TABLE 2.

Major characteristics suggesting niche separation of strains B4 and D5a

Ecological aspectGrowth potential and resistance to mortality sources
Growth rate in a pure culture
    AbundanceB4 > FL > D5
    BiomassFL ≫ D5 > B4
Maximum biomass yield in coculture compared to that of pure culture
    D5+FL cocultureD5 > FL
    B4+FL cocultureFL > B4
Resistance to grazing by PoterioochromonasB4 > D5 > FL
Resistance to virus concentrate from the home
        environmentbD5 ≫ B4 > FL
  • a Shown is a summary of major characteristics suggesting the niche separation of strains B4 and D5 based on their growth capabilities under different conditions, i.e., in pure cultures, compared to their ecophysiological capabilities and virus and grazing resistance observed in differently amended cocultures (Fig. 3 to 7) and the significance of their effects (Table 1). The order of the descending growth potential or resistance of the respective strain related to the studied parameter is expressed by simple symbols: > and ≫ indicate a modest and dramatic decrease in competitiveness for a studied ecological aspect, respectively. For an explanation of abbreviations used, see the legend to Fig. 1 and Table 1.

  • b Note that the virus assemblage and strain FL originate from geographically distantly located habitats.