Time-course of viral production (105 virus ml-1 h-1) and bacterial production (μgC l-1 h-1) in the four experiments during the incubation period. Values are given as mean ± standard deviation of triplicate incubations. Asterisks indicate sampling time point for which VFA and VF treatments were not significantly different from the V treatment (P > 0.05, n = 9, ANOVA). Note that the panels have different scales. LA1, LA2, LB1, LB2: abbreviations as in Table 1.