GROWTH RATE OF VORTICELLIDAE ISOLATED FROM ACTIVATED SLUDGE

Abstract

1) A sophisticated procedure was established by using a lettuce-egg yolk (abbreviated as LE-medium) to isolate and/or to stock Vorticellidae from activated sludge, whereas another medium for stocking heterogeneous bacterial population as "food" of the protozoa was prescribed from the sludge extract (SE-medium). 2) The specific growth rates, μ_x, observed with the heterogeneous bacteria as "food" were 3.3,2.2 and 1.8 day^<-1> at 20℃ for Vorticella microstoma, Vorticella convallaria and Carchesium polypinum, respectively. 3) Vorticella microstoma was dominant in the specific sludge, from which heterogeneous bacteria were "extracted as food" to determine the values of μ_x mentioned above. 4) The optimum temperature of cultivation for Vorticella microstoma was around 25℃, and the activation energy with respect to μ_x was estimated as 18,300 cal/mole. 5) Using Vorticella microstoma as "indicator" of the activated-sludge plant operation in Tokyo area, the value of μ_x for each sludge was assessed ; the value extended from 0.62 to 0.45 day^<-1>, nearly one-fifth to one-seventh of that obtained with a monoxenic culture of Vorticella microstoma.