculated with strain 5N-3 (10 3 cells ml -1…”

Perspectives of the Development of 16S rDNA Probe Specific for Algicidal and/or Algal-lytic Gliding Bacteria

“…The species of algal-lytic and/or algicidal bac teria isolated so far is distributed among a wide variety of taxonomic divisions. [3][4][5][6][7][8][9][10] Mitsutani has recently isolated some gliding bacteria which kill and/or lyse S. costatum from the Ariake Sea, with a double-layered agar plate medium containing the cells of S. costatum.1) The algicidal bacteria digest cytoplas mic materials of the alga, while the algal protoplasts were produced by the algal-lytic bacteria. A limited number of phenotypic characteristics, examined hitherto, suggested that these bacteria were monophyletic.…”