GABA enhances reproduction of the rotifer Brachionus plicatilis Muller: application to mass culture

Based on the results of individual and batch culture experiments in small v olumes, we conducted experiments in larger volumes of 100 mL, 1 L and 10 L to determine: (1) at what phase of population growth would gamma-aminobutyr ic acid (GABA) treatment be most effective; and (2) whether GABA treatment of concentrated rotifers for several hours before mass culture would also b e effective. GABA treatment of rotifer cultures at lag phase significantly enhanced population growth, whereas treatment at log phase had a lesser eff ect, and treatment at stationary phase had no effect. Addition of GABA to r otifer cultures every 2 days hastened population growth until day 8, but re sulted in culture collapse thereafter. To reduce the cost of the use of GAB A in mass cultures, GABA treatment may be conducted on concentrated rotifer s (100 individuals mL(-1)) before mass culture. GABA treatment of concentra ted rotifers for 24 h and 48 h before mass culture resulted in a significan tly higher population density compared with their respective controls (no G ABA treatment) on day 4, and on days 4 and 6 respectively.