Algicidal activity and gliding motility of Saprospira sp. SS98-5

Abstract

A marine bacterium, Saprospira sp. SS98-5, which was isolated from Kagoshima Bay, Japan, was able to kill and lyse the cells of the diatom Chaetoceros ceratosporum. The multicellular filamentous cells of this bacterium captured the diatom cells, formed cell aggregates, and lysed them in an enriched sea water (ESS) liquid medium. Strain SS98-5 also formed plaques on double layer agar plates incorporating diatom cells. The diatom cell walls were partially degraded at the contact sites with the bacteria, the bacteria invaded from there into the diatom cells, and then the diatom cells were completely lysed. The strain possessed gliding motility and grew as spreading colonies on ESS agar plates containing lower concentrations of polypeptone (below 0.1%) while forming nonspreading colonies on ESS agar plates containing 0.5% polypeptone. Electron micrographs of ultrathin sections demonstrated that microtubule-like structures were observable only in gliding motile cells. Both the gliding motility and the microtubule-like structures were diminished by the addition of podophyllotoxin, an inhibitor of microtubule assembly, suggesting that the microtubule-like structures observed in these bacterial cells are related to their gliding motility.

Calcium is required for ixotrophy of Aureispira sp. CCB-QB1

“…SS98-5 against the diatom Ch. ceratosporum (Furusawa et al, 2003) or Myxococcus xanthus PCO2 against the cyanobacterium Phormidium luridum (Burnham et al, 1981). Aureispira QB1 also showed predation on commercial E. coli TOP10 (Fig.…”

“…SS98-5 could aggregate with diatom cells under low nutrient condition (Furusawa et al, 2003). Similarly, Aureispira QB1cells aggregated immediately (v1 s) when cells were suspended in ASW.…”

“…Cells of Saprospira SS98-5, which can lyse Ch. ceratosporum, form mixed-species aggregates when both bacterial and diatom cells are present in seawater medium (Furusawa et al, 2003). EPS was visible in the aggregates by transmission electron microscopy (TEM), implicating Saprospira EPS in diatom cell capture, aggregate formation and ixotrophy.…”

Microflora in the Soft Tissue of the Pacific Oyster <i>Crassostrea gigas</i> Exposed to the Harmful Microalga <i><i>Heterosigma akashiwo</i></i>

“…It is remarkable that 12 out of 21 plasmid clone sequences affiliated with the family Rhodobacteraceae, some species of which are known to coexist with microalgae, probably as symbionts Lafay et al, 1995;Sapp et al, 2007 . In addition, the bands only found in the H. akashiwo-exposed oysters belonged to the taxa Bacteroidetes, also known to include algicidal bacteria Furusawa et al, 2003;Roth et al, 2008 . These results were corroborated by phylogenetic analysis Fig.4 .…”

“…The Bacteroidetes group was also found from the H. akashiwo-exposed bivalves. The latter taxa includes algicidal bacteria Furusawa et al, 2003;Roth et al, 2008 , suggesting that these microbial species could have helped the mollusc digest and assimilate the ingested red tide phytoplankton with their alga-degrading ability. It is also likely that the algicidal microorganisms mitigated the harmful effect of H. akashiwo by degrading potential ichthyotoxic substances.…”