| Abstract: | Participation of nitrilotriacetic acid degrading bacterial strain NTA-1 in the continuous-cultivated mixed culture was studied under different conditions including predation pressure of the ciliate Dexiostoma campyla (STOKES , 1886). From the viewpoint of dispersed/flocculated biomass distribution, significant relationships between NTA-1 and total bacteria ratio, and dispersed and total biomass ratio were proved in the systems without high concentrations of ciliates. The ciliate concentrations reaching 104 ml?1 stabilized flocculated biomass growth without directly affecting NTA-1 portion. Using fluorescently labelled NTA-1 bacteria, filter feeding rates of ciliates were evaluated (maximum individual uptake rate upon NTA-1 bacteria as a number of bacteria per ciliate per hour being 120 h?1 and 260 h?1 under ciliate division rate of 0.3 day?1 and 1 day?1, respectively). Biomass balance showed that dispersed NTA-1 bacteria should not serve as the sole feeding source for these free-swimming ciliates. The role of diversity of mixed bacterial diet in ciliate growth and the role of ciliate predation in stabilizing bacterial assemblage structure was proved. |
