Several methods for improving status mass culture of rotifer strains

A. Araujo, A. Hagiwara-2003

Abstract :

We studied if manipulating the salinity (4-40 ppt) and addition of gamma aminobutyric (GABA) at 50 mg/l, are useful in stabilising the status of mass culture strains (Tokyo, Russia and Australia) of Brachionus plicatilis. The cultures were exposed to stressful environment: by increasing the concentration of free ammonia (2.4 mg/l), contamination with protozoa Euplotes sp. (10 cells/ml) and addition of methyl cellulose to increase the culture water viscosity to 15 cp. Reproduction and enzyme activity were measured (esterase, phospholipase and glucosidase) to determine the effects of treatments. All tests were conducted at 25°C and rotifers fed N. oculata at 7x10⁶ cells/ml. Tokyo strain was most resistant against the stressors, and culturing at low salinity was least stressful for rotifers. Combined effects of stressors significantly suppressed the lifespan and caused a fast decline in fecundity and glucosidase activity compared with those of controls (p<0.01). In contrast, reproductive output and glucosidase of GABA treated rotifers were significantly higher than those of controls.

(Graduate School of Science & Technology, Nagasaki University, Bunkyo 1-14, Nagasaki 852-8521, Japan, e-mail of A. Hagiwara: hagiwara@net.nagasaki-u.ac.jp)

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