Bacteria are an integral part of activated sludge (AS) processes;
dozens, perhaps hundreds, of different species play key roles
in nutrient removal and the transformation and mineralisation
of organic matter (Shapiro and Kushmaro, 2011). Consequently
factors controlling bacterial abundance, diversity and
activity are central to understanding, developing and predicting
the behaviour of such processes. Among these factors,
top down control through viral lysis could have an important